The nature of SrLn2BIVBIIIO7(Ln=La-Sm, BIV = Ti, Sn, BIII= Sc, In) with slab perovskite-like structure

Titov, YA
1Slobodyanik, MS
2Chumak, VV
Timoshenko, MV
1Taras Shevchenko National University of Kyiv
2Ivan Franko State University of Zhytomyr
Dopov. Nac. akad. nauk Ukr. 2020, 2:68-75
https://doi.org/10.15407/dopovidi2020.02.068
Section: Chemistry
Language: Ukrainian
Abstract: 

The areas of existence and crystallographic characteristics of phases with a two-slab structure in the Sr3–xLnxBIV 2–xBx IIIO7 (Ln = La—Tb, BIV = Sn, Ti, BIII = Sc, In). have been defined by X-ray powder diffraction and nonlinear optics methods. The continuous phase area formation with a two-slab structure in the Sr3–xLnxTi2–xScxO7 (Ln = La—Sm), Sr3–xLnxSn2–xScxO7 (Ln = La, Pr) systems and a limited (0 ≤ х ≤ 1) phase area with a two-slab structure in the Sr3–xLnxTi2–xScxO7 (Ln = La—Sm) and Sr3–xLnxSn2–xScxO7 (Ln = La, Pr) systems have been established. In other Sr3–xLnxBIV 2–xBx IIIO7 systems, a rather narrow (x value is significantly less than 1) phase area forma tion with a two-slab structure based on Sr3B2 IVO7 has been observed. The nature of the phase relations in the Sr3–xLnxTi2–xScxO7 (Ln = La—Sm), Sr3–xLnxSn2–xScxO7 (Ln = La, Pr) systems and the linear type of concentration dependences of the parameters of the unit cell phases with a two-slab struc ture indicate that the compositions of Sr2LnTiScO7 (Ln = La—Sm) and Sr2LnSnScO7 (Ln = La, Pr) phases represent a common point in a continuous series of solid solutions of the pseudobinary Sr3B2 IVO7 – SrLn2Sc2O7 (BIV = Ti, Sc) systems. The restrictions of the possibility of the substitution of strontium and titanium atoms in the Sr3–xLnxТі2–xInxO7 (Ln = La—Sm) and Sr3–xLnxSn2–xInxO7 (Ln = La, Pr) systems with the value х = 1 gives grounds for the well-reasoned assum ption that the titanatoindates Sr2LnTiInO7 (Ln = La—Sm) and stannatoindates Sr2LnSnInO7 (Ln = La, Pr) represent individual compounds with a two-slab structure. This conclusion is also confirmed by the possibility of their formation by “growing” a second layer of InO6 octahedra in a single-slab perovskite-like block of the Sr2BIVO4 compound (BIV = Ti, Sn) with LnInО3 perovskite: Sr2BIVO4 + LnInО3 = Sr2LnBIVInO7.

Keywords: isomorphism, slab perovskite-like structure, X-ray powder diffraction
References: 

