55

D
O

I:
 1

0.
15

82
6/

ch
im

te
ch

.2
01

8.
5.

1.
04

Volkova N. E., Khvostova L. V., Galaida A. P., Gavrilova L. Ya., Cherepanov V. A.
Chimica Techno Acta. 2018. Vol. 5, No. 1. P. 55–79.

ISSN 2409–5613

N. E. Volkova, L. V. Khvostova, A. P. Galaida, 
L. Ya. Gavrilova, V. A. Cherepanov

Department of Physical and Inorganic Chemistry, 
Ural Federal University, 

19 Mira St., Ekaterinburg, 620002, Russian Federation 
nadezhda.volkova@urfu.ru

Phase equilibria, crystal structure and oxygen 
nonstoichiometry of the complex oxides  
in Sm – (Sr, Ba) – (Co, Fe) – O systems

Present paper contains available information on the phase equilibria in the 
Sm – (Sr, Ba) – (Co, Fe) – O systems, including the synthesis routes used, 
crystal structure, which is often depended on oxygen nonstoichiometry, the 
data on thermodynamic stability of complex oxides, the obtained results on the 
homogeneity ranges of solid solutions, formed in the systems, and graphical 
presentation of phase relations in a form of phase diagrams.

Keywords: phase equilibrium; solid solutions; crystal structure; phase diagram

Received: 18.01.2018. Accepted: 14.02.2018. Published: 10.05.2018.

© Volkova N. E., Khvostova L. V., Galaida A. P., Gavrilova L. Ya., Cherepanov V. A., 2018

Introduction
Complex oxides based on sa-

marium, alkali earth (Sr, Ba) and 3d tran-
sition (Co, Fe) metals have attracted great 
interest of researchers during the last few 
decades because of a variety of potential 
practical applications such as cathodes for 
the SOFCs [1–6], membranes [7–9], mag-
nets [10–12], catalysts [13–16], gas sensors 
[17–19]. Traditionally, most of the publi-
cations devoted to the modern materials 
focus on their functional properties. At 
the same time, information concerning the 
phase equilibria and stability ranges often 
remains undisclosed or appears fragmen-
tary. Systematic studies of phase equilibria 
are rare. Another important characteristic 

of these oxides, closely linked with their 
stability, is the value of oxygen nonstoi-
chiometry.

Since the overall information con-
cerning the crystal structure, phase equi-
libria, phase stability, oxygen nonstoichi-
ometry and defect structure constitutes the 
physicochemical basis of the preparation 
and usage of these materials, it is vitally im-
portant. Thus, the present work was aimed 
to overview the available data concerning 
the phase equilibria within the Sm – (Sr, 
Ba) – (Co, Fe) – O system, as well as the 
crystal structure and oxygen nonstoichi-
ometry of the complex oxides formed in 
these systems.

Phase equilibria in Sm – Co – O system
A systematic study of phase equilibria 

in the Sm – Co – O system was performed 
for the first time by Kropanev et al [20, 
21], and later by Kitayama [22]. Samarium  



56

cobaltate SmCoO3 was the only phase 
found to exist in this system. This com-
plex oxide was first described by Wold and 
Ward [23] as perovskite type with the cubic 
structure (a = 3.75±0.01 Å), although later 
it was suggested that the ideal perovskite 
structure is orthorhombically distorted 
(Table 1) [22, 24–28].

Different techniques have been used 
for preparation of SmCoO3: a conventional 
ceramic technique from oxides [20, 21], or 
from mixture of nitrates dried from their 
solution [24, 27], or from the mixture of 
cobalt carbonate and samarium nitrate 
[23]; via co-precipitation from the nitrates 
solution by Na2CO3 with following anne-
aling in air [22]. The mechanism and kine-
tics of solid state SmCoO3 synthesis from 
oxides has been studied in [29–32]. It was 
shown that the diffusion stage of synthe-
sis occur by transport of Con+ (n  = 2, 3) 
and O2– ions through the layer of product 
to the reaction zone that is located on the 
SmCoO3 – Sm2O3 interphase boundary 
[29, 30]. The kinetics of synthesis depends 
on the grain size, oxygen partial pressure 
and compacting pressure of oxides mixture 
for both Sm2O3 – CoO and Sm2O3 – Co3O4 
systems [30, 31].

Samarium cobaltate SmCoO3 is stable 
in air up to the incongruent melting point 
equal to 1344±4 °C [21]. The subsolidus 

part of the “T – composition” phase dia-
gram for the Sm – Co – O system in air is 
shown in Fig. 1.

Thermodynamic properties and sta-
bility ranges measured by means of EMF 
technique in the galvanic cells with solid 
electrolyte are presented in [20, 21, 33, 34] 
and those measured by thermogravimetric 
(TGA) method – in [22]. The equilibrium 
oxygen partial pressure for the reaction:

½ Sm2O3 + CoO + ¼ O2 = SmCoO3, (1)

examined in the galvanic cell with the solid 
electrolyte (ZrO2 doped by Y2O3) can be 
written as follows [20]:

Table 1
The values of unit cell parameter of orthorhombically distorted SmCoO3 (Pbnm space group)

a, Å b, Å c, Å Treatment conditions Ref.
5.284±0.006 5.343±0.006 7.506±0.006 Prepared in air, with the excess of CoO [22]
5.283±0.005 5.344±0.005 7.502±0.005 Prepared in air, with the excess of Sm2O3 [22]

5.289 5.354 7.541 Treated in oxygen at 930 °C [24,25]

5.294±0.002 5.352±0.002 7.504±0.003
Prepared at 930 °C and under pressure 
60 kbar

[26,27]

5.2831(1) 5.3502(1) 7.4962(1)
Standard solid state ceramic procedures 
at 1200 °C in air, with intermediate 
grindings

[28]

Fig. 1. The cross-sections of phase diagram 
for the Sm – Co – O system  

“T – composition” in air [21]



57

lg
,

. ,
P

P T K
O

O

2

2

14800
8 46














= − +

(1076 ≤ T, K ≤1474). (2)

where is a standard pressure, and standard 
Gibbs energy corresponding to the reaction 
(1) is expressed by the equations:
Ref. [33]:
∆G J mol T K1 70820 40 47

( / ) . ( ),= − + ×  (3)
(1076 ≤ T, K ≤1474).

Ref. [34]:
∆G J mol T K1 52530 25 0

( / ) . ( ),= − + ×  (4)
(1080 ≤ T, K ≤1180).

The standard Gibbs energy of forma-
tion from elements ΔG°f (SmCoO3) was 
presented in [33] by following equation:

∆G J mol
T T

f
 ( / )

. lg . .
=

= − − × × +1215600 3 66 270 5  
(5)

The cross sections of phase diagram for 
the Sm – Co – O system corresponding to 
the different fixed parameters are shown 
in Figs. 2–4.

Phase equilibrium in Sm – Fe – O system
The detailed study of phase equilibria 

in the Sm – Fe – O system was performed 
by Kitayama and Katsura (Fig. 5) [35] and 
later by Parida et al [36]. Two ternary oxi-
des – SmFeO3–δ and Sm3Fe5O12 – exist in 
the system. Samarium ferrite SmFeO3–δ 
possesses orthorhombically distorted pe-
rovskite structure (space group Pbnm) [24, 
35–41], Sm3Fe5O12 crystallizes in the cubic 

garnet structure (space group Ia3d) [35, 
36, 42–45].

It was shown that despite of Sm2O3/
Fe2O3 ratio SmFeO3–δ always appears as 
the first product in the initial stages of 
synthesis within the temperature range 
700–1300 °C; the reaction rate was greater 
in the mixtures with the iron oxide excess 
[46]. This is consistent with the fact that 
most of the samples with the nominal 

Fig. 2. The cross sections of phase diagram for the Sm – Co – O system at fixed metal ratio (εSm): 
a – 0.75; b – 0.5 and c – 0.33. Filled circles – single-phase,  

half-filled circles – double-phase samples [20]. Dashed lines are SmCoO3  
decomposition oxygen partial pressure calculated from [34]



58

composition of Sm3Fe5O12 fired at 700 °C 
contained SmFeO3–δ as the impurity phase, 
even if the citrate technique had been used 
as preparation method [43]. Taking into 
account these findings, the temperature 
of final synthesis’ anneals in order to get 
a single phase samarium ferrite with gar-
net structure has to be high enough (≥ 
1200 °C). The unit cell parameters for the 
samarium ferrites SmFeO3–δ and Sm3Fe5O12 
are listed in Table 2.

A detailed study of crystal struc-
ture performed on the single crystal of 
Sm3Fe5O12 within the range 20 ≤ T, K ≤ 
297 reveals the second order phase transi-
tion at 68 and 40 K [44]. The coefficients 
for the temperature dependency of unit cell 
parameter for Sm3Fe5O12

a T a a a T( ) = + +0 1 2
2

 (6)
are listed in Table 3.

Thermodynamic properties of sama-
rium ferrites were reported in [35, 36,  
47–49]. At 1200  °C SmFeO3–δ is stable 
from air down to pO2 = 10

–12.68 atm and 
Sm3Fe5O12 – down to pO2 = 10

–3.72 atm [35].

Fig. 4. Gibbs triangle of phase equilibria in 
the Sm – Co – O system at 1273 K [20].  

The values of equilibrium oxygen pressure in 
logarithmic scale are:  

1) ≈ 5, 2) ≈1.3, 3) –3.17, 4) –11.8

Fig. 3. The cross sections of phase diagram for the Sm – Co – O system at fixed temperatures: 
a – 1173 K; b – 1373 K [20]. The composition is represented by molar fraction  

of metal components



59

Table 2
The values of unit cell parameter of SmFeO3–δ and Sm3Fe5O12

SmFeO3–δ Sm3Fe5O12
(3 – δ) a, Å b, Å c, Å Ref. a, Å Ref.

