|Titov, YA |
1Taras Shevchenko National University of Kyiv
2Ivan Franko State University of Zhytomyr
|Dopov. Nac. akad. nauk Ukr. 2019, 7:59-65|
The substitution conditions of scandium atoms in SrLaScO4 slab perovskite-like structure (SPS) of Sr1–xCaxLaScO4- type (0 ⩽ x ⩽ 0,3) have defined by X-ray powder diffraction methods. SPS (Abma space group) of Sr0.7Ca0.3LaScO4 phase with a substitution degree of strontium atoms equal 0,3 is determined by the Rietveld procedure. The crystal structure of Sr0.7Ca0.3LaScO4 is formed by two-dimensional perovskite-like blocks consisting of a slab of distorted ScO6 octahedra joined by vertices. Blocks are separated by the slab of (Sr, Ca, La)О9 polyhedra. Analysis of the obtained data has shown that, in a case of the substitution of Sr atoms by Ca atoms in SPS of Sr1–xCaxLaScO4, a gradual reduction of the length of the (Sr, Ca, La) — О2 interblock bond and the increases of the deformation degree (Δ) of interblock (Sr,Ca,La)О9 polyhedra and the mutual inclination of octahedrons ScO6 take place. Reduction in the distance between perovskite-like blocks approaches a construction of SPS to the thermodynamically stable perovskite structure, and the increase of Δ(Sr, Ca, La)О9 strains and destabilizes SPS. The total effect of these factors leads to the destruction of SPS, limits the range of Sr1–xCaxLaScO4 solid solutions with a slab perovskite-like structure (0 ⩽ x ⩽ 0,3), and makes the formation of SrLaScO4 scandate with this type of structure impossible. The results obtained can be used to regulate the functional (electrophysical, optical, etc.) structurally dependent properties of the Sr1–xCaxLaScO4 phases by successively isovalent substitution atoms in the A-positions of their layered perovskite-like structure.
|Keywords: calcium, isomorphism, lanthanum scandates, Rietveld method, slab perovskite-like structure, strontium, X-ray powder diffraction|
1. Alexandrov, K. C. & Beznosikov, B. V. (2004). Perovskites. Present and future. Novosibirsk: Izd-vo SO RAN (in Russian).
2. Schaak, R. E. & Mallouk, T. E. (2002). Perovskites by design: a toolbox of solid-state reactions. Chem. Mater., 14, No. 4, pp. 1455-1471. https://doi.org/10.1021/cm010689m
3. 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. Mater. Res. Bull., 27, No. 10, pp. 1193-1203. https://doi.org/10.1016/0025-5408(92)90227-Q
4. Kim, I.S ., Nakamura, T. & Itoh, M. (1993). Humidity sensing effects of the layered oxides SrO·(LaScO3)n (n = 1,2, ∞). J. Ceram. Soci. Jap., 101, No. 7, pp. 800-803. https://doi.org/10.2109/jcersj.101.800
5. 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. https://doi.org/10.1016/S0167-2738(02)00138-8
6. 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. https://doi.org/10.4028/www.scientific.net/SSP.230.67
7. Ueda, K., Yamashita, T., Nakayashiki, K., Goto, K., Maeda, T., Furui, K., Ozaki, K., Nakachi, Y., Nakamura, S., Fujisawa, M. & Miyazaki, T. (2006). Green, orange, and magenta luminescence in strontium stannates with perovskite-related structures. Jap. J. Appl. Phys., 45, No. 9A, pp. 6981-6983. https://doi.org/10.1143/JJAP.45.6981
8. Titov, Y. O., Belyavina, N. M., Slobodyanik, M. S., Babaryk, А. А. & Timoschenko, М. V. (2017). Influence of composition on organization of layered perovskite-like structure of indates AIILаInO4. Dopov. Nac. akad. nauk Ukr., No. 4, pp. 70-75 (in Ukrainian). https://doi.org/10.15407/dopovidi2017.04.070
9. Dashevskyi, M., Boshko, O., Nakonechna, O. & Belyavina, N. (2017). Phase transformations in equiatomic Y–Cu powder mixture at mechanical milling. Metallofizika i Noveishie Tekhnologii, 39, No. 4, pp. 541-552. https://doi.org/10.15407/mfint.39.04.0541
10. Patel, R., Simon, C. & Weller, M. T. (2007). LnSrScO4 (Ln = La, Ce, Pr, Nd and Sm) systems and structure correlations for A2BO4 (K2NiF4) structure types. J. Solid State Chem., 180, pp. 349-359. https://doi.org/10.1016/j.jssc.2006.10.023
11. Shannon, R. D. (1976). Revised effective ionic radii and systematic studies of interatomic distances in halides and halcogenides. Acta Crystallogr., A32, pp. 751-767.