Phosphorus-doped protonic conductors based on BaLanInnO3n+1 (n = 1, 2): applying oxyanion doping strategy to the layered perovskite structure published by Ural Federal University eISSN 2411-1414; chimicatechnoacta.ru LETTER 2022, vol. 9(4), No. 20229405 DOI: 10.15826/chimtech.2022.9.4.05 1 of 6 Phosphorus-doped protonic conductors based on BaLanInnO3n+1 (n = 1, 2): applying oxyanion doping strategy to the layered perovskite structures Natalia Tarasova * , Anzhelika Galisheva Institute of High Temperature Electrochemistry, the Ural Branch of the Russian Academy of Sciences, Ekaterinburg 620990, Russia. * Corresponding author: Natalia.Tarasova@urfu.ru This paper belongs to a Regular Issue. © 2022, the Authors. This article is published in open access under the terms and conditions of the Creative Com- mons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Abstract The creation of highly efficient and eco-friendly energy sources such as hydrogen energy systems is one of main vectors for the sustaina- ble development of human society. Proton-conducting ceramic mate- rials can be applied as one of the main components of such hydrogen- fueled electrochemical devices, including protonic ceramic fuel cells. The oxyanion doping strategy is a promising approach for improving transport properties of proton-conducting complex oxides. In this paper, this strategy was applied to proton-conducting layered perov- skites for the first time. The phosphorus-doped protonic conductors based on BaLanInnO3n+1 (n = 1, 2) were obtained, and their electrical conductivity was thoroughly investigated. It was found that the phosphorous doping leads to an increase in the electrical conductivi- ty values by ~0.7 orders of magnitude. Keywords layered perovskite oxyanion doping phosphorus doping proton conductivity BaLaInO4 BaLa2In2O7 Received: 20.06.22 Revised: 05.07.22 Accepted: 05.07.22 Available online: 12.07.22 Key findings ● The oxyanion doping strategy is a promising method for improving transport properties of proton- conducting layered perovskites. ● The phosphorous-doping leads to a considerable increase of electrical conductivity of the BaLaIn0.9P0.1O4.1 and BaLa2In1.9P0.1O7.1 compared to the P-free materials. 1. Introduction The creation of high-efficiency and eco-friendly energy source is one of main objectives for the sustainable global development of human society [1−8]. Hydrogen energy belongs to the renewable energy industry and includes the systems for storage, transport and using of hydrogen for power generation [9−12]. Proton-conducting ceramic ma- terials can be applied as the one of main component of such hydrogen-based electrochemical devices for various purposes, including electricity generation in protonic ce- ramic fuel cells, PCFCs [13−25]. The most studied protonic conductors have perovskite or perovskite-related struc- tures [26−30]. Doping of cationic sublattices is a common way for improving their transport properties. However, the anion [31−35] and oxyanion [36, 37] doping methods can increase proton conductivity in the complex oxides as well. The oxyanion doping strategy is based on the dis- placement of the [BO6] octahedra to the [B'O4] tetrahedra such as phosphate, sulphate and silicate (Figure 1). Slater et al. proved the validity of this strategy for the proton- conducting materials, studying barium indate, Ba2In2O5, as an example [36]. This confirms that substitution [PO4] → [InO6] is fundamentally possible, and the proton conduc- tivity in such compositions can be improved by phospho- rus doping. Figure 1 The scheme of oxyanion doping strategy of layered per- ovskites. http://chimicatechnoacta.ru/ https://doi.org/10.15826/chimtech.2022.9.4.05 mailto:Natalia.Tarasova@urfu.ru