Modeling of lattice parameters of cubic perovskite oxides and halides

Abstract

Perovskites having the chemical formulae of ABX 3 are promising candidates for various electronic, magnetic, and thermal applications. One of the important structural factors is a (the lattice constant), which represents the unit cell size. The variation in the lattice constant is a combined result of interactions between different ions, determined by valence electrons and ionic radii. The size and stability of unit cells have important influences on structural stabilities, bandgap structures, and therefore performance of materials. To obtain the lattice constant of cubic perovskites without going through experimental efforts such as synthesis and measurements, we construct a model based on Gaussian process regressions for cubic perovskite lattice constant predictions. The model utilizes the number of valence electrons as well as ionic radii of alloying elements as predictors. A total of 149 cubic perovskites containing fluorides, chlorides, and bromides with cation combinations of A 1+ B 2+ , as well as oxides with cation combinations of A 1+ B 5+ , A 2+ B 4+ , and A 3+ B 3+ are explored. The model demonstrates good performance in terms of stabilities and accuracy, and thus could be a rapid approach to estimate lattice constants.

On the properties of NiO powders obtained by different wet chemical methods and calcination

“…The lattice parameter of oxides is influenced by several factors, mainly by the size and charge of the constituent ions, impurities, and internal strain. 33 As demonstrated by EDS experiments (see Figure S5), only nickel and oxygen are present in the studied samples, so lattice parameters should be mainly fixed by the Ni 2+ /O 2− ratio and strain. Given that the observed lattice parameters for the studied samples are larger than those expected from the literature, and that the Ni 2+ ionic radius (69 pm) is smaller than the O 2− ionic radius (138 pm), 34,35 a possibility is that all the NiO samples contain excess oxygen.…”

“…In Figure 4B, the following trends can be observed: (i) For the sample obtained by hydrothermal synthesis, the lattice parameter increased after the recalcination in the O 2 ‐rich atmosphere, contrasting with the sol‐gel and coprecipitation powders, whose lattice parameter decreased; (ii) The values for hydrothermal synthesis were higher than those obtained by the two other methods; (iii) For the sol‐gel route, the lattice parameter changed very slightly after the different calcination process, while it was considerably modified for the sample obtained by coprecipitation. The lattice parameter of oxides is influenced by several factors, mainly by the size and charge of the constituent ions, impurities, and internal strain 33 . As demonstrated by EDS experiments (see Figure S5), only nickel and oxygen are present in the studied samples, so lattice parameters should be mainly fixed by the Ni 2+ /O 2− ratio and strain.…”

Computational study of stability, photovoltaic, and thermoelectric properties of new inorganic lead-free halide perovskites

“…Structural stability. The XZnI 3 (X = Na, K, Rb, Cs) materials have been studied in the ideal cubic structure with a space group No = 221 noted P m3m [48]. The Wyckoff position of each atom in the unit cell is known as (0, 0, 0), (1/2, 1/2, 1/2), and (1/2, 1/2, 0), respectively for X, Zn, and I atoms.…”

Study of structural, dynamical stability, electronic magnetic and optical properties of RbSnO3 oxide perovskite compound using the density functional theory approach

“…where, r Rb (1.72 Å), r Sn (0.69 Å) and r O (1.35 Å) [33] are the ionic radii of the atoms Rb, Sn and O, respectively. Compounds with t G values between 0.7 and 1.1 are known to be stable in the cubic phase for this family of perovskites [34].…”