.


53 http://journals.cihanuniversity.edu.iq/index.php/cuesj CUESJ 2019, 3 (2): 53-57

ReseaRch aRticle

Long Time Stability Investigation for Structural and Magnetic 
Properties of Ti-doped Barium Ferrite
Mohammed Abdul Malek Al Saadi*

Department of Computer and Communication Engineering, Cihan University-Erbil, Kurdistan Region, Iraq

ABSTRACT

Barium hexaferrite (BHF) (BaFe12O19) and its substituted derivatives have been considered as the most potential magnetic candidates 
with considerable chemical stability and physiochemical characteristics. BHF with x ferrite ions substituted by titanium (Ti-doped 
BTHF) (BaTixFe12-xO19) (x=1 and x=3) was prepared from ferric oxide (Fe2O3), barium oxide (BaO), and titanium oxide (TiO2) of purity 
>98%. The materials were mixed with deionized water and then dried at 1100°C and 1200°C overnight. For the formation of BaFe12O19  
phase, the mixture was annealed at a rate of 10°C/min in static air atmosphere until reaching 1200°C and then maintained for 10 h. 
Structural properties of these samples were measured using X-ray diffraction (XRD) and scanning electron microscopy, while magnetic 
properties were measured using vibrating sample magnetometer (VSM) device. Magnetic and structural characteristics are investigated 
after preserving Ti-doped BHF samples at room temperature and ambient conditions for 12 years. The samples are characterized using 
the same previous techniques to find out the possible effect of long period storage on their properties. The results showed that the storage 
process has little effect on these properties where the granular size increased due to increased oxidation. XRD tests also showed the 
absence of Ti at low ratios due to increased oxidation of ferrite. VSM results showed increased magnetic properties after storage due to 
increased iron oxide.

Keywords: Material, electromagnetic, microwave, ferrite

INTRODUCTION

The ferrites are homogeneous ceramic materials dark gray or black color which is made up of a blend of different types of oxides with iron oxide and have 
different crystalline structures.[1] It is also considered as 
ionic compounds and its magnetic properties due to the 
magnetic ions they contain. The high permeability due to the 
distribution of the wall of the field controlled by the sintering 
density and by increasing the size of particleboard.[2] Barium 
hexaferrite (BHF) and its substituted derivatives have been 
considered as candidates with the most potential due to their 
chemical stability and suitable magnetic characteristics.[3]

Ferrites are ideally suited for making device such as 
inductor cores, circulators, memory devices, and also for 
various microwave application. A reduction in size and weight 
of power supplies can be achieved using switched-mode or 
resonant concepts. For the voltage conversion, several circuit 
designs are in use with ferrites as transformer core materials. 
Transformer ferrites must show low-energy losses at high 
induction levels at higher and higher frequencies; this requires 
the development of new ferrite materials with constantly 
improving loss characteristics.[4] Although the saturation 
magnetization of ferrites is less than that of ferromagnetic 
alloys, they have advantages such as applicability at higher 
frequency, lower price, and greater electrical resistance. Ferrites 

are classified into two groups, namely, magnetically soft and 
hard. Furthermore, depending on their crystal symmetry, they 
may be cubic, hexagonal, or orthorhombic.[5]

Ti, a tetravalent element, is well known candidate to 
cosubstitute Fe3+ ions. The ionic radius of Ti4+ ion is 0.605 Å, 
which is smaller than Fe3+ ion (0.645 Å). Furthermore, the 
electronegativity of Ti (1.54) is small compared with Fe 
(1.83). Hence, Ti4+ ions may easily substitute Fe3+ ions in the 
structure with minimal impact on the intrinsic structure of 
the ferrite.[6]

The main applications of these materials intend to reduce 
the human exposure to microwaves by means of absorbing 
coatings.[2,7] Ti-doped BHF powder is an efficient absorber 
of electromagnetic waves in the microwave spectrum. To 

Corresponding Author: 
Mohammed Abdul Malek Al Saadi, Cihan University-Erbil, Kurdistan 
Region, Iraq. E-mail: mohammed.alsaadi@cihanuniversity.edu.iq

Received: Apr 20, 2019 
Accepted: Apr 23, 2019 
Published: Aug 20, 2019

DOI: 10.24086/cuesj.v3n2y2019.pp53-57

Copyright © 2019 Mohammed Abdul Malek Al Saadi. This is an open-access 
article distributed under the Creative Commons Attribution License.