– 5.394 5.592 7.711 [24, 37] 12.519±0.002 [35]
3.0 5.398±0.002 5.598±0.002 7.708±0.002 [35] 12.529±0.001 [42]

2.982 5.398±0.001 5.591±0.001 7.706±0.001 [35] – –
– 5.400±0.001 5.597±0.001 7.711±0.001 [38] – –
– 5.39853(4) 5.59683(4) 7.70715(5) [39] – –

3.034 5.588(3)* 7.710(6)* 5.392(3)* [40] – –
– 5.39 5.58 7.71 [41] – –

* Pnma space group

Table 3
Polynomial’s coefficients (Eq. 6) for the single crystal Sm3Fe5O12 unit cell parameter [44]

Temperature range (K) a0 (Å) a1×10
4 (Å/K) a0×10

6 (Å/K2)
20–297 12.5235 –1.53×10–1 2.21×10–1

20–40 12.5197 2.24 –3.18
40–68 12.5270 –1.407 1.35

68–297 12.5226 –4.9×10–2 1.95×10–1

Fig. 5. Phase equilibria in the Fe – Fe2O3 – Sm2O3 system at 1200 °C (mol%) [35]. Numbers in 
the figure mean values of –log pO2 at which three crystalline phases are in equilibrium state. 
Letters R, P, G, and M represent stoichiometric compositions of Sm2O3, SmFeO3, Sm3Fe5O12, 
and Fe3O4, respectively. M1 is the end member of the magnetite solid solution with chemical 
composition Fe2.957O4. Pss, Wss, and Mss are the solid solutions of SmFeO3 from P to P1, of FeO 

from W to W2, and Fe3O4 from M to M1, respectively. W and W2 are the end members of 
the wustite solid solution with chemical compositions FeO1.049 and FeO1.166, respectively. P1 is 

nonstoichiometric perovskite phase SmFeO2.982



60

The limits of thermodynamic stability 
for SmFeO3–δ and Sm3Fe5O12 that can be 
represented by the reactions (7) and (8) 
[36] are shown in Fig. 6.

18 SmFeO3 + 4 Fe3O4 + O2 =
= 6 Sm3Fe5O12 

(7)

2/3 Sm2O3 + 4/3 Fe + O2 = SmFeO3 (8)

The temperature dependencies of Gibbs 
energy that correspond to the processes (7) 
and (8) are written as follows [36]:

∆μ(O2)/kJ×mol
-1 (±0.8) =

= –607.3 + 0.2333×(T/K)
1030 ≤ T/K ≤ 1252 (9)

∆μ(O2)/kJ×mol
–1 (±0.6) = 

=–590.7 + 0.1587×(T/K)
1005 ≤ T/K ≤ 1259 (10)

The phase diagram for the Sm – Fe – O 
system in the “log(pO2) – composition” 
coordinates at 1250 K is shown in Fig 7.

The heat capacity anomaly that was 
detected for SmFeO3 at 673 K and for 
Sm3Fe5O12 at 560 K was attributed to the 
second-order magnetic order  disorder 
transformation [36].

Phase equilibrium in Sm – Sr – Co – O system
Two types of solid solutions were found 

to exist in the Sm – Sr – Co – O system: 
with the perovskite structure and with the 
K2NiF4 type structure.

The perovskite-type solid solutions 
Sm1–хSrxCoO3–δ can be prepared by the con-
ventional ceramic technique [1, 50–52] or 
through the solution precursors me thods 
[53–59] within the temperature range 

900–1200 °C in air or in the oxygen flow. It 
should be noted that using of conventional 
ceramic technique often yields the samples 
contaminated by small amounts of impuri-
ties, for example, they were detected in the 
Sm0.5Sr0.5CoO3–δ sample after annealing at 
1100 °C in air for 240 h. On the contrary, 
using the solution precursors routes allow 
to obtain single-phase samples much faster. 

Fig.6. Thermodynamic stability of the SmFeO3 and Sm3Fe5O12, constructed from the data in 
[36] (straight line); circle points are taken from [47], square points are calculated from [48, 49]



61

The synthesis conditions, structure type 
and unit cell parameters for the various 
Sm1–хSrхCoO3–δ compositions are listed in 
Table 4.

Sm-enriched Sm1–хSrхCoO3–δ (0 < х < 
0.5) obtained at 1200 °C in air possesses 
the perovskite structure with orthorhom-
bic [1, 52] or tetragonal [53] distortions. 
The increase of strontium content leads to 
the decrease of orthorhombic distortions 
[1]. It should be noted that annealing tem-
perature not less than 1200 °C is important 
since the samples Sm1–хSrхCoO3–δ with x ≤ 
0.40 annealed at 1100 °C in air for 300 h 
were double-phase.

Depending on the preparation condi-
tions, Sr-enriched samples could be ob-
tained either with tetragonal (2a×2a×4a) 

Table 4
The synthesis conditions, structure type and unit cell parameters  

for the various Sm1–хSrхCoO3–δ compositions

Composition
Synthesis 

route
Final treatment 

conditions
Crystal structure and unit cell 

parameters
Ref.

SmCoO3–δ

ceramic route 1200 °C, in air

Orthorhombic 
a = 5.357(1), b = 5.294(1),  
c = 7.513(2) 

[1]

Sm0.9Sr0.1CoO3–δ
Orthorhombic 
a = 5.363(1), b = 5.298(2),  
c = 7.518(3)

Sm0.8Sr0.2CoO3–δ
Orthorhombic 
a = 5.361(1), b = 5.371(2),  
c = 7.577(2)

Sm0.75Sr0.25CoO3–δ nitrate route
800–1200 °C, 
in air, finally 
1000 °C, 3 days 

a = 10.877(1), c = 7.716(1) [53]

Sm0.7Sr0.3CoO3–δ

ceramic route 1200 °C, in air

Orthorhombic 
a = 5.366(1), b = 5.377(2),  
c = 7.583(1)

[1]

Sm0.6Sr0.4CoO3–δ
Orthorhombic 
a = 5.369(2), b = 5.389(2),  
c = 7.588(2)

Sm0.5Sr0.5CoO3–δ ceramic route 1200 °C, in air
Orthorhombic 
a = 5.367(2), b = 5.406(1),  
c = 7.588(2)

[1]

Fig. 7. The phase diagram  
for the Sm – Fe – O system at 1250 K [36]



62

Composition
Synthesis 

route
Final treatment 

conditions
Crystal structure and unit cell 

parameters
Ref.

Sm0.5Sr0.5CoO3–δ

nitrate route 1100 °C, in air
Orthorhombic 
a = 5.366(7), b = 5.370(9),  
c = 7.587(3)

[57]

EDTA-citrate 
complexing 
sol-gel process

900 °C, in air
Orthorhombic Pnma 
a = 5.366, b = 5.398, c = 7.585 [58]

ceramic route 1150 °C, in air
Cubic 
a = 3.8086(5) [50]

nitrate route
800–1200 °C, in 
air, finally  
1000 °C, 3 days

Cubic 
a = 3.795(1) [53]

glycerin-
nitrate route

1100 °C, in air
Tetragonal (2a×2a ×4a), I4/mmm 
a = 7.587(1), c = 15.253(1)

[59]

Sm0.45Sr0.55CoO3–δ
glycerin-
nitrate route

1100 °C, in air
Tetragonal (2a×2a ×4a), I4/mmm 
a = 7.593(1), c = 15.333(1)

[59]

Sm0.4Sr0.6CoO3–δ

ceramic route
1150–1200 °C, 
in air

Cubic 
a = 3.808(2) 
a = 3.8178(5)

[1] 
[50]

glycerin-
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.582(1), c = 15.339(1)

[59]

Sm0.35Sr0.65CoO3–δ
glycerin-
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.596(1), c = 15.328(1)

[59]

Sm0.33Sr0.67CoO3–δ
citrate-nitrate 
route

1100 °C, oxygen 
flow

Tetragonal (2a×2a×4a), I4/mmm 
a = 7.6149(4), c = 15.3472(10)

[54]

Sm0.3Sr0.7CoO3–δ

ceramic route
1150–1200 °C, 
in air

Cubic 
a = 3.823(2) 
a = 3.8306(1) 
a =3.830

[1] 
[50] 
[51]

glycerin 
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.625(1), c = 15.368(1)

[59]

Sm0.25Sr0.75CoO3–δ

nitrate route
800–1200 °C, 
in air, finally 
1000 °C, 3 days 

Orthorhombic GdFeO3 type 
a =5.363(1), b =5.353(1), c 
=7.592(1)

[53]

glycerin 
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.631(1), c = 15.364(1)

[59]

Sm0.2Sr0.8CoO3–δ

citrate nitrate 
route

1100 °C, oxygen 
flow

Tetragonal (2a×2a×4a), I4/mmm 
a = 7.6724(4), c = 15.3983(11)

[54]

ceramic route
1150–1200 °C, 
in air

Cubic 
a =3.846(2) 
a = 3.8407(3)

[1] 
[50]

glycerin 
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.669(1), c = 15.405(1)

[59]

Сontinuation of table 4



63

[54, 59] or cubic [1, 50] structure. One can 
see that the samples with the tetragonal 
structure appear in the relatively more 
oxidizing conditions and the samples 
with the cubic structures formed in the 
relatively more reducing conditions (Table 
4). Fig. 8 illustrates the XRD pattern for 
Sr0.8Sm0.2CoO3–δ with the 2ap×2ap×4ap  
superstructure.

Electron diffraction measurements 
uncovered the formation of 2ap×2ap×4ap 
superstructure (sp. gr. I4/mmm) within the 
tetragonal cell, but the intensity of reflec-
tions corresponding to the superstructure 
decreases with the increase of strontium 
content [54, 55]. The superstructure forms 

because of the ordering of Sm and Sr cati-
ons in the A-site sublattice accompanied 
by the ordering of oxygen vacancies. For 
Sr1–xSmxCoO3–δ with x < 0.25, Sm atoms 
are first incorporated into the A1 position 
until substitution is complete, while the 
A2 and A3 sites remain fully occupied by 
Sr2+. Further increase of samarium content 
leads to the incorporation of Sm cations 
into the A3 position, while A1 is fully oc-
cupied by Sm3+ and A2 is completely filled 
with Sr2+. The value of Sm content, x = 0.5, 
corresponding to the limiting composition 
of solid solution, represents the situation 
when half of A3 positions are occupied by 
Sm3+ and the other half – by Sr2+ [54, 59].