http://creativecommons.org/licenses/by/4.0/ https://orcid.org/0000-0001-7800-0172 https://orcid.org/0000-0003-4346-5644 https://crossmark.crossref.org/dialog/?doi=https://doi.org/10.15826/chimtech.2022.9.4.05&domain=pdf&date_stamp=2022-7-12 Chimica Techno Acta 2022, vol. 9(4), No. 20229405 LETTER 2 of 6 Barium lanthanum indates, BaLaInO4 and BaLa2In2O7, have a layered perovskite structure and can be written using a general formula, BaLanInnO3n+1 (n = 1, 2). They belong to the newly opened class of proton-conducting solid oxide materials [38−49]. It was proved that they are nearly pure (~95–98 %) protonic conductors under wet air below 350–400 °C [50]. Different ways of cation- ic (iso- and heterovalent) doping lead to increasing the protonic conductivity up to ~1.5 orders of magnitude (from 2∙10–7 S cm–1 for BaLaInO4 to 8∙10–6 S cm–1 for Ba1.1LaInO3.95 at 400 °C) [51−56]. Based on this fact, the other doping strategies, such as oxyanion (phosphorus) doping, can be applied to these materials. The reason of this materials search is necessity to create high- conductive proton conductors with the layered perov- skite structure because the promising cathode materials based on nickelates lanthanides [57−60] belong to the layered perovskites as well. In the present study, the oxyanion doping strategy was applied to the proton-conducting layered perovskites for the first time. The phosphorus-doped protonic con- ductors based on BaLanInnO3n+1 (n = 1, 2) were obtained, and electrical conductivity of ceramic samples was inves- tigated. 2. Experimental The complex oxides of BaLaIn0.9P0.1O4.1 and BaLa2In1.9P0.1O7.1 were obtained by a solid state method. Firstly, high-purity starting powder materials were dried and the stoichiometric amounts of the reagents were weighed on a Sartorius analytical balances (Goettingen, Germany). The chemical reactions can be presented in as: BaCO3 + 0.5La2O3 + 0.45In2O3 + 0.1NH4H2PO4 → BaLaIn0.9P0.1O4.1 + 0.1NH3 + 0.15H2O + CO2 (1) BaCO3 + La2O3 + 0.95In2O3 + 0.1NH4H2PO4 → BaLa2In1.9P0.1O7.1 + 0.1NH3 + 0.15H2O + CO2 (2) Further, the milling of all reagents in an agate mortar followed by calcination of the obtained mixtures was made. The calcination was performed in a temperature range from 800 to 1300 °С with a step of 100 °С and 24 h of time treatments. The X-ray diffraction (XRD) studies were performed by a Bruker Advance D8 diffractometer (Rheinstetten, Ger- many) with a Cu Kα radiation with a step of 0.01o and at a scanning rate of 0.5o min–1. The morphology and chemical composition of the samples were studied using a Phenom ProX Desktop scanning electron microscope (Waltham, MA, USA) (SEM) integrated with an energy-dispersive X- ray diffraction (EDS) detector. For the investigations of the electrical properties, the pressed cylindrical pellets (1300 °C, 24 h, dry air) were obtained. The samples had a relative density of ~90% (density of the sintered samples was determined by the Archimedes method). The AC conductivity measurements were performed by a Z-1000P (Elins, RF) impedance spectrometer within a frequency range of 1–106 Hz. Elec- trical measurements were performed using Pt paste elec- trodes (sintering at 1000 °C for 2 h). The temperature dependencies of electrical conductivity were obtained in a temperature range 200–1000 °C (step 10–20 °C, 1 °C min–1 cooling rate). These investigations were per- formed under “dry” and “wet” air atmospheres. The dry air was produced by circulating the gas through P2O5 (pH2O = 3.5·10−5 atm). The wet air was obtained by bub- bling the gas at room temperature first through distilled water and then through a saturated solution of KBr (pH2O = 2·10−2 atm). The humidity of the gas was con- trolled by a Honeywell HIH-3610 H2O-sensor (Freeport, USA). 