Cihan University-Erbil Scientific Journal (CUESJ)

https://creativecommons.org/licenses/by-nc-nd/4.0/


Al Saadi: Long time stability investigation for structural and magnetic properties of (Ti-doped barium ferrite)

54 http://journals.cihanuniversity.edu.iq/index.php/cuesj CUESJ 2019, 3 (2): 53-57

optimize the Ti-doped BHF microwave absorption properties 
increase in the saturation magnetization (M

S
) and a decrease 

in the coercivity (JH
C
) are required.[8,9] These properties 

depend on the localization of the Ti4+ in BHF structure. 
According to literature,[10,11] the Ti4+ ions preferentially occupy 
the octahedral 4f

2
 sites of the BHF structure when the Ti-doped 

BHF is synthesized using the ceramic route, especially at low 
doping rates.[12]

BHF in powder form is one of widely implicated magnetic 
ceramic materials by both researchers and manufacturers in 
many applications such as permanent magnets, microwave 
absorber devices, and recording media. BHF is attractive 
due to its high stability, excellent high-frequency response, 
narrow switching field distribution and its temperature 
coefficient of coercivity in various applications, fairly large 
magnetocrystalline isotropy, high Curie temperature and 
relatively large magnetization, corrosion resistivity as well as 
chemical stability.[1-13]

In this paper, BHF substituted by Ti4+ (chose cosubstitution 
non-magnetic Ti4+ ions for Fe3+ at different levels to obtain a 
wide range of coercivity and high magnetic permeability) using 
conventional ceramic techniques is investigated by differential 
thermal analysis, X-ray diffraction (XRD), scanning electron 
microscopy (SEM), and magnetic measurements by vibrating 
sample magnetometer (VSM). The approach to saturation law 
was used to determine zero-field saturation magnetization M

s
 

and anisotropy field H
a
.

EXPERIMENTAL

Ti-doped BHF (BaTi
x
Fe

12-x
O

19
) is prepared by conventional 

ceramic techniques (the conventional ceramic methods, 
i.e., high-energy ball milling was employed to obtain high 
quality of BHF). The materials used were ferric oxide (Fe

2
O

3
), 

barium oxide (BaO), and titanium oxide (TiO
2
) of purity 

greater than 98%. Ratios were calculated accurately by 
weighing of materials involved in the preparation of ferrite 
samples using an electronic balance its sensitive up to 0.0001 
g. After grinding, the mixed oxides individually to obtain 
homogeneous size distribution and to facilitate the process 
of granule homogeneity between these compounds during 
the mixing. The powdered oxides were mixed with deionized 
water and then placed in the furnace. A time-temperature 
program was started in the furnace after placing the mixture 
sample. Heating rate was 10°C/min until it reaches the reaction 
temperature (Tc) (1100 or 1200°C) which remained for 10 h 
then cooling started before collecting the samples.

The crystallite phases present in the different samples 
were identified by XRD utilizing Bruker axis D8 diffract 
meter using Cu-Ka (ƛ=1.5406) radiation operating at 40 kV 
and 30 mA at a rate of 2°/min. The diffraction data were 
recorded for 2θ values between 20° and 80°. The particles 
morphology was observed using the SEM to study the surfaces 
micrographic appearance, to find out the effect of substitution 
on the structural properties, and to investigate the particle size 
measurements distribution of Ti-doped BHF samples.

The magnetic properties of the ferrites were measured at 
room temperature using a (VSM; 9600-1 LDJ, USA) in maximum 
applied field of 15 G. From the obtained hysteresis loops, the 

saturation magnetization (M
s
), remanence magnetization 

(M
r
), and the coercive field (Hc) were determined.

The same samples were marked and preserved on 
laboratory shelve in ambient conditions for 12 years and then 
the same above-mentioned characterization routines were 
employed for comparison and revealing the effect of long 
period storage.

RESULTS AND DISCUSSION

Structure and Morphology of Samples

XRD before 12 years

Figure 1 shows XRD patterns of Ti-doped BHF sintering at 
1100°C–1200°C for 10 h. When comparing the XRD schemes 
of x=0, x=1, and x=3, we find that there is a significant 
correlation in the results. In addition to the appearance of 
Fe

3
O

4
 phase at x=3, indicating that the increased titanium 

ratio generated an increase in ion exchange iron; hence, the 
Fe

3
O

4
 phase will appear. It is also clear that increasing the 

amount of substitution of x gives a lower relative intensity and 
width peaks indicating a decrease in particle size.[8]

XRD after 12 years

Figure 2 shows the results of the same samples under the same 
conditions after 12 years. New and very well phases can be 
seen.