Thermodynamic stability of the 
Sm1–хSrхCoO3–δ solid solutions has not been 
studied yet. Usually partial substitution of 
alkaline-earth elements for rare-earth in 
the cobaltites with the perovskite structure 
decreases their thermodynamic stability 
[60]. The only information concerning 
the behavior of Sm0.5Sr0.5CoO3–δ under ex-
tremely reducing conditions at low tempe-
rature is available [61]. It was found that at 
250 °C under 4% H2O-96% H2 atmosphere 
samarium-strontium cobaltite decomposes 
to SrO, Co(OH)2 and CoO on the surface 

Composition
Synthesis 

route
Final treatment 

conditions
Crystal structure and unit cell 

parameters
Ref.

Sm0.15Sr0.85CoO3–δ
glycerin 
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.678(1), c = 15.372(1)

[59]

Sm0.1Sr0.9CoO3–δ

citrate nitrate 
route

1100 °C, oxygen 
flow

Tetragonal (2a×2a×4a), I4/mmm 
a = 7.6968(8), c = 15.4672(16)

[54]

ceramic route
1150–1200 °C, 
in air

Cubic 
a = 3.848(2) 
a = 3.8531(4)

[1] 
[50]

glycerin 
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.668(1), c = 15.410(1)

[59]

Sm0.05Sr0.95CoO3–δ
glycerin 
nitrate route

1100 °C, in air
Tetragonal (2a×2a×4a), I4/mmm 
a = 7.668(1), c = 15.431(1)

[59]

Fig. 8. XRD pattern for Sr0.8Sm0.2CoO3–δ with 
the 2ap×2ap×4ap superstructure [59]

Сontinuation of table 4



64

of the reduced Sm0.5Sr0.5–αCo1–βO3–γ layer. 
In the atmosphere of pure H2 at 350  °C 
Sr0.5Sm0.5CoO3–δ completely decomposes 
into Sm2O3, SrO and CoO [61].

The solid solutions Sm2–хSrxCoO4 with 
K2NiF4 type structure (sp. gr. I4/mmm) 
within the range 0.8 ≤ х ≤ 1.50 were pre-
pared either by the conventional ceramic 
technique at 1200–1300 °C in air [56, 62], 
or at 1450 K in oxygen flow [63], or by the 
EDTA-citrate sol-gel method at 1000  °C 
in oxygen flow [64], or by the glycerin-
nitrate technique at 1100  °C in air [59]. 
The homogeneity range of Sm2–хSrxCoO4 
solid solutions, estimated by EDX analy-
sis, was reported as 0.79 ≤ х ≤ 1.68 [63]. 
The samples quenched in air from 1100 °C 
were single-phase within the range 0.7 ≤ 
x ≤ 1.1 [59]. The unit cell parameters for 
Sm2–хSrxCoO4 are listed in Table 5.

Another representative of the Rud-
dlesden-Popper series Sm2SrCo2O7 was 

reported earlier [64]. It was prepared from 
Sm2O3, SrCO3 and Co2O3 by solid state 
synthesis at 1450 K in the flow of oxygen 
for 3 days [64]. According to the powder 
X-ray diffraction measurements, it pos-
sesses the tetragonal structure with the unit 
cell parameters: a = 0.3801 nm, c = 1.9562 
nm, V = 0.2826 nm3. It was shown that 
thermal stability of this phase is limited. 
The X-ray diffraction of the sample after 
heating at 1550 K for 6 h indicated that 
the compound decomposes to SmSrCoO4 
and SmCoO3 [64]. It worth to mention that 
Sm2SrCo2O7 formation was not confirmed 
during the systematic study of phase equi-
libria in the ½ Sm2O3 – SrO – CoO system 
at 1100 °C in air.

The projection of isothermal–isobaric 
phase diagram for the Sm – Sr – Co – O 
system to the compositional triangle ½ 
Sm2O3 – SrO – CoO is shown in Fig. 9 [59].

Phase equilibria in Sm – Sr – Fe – O system
Three types of solid solutions were re-

ported to exist in the Sm-Sr-Fe-O system: 
Sm1–xSrxFeO3–δ [56, 65–70], Sm2–ySryFeO4±δ 
[56, 62], and Sr3–zSmzFe2O7–δ [71].

Complex oxides with the overall com-
position Sm1–xSrxFeO3–δ may be prepared 

by solid state [66], glycine nitrate [56, 68, 
70], EDTA-citrate sol-gel [7, 67, 69] or co-
precipitation [56] methods at 900–1300 °C. 
All samples of Sm1–xSrxFeO3–δ solid solution 
range, whether as-prepared in air or treated 
at high oxygen pressure (100 bar at 600 °C 

Table 5
The unit cell parameters and unit cell volumes for Sm2–хSrxCoO4 [59, 62, 63]

Sample composition a, Å c, Å V, (Å)3 Ref.

Sm0.5Sr1.5CoO4–δ
3.761 12.234 173.4 [62]

3.7699(2) 12.4085(6) 176.35(1) [63]
Sm0.75Sr1.25CoO4–δ 3.7620(2) 12.3575(8) 174.89(2) [63]
Sm0.8Sr1.2CoO4–δ 3.753(1) 12.304(1) 173.36(2) [59]
Sm0.9Sr1.1CoO4–δ 3.756(1) 12.266(1) 173.04(2) [59]

SmSrCoO4–δ
3.7609(3) 12.2454(9) 173.20(2) [63]
3.752(1) 12.200(1) 171.76(2) [59]

Sm1.1Sr0.9CoO4–δ 3.765(1) 12.198(1) 172.95(2) [59]
Sm1.2Sr0.8CoO4–δ 3.768(1) 12.171(1) 172.77(2) [59]
Sm1.3Sr0.7CoO4–δ 3.777(1) 12.180(1) 173.74(2) [59]



65

[66]), possess orthorhombically distorted 
perovskite type structure (sp. gr. Pbnm). 
The unit cell parameters for Sm1–xSrxFeO3–δ 
are listed in Table 6.

Single-phase Sr2–ySmyFeO4±δ samples 
were synthesized by the glycine nitrate 
route [56] or by the solid-state technique 
[62] with the final annealing temperature 
within the range 1000–1250 °C. The ho-
mogeneity range of Sr2–ySmyFeO4±δ solid 
solution was reported to be equal to 0.5 ≤ 
y ≤ 1.2 [62].

Sr3–zSmzFe2O7–δ solid solutions were 
synthesized by the glycine-nitrate method 
at 1100 °C in air [71]. It was shown that 
single-phase Sr3–zSmzFe2O7–δ formed in the 
composition range 0 ≤ z ≤ 0.3 and at z = 
1.80. Similarly to the undoped Sr3Fe2O7–δ, 
partially Sm-substituted Sr3–zSmzFe2O7–δ 
(z =0–0.3) possesses the tetragonal struc-
ture (sp. gr. I4/mmm). Sm-enriched single 
phase Sr1.2Sm1.8Fe2O7–δ also crystallizes in 
the tetragonal system, although the space 
group is different (P42/mnm).

All attempts to synthesize Sm-substi-
tuted strontium hexaferrite Sr1–zSmzFe12O19 
(0.06 ≤ z ≤ 0.5) solid solutions by hydro-
thermal [10, 11] or solid state [12] methods 
failed. It was found that all Sm-containing 
powders were multiphase; together with 
SrFe12O19 they contained Fe2O3 and (Sm, 
Sr)FeO3–δ as the impurity phases.

Phase equilibrium in Sm – Ba – Co – O system
Relatively large difference in ionic radii 

between samarium and barium, in com-
parison with that between samarium and 
strontium, results in the formation of so-
called “112 type” phase with the formula 
SmBaCo2O6–δ [72–74] instead of solid so-

lution that is typical for the Sr-containing 
system. The structure of SmBaCo2O6–δ is 
also called as double perovskite since Sm 
and Ba atoms are separated to the alter-
nating layers along the c axis. Therefore, 
the value of the c parameter is doubled 

Fig. 9. The phase diagram of  
the ½ Sm2O3 – SrO – CoO system at 

1100 °C in air: 1 – SmCoO3, CoO, 
Sr0.5Sm0.5CoO3–δ; 2 – CoO, Sr1–xSmxCoO3–δ 

(0.05 ≤ x ≤ 0.5); 3 – CoO, Sr0.95Sm0.05CoO3–δ, 
SrCoO3–δ; 4 – SmCoO3–δ, Sr0.5Sm0.5CoO3, 

Sr0.7Sm1.3CoO4+δ; 5 – Sr1–xSmxCoO3–δ (0.05 ≤ 
x ≤ 0.5), Sr2–ySmyCoO4+δ (0.9 ≤ y ≤ 1.3); 6 – 

Sr1.1Sm0.9CoO4+δ, SrCoO3–δ, Sr0.95Sm0.05CoO3–δ, 
SrCoO3–δ; 7 – SrCoO3–δ, Sr3Co2O7–δ, 

Sr1.1Sm0.9CoO4+δ; 8 – Sm2O3, SmCoO3–δ, 
Sr0.7Sm1.3CoO4+δ;  9 – Sr2–ySmyCoO4+δ 
(0.9 ≤ y ≤ 1.3), Sm2O3; 10 – Sm2O3, 

Sm2SrO4–δ, Sr1.1Sm0.9CoO4+δ; 11 – SrO, 
Sm2SrO4–δ, Sr1.1Sm0.9CoO4+δ; 12 – SrO, 

Sr3Co2O7–δ, Sr1.1Sm0.9CoO4+δ [59]
Table 6

The unit cell parameters for the Sr1–xSmxFeO3–δ solid solution

x Structure a, Å b, Å c, Å Ref.
0.5

Orthorhombic
sp. gr. Pbnm

5.4622(1) 5.4627(4) 7.7249(1) [70]
0.667 5.4728(2) 5.4454(2) 7.6973(2) [66]

0.8 5.396 5.562 7.711 [69]



66

relatively to the ordinary perovskite struc-
ture, and the unit cell can be represented 
as ap×ap×2ap. Another specific feature of 
this structure that is caused by the cati-
on separation is the location of oxygen 
vacancies. It is generally acknowledged 
that oxygen vacancies are not distributed 
randomly in the lattice while the oxy-
gen content changes within the range 5 
< (6–δ) < 6, but are concentrated in the 
particular planes. According to the most 
widespread point of view, oxygen vacan-
cies are located in the SmOδ planes while 
BaO planes remain completed [74–76], 
however, alternatively the opposite model 
was suggested in [77]. Such accumulation 
of oxygen vacancies in the specific planes 
(doesn’t matter what they are – either 
SmOδ or BaOδ) results in the ordering of 
oxygen vacancies when the value of (6–δ) 
is equal approximately to 5.5, leading to 
the doubling of b-parameter and forma-
tion of the ap×2ap×2ap supercell.