3. Results and discussions The XRD analysis of the powder samples BaLaIn0.9P0.1O4.1 and BaLa2In1.9P0.1O7.1 confirmed the single phase for both compositions. The XRD-patterns for the compositions of BaLaIn0.9P0.1O4.1 and BaLa2In1.9P0.1O7.1 are presented in the Figure 2 and 3 correspondingly. Phosphorous-doped BaLaIn0.9P0.1O4.1 and BaLa2In1.9P0.1O7.1 samples are isostructural to theirs matrix compositions, BaLaInO4 and BaLa2In2O7, correspondingly. The monolayer BaLaIn0.9P0.1O4.1 composition belongs to the Pbca space group (orthorhombic symmetry), and the two- layered composition of BaLa2In1.9P0.1O7.1 crystallizes in the P42/mnm space group (tetragonal symmetry). The values of lattice parameters and unit cell volume are presented in Table 1. Figure 2 The XRD-results for BaLaIn0.9P0.1O4.1 composition. The SEM-image is presented in the inset. Chimica Techno Acta 2022, vol. 9(4), No. 20229405 LETTER 3 of 6 Figure 3 The XRD-results for BaLa2In1.9P0.1O7.1 composition. The SEM-image is presented in the inset. Table 1 The lattice parameters and unit cell volume of investigat- ed compositions. Composition a, Å b, Å c, Å V, Å3 BaLaInO4 [50] 12.932 5.906 5.894 450.19 BaLaIn0.9P0.1O4.1 12.803 5.939 5.906 449.04 BaLa2In2O7 [50] 5.891 5.891 20.469 710.520 BaLa2In1.9P0.1O7.1 5.909 5.909 20.868 728.605 As can be seen, phosphorous-doping leads to a change in these characteristics for both doped compositions com- pared with undoped. The oxyanion doping for the mono- layer composition of BaLaInO4 leads to a decrease in the a parameter and to an increase in the b and c parameters. The applying of this doping strategy to the two-layered compositions of BaLa2In2O7 leads to an increase of all (a, b and c) lattice parameters. As it is known [61], the ionic radius of phosphorous is smaller than ionic radius of indi- um (r(P5+) = 0.38 Å, r(In3+) = 0.8 Å). However, the dis- placement of [InO6] octahedra to the [PO4] tetrahedra should inevitably lead to the appearance of local distor- tions and to a redistribution of bond lengths in the crystal structure. The microphotography (SEM-image) of the BaLa2In1.9P0.1O7.1 powder sample is presented in the inset of Figure 3. This composition consists of grains ~5 μm, forming agglomerates of ~15−30 μm. The electrical conductivity was measured by the im- pedance spectroscopy method. The Nyquist-plots for BaLaIn0.9P0.1O4.1 composition obtained under dry air are presented in the Figure 4a, b. The fitting of the spectra was made using ZView software, and the obtained results are presented in the Table 2. According to the fitting of the spectra (red line) with using the equivalent circuit pre- sented in the Figure 4c, three different electrochemical processes can be defined. As it was shown earlier [51], the Nyquist-plots for undoped BaLaInO4 composition were represented by one visible semicircle with a capacitance of around 10–11 F. For the calculation of electrical conductivi- ty, the bulk resistance values (R1) were used and dis- cussed below. It can be noted, that due to a small depres- sion of the semicircles, the constant phase element (CPE) was used during the analysis of Nyquist plots. The results of the electrical conductivity investigations are presented in the Figure 5. As can be seen, phospho- rous-doping leads to an increase in the conductivity values for both monolayer (BaLaInO4) and two-layered (BaLa2In2O7) compositions and. The conductivity growth is about 0.7 orders of magnitude for both compositions. We can assume that such increasing electrical conductivity is due to two factors. Firstly, an increase in the lattice pa- rameters for the layered perovskites of BaLanInnO3n+1 re- sults in a higher conductivity due to facilitating ionic transport [50]. Secondly, the phosphorous-doping can be