SEM before 12 years

Figure 3 shows the images of the surface of Ti-doped BHF. 
Image (a) shows that the interaction of this sample when x=1 
at T=1100°C for 10 h did not complete and the large pores 

Figure 1: X-ray diffraction patterns of Ti-doped barium hexaferrite 
(a) x=0, (b) x=1, and (c) x=3 at T=1200°C for 10 h before 12 years

a

b

c



Al Saadi: Long time stability investigation for structural and magnetic properties of (Ti-doped barium ferrite)

55 http://journals.cihanuniversity.edu.iq/index.php/cuesj CUESJ 2019, 3 (2): 53-57

have been shown in the surface, while the image (b) shows 
that the interaction will be integrated and homogeneous 
when T is increased to T=1200°C for 10 h. The interaction 
of the ferrite and particle size will be better than in the lower 
sintering, therefore, less porosity and better homogeneity of 
the sample, while image (c) shows the surface of Ti-doped BHF 
when x=3 at 1200°C for 10 h. It is expected that increasing of 
replacing of iron ions by Ti ions will decrease the diameter of 
the crystal; hence, the particle size and porosity will decrease, 
this is shown by the XRD (1) from the width and low height 
of the peaks.

The pictures above and the table below have shown that 
grain size decreased with increasing of x and it increased 
with increasing of Tc. The decreasing of x will be better than 
increasing it. Table 1 shows the grain size of the samples.

SEM after 12 years

Figure 4 and Table 2 show that the grain size decreased 
with increasing of x while it increased with increasing of Tc 
for the same reasons mentioned above, these granular sizes 
correspond to the results 12 years ago. However, we note 
from the results that granular size increases overtime due to 
increase of oxidation in samples.

Magnetic Properties of Prepared Samples

The hysteresis loop (B-H loop) is an important property of any 
magnetic material and it is a measure of the lost energy per 
volume during a magnet cycle. The density of the magnetic 
saturation is dependent on the composition of the ferrite 

structure and it increases when the Tc increases, and its 
effective values reduce due to the porosity of samples.[14]

Nanoparticles with a coercive field strength above 5 kOe 
derived BHF are convenient for permanent magnets, but the 
magnetocrystalline anisotropy is too large for recording media 
applications. Therefore, the partially substituted Fe3+ ions of 
the hexaferrite phase, for example, with metals CO

2
+, Mn2+, 

Ni2+, and Ti4+, etc., were attempted to reduce anisotropy 
constant.

Before12 years

Figure 5 shows magnetic hysteresis loops of the Ti-doped 
BHF samples. Saturation magnetization (M

s
) and coercivity 

Figure 2: X-ray diffraction patterns of Ti-doped barium hexaferrite 
after 12 years

Figure 3: Scanning electron microscopy images and grain size of 
Ti-doped barium hexaferrite (a) x=1 at 1100°C, (b) x=1 at 1200°C, 
(c) x=3 at 1200°C

Table 1: Grain size of samples before 12 years

Number of samples T (°C) x Grain size (µm)

a 1100 1 0.21

b 1200 1 0.38

c 1200 3 0.28

Table 2: Particle size of samples after 12 years

Number of samples T (oC) x Grain size (µm)

A 1100 1 0.57

B 1200 1 0.76

C 1100 3 0.25

D 1200 3 0.59

a

b

c



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(Hc) extracted from the loops are given in Table 3 as 
functions of the x and Tc values. It is seen that both M

s
 and 

Hc decreased with increasing x. Hc decreased more rapidly 
at lower x values, whereas M

s
 decreased more at higher x 

values.

Figure 5 shows the hysteresis loop of Ti-doped BHF at 
1100°C and 1200°C, respectively, for 10 h. Figure 5 shows 
that Mr and Ms increased with increasing of Tc and they 
decreased with increasing of x,[4] while 11 Hc decreased 
with increasing of x and Tc; therefore, the samples will 
change from hard to soft material when the concentration 
and temperature increase. These parameters of all samples 
are shown in Table 3.