SmBaCo2O6–δ can be prepared by a 
conventional ceramic technique [3, 74, 
78–81] and via solution methods using 
different precursors [82–84]. It possesses 
the orthorhombic structure (space group 
Pmmm) with the ap×2ap×2ap supercell. 
The value of oxygen content at room tem-
perature in the sample slowly cooled in 
air was found to be 5.61 [81]. This value 
corresponds to the orthorhombic structure. 
The X-ray diffraction pattern for SmBa-
Co2O5.61 refined by the Rietveld analysis is 
shown in Fig. 10 and the structural para-
meters are listed in Table 7.

The samples within the composi-
tional range Sm1–xBaxCoO3–δ with x < 0.5 
annealed at 1100  °C in air were double-
phase and consisted of SmBaCo2O5.61 and 
SmCoO3–δ, while the samples with x > 0.5 
were the mixtures of SmBaCo2O5.61 and 
BaCoO3–δ [72, 73].

High temperature in situ XRD mea-
surements reveals the structural transfor-

Table 7
The unit cell parameters and atomic coordinates for SmBaCo2O5.61 [81]

Space group Pmmm
atom x y z
Sm 0.5 0.229(3) 0.5
Ba 0.5 0.250(1) 0

Co1 0 0.5 0.255(2)
Co2 0 0 0.254(2)
O1 0 0 0
O2 0 0.5 0
O3 0 0.5 0.5
O4 0 0 0.5
O5 0.5 0 0.239(3)
O6 0.5 0.5 0.247(3)
O7 0 0.244(2) 0.238(2)

a = 3.886(1) Å; b = 7.833(1) Å; c = 7.560(1) Å;
V = 230.22(2) (Å)3;
RBr = 10.7%; Rp = 7.73%; Rexp = 4.46%



67

mation from orthorhombic to tetragonal 
cell between 450 and 550 °C (Fig. 11) that is 
in good agreement with the value of oxygen 
content in SmBaCo2O6–δ within this tem-
perature range. Temperature dependence 
of unit cell parameters for SmBaCo2O6–δ is 
shown in Fig. 12.

Although the radius of samarium is 
significantly larger than radius of cobalt 
ions, it was found that the solid solutions 
represented by the formula BaCo1–zSmzO3–δ 
can be prepared by citrate-nitrate method 
at 1100 °C in air within the range 0.1≤ z 
≤0.2. Partial substitution of Sm for Co 
stabilized the cubic structure similarly to 
BaCo1–zYzO3–δ [85]. Fig. 13 illustrates XRD 
pattern for the single-phase cubic solid so-
lution BaCo0.85Sm0.15O3–δ as an example. The 
unit cell parameters refined by the Rietveld 
method are listed in Table 8. The sample 
with nominal composition z = 0.05 con-

sisted of cubic BaCo0.9Sm0.1O3–δ and hexa-
gonal BaCoO3–δ.

One more complex oxide with the 
formula Sm2BaCo2O7 representing the 
Ruddlesden-Popper (RP) (n=2) phase was 
reported to exist in the Sm – Ba – Co – O 
system [63, 86]. It was obtained by solid-
state reaction from Sm2O3, BaCO3 and 
Co2O3 at 1300 K in the flow of oxygen for 2 
weeks. The crystal structure was described 
by the orthorhombic cell with the parame-
ters a = 3.821 Å, b = 3.776 Å and c = 19.426 
Å [85]. However, Gillie et al. [87] using 
same preparation method with prolonged 
annealing in flowing oxygen at 1100 °C did 
not obtain the single phase but the mixture 
composed of two distinct phases: an oxy-

Fig. 11. High-temperature in situ diffraction 
data for SmBaCo2O6–δ [84]

Fig. 12. Temperature dependencies of the unit 
cell parameters and unit cell volume for  

SmBaCo2O6–δ in air [84]

Fig. 10. The X-ray diffraction pattern for 
SmBaCo2O5.61, refined by the Rietveld method 

[72]

Fig. 13. XRD pattern for the cubic solid 
solution BaCo0.85Sm0.15O3–δ, refined by the 

Rietveld method [72]



68

genated 112-type phase SmBaCo2O5+x (x ≈ 
0.5), and double-layered RP target com-
pound. From a set of obtained results it 
was concluded that the composition of RP 
phase is probably close to Sm2.1Ba0.8Co2.1O7-δ 
(where δ ≈ 1). The unit cell parameters re-
fined within the Pnnm space group were 
equal to a = 5.4371(4) Å, b = 5.4405(4) Å, 
and c = 19.8629(6) Å [87].

The only one complex oxide Sm2BaO4±δ 
was described in the Sm – Ba – O system 
[73, 88, 89]. It can be prepared as a single 
phase by a conventional ceramic tech-
nique at 1500 °C in air for about 24 h [88]. 
Sm2BaO4±δ demonstrates low stability at 
room temperature due to high hygrosco-
picity and reactivity with CO2 [88, 89]. 
However, DTA curves in the temperature 
range 950–1400  °C in air indicated no 
phase transitions occurred. The presumed 

space group is Pbna with the lattice pa-
rameters a = 12.313 Å, b = 10.535 Å, c = 
3.564 Å [88]. The standard Gibbs energy of 
Sm2BaO4 formation from the binary oxides 
Sm2O3 and BaO, determined by the high-
temperature CaF2-based EMF method, was 
evaluated as –110 kJ/mol at 1100 K [89].

According to the XR results, partial dis-
solution of BaO in Sm2O3 at 1100  °C in 
air was about 15 mol% [72]. The unit cell 
parameters for the Sm2–xBaxO3 solid solu-
tions are listed in Table 9.

The phase diagram for the Sm – Ba – 
Co – O system at 1100  °C in air [72] is 
shown in Fig. 14. According to the ob-
tained results, it could be assumed that 
RP phase is thermodynamically unstable 
at 1100 °C in air but could be synthesized 
in more oxidizing conditions.

Phase equilibria in Sm – Ba – Fe – O system
In contrast with SmBaCo2O6–δ, simi-

lar samarium-barium ferrite SmBaFe2O6–δ 
with the double perovskite structure can 
be obtained only under reduction con-

ditions. Karen et al. [90, 91] synthesized 
SmBaFe2O6–δ at 985–1020 °C in atmosphere 
with oxygen partial pressure pO2 about 
10–14.88–10–15.5 bar that was achieved by 

Table 8
The unit cell parameters for BaCo1–zSmzO3–δ, refined by the Rietveld method [72]

z a, Å V, (Å)3 RBr,% Rf ,% Rp,%

0.1 4.108(1) 69.33(1) 2.04 1.72 13.4
0.15 4.131(1) 70.51(1) 1.59 1.50 9.76
0.2 4.143(1) 71.13(2) 1.30 1.09 16.4

Table 9
The unit cell parameters for the Sm2–xBaxO3 solid solutions

Sm2–xBaxO3 
Space group C2/m

x a, Å b, Å c, Å V, (Å)3 RBr,% Rf ,% Rp,%

0.05 14.191(1) 3.628(1) 8.860(1) 449.22(2) 1.27 1.15 10.2
0.1 14.180(1) 3.626(1) 8.855(1) 448.39(1) 3.20 2.45 13.9
0.2 14.177(1) 3.625(1) 8.853(1) 448.08(1) 2.40 2.21 13.7
0.3 14.175(1) 3.625(1) 8.851(1) 447.92(2) 1.82 2.01 13.3



69

mixing of hydrogen, argon or oxygen and 
water vapor. Moritomo et al. [92] prepared 
SmBaFe2O6–δ at 985 °C for 40 h in an evacu-
ated fused-silica tube with Fe metal grains 
put inside the tube, which served as a get-
ter mixture (Fe/FeO) and provided the 
oxygen partial pressure of about 7.6×10–16 
atm. Although it is impossible to prepare 
SmBaFe2O6–δ in air, it remains single-phase 
after annealing at 900 °C in air [93] or even 
at 985ºC in pure oxygen [91].

The crystal structure of SmBaFe2O6–δ 
is well described within the tetragonal or 
the orthorhombic unit cell (ap×ap×2ap), 
depending on the oxygen content [90–93]. 
Similarly to the Co-containing double per-
ovskite, the appearance of the (ap×2ap×2ap) 
supercell takes place in the vicinity of oxy-
gen content equal to 5.5. The values of unit 
cell parameters and synthesis conditions 
for SmBaFe2O6–δ are listed in Table 10.

The complex oxide SmBa2Fe3O8+δ can 
be obtained at 500 °C in oxygen flow [93] 
or at 1100 °C for 200 h [94]. The structural 
refinements were performed by the Riet-
veld method within the ideal perovskite 
cubic structure (space group Pm3m).

The on ly sing le-phas e s ample 
Sm0.375Ba0.625FeO3–δ was prepared at 1100 °C 
in air [95, 96] and described within a cu-
bic unit cell (space group Pm3m) with a = 
3.934(1) Å. However, transmission electron 
microscopy revealed that Sm0.375Ba0.625FeO3–δ 
possesses tetragonal structure with 5-fold c 
para meter ap×ap×5ap. Such complex struc-
ture is formed by alternation of the lay-
ers contai ning exclusively samarium and 
barium with the mixed layers, as follows: 
Sm–Ba– (Sm, Ba)–(Sm, Ba)–Ba–Sm [95, 
96] (Fig. 15).