considered as a donor doping (P5+ → In3+) that causes the appearance of interstitial (“additional”) oxygen in the structure. It is obvious that an increase in the concentra- tion of charge carriers (oxygen ions) should lead to the corresponding increase in the conductivity as well. The change in atmospheric humidity also affects the electrical conductivity values (Figure 5). The air humudifi- cation leads to an increase in the conductivity values at low temperatures (450 °C). Figure 4 The Nyquist-plots obtained at the different temperatures under dry air for the composition BaLaIn0.9P0.1O4.1: 600 °С (a), 500 °С (b), and the equivalent circuit of fitting (red line) (c). Chimica Techno Acta 2022, vol. 9(4), No. 20229405 LETTER 4 of 6 Table 2 Results of Nyquist-plots fitting, where CPE is the constant phase element (F) and the R is the resistance (kΩ). Element Value (600 °С) Value (500 °С) CPE1 2.1∙10−12 3.6∙10−12 R1 11 280 CPE2 4.5∙10−10 4.8∙10−10 R2 4.5 40 CPE3 3.4∙10−7 5.1∙10−7 R3 2 70 0.8 1.0 1.2 1.4 1.6 1.8 -9 -8 -7 -6 -5 -4 -3 -2 (a) 10 3 /Т, К -1 lo g  ( S /c m ) BaLaInO 4 BaLaIn 0.9 P 0.1 O 4.1 0.8 1.0 1.2 1.4 1.6 1.8 -9 -8 -7 -6 -5 -4 -3 -2 (b) BaLaIn 0.9 P 0.1 O 4.1 BaLa 2 In 2 O 7 lo g  ( S /c m ) 10 3 /Т, К -1 Figure 5 The temperatures dependencies of conductivity for the compositions BaLaIn0.9P0.1O4.1 (a) and BaLa2In1.9P0.1O7.1 (b) under dry (filled symbols) and wet (open symbols) air. Because layered perovskites BaLaInO4 and BaLa2In2O7 are capable for the dissociative absorption of water from the gas phase [50], the reason of better conductivity is the appearance of proton contribution of conductivity. It can be concluded that the oxyanion doping strategy can be applied for layered perovskites for improving their transport properties. 4. Conclusions In this paper, the oxyanion doping strategy was purpose- fully applied to the proton-conducting layered perovskites for the first time. The phosphorus-doped protonic conduc- tors based on BaLanInnO3n+1 (n = 1, 2) were obtained, and their electrical properties were investigated. The BaLaIn0.9P0.1O4.1 and BaLa2In1.9P0.1O7.1 oxides were obtained for the first time. It was found that the phosphorous- doping leads to an increase in the electrical conductivity values by ~0.7 orders of magnitude. The oxyanion doping strategy is a promising method for improving transport properties of proton-conducting layered perovskites. Supplementary materials No supplementary materials are available. Funding This research was performed according to the budgetary plan of the Institute of High Temperature Electrochemis- try and funded by the Budget of Russian Federation. Acknowledgments None. Author contributions Conceptualization: N.T. Data curation: A.G., N.T. Methodology: N.T. Validation: A.G., N.T. Visualization: A.G., N.T. Writing – original draft: N.T. Writing – review & editing: N.T. Conflict of interest The authors declare no conflict of interest. Additional information Author IDs: Natalia Tarasova, Scopus ID 37047923700; Anzhelika Galisheva, Scopus ID 57195274932. https://www.scopus.com/authid/detail.uri?authorId=37047923700 https://www.scopus.com/authid/detail.uri?authorId=57195274932 Chimica Techno Acta 2022, vol. 9(4), No. 20229405 LETTER 5 of 6 Website: Institute of High Temperature Electrochemistry UB RAS, http://www.ihte.uran.ru/ References 1. Panwar NL, Kaishik SC, Kothari S. Winkler T, Sass FA, Duda GN, Schmidt-Bleek K. Role of renewable energy sources in environmental protection: A review. Renew Sustain Energy Rev. 2011;15(3):1513–1524. doi:10.1016/j.rser.2010.11.037 2. Chu S, Majumdar A. Opportunities and challenges for a sus- tainable energy future. Nature. 