After 12 years

It is known that magnetic property of ferrite is influenced 
by the chemical composition and ion distribution in the 
crystallographic sites. In the basic structure of M-type barium 
ferrite, Fe3+ ions occupy five different interstitial sites: One 
tetrahedral site 4f1 (↓), one bipyramidal site 2b (↑), and 
three octahedral sites12k (↑), 2a (↑), and 4f2 (↓). In addition 
to the reduction of the magnetocrystalline anisotropy due 

Figure 5: X-ray diffraction of Ti-doped BHF: (a) x=1 at 1100°C

Figure 4: Scanning electron microscopy images and grain size of 
Ti-doped barium hexaferrite (a) x=1 at 1100°C after 12 years

Table 3: The magnetic parameters of Ti-doped barium hexaferrite 
before 12 years

X T 
(°C)

Hc 
(KOe)

Ms 
(emu/g)

Mr 
(emu/g)

Type of 
material

0 1100 4.5 1.35 0.42 Hard

1 = 5.96 1.3 0.76 Hard

3 = 0.06 1.1 0.37 soft

0 1200 6.9 16.3 8.94 Hard

1 = 2.7 3.85 1.58 Hard

3 = 0.04 2.95 0.56 Soft

Table 4: The magnetic parameters of Ti-doped barium hexaferrite 
after 12 years

X T 
(°C)

Hc 
(KOe)

Ms 
(emu/g)

Mr 
(emu/g)

Type of 
material

1 1100 1790 G 30 14.26 Hard

3 1100 168 G 20.7 3.25 Soft

1 1200 909.1 G 32.73 10.17 Hard

3 1200 145.5 17.87 2.45 Soft

a b

c d

a

b

c

d



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57 http://journals.cihanuniversity.edu.iq/index.php/cuesj CUESJ 2019, 3 (2): 53-57

to the substitution of iron by titanium, a decrease in the Hc 
has resulted. This is in agreement with the magnetic results, 
Figures 5 and 6. The magnetic hysteresis curves show that the 
original hard magnetic behavior is shifted to soft magnetic by 
means of high doping content. In effect, it is clearly observed 
that Ti-doped BHF samples exhibit a decrease of Hc and Ms.

It is clear from the patterns below that samples were not 
significantly affected by the time factor, where they retained their 
properties. The hard sample remained hard and soft remained 
soft. Furthermore, we will see that Hc and Mr decreased with 
increasing of x and Tc, while Ms will decrease when x increases, 
but it will increase at x=1 when Tc increases while it will 
decrease at x=3 when Tc increases. The ratio of Ti is affected by 
the increasing of oxidation of ferrite due to the storage factor; 
hence, the samples with the low substitution ratio of x are close 
to the pure BHF. Figure 6 and Table 4 show B-H loop and the 
magnetic parameters of our samples after 12 years.

CONCLUSIONS

Ti-doped BHF (BaTi
x
Fe

12-x
O

19
) prepared by conventional 

ceramic techniques. In addition to the appearance of Fe
3
O

4
 

phase at x=3, indicating that the increased titanium ratio 
generated an increase in ion exchange iron; hence, the Fe

3
O

4
 

phase will appear. It is also clear that increasing the amount 
of substitution of x gives a lower relative intensity and width 
peaks indicating a decrease in particle size. The results show 
that the deviation in the value of d is very low, not exceeding 
0.007, due to convergence of fixed network values between 
Fe3+ (0.63 A°) and Ti4+ (0.68A) ions.

The density of the magnetic saturation is dependent on 
the composition of the ferrite structure and it increases when 
the temperature increases, and its effective values reduce due 
to the porosity of samples. The magnetic parameters (Mr, Mrs, 
and Hc) are increasing with increasing temperature. BHF has 
been substituted by Ti4+ with formula (BaiTi

x
Fe

12-x
O

19
), at 

different x and temperature. The forms of the B-H loop shown 
the material changes from the solid to the soft material at high 
concentrations as well as to all temperatures.

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 ىلع زينغنملاو مويناتيتلا ريثأت» ريتسجام ةلاسر فيان ديعس .13
 «ةينيسلا.ةمزحلا تايدمل ةقيقدلا تاجوملل ةصام داومك مويرابلا تيارف
 .2001 ، رابنالا ةعماج ، مولعلا ةيلك

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Figure 6: X-ray diffraction of Ti-doped barium hexaferrite: (a) x=1 
at 1100°C, (b) x=1 at 1200°C, (c) x=3 at 1100°C, (d) x=3 at 1200°C

a b

c d