Table 10
The values of unit cell parameters and synthesis conditions for SmBaFe2O6–δ [90]

6–δ a, Å b, Å c, Å structure Ar/H2 log(pH2O) log(pO2) T, °C
4.980 3.963 3.946 7.609

orthorhombic  
ap×ap×2a 
(sp.gr. Pmmm)

8.78 –4.1 –27.6 670
4.999 3.963 3.945 7.612 8.65 –4.4 –29.3 630
5.002 3.962 3.945 7.611 8.65 –4.2 –28.6 640
5.007 3.962 3.944 7.611 8.65 –4.3 –29.4 620
5.014 3.962 3.946 7.612 8.78 –4.1 –27.9 660
5.016 3.963 3.946 7.612 8.78 –4.1 –28.2 650
5.022 3.962 3.944 7.617 8.78 –4.1 –28.5 640
5.030 3.959 3.948 7.621 16.3 –1.68 –15.31 1000
5.064 3.953 7.628

tetragonal 
(sp.gr P4/
mmm) 
ap×2ap×2a

24.9 –1.67 –14.93 1000
5.095 3.952 7.636 41.3 –1.68 –14.53 1000
5.137 3.949 7.649 74.2 –1.68 –14.03 1000
5.142 3.950 7.654 83.2 –1.64 –13.85 1000
5.182 3.949 7.664 101 –1.68 –13.76 1000
5.202 3.947 7.671 137 –1.69 –13.51 1000
5.249 3.946 7.686 238 –1.66 –12.96 1000
5.320 3.943 7.705 398 –1.62 –12.44 1000
5.346 3.943 7.714 341 –1.65 –12.64 1000



70

Phase equilibrium in Sm – Co – Fe – O system
The solid solutions between sama-

rium ferrite and samarium cobaltite Sm-
Fe1–xCoxO3–δ were extensively studied [52, 
97–102] because of their possible applica-
tion as gas sensors. Polycrystalline samples 
of SmFe1–xCoxO3–δ can be prepared by the 
pyrolysis of cyanide complexes [97, 99], 
sol–gel method [98, 100, 102] or conven-
tional solid-state technique [52] at 800–
1100 °C. It was shown that the homogene-
ity range of SmFe1–xCoxO3–δ solid solutions 
extended to the entire range of composi-
tions (0 ≤ x ≤ 1). Similarly to the undoped 
parent oxides SmFeO3–δ and SmCoO3–δ, the 
structure of all SmFe1–xCoxO3–δ solid solu-
tions was identified as orthorhombic. The 
unit cell parameters and unit cell volume 
values are listed in Table 11 [98, 102].

Another solid solution in the Sm – Fe – 
Co – O system was obtained by partial sub-
stitution of Sm for Fe in the cobalt ferrite 
CoFe2O4 with spinel structure [103–107]. 
The solid oxides with overall composi-

tion CoFe2–ySmyO4 were prepared at 400–
1000 °C by co-precipitation [103–105] or 
sol-gel decomposition [105, 107] me thods. 
Single-phase samples CoFe2–ySmyO4 were 
obtained at temperatures 400–700  °C 
within the ranges 0 ≤ y ≤ 0.2 [105] and 
0 ≤ y ≤ 0.4 [107] by sol-gel technology or 

Fig. 14. A projection of isobaric-isothermal phase diagram of the Sm–Ba–Co–O system to 
the metallic components triangle (T = 1100 °C, pO2 = 0.21 atm):  1 – SmCoO3–δ, CoO and 
SmBaCo2O6–δ; 2 – CoO, SmBaCo2O6–δ and BaCoO3–δ; 3 – melt; 4 – Sm2O3, SmCoO3–δ and 

SmBaCo2O6–δ; 5 – SmBaCo2O6–δ and Sm2–xBaxO3–δ (0 ≤ x ≤ 0.3); 6 – SmBaCo2O6–δ, BaCoO3–δ and 
BaCo0.9Sm0.1O3–δ; 7 – SmBaCo2O6–δ, BaCo0.9Sm0.1O3–δ and Sm1.7Ba0.3O3–δ; 8 – Sm1.7Ba0.3O3–δ and 

BaCo1–zSmzO3–δ (0.1 ≤ z ≤ 0.2); 9 – Sm1.7Ba0.3O3–δ, Sm2BaO4 and BaCo0.8Sm0.2O3–δ; 10 – BaCoO3–δ, 
Ba2CoO4 and BaCo0.9Sm0.1O3–δ; 11 – Ba2CoO4 and BaCo1–zSmzO3–δ (0.1 ≤ z ≤ 0.2); 12 – Sm2BaO4, 

Ba2CoO4 and BaCo0.8Sm0.2O3–δ; 13 – Sm2BaO4, Ba2CoO4 and BaO [72]

Fig. 15. Crystal structure of five-layered 
ordered perovskite Sm1.875Ba3.125Fe5O15–δ  

[95, 96]



71

Table 11
The unit cell parameters and unit cell volume of the SmFe1–xCoxO3–δ solid solutions [98, 102]

x a, Å b, Å c, Å V, Å 3 Ref.

0
5.5871 7.6977 5.3852 231.61 [98]
5.400 5.593 7.708 232.83 [102]

0.1
5.8551 7.5196 5.0739 223.40 [98]
5.390 5.557 7.691 231.19 [102]

0.2
5.8421 7.4964 5.0670 221.91 [98]
5.378 5.554 7.668 229.01 [102]

0.3
5.7916 7.4653 5.0618 218.85 [98]
5.364 5.520 7.634 226.03 [102]

0.4
5.7812 7.4689 5.0533 218.20 [98]
5.363 5.448 7.620 224.26 [102]

0.5
5.7189 7.4671 5.0649 216.29 [98]
5.340 5.453 7.584 220.83 [102]

0.6 5.324 5.422 7.554 218.09 [102]
0.7 5.316 5.412 5.548 217.17 [102]

0.8
5.6564 7.3754 4.9933 208.31 [98]
5.308 5.394 7.536 215.76 [102]

0.9 5.297 5.371 5.518 213.91 [102]

1.0
5.5148 7.2953 4.9582 199.48 [98]
5.286 5.353 7.499 212.18 [102]

Fig. 16. A projection of isobaric-isothermal phase diagram for the Sm–Fe–Co–O system to the 
compositional triangle (T = 1100 °C, pO2 = 0.21 atm): 1 – Sm2O3, SmFe1–xCoxO3–δ  

(0 ≤ x ≤ 1.0); 2 – Co1–uFeuO (0 ≤ u ≤ 0.13), SmFe1–xCoxO3–δ (0.2 ≤ x ≤ 1.0); 3 – Co0.87Fe0.13O, 
Co1.35Fe1.65O4, SmFe0.8Co0.2O3–δ; 4 – SmFe1–xCoxO3–δ (0 ≤ x ≤ 0.2), Co1+vFe2–vO4 (–0.1 ≤ v ≤ 0.35); 
5 – SmFeO3, Sm3Fe5O12, Co0.9Fe2.1O4; 6 – Sm3Fe5O12, Co0.9Fe2.1O4, Fe1.985Co0.015O3; 7 – Sm3Fe5O12, 

Fe2–wCowO3 (0 ≤ w ≤ 0.03) [102]



72

within the range 0 ≤ y ≤ 0.5 [106] by co-
precipitation by sodium hydroxide with 
following annealing at 800 °C. However, 
further increase of temperature (> 800 °C) 
led to the decomposition of CoFe2–ySmyO4 
(y > 0.1 [105, 107] or y ≥ 0.3 [106]) with a 
decrease in Sm content and formation of 
SmFeO3 as a secondary phase. The increase 
of calcination temperature up to 1000 °C 

resulted in the complete decomposition of 
the CoFe2–ySmyO4 solid solution even with 
y = 0.1 [107].

The phase equilibria in the Sm–Fe–Co–
O system at T = 1100 °C in air is presented 
in Fig. 16 [102] in the form of the isother-
mal-isobaric projections to the composi-
tional triangle.

References
1. Tu HY, Takeda Y, Imanishi N, Yamamoto O. Ln1–xSrxCoO3 (Ln  = Sm, Dy) 

for the electrode of solid oxide fuel cells. Solid State Ionics. 1997;100:283–8.  
DOI: 10.1016/S0167-2738(97)00360-3.

2. Kim J-H, Manthiram A. LnBaCo2O5+d oxides as cathodes for intermediate-
temperature solid oxide fuel cells. J Electrochem Soc. 2008;155: B385–90.  
DOI: 10.1149/1.2839028.

3. Zhou Q, He T, Ji Y. SmBaCo2O5+x double-perovskite structure cathode material for 
intermediate-temperature solid-oxide fuel cells. J Power Sources. 2008;185:754–8. 
DOI: 10.1016/j.jpowsour.2008.07.064.

4. Chen D, Wang F, Shi H, Ran R, Shao Z. Systematic evaluation of Co-free 
LnBaFe2O5+ı (Ln = Lanthanides or Y) oxides towards the application as cathodes for 
intermediate-temperature solid oxide fuel cells. Electrochimica Acta. 2012;78:466–74. 
DOI: 10.1016/j.electacta.2012.06.073.

5. Kim J-H, Manthiram A. Characterization of Sr2.7Ln0.3Fe1.4Co0.6O7 (Ln=La, Nd, Sm, 
Gd) intergrowth oxides as cathodes for solid oxide fuel cells. Solid State Ionics. 
2009;180:1478–83. DOI: 10.1016/j.ssi.2009.09.007.

6. Chavez E, Mueller M, Mogni L, Caneiro A. Study of LnBaCo2O6–d (Ln=Pr, Nd, Sm 
and Gd) double perovskite as new cathode material for IT-SOFC. J Phys: Conf Ser. 
2009;167(012043):1–6. DOI: 10.1088/1742-6596/167/1/012043.

7. Li Q, Zhu X, Yang W. Single-step fabrication of asymmetric dual-phase com-
posite membranes for oxygen separation. J Membr Sci. 2008;325:11–5.  
DOI: 10.1016/j.memsci.2008.08.002.

8. Kovalevsky AV, Kharton VV, Tikhonovich VN, Naumovich EN, Tonoyan AA,  
Reut OP, Boginsky LS. Oxygen permeation through Sr(Ln)CoO3–δ (Ln=La, 
Nd, Sm, Gd) ceramic membranes. Mater Sci Eng. 1998; B52:105–16.  
DOI: 10.1016/S0921-5107(97)00292-4.