2012;488:294–303. doi:10.1038/nature11475 3. Dincer I, Rosen MA. Sustainability aspects of hydrogen and fuel cell systems. Int J Sustain Energy Dev. 2011;15(2):137– 146. doi:10.1016/j.esd.2011.03.006 4. Branco H, Castro R, Lopes AS. Battery energy storage systems as a way to integrate renewable energy in small isolated power systems. Int J Sustain Energy Dev. 2018;43:90–99. doi:10.1016/j.esd.2018.01.003 5. Malerba D. Poverty-energy-emissions pathways: Recent trends and future sustainable development goals. Int J Sus- tain Energy Dev. 2019;49:109–124. doi:10.1016/j.esd.2019.02.001 6. Buonomano A, Barone G, Forzano C. Advanced energy tech- nologies, methods, and policies to support the sustainable development of energy, water and environment systems. Energy Rep. 2022;8:4844–4853. doi:10.1016/j.egyr.2022.03.171 7. Olabi AG, Abdelkareem MA. Renewable energy and climate change. Renew Sustain Energy Rev. 2022;158:112111. doi:10.1016/j.rser.2022.112111 8. Østergaard PA, Duic N, Noorollahi Y, Mikulcic H, Kalogirou S. Sustainable development using renewable energy technology. Renew Energy. 2020;146:2430–2437. doi:10.1016/j.renene.2019.08.094 9. International Energy Agency. The Future of Hydrogen: Seiz- ing today’s opportunities. OECD. 2019. doi:10.1787/1e0514c4-en 10. Abdalla AM, Hossain S, Nisfindy OB, Azad AT, Dawood M, Azad AK. Hydrogen production, storage, transportation and key challenges with applications: A review. Energy Convers Manag. 2018;165:602–627. doi:10.1016/j.enconman.2018.03.088 11. Dawood F, Anda M, Shafiullah GM. Hydrogen production for energy: An overview. Int J Hydrog Energy. 2020;45(7):3847– 3869. doi:10.1016/j.ijhydene.2019.12.059 12. Arsad AZ, Hannan MA, Al-Shetwi AQ, Mansur M, Muttaqi KM, Dong ZY, Blaabjerg F. Hydrogen energy storage integrated hybrid renewable energy systems: A review analysis for fu- ture research directions. Int J Hydrog Energy. 2022;47(39):17285–17312. doi:10.1016/j.ijhydene.2022.03.208 13. Hossain S, Abdalla AM, Jamain SNB, Zaini JH, Azad AK. A review on proton conducting electrolytes for clean energy and intermediate temperature-solid oxide fuel cells. Renew Sustain Energy Rev. 2017;79:750–764. doi:10.1016/j.rser.2017.05.147 14. Kim J, Sengodan S, Kim S, Kwon O, Bu Y, Kim G. Proton con- ducting oxides: A review of materials and applications for re- newable energy conversion and storage. Renew Sustain Energy Rev. 2019;109:606–618. doi:10.1016/j.rser.2019.04.042 15. Zhang W, Hu YH. Progress in proton-conducting oxides as electrolytes for low-temperature solid oxide fuel cells: From materials to devices. Energy Sci Eng. 2021;9(7):984–1011. doi:10.1002/ese3.886 16. Meng Y, Gao J, Zhao Z, Amoroso J, Tong J, Brinkman KS. Re- view: recent progress in low-temperature proton-conducting ceramics. J Mater Sci. 2019;54:9291–9312. doi:10.1007/s10853-019-03559-9 17. Medvedev D. Trends in research and development of protonic ceramic electrolysis cells. Int J Hydrog Energy. 2019;44(49):26711–26740. doi:10.1016/j.ijhydene.2019.08.130 18. Medvedev DA. Current drawbacks of proton-conducting ce- ramic materials: How to overcome them for real electro- chemical purposes. Curr Opin Green Sustain Chem. 2021;32:100549. doi:10.1016/j.cogsc.2021.100549 19. Zvonareva I, Fu X-Z, Medvedev D, Zhao Z. Electrochemistry and energy conversion features of protonic ceramic cells with mixed ionic-electronic electrolytes. Energy Environ Sci. 2022;15:439–465. doi:10.1039/D1EE03109K 20. Shim JH. Ceramics breakthrough. Nature Energy. 2018;3:168–169. doi:10.1038/s41560-018-0110-7 21. Bello IT, Zhai S, He Q, Cheng C, Dai Y, Chen B, Zhang Y, Ni M. Materials development and prospective for protonic ceramic fuel cells. Int J Energy Res. 2021;46(3):2212–2240. doi:10.1002/er.7371 22. Irvine J et al. Roadmap on inorganic perovskites for energy applications. J Phys Energy. 