1. Alexandrov, K. C. & Beznosikov, B. V. (2004). Perovskites. Present and future. Novosibirsk: Izd-vo SO RAN (in Russian).
2. Kim, I. S., Kawaji, H., Itoh, M. & Nakamura, T. (1992). Structural and dielectric studies on the new series of layered compounds, strontium lanthanum scandium oxides. Mat. Res. Bull., 27, No. 10, pp. 1193-1203. Doi: https://doi.org/10.1016/0025-5408(92)90227-Q
3. Kim, I. S., Nakamura, T. & Itoh, M. (1993). Humidity sensing effects of the layered oxides SrO · (LaScO3)n (n = 1, 2, ∞). J. Ceram. Soc. Jap., 101, No. 7, pp. 800-803. Doi: https://doi.org/10.2109/jcersj.101.800
4. Kato, S., Ogasawara, M., Sugai, M. & Nakata, S. (2002). Synthesis and oxide ion conductivity of new layered perovskite La1–xSr1+xInO4–d. Solid state ionics, 149, No. 1-2, pp. 53-57. Doi: https://doi.org/10.1016/S0167-2738(02)00138-8
5. Titov, Yu., Nedilko, S. G., Chornii, V., Scherbatskii, V., Belyavina, N., Markiv, V. & Polubinskii, V. (2015). Crystal structure and luminescence of layered perovskites Sr3LnInSnO8. Solid State Phenomena, 230, pp. 67-72. Doi: https://doi.org/10.4028/www.scientific.net/SSP.230.67
6. Titov, Y. A., Belyavina, N. M., Markiv, V. Ya., Slobodyanik, M. S. & Polubinskii, V. V. (2014). Synthesis and crystal structure of two-layer indotitanates Sr2LnInTiO7. Dopov. Nac. akad. nauk Ukr., No. 6, pp. 120-125 (in Ukrainian). Doi: https://doi.org/10.15407/dopovidi2014.06.120
7. Titov Y.A., Belyavina, N.M., Markiv, V. Ya., Slobodyanik, M. S. & Polubinskii, V. V. (2015). Synthesis and crystal structure of layer scandotitanates Sr2LnScTiO7. Dopov. Nac. akad. nauk Ukr., No. 2, pp. 130-136 (in Ukrainian). Doi: https://doi.org/10.15407/dopovidi2015.02.130
8. Titov, Y. A., Belyavina, N. M., Markiv, V. Ya., Slobodyanik, M. S. & Polubinskii, V. V. (2015). New compounds Sr2LnBIIISnO7 (BIII — Sc, In) with two-layer perovskite-like structure. Dopov. Nac. akad. nauk Ukr., No. 4, pp. 117-122 (in Ukrainian). Doi: https://doi.org/10.15407/dopovidi2015.04.117
9. Titov, Y. A., Slobodyanik, M. S., Krayevska, Ya. A. & Chumak, V. V. (2008). Peculiarities of formation of slab scandates (SrO)(LaScO3)n from the systems of co-precipitated hydroxy-oxalates and crystallized nitrates. Ukr. Khim. Zhurn., 74, No. 9, pp. 34-39 (in Ukrainian).
10. Titov, Y. A., Slobodyanik, M. S. & Krayevska, Ya. A. (2008). Peculiarities of formation and isomorphism of Ruddlesden — Popper compounds Srn+1BnO3n+1-type (B = Sn, Ti, n = 1, 2). Ukr. Khim. Zhurn., 74, No. 7, pp. 17-22 (in Ukrainian).
11. Titov, Y. A., Belyavina, N. M., Markiv, V. Ya., Slobodyanik, M. S., Krayevska, Ya. A. & Yaschuk, V. P (2010). Synthesis and crystal structure of BaLn2In2O7. Dopov. Nac. akad. nauk Ukr., No. 1, pp. 148-154 (in Ukrainian).
12. Dashevskyi, M., Boshko, O., Nakonechna, O. & Belyavina, N. (2017). Phase transformations in equiatomic Y—Cu powder mixture at mechanical milling. Metallofiz. Noveishie Tekhnol., 39, No. 4, pp. 541-552. Doi: https://doi.org/10.15407/mfint.39.04.0541
13. Leonov, A. P., Stefanovich, S. Yu. & Venevtsev, Yu. N. (1984). The development of second harmonic generation methods for identifying and studying noncentrosymmetric phases on polycrystalline samples. In Preparation and application of ferroelectrics in industry (pp. 21-26). Moscow: Izd-vo Moscovskogo Doma Nauchno-Tekhnicheskoj Propagandy (in Russian).
14. Titov, Y. A., Belyavina, N. M., Markiv, V. Ya., Slobodyanik, M. S., Krayevska, Ya. A. & Chumak, V. V. (2009). Synthesis and determination of the crystal structure of layer scandates SrLn2Sc2O7. Dopov. Nac. akad. nauk Ukr., No. 3, pp. 155-161 (in Ukrainian).