9. Ikeguchi M, Mimura T, Sekine Y, Kikuchi E, Matsukata M. Reaction and oxy-
gen permeation studies in Sm0.4Ba0.6Fe0.8Co0.2O3–d membrane reactor for 
partial oxidation of methane to syngas. Appl Catal, A. 2005;290:212–20.  
DOI: 10.1016/j.apcata.2005.05.033.

10. Lechevalliera L, Le Breton JM, Wang JF, Harris IR. Structural analysis of hydro-
thermally synthesized Sr1–xSmxFe12O19 hexagonal ferrites. J Magn Magn Mater. 
2004;269:192–6. DOI: 10.1016/S0304-8853(03)00591-2.



73

11. Wang JF, Ponton CB, Harris IR. A study of Sm-substituted SrM magnets sintered 
using hydrothermally synthesized powders. J Magn Magn Mater. 2006;298:122–31. 
DOI: 10.1016/j.jmmm.2005.03.012.

12. Lechevallier L, Le Breton JM, Morel A, Teillet J. Structural and magnetic properties of 
Sr1–xSmxFe12O19 hexagonal ferrites synthesised by a ceramic process. J Alloys Compd. 
2003;359:310–4. DOI: 10.1016/S0925-8388(03)00206-8.

13. Arakawa T, Tsuchi-ya S-ishi, Shiokawa J. Catalytic properties and acti vity of 
rare earth orthoferrites in oxidation of methanol. J Catal. 1982;74:317–22.  
DOI: 10.1016/0021-9517(82)90037-9.

14. Li L, Wang X, Zhang Y. Enhanced visible light-responsive photocatalytic activity 
of LnFeO3 (Ln  = La, Sm) nanoparticles by synergistic catalysts. Mater Res Bull. 
2014;50:18–22. DOI: 10.1016/j.materresbull.2013.10.027.

15. Sazonov LA, Moskvina ZV, Artamonov EV. Investigation of catalytic properties of 
compounds LnMeO3 type in the reactions of homomolecular exchange of oxygen. 
Kinet Catal. 1974;15(1):120–6.

16. Arakawa T, Yoshida A, Shiokawa J. Catalytic properties of rare earth co-
baltites and related compounds. Mater Res Bull. 1980;15(3):347–52.  
DOI: 10.1016/0025-5408(80)90178-6.

17. Michel CR, Delgado E, Santillán G, Martínez AH, Chávez-Chávez A. An alternative 
gas sensor material: Synthesis and electrical characterization of SmCoO3. Mater Res 
Bull. 2007;42:84–93. DOI: 10.1016/j.materresbull.2006.05.008.

18. Delgado E, Michel CR. CO2 and O2 sensing behavior of nanostructured barium – 
doped SmCoO3. Mater Lett. 2006:60;1613–6. DOI: 10.1016/j.matlet.2005.11.080.

19. Mochinaga R, Yamasaki T, Arakawa T. The gas-sensing of SmCoOX/MOX (M=Fe, 
Zn, In, Sn) having a heterojunction. Sens Actuators, B: Chemical. 1998;52(1–2):96–9. 
DOI: 10.1016/S0925-4005(98)00262-7.

20. Kropanev AYu, Petrov AN, Zhukovsky VM. The phase diagrams of the Ln – Co – O 
systems (Ln = Sm, Eu, Gd, Tb, Dy, Ho). Russ J Inorg Chem. 1983;28(11):2938–43.

21. Kropanev AYu, Petrov AN. Thermal stability of SmCoO3, EuCoO3, GdCoO3, TbCoO3, 
DyCoO3, HoCoO3 cobaltites in air. Inorg Mater. 1983;19(12):1782–5.

22. Kitayama K. Thermogravimetric study of the Ln2O3-Co-Co2O3 sys-
tem III. Ln=Pr, Sm, Eu and Tb. J Solid State Chem. 1988;77(2): 366–75.  
DOI: 10.1016/0022-4596(88)90260-5.

23. Wold A, Ward R. Perovskite type oxides of cobalt, chromium and vana-
dium with some rare earth elements. J Am Chem Soc. 1954;76(4):1029–30.  
DOI: 10.1021/ja01633a031.

24. Bertaut F, Forrat F. Sur les deformations dans les perovskites a base de terres 
rares et d’elements de transition trivalents. J Phys Radium. 1956;17:129–31.  
DOI: 10.1051/jphysrad:01956001702012900.

25. Kappatsch A, Qezel-Ambrunaz S, Sivardiere J. Structure et properties magne-
tiques des orthocobaltites de terres rares TCoO3. J Phys France. 1970;31(4):369–76.  
DOI: 10.1051/jphys:01970003104036900.



74

26. Demazeau G, Pouchard M, Hagenmuller P. Sur de nouveaux composes oxygenes 
du cobalt +III derives de la perovskite. J Solid State Chem. 1974;9(3):202–9.  
DOI: 10.1016/0022–4596(74)90075–9.

27. Demazeau G, Pouchard M, Hagenmuller P. Les composes oxygenes ternaries du 
cobalt +3 et des terres. C r Acad Sci. 1973;277(2):109–12.

28. Pérez-Cacho J, Blasco J, García J, Sanchez R. Relationships between Structure 
and Physical Properties in SmNi1–xCoxO3. J Solid State Chem. 2000;150:145–53.  
DOI: 10.1006/jssc.1999.8570.

29. Petrov AN, Kropanev AYu, Zhukovsky VM, Cherepanov VA, Neudachina GK. The 
conditions and mechanism of solid state synthesis of the rare earth cobaltates RCoO3 
(R=La, Pr, Nd, Sm, Gd). Zhurnal Neorganicheskoi Khimii. 1981;26(12):3190–4.

30. Kropanev AYu, Petrov AN, Rabinovich LYa. Investigations of solid state interactions 
of Ln2O3 with CoO (Ln = Sm, Eu, Gd, Dy, Ho). Zhurnal Neorganicheskoi Khimii. 
1983;28(10):2609–12.

31. Kropanev AYu, Petrov AN, Rabinovich LYa. Solid state synthesis of RE cobaltites 
with RCoO3 composition (R – Sm, Eu. Gd). Inorg Mater 1984;20(1):116–20.

32. Kniga MV, Akhrem LI. Kinetics of reaction of samarium oxide and cobalt oxide. Izv 
AN BSSR Ser Khim Nauk. 1968;2:56–60.

33. Petrov AN, Kropanev AYu, Zhukovsky VM. Thermodynamic properties of rare earth 
cobaltites with composition RCoO3. Zhurnal Fizicheskoj Khimii. 1984;58(1):50–3.

34. Sabasri R, Pankajavalli R, Sreedharan OM. High temperature thermodynamic 
stabilities of RCoO3 (R=Nd, Sm, Eu, Gd or Dy) using solid oxide-electrolyte emf 
technique. J Alloy Compd. 1998;269:71–4. DOI: 10.1016/S0925-8388(98)00004-8.

35. Kitayama K, Katsura T. Phase equilibria in Fe-Fe2O3-Ln2O3 (Ln=Sm and Er) systems 
at 1200 °C. Bull Chem Soc Jpn. 1976;49(4):998–1001. DOI: 10.1246/bcsj.49.998.

36. Parida SC, Jacob KT, Venugopal V. Thermodynamic Properties of SmFeO3(s) and 
Sm3Fe5O12 (s). J Phase Equilibria. 2003;24(5):431–40. DOI: 10.1361/1054971037.

37. Geller S, Wood EA. Crystallographic studies of perovstite-like compounds. I. Rare 
earth orthferrites and YFeO3, YCrO3, YAlO3. Acta Crystallogr. 1956;9:563–8.  
DOI: 10.1107/S0365110X56001571.

38. Marezio M, Remeika JP, Dernier PD. The crystal chemistry of the rare earth ortho-
ferrites. Acta Crystallogr. 1970; B26:2008–22. DOI: 10.1107/S0567740870005319.

39. Berenov A, Angeles E, Rossiny J, Raj E, Kilner J, Atkinson A. Structure 
and transport in rare-earth ferrates. Solid State Ionics. 2008;179:1090–3.  
DOI: 10.1016/j.ssi.2008.01.025.

40. Porta P, Cimino S, De Rossi S, Faticanti M, Minelli G, Pettiti I. AFeO3 (A=La, Nd, 
Sm) and LaFe1–xMgxO3 perovskites: structural and redox properties. Mater Chem 
Phys. 2001;71:165–73. DOI: 10.1016/S0254–0584(01)00273–5.

41. Niu X, Li H, Liu G. Preparation, characterization and photocatalytic prop-
erties of REFeO3 (RE  = Sm, Eu, Gd). J Mol Catal A: Chem. 2005;232:89–93.  
DOI: 10.1016/j.molcata.2005.01.022.

42. Espinosa GP. Crystal chemistry study of the rare-earth iron garnets. J Chem Phys. 
1962;10:2344–7. DOI: 10.1063/1.1733008.



75

43. Narayanan VKS, Gajbhiye NS, Bahadur D. Characterization of dysprosium and 
samarium iron garnets synthesized by the citrate gel process. J Mater Sci Lett. 
1987;6:281–4. DOI: 10.1007/BF01729325.

44. Guillot M, Rodic D, Mitric M. Temperature dependencies of the lattice constants 
and thermal expansion coefficients of Sm3Fe5O12 and Er3Fe5O12 single crystals. J Appl 
Phys. 993;73(1):6304–6. DOI: 10.1063/1.352678.

45. Cheng Z, Yang H. Synthesis and magnetic properties of Sm–Y3Fe5O12 nanoparticles. 
Physica E. 2007;39:198–202. DOI: 10.1016/j.physe.2007.04.003.

46. Kniga MV, Rubinchik YaS, Kuligina MP. Kinetics of reaction in the Sm2O3-Fe2O3 sys-
tem. Izv AN BSSR Ser Khim Nauk. 1969;3:30–3.

47. Katsura T, Kitayama K, Sugihara T, Kimizuka N. Thermochemical properties of Lan-
thanoid-Iron-Perovskite at high temperatures. Bull Chem Soc Jpn. 1975;48(6):1809–11.