2021;3:031502. doi:10.1088/2515-7655/abff18 23. Chiara A, Giannici F, Pipitone C, Longo A, Aliotta M, Gambino M, Martorana A. Solid-Solid Interfaces in Protonic Ceramic Devices: A Critical Review. ACS Appl Mater Interfaces. 2020;12:55537–55553. doi:10.1021/acsami.0c13092 24. Cao J, Ji Y, Shao Z. New Insights into the Proton-Conducting Solid Oxide Fuel Cells. J Chin Ceram Soc. 2021;49:83–92. doi:10.14062/j.issn.0454-5648.20200390 25. Bello IT, Zhai S, Zhao S, Li Z, Yu N, Ni M. Scientometric re- view of proton-conducting solid oxide fuel cells. Int J Hydrog Energy. 2021;46(75):37406–37428. doi:10.1016/j.ijhydene.2021.09.061 26. Iwahara H, Esaka T, Uchida H, Maeda N. Proton conduction in sintered oxides and its application to steam electrolysis for hydrogen production. Solid State Ion. 1981;3–4:359–363. doi:10.1016/0167-2738(81)90113-2 27. Iwahara H, Uchida H, Maeda N. High temperature fuel and steam electrolysis cells using proton conductive solid electro- lytes. J Power Sources. 1982;7(3):293–301. doi:10.1016/0378-7753(82)80018-9 28. Tarasova N, Colomban P, Animitsa I. The short-range struc- ture and hydration process of fluorine-substituted double perovskites based on barium-calcium niobate Ba2CaNbO5.5. J Phys Chem Solids. 2018;118:32–39. doi:10.1016/j.jpcs.2018.02.049 29. Fop S, McCombie KS, Wildman EJ, Skakle MS, Irvine JTS, Connor PA, Savaniu C, Ritter C, Mclaughlin AC. High oxide ion and proton conductivity in a disordered hexagonal perov- skite. Nature Mater. 2020;19:752–757. doi:10.1038/s41563-020-0629-4 30. Yashima M, Tsujiguchi T, Sakuda Y, Yasui Y, Zhou Y, Fujii K, Torii S, Kamiyama T, Skinner SJ. High oxide-ion conductivity through the interstitial oxygen site in Ba7Nb4MoO20-based hexagonal perovskite related oxides. Nature Comm. 2021;12:556. doi:10.1038/s41467-020-20859-w 31. Wang Y, Wang H, Liu T, Chen F, Xia C. Improving the chemi- cal stability of BaCe0.8Sm0.2O3−δ electrolyte by Cl doping for proton-conducting solid oxide fuel cell. Electrochem Comm. 2013;28:87–90. doi:10.1016/j.elecom.2012.12.012 32. Zhou H, Dai L, Jia L, Zhu J, Li Y, Wang L. Effect of fluorine, chlorine and bromine doping on the properties of gadolinium doped barium cerate electrolytes. Int J Hydrog Energy. 2015; 40(29):8980–8988. doi:10.1016/j.ijhydene.2015.05.040 33. Tarasova N, Animitsa I. The influence of anionic heterovalent doping on transport properties and chemical stability of F-, Cl-doped brownmillerite Ba2In2O5. J Alloys Compd. 2018;739:353–359. doi:10.1016/j.jallcom.2017.12.317 http://www.ihte.uran.ru/ https://doi.org/10.1016/j.rser.2010.11.037 https://doi.org/10.1038/nature11475 https://doi.org/10.1016/j.esd.2011.03.006 https://doi.org/10.1016/j.esd.2018.01.003 https://doi.org/10.1016/j.esd.2019.02.001 https://doi.org/10.1016/j.egyr.2022.03.171 https://doi.org/10.1016/j.rser.2022.112111 https://doi.org/10.1016/j.renene.2019.08.094 https://doi.org/10.1787/1e0514c4-en https://doi.org/10.1016/j.enconman.2018.03.088 https://doi.org/10.1016/j.ijhydene.2019.12.059 https://doi.org/10.1016/j.ijhydene.2022.03.208 https://doi.org/10.1016/j.rser.2017.05.147 https://doi.org/10.1016/j.rser.2019.04.042 https://doi.org/10.1002/ese3.886 https://doi.org/10.1007/s10853-019-03559-9 https://doi.org/10.1016/j.ijhydene.2019.08.130 https://doi.org/10.1016/j.cogsc.2021.100549 https://doi.org/10.1039/D1EE03109K https://doi.org/10.1038/s41560-018-0110-7 https://doi.org/10.1002/er.7371 https://doi.org/10.1088/2515-7655/abff18 https://doi.org/10.1021/acsami.0c13092 https://doi.org/10.14062/j.issn.0454-5648.20200390 https://doi.org/10.1016/j.ijhydene.2021.09.061 https://doi.org/10.1016/0167-2738(81)90113-2 https://doi.org/10.1016/0378-7753(82)80018-9 https://doi.org/10.1016/j.jpcs.2018.02.049 https://doi.org/10.1038/s41563-020-0629-4 https://doi.org/10.1038/s41467-020-20859-w