Syntheses, structures, and optical properties of n=3 layered Dion-Jacobson perovskites, RbEu2-xBixTi2NbO10 (0? x? 2)

A series of n = 3 Dion-Jacobson type perovskites, RbEu2-xBixTi2NbO10 (0 <= x <= 2) have been synthesized by high temperature solid-state reactions. The Rietveld refinements using powder X-ray diffraction data indicate that the reported materials crystallizing in the noncentrosymmetric (NCS) polar orthorhombic space group, Ima2 (No. 46) or centrosymmetric (CS) tetragonal space group, P4/mmm (No. 123) reveal solid-solution behaviors depending on the amount of Eu3+ and Bi3+ cations. Detailed structural analyses indicate that once more than 30% of A-site cations are occupied by Eu3+ cations in RbEu2-xBixTi2NbO10, the centricity of the solid solutions changes from NCS to CS. Powder second-harmonic generation (SHG) measurements suggest while RbBi2Ti2NbO10 reveals strong SHG (2.5 x KDP), the SHG intensity abruptly decreases as small amount of Eu3+ cations occupy the site of lone pair cation, Bi3+. The origin of the large SHG response of polar RbBi2Ti2NbO10 and the abrupt decrease of SHG for the Eu3+-doped RbEu2-xBixTi2NbO10 solid solutions are explained by a detailed structural analysis and dipole moment calculations along with the electron localization function diagrams. Detailed characterizations including infrared and ultraviolet-visible spectroscopy, thermogravimetric analysis, density functional theory calculations, energy dispersive X-ray analysis, and photoluminescence measurements are provided.(c) 2022 Elsevier B.V. All rights reserved.