48. Katsura T, Sekine T, Kitayama K, Sugihara T. Thermodynamic properties of Fe-
Lanthanoid-O compounds at high temperatures. J Solid State Chem. 1978;23:43–57. 
DOI: 10.1016/0022-4596(78)90052-X.

49. Kimizuka N, Yamamoto A, Ohashi H, Sugihara T, Sekine T. The stability of 
the phases in the Ln2O3-FeO-Fe2O3 systems which are stable at elevated tem-
peratures (Ln: lanthanide elements and Y). J Solid State Chem. 1983;49:65–76.  
DOI: 10.1016/0022-4596(83)90217-7.

50. Istomin SYa, Drozhzhin OA, Svensson G, Antipov EV. Synthesis and characteriza-
tion of Sr1–xLnxCoO3–δ, Ln = Y, Sm–Tm, 0.1≤x≤0.5. Solid State Scien. 2004;6:539–46. 
DOI: 10.1016/j.solidstatesciences.2004.03.029.

51. Kovalevsky AV, Kharton VV, Tikhonovich VN, Naumovich EN, Tonoyan AA,  
Reut OP, Boginsky LS. Oxygen permeation through Sr(Ln)CoO3–d (Ln=La, 
Nd, Sm, Gd) ceramic membranes. Mater Sci Eng B. 1998; B52:105–16.  
DOI: 10.1016/S0921-5107(97)00292-4.

52. Jung KH, Choi S-M, Park H-H, Seo W-S. High temperature thermoelectric properties 
of Sr and Fe doped SmCoO3 perovskite structure. Current Applied Physics. 2011;11: 
S260–5. DOI: 10.1016/j.cap.2010.12.032.

53. Kang JW, Ryu KH, Yo CH. Studies of nonstoichiometry and physical properties of 
the perovskite Sm1–xSrxCoO3–y system. Bull Korean Chem Soc. 1995;16(7):600–3.

54. James M, Cassidy D, Glossens DJ, Withers RL. The phase diagram and tetrago-
nal superstructures of the rare earth cobaltate phases Ln1–xSrxCoO3–δ (Ln = La

 3+, 
Pr 3+, Nd 3+, Sm 3+, Gd3+, Y3+, Ho 3+, Dy3+, Er 3+, Tm 3+ and Yb3+). J Solid State Chem. 
2004;177:1886–95. DOI: 10.1016/j.jssc.2004.01.012

55. James M, Cassidy D, Wilson KF, Horvat J, Withers RL. Oxygen vacancy ordering 
and magnetism in the rare earth stabilized perovskite form of “SrCoO3–δ”. Solid State 
Scien. 2004;6:655–62. DOI: 10.1016/j.solidstatesciences.2003.03.001.

56. Baek SW, Kim JH, Bae J. Characteristics of ABO3 and A2BO4 (A  = Sm, Sr; B = 
Co, Fe, Ni) samarium oxide system as cathode material for intermediate tem-
perature-operating solid oxide fuel cell. Solid State Ionics. 2008;179:1570–4.  
DOI: 10.1016/j.ssi.2007.12.010.



76

57. Yang S, He T, He Q. Sm0.5Sr0.5CoO3 cathode material from glycine-nitrate process: 
Formation, characterization, and application in LaGaO3-based solid oxide fuel cells. 
J Alloys Compd. 2008;450:400–4. DOI: 10.1016/j.jallcom.2006.10.147.

58. Dong F, Chen D, Ran R, Park H, Kwak C, Shao Z. A comparative study of 
Sm0.5Sr0.5MO3–d (M = Co and Mn) as oxygen reduction electrodes for solid oxide fuel 
cells. Int J Hydrogen Energy. 2012; 37:4377–87. DOI: 10.1016/j.ijhydene.2011.11.150.

59. Volkova NE, Maklakova AV, Gavrilova LYa, Cherepanov VA. Phase equilibria, crystal 
structure and properties of intermediate oxides in the Sm2O3 – SrO – CoO system. 
Eur J Inorg Chem. 2017;2017(26):3285–92. DOI: 10.1002/ejic.201700321.

60. Cherepanov VA, Barkhatova LYu, Petrov AN, Voronin VI. Phase equilibria in the 
La-Sr-Co-O system and thermodynamic stability of the single phases. Solid Oxide 
Fuel Cells IV. M. Dokiya, O. Yamamoto, H. Tagawa, S. C. Singhal, editors. PV 95–1, 
p.434–443, The Electrochemical Society Proceedings Series, Pennington, NJ (1995).

61. Song HS, Min J-H, Kim J, Moon J. Phase stability of Sm0.5Sr0.5CoO3 cathodes for on-
planar type, single-chamber, solid oxide fuel cells. J Power Sources. 2009;191:269–74. 
DOI: 10.1016/j.jpowsour.2009.02.028.

62. Wang Y, Nie H, Wang S, Wen T-L, Guth U, Valshook V. A2–αA’αBO4-type oxides 
as cathode materials for IT-SOFCs (A = Pr, Sm; A’ = Sr; B = Fe, Co). Mater Lett. 
2006;60:1174–8. DOI: 10.1016/j.matlet.2005.10.104.

63. James M, Tedesco A, Cassidy D, Colella M, Smythe PJ. The phase diagram and crystal 
chemistry of strontium-doped rare earth cobaltates: Ln2–xSrxCoO4+δ (Ln = La–Dy). 
J Alloy Compd. 2006;419:201–7. DOI: 10.1016/j.jallcom.2005.08.080.

64. Siwen L, Yufang R. The synthesis and physical properties of the new layered lantha-
nide alkaline earth cobalt oxides [Ln2MCo2O7 (Ln = Sm, Gd; M = Sr, Ba)]. Mater 
Res Bull. 1994;29:993–1000. DOI: 10.1016/0025–5408(94)90061–2.

65. Park SK, Ishikawa T, Tokura Y, Li JQ, Matsui Y. Variation of charge-ordering 
in R1/3Sr2/3FeO3 (R=La, Pr, Nd, Sm, and Gd). Phys Rev B. 1999;60:10788–95.  
DOI: 10.1103/PhysRevB.60.10788.

66. Zhao YM, Hervieu M, Nguyen N, Raveau B. Charge Ordering and Magne-
totransport Transitions in Sm1/3Sr2/3FeO3–δ. J Solid State Chem. 2000;153:140–4.  
DOI: 10.1006/jssc.2000.8763.

67. Lu X, Chen Y, Ding Y, Lin B. A cobalt-free Sm0.5Sr0.5FeO3-δ – BaZr0.1Ce0.7Y0.2O3–δ com-
posite cathode for proton-conducting solid oxide fuel cells. Int J Hydrogen Energy. 
2012;37:8630–4. DOI: 10.1016/j.ijhydene.2012.02.050.

68. Anderson MD, Stevenson JW, Simner SP. Reactivity of lanthanide fer-
rite SOFC cathodes with YSZ electrolyte. J Power Sources. 2004;129:188–92.  
DOI: 10.1016/j.jpowsour.2003.11.039.

69. Ren Y, Küngas R, Gorte RJ, Deng C. The effect of A-site cation (Ln=La, Pr, Sm) on 
the crystal structure, conductivity and oxygen reduction properties of Sr-doped fer-
rite perovskites. Solid State Ionics. 2012;212:47–54. DOI: 10.1016/j.ssi.2007.12.010.

70. Kharton VV, Kovalevsky AV, Patrakeev MV, Tsipis EV, Viskup AP, Kolotygin 
VA, Yaremchenko AA, Shaula AL, Kiselev EA, Waerenborgh JC. Oxygen Non-
stoichiometry, Mixed Conductivity, and Mössbauer Spectra of Ln0.5A0.5FeO3–δ 



77

(Ln = La-Sm, A = Sr, Ba): Effects of Cation Size. Chem Mater. 2008;20:6457–67.  
DOI: 10.1021/cm801569j.

71. Khvostova LV, Volkova NE, Gavrilova LYa, Cherepanov VA. Crystal structure, oxygen 
nonstoichiometry and properties of novel Ruddlesden-Popper phase Sm1.8Sr1.2Fe2O7–δ. 
Mater Lett. 2018;213:158–61. DOI: 10.1016/j.matlet.2017.11.041.

72. Gavrilova LYa, Aksenova TV, Volkova NE, Podzorova AS, Cherepanov VA. Phase 
equilibria and crystal structure of the complex oxides in the Ln–Ba–Co–O (Ln=Nd, 
Sm) systems. J Solid State Chem. 2011;184:2083–7. DOI: 10.1016/j.jssc.2011.06.006.

73. Khalyavin DD, Sazonov AP, Troyanchuk IO, Szymczak R, Szymczak H. Phase re-
lations in the systems Ln1–xBaxCoO3–δ (0 < x ≤ 0.66; Ln = Nd, Sm). Inorg Mater. 
2003;39:1092–6. DOI: 10.1023/A:10260556.

74. Maignan A, Martin C, Pelloquin D, Nguyen N, Raveau B. Structural and Magnetic 
Studies of Ordered Oxygen-Deficient Perovskites LnBaCo2O5+δ, Closely Related to the 
“112” Structure. J Solid State Chem. 1999;142:247–60. DOI: 10.1006/jssc.1998.7934.

75. Millange F, Caignaert V, Domengès B, Raveau B. Order-Disorder Phenomena in 
New LaBaMn2O6–x CMR Perovskites. Crystal and Magnetic Structure. Chem Mater. 
1998;10:1974–83. DOI: 10.1021/cm980130v

76. Zhou W, Lin CT, Liang WY. Synthesis and Structural Studies of the Per-
ovskite-Related Compound YBaCo2O5+x. Adv Mater. 1993; 5(10)735–8.  
DOI: 10.1002/adma.19930051010.

77. Tsvetkov DS, Sereda VV, Zuev AYu. Oxygen nonstoichiometry and defect struc-
ture of the double perovskite GdBaCo2O6–δ. Solid State Ionics. 2010;180:1620–5.  
DOI: 10.1016/j.ssi.2009.10.014.

78. Anderson PS, Kirk CA, Knudsen J, Reaney IM, West AR. Structural characterization 
of ReBaCo2O6–δ phases (RE = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Но). Solid State Scien. 
2005;7:1149–56. DOI: 10.1016/j.solidstatesciences.2005.03.004.