https://doi.org/10.1016/j.elecom.2012.12.012 https://doi.org/10.1016/j.ijhydene.2015.05.040 https://doi.org/10.1016/j.jallcom.2017.12.317 Chimica Techno Acta 2022, vol. 9(4), No. 20229405 LETTER 6 of 6 34. Ushakov AE, Merkulov OV, Markov AA, Patrakeev MV, Le- onidov IA. Ceramic and transport properties of halogen- substituted strontium ferrite. Ceram Int. 2018;44(10):11301– 11306. doi:10.1016/j.ceramint.2018.03.177 35. Liu J, Jin Z, Miao L, Ding J, Tang H, Gong Z, Peng R, Liu W. A novel anions and cations co-doped strategy for developing high-performance cobalt-free cathode for intermediate- temperature proton-conducting solid oxide fuel cells. Int J Hydrog Energy. 2019;44(21):11079–11087. doi:10.1016/j.ijhydene.2019.03.001 36. Shin JF, Orera A, Apperley DC, Slater PR. Oxyanion doping strategies to enhance the ionic conductivity in Ba2In2O5. J Ma- ter Chem. 2011;21(3):874–879. doi:10.1039/c0jm01978j 37. Hancock CA, Porras-Vazquez JM, Keenan PJ, Slater PR. Oxyan- ions in perovskites: from superconductors to solid oxide fuel cells. Dalton Trans. 2015;44(23):10559. doi:10.1039/c4dt03036b 38. Tarasova N, Animitsa I. AIILnInO4 with Ruddlesden-Popper structure for electrochemical applications: relationship be- tween ion (oxygen-ion, proton) conductivity, water uptake and structural changes. Materials. 2022;15(1):114. doi:10.3390/ma15010114 39. Fujii K, Shiraiwa M, Esaki Y, Yashima M, Hoshikawa A, Ishi- gaki T, Hester JR. New Perovskite-Related Structure Family of Oxide-Ion Conducting Materials NdBaInO4. Chem Mater. 2014;26(8):2488–2491. doi:10.1021/cm500776x 40. Fujii K, Shiraiwa M, Esaki Y, Yashima M, Kim SJ, Lee S. Im- proved oxide-ion conductivity of NdBaInO4 by Sr doping. J Mater Chem A. 2015;3(22):11985–11990. doi:10.1039/c5ta01336d 41. Ishihara T, Yan Y, Sakai T, Ida S. Oxide ion conductivity in doped NdBaInO4. Solid State Ion. 2016;288:262–265. doi:10.1016/j.ssi.2016.01.011 42. Yang X, Liu S, Lu F, Xu J, Kuang X. Acceptor Doping and Oxy- gen Vacancy Migration in Layered Perovskite NdBaInO4-Based Mixed Conductors. J Phys Chem C, 2016;12:6416–6426. doi:10.1021/acs.jpcc.6b00700 43. Fujii K, Yashima M. Discovery and development of BaNdInO4 - A brief review. J Ceram Soc Japan. 2018;126(10):852–859. doi:10.2109/jcersj2.18110 44. Zhou Y, Shiraiwa M, Nagao M, Fujii K, Tanaka I, Yashima M, Baque L, Basbus JF, Mogni LV, Skinner SJ. Protonic Conduc- tion in the BaNdInO4 Structure Achieved by Acceptor Doping. Chem Mater. 2021;33(6):2139–2146. doi:10.1021/acs.chemmater.0c04828 45. Kato S, Ogasawara M, Sugai M, Nakata S. Synthesis and oxide ion conductivity of new layered perovskite La1-xSr1+xInO4-d. Solid State Ion. 2002;149(1–2):53–57. doi:10.1016/S0167-2738(02)00138-8. 46. Troncoso L, Alonso JA, Aguadero A. Low activation energies for interstitial oxygen conduction in the layered perovskites La1+xSr1-xInO4+d. J Mater Chem A. 2015;3(34):17797–17803. doi:10.1039/c5ta03185k 47. Troncoso L, Alonso JA, Fernández-Díaz MT, Aguadero A. In- troduction of interstitial oxygen atoms in the layered perov- skite LaSrIn1−xBxO4+δ system (B=Zr, Ti). Solid State Ionics. 2015;282:82–87. doi:10.1016/j.ssi.2015.09.014 48. Troncoso L, Mariño C, Arce MD, Alonso JA. Dual oxygen de- fects in layered La1.2Sr0.8-xBaxInO4+d (x = 0.2, 0.3) oxide-ion conductors: a neutron diffraction study. Mater. 2019;12(10):1624. doi:10.3390/ma12101624 49. Troncoso L, Arce MD, Fernández-Díaz MT, Mogni LV, Alonso JA. Water insertion and combined interstitial-vacancy oxygen conduction in the layered perovskites La1.2Sr0.8-xBaxInO4+d. New J Chem. 2019;43(15):6087–6094. doi:10.1039/C8NJ05320K 50. Tarasova N, Galisheva A, Animitsa I, Korona D, Kreimesh H, Fedorova I. Protonic Transport in Layered Perovskites BaLanInnO3n+1 (n = 1, 2) with Ruddlesden-Popper Structure. Appl Sci. 2022;12(8):4082. doi:10.3390/app12084082 51. Tarasova N, Animitsa I, Galisheva A. Electrical properties of new protonic conductors Ba1+хLa1–хInO4–0.5х with Ruddlesden- Popper structure. J Solid State Electrochem. 