Temperature and nickel substitution effects on the phase transitions in the Sr2Zn1−xNixWO6 (0 ≤ x ≤ 1) double perovskite

Sr2Zn1−xNixWO6 solid solutions (with 0 ≤ x ≤ 1) have been