79. Seikh MdM, Simon Ch, Caignaert V, Pralong V, Lepetit MB, Boudin S, Raveau B. New 
Magnetic Transitions in the Ordered Oxygen-Deficient Perovskite LnBaCo2O5.50+δ. 
Chem Mater. 2008;20:231–8. DOI: 10.1021/cm7026652.

80. Kim J-H, Kim Y, Connor PA, Irvine J, Bae J, Zhou W. Structural, thermal and electro-
chemical properties of layered perovskite SmBaCo2O5+d, a potential cathode material 
for intermediate-temperature solid oxide fuel cells. J Power Sources. 2009;194:704–11. 
DOI: 10.1016/j.jpowsour.2009.06.024.

81. Aksenova TV, Gavrilova LYu, Yaremchenko AA, Cherepanov VA, Kharton VV. 
Oxygen nonstoichiometry, thermal expansion and high-temperature electrical 
proper ties of layered NdBaCo2O5+δ and SmBaCo2O5+δ. Mat Res Bull. 2010;45:1288–92.  
DOI: 10.1016/j.materresbull.2010.05.004.

82. Sun W, Bi L, Yan L, Peng R, LiuW. Synthesis of SmBaCo2O6–δ powder by the 
combustion process using Co3O4 as precursor. J Alloys Compd. 2009;481: L40–2.  
DOI: 10.1016/j.jallcom.2009.03.150.

83. Zhang K, Ge L, Ran R, Shao Z, Lio S. Synthesis, Characterization and Evalu-
ation of Cation-Ordered LnBaCo2O5+δ as Materials of Oxygen Permea-
tion Membranes and Cathodes of SOFCs. Acta Mater. 2008;56:4876–89.  
DOI: 10.1016/j.actamat.2008.06.004.



78

84. Volkova NE, Gavrilova LYa, Cherepanov VA, Aksenova TV, Kolotygin VA,  
Kharton VV. Synthesis, crystal structure and properties of SmBaCo2–xFexO5+δ. J Solid 
State Chem. 2013;204:219–23. DOI: 10.1016/j.jssc.2013.06.001.

85. Lomakov MV, Istomin SYa, Abakumov AM, Van Tandeloo G, Antipov EV. Syn-
thesis and characterization of oxygen-deficient oxides BaCo1–xYxO3–y, x=0.15, 
0.25 and 0.33, with the perovskite structure. Solid State Ionics. 2008;179:1885–9.  
DOI: 10.1016/j.ssi.2008.05.004.

86. Siwen L, Yufang R. Studies on the synthetic, structural, electrical, and magnetic 
properties of the new layered oxides Ln2MCo2O7 (Ln = Sm, Gd; M = Sr, Ba). J Solid 
State Chem. 1995;114:286–8. DOI: 10.1006/jssc.1995.1042.

87. Gillie LJ, Hadermann J, Hervieu M, Maignan A, Martin C. Oxygen Vacancy Ordering 
in the Double-layered Ruddlesden-Popper Cobaltite Sm2BaCo2O7–δ. Chem Mater. 
2008;20:6231–7. DOI: 10.1021/cm8010138.

88. Zhiyu Q, Xianran X, Wenxia Y, Soukun W, Xiaolong C, Jingkui L, Sishen X. Phase 
relations and compounds in the Sm2O3 – BaO – CuO system at 950 °C in air. J Alloys 
Compd. 1993;202:77–80. DOI: 10.1016/0925-8388(93)90521-N.

89. Subasri R, Sreedharan OM. Thermodynaqmic stabilities of Ln2BaO4 (Ln = Nd, Sm, 
Eu or Gd) by CaF2 – based Emf measurements. J Alloys Compd. 1998;274:153–6. 
DOI: 10.1016/S0925-8388(98)00548-9.

90. Karen P, Woodward PM, Santhosh PN, Vogt T, Stephens PW, Pagola SJ. Verwey 
transition under oxygen loading in RBaFe2O5+w (R=Nd and Sm). J Solid State Chem. 
2002;167:480–93. DOI: 10.1006/jssc.2002.9665.

91. Karen P, Woodward PM. Synthesis and structural investigations of the double 
perovskites REBaFe2O5+w (RE=Nd, Sm). J Mater Chem. 1999;9:789–97.  
DOI: 10.1039/A809302D.

92. Moritomo Y, Hanawa M, Ohishi Y, Kato K, Nakamura J, Karppinen M, Yamauchi 
H. Physical pressure effect on the charge-ordering transition of BaSmFe2O5.0. Phys 
Rev B. 2003;68:060101(4). DOI: 10.1103/PhysRevB.68.060101.

93. Elzubair A, El Massalami M, Domingues PH. On the structure and magnetic proper-
ties of the series RBa2Fe3O8+x (R = La, Nd, Sm, Gd). Physica B. 1999;271:284–93. DOI: 
10.1016/S0921-4526(99)00205-7.

94. Lindén J, Karen P, Kjekshus A, Miettinen J, Karppinen M. Partial oxygen orde-
ring in cubic perovskite REBa2Fe3O8+w (RE = Gd, Eu, Sm, Nd). J Solid State Chem. 
1999;144:398–404. DOI: 10.1006/jssc.1999.8178.

95. Volkova NE, Lebedev OI, Gavrilova LYa, Turner S, Gauquelin N, Seikh MdM,  
Caignaert V, Cherepanov VA, Raveau B, van Tendeloo G. Nanoscale Ordering in 
Oxygen Deficient Quintuple Perovskite Sm2–εBa3+εFe5O15–δ: Implication for Magnetism 
and Oxygen Stoichiometry. Chem Mater. 2014;26:6303–10. DOI: 10.1021/cm503276p.

96. Volkova NE, Urusova AS, Gavrilova LYa, Bryuzgina AV, Deryabina KM, Mychinko 
MYu, Lebedev OI, Raveau B, Cherepanov VA. Special Features of Phase Equilibriums 
in Ln–Ba–Fe–O Systems. Russian Journal of General Chemistry. 2016;86(8):1800–4. 
DOI: 10.1134/S1070363216080041.



79

97. Itagaki Y, Mori M, Hosoya Y, Aono H, Sadaoka Y. O3 and NO2 sensing properties of  
SmFe1–xCoxO3 perovskite oxides. Sens Actuators, B. 2007;122:315–20.  
DOI: 10.1016/j.snb.2006.06.001.

98. Zhao M, Peng H, Hu J, Han Z. Effect of Cobalt doping on the microstructure, electrical 
and ethanol-sensing properties of SmFe1–xCoxO3. Sens Actuators, B. 2008;129:953–7.  
DOI: 10.1016/j.snb.2007.10.012.

99. Mori M, Itagaki Y, Sadaoka Y. Effect of VOC on ozone detection using semiconducting 
sensor with SmFe1–xCoxO3 perovskite-type oxide. Sens Actuators, B. 2012;163:44–50.  
DOI: 10.1016/j.snb.2011.12.047.

100. Zhao M, Peng H, Fang S, Hu J. Microstructure, electrical and ethanol-sensing 
properties of perovskite-type SmFe0.7Co0.3O3. Sens Actuators, B. 2008;130:609–13.  
DOI: 10.1016/j.snb.2007.10.017.

101. Zhang R, Hu J, Zhao M, Han Z, Wei J, Wu Z, Qin H, Wang K. Elecctrical and CO-sen-
sing properties of SmFe0.7Co0.3O3 perovskite oxide. Mater Sci Eng, B. 2010;171:139–43.  
DOI: 10.1016/j.mseb.2010.03.087.

102. Galayda AP, Volkova NE, Gavrilova LYa, Balymov KG, Cherepanov VA. Phase 
equilibria, structure and properties of intermediate phases in the Sm2O3 – Fe2O3 
– CoO and Sm2O3 – CaO – CoO systems. J Alloys Compd. 2017;718:288–97.  
DOI: 10.1016/j.jallcom.2017.05.044.

103. Ben Tahar L, Smiri LS, Artus M, Joudrier A-L, Herbst F, Vaulay MJ, Ammar S, Fiévet F.  
Characterization and magnetic properties of Sm- and Gd-substituted CoFe2O4 nano-
particles prepared by forced hydrolysis in polyol. Mater Res Bull. 2007;42:1888–96. 
DOI: 10.1016/j.materresbull.2006.12.014.

104. Ben Tahar L, Artus M, Ammar S, Smiri LS, Herbst F, Vaulay M-J, Richard V,  
Grenèche J-M, Villain F, Fiévet F. Magnetic properties of CoFe1.9RE0.1O4 nanoparti-
cles (RE = La, Ce, Nd, Sm, Eu, Gd, Tb, Ho) prepared in polyol. J Magn Magn Mater. 
2008;320:3242–50. DOI: 10.1016/j.jmmm.2008.06.031.

105. Guo L, Shen X, Song F, Lin L, Zhu Y. Structure and magnetic properties of 
CoFe2–xSmxO4 (x = 0–0.2) nanofibers prepared by sol-gel route. Mater Chem Phys. 
2011;129:943–7. DOI: 10.1016/j.matchemphys.2011.05.023.

106. Ruiz MM, Mietta JL, Antonel PS, Pérez OE, Negri RM, Jorge G. Structural and 
magnetic properties of Fe2–xCoSmxO4-nanoparticles and Fe2–xCoSmxO4-PDMS 
magnetoelastomers as a function of Sm content. J Magn Magn Mater. 2013;327:11–9. 
DOI: 10.1016/j.jmmm.2012.09.020.

107. Rashad MM, Mohamed RM, El-Shall H. Magnetic properties of nanocrystalline 
Sm-substituted CoFe2O4 synthesized by citrate precursor method. J Mater Process 
Technol. 2008;198:139–46. DOI: 10.1016/j.jmatprotec.2007.07.012.

108. Alifanti M, Bueno G, Parvulescu V, Parvulescu VI, Corberán VC. Oxidation of 
ethane on high specific surface SmCoO3 and PrCoO3 perovskites. Catal Today. 
2009;143:309–14. DOI: 10.1016/j.cattod.2009.02.026.