2020;24:1497– 1508. doi:10.1007/s10008-020-04630-1 52. Tarasova N, Galisheva A, Animitsa I. Improvement of oxygen- ionic and protonic conductivity of BaLaInO4 through Ti dop- ing. Ionics. 2020;26:5075–5088. doi:10.1007/s11581-020-03659-6 53. Tarasova N, Galisheva A, Animitsa I. Ba2+/Ti4+- co-doped lay- ered perovskite BаLaInO4: the structure and ionic (O 2−, H+) conductivity. Int J Hydrog Energy. 2021;46(32):16868–16877. doi:10.1016/j.ijhydene.2021.02.044 54. Tarasova NA, Galisheva AO, Animitsa IE, Lebedeva EL. Oxy- gen-Ion and Proton Transport in Sc-Doped Layered Perov- skite BaLaInO4. Russ J Electrochem. 2021;57(10):1008–1014. doi:10.1134/S1023193521080127 55. Tarasova N, Galisheva A, Animitsa I, Anokhina I, Gilev P, Cheremisina P. Novel mid-temperature Y3+ → In3+ doped pro- ton conductors based on the layered perovskite BaLaInO4. Ceram Int. 2022;48(11):15677–15685. doi:10.1016/j.ceramint.2022.02.102 56. Tarasova N, Galisheva A, Animitsa I, Korona D, Davletbaev K. Novel proton-conducting layered perovskite based on BaLaInO4 with two different cations in B-sublattice: Synthe- sis, hydration, ionic (O2+, H+) conductivity. Int J Hydrog Energy. 2022;47(44):18972–18982. doi:10.1016/j.ijhydene.2022.04.112 57. Tarutin A, Lyagaeva J, Medvedev D, Bi L, Yaremchenko A. Recent advances in layered Ln2NiO4+δ nickelates: fundamen- tals and prospects of their applications in protonic ceramic fuel and electrolysis cells. J Mater Chem A. 2021;9(1):154– 195. doi:10.1039/D0TA08132A 58. Tarutin A, Gorshkov Yu, Bainov A, Vdovin G, Vylkov A, Lya- gaeva J, Medvedev D. Barium-doped nickelates Nd2–xBaxNiO4+δ as promising electrode materials for protonic ceramic elec- trochemical cells. Ceram Int. 2020;46(15):24355–24364. doi:10.1016/j.ceramint.2020.06.217 59. Tarutin A, Lyagaeva J, Farlenkov A, Plaksin S, Vdovin G, De- min A, Medvedev D. A Reversible protonic ceramic cell with symmetrically designed Pr2NiO4+δ-based electrodes: fabrica- tion and electrochemical features. Mater. 2019;12(1):118. doi:10.3390/ma12010118 60. Tarutin AP, Lyagaeva JG, Farlenkov AS, Vylkov AI, Medvedev DA. Cu-substituted La2NiO4+δ as oxygen electrodes for proton- ic ceramic electrochemical cells. Ceramic Int. 2019;45(13): 16105–16112. doi:10.1016/j.ceramint.2019.05.127 61. Shannon RD, Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst. 1976;A32:751–767. doi:10.1107/S0567739476001551 https://doi.org/10.1016/j.ceramint.2018.03.177 https://doi.org/10.1016/j.ijhydene.2019.03.001 https://doi.org/10.1039/c0jm01978j https://doi.org/10.1039/c4dt03036b https://doi.org/10.3390/ma15010114 https://doi.org/10.1021/cm500776x https://doi.org/10.1039/c5ta01336d https://doi.org/10.1016/j.ssi.2016.01.011 https://doi.org/10.1021/acs.jpcc.6b00700 https://doi.org/10.2109/jcersj2.18110 https://doi.org/10.1021/acs.chemmater.0c04828 https://doi.org/10.1016/S0167-2738(02)00138-8. https://doi.org/10.1039/c5ta03185k https://doi.org/10.1016/j.ssi.2015.09.014 https://doi.org/10.3390/ma12101624 https://doi.org/10.1039/C8NJ05320K https://doi.org/10.3390/app12084082 https://doi.org/10.1007/s10008-020-04630-1 https://doi.org/10.1007/s11581-020-03659-6 https://doi.org/10.1016/j.ijhydene.2021.02.044 https://doi.org/10.1134/S1023193521080127 https://doi.org/10.1016/j.ceramint.2022.02.102 https://doi.org/10.1016/j.ijhydene.2022.04.112 https://doi.org/10.1039/D0TA08132A https://doi.org/10.1016/j.ceramint.2020.06.217 https://doi.org/10.3390/ma12010118 https://doi.org/10.1016/j.ceramint.2019.05.127 https://doi.org/10.1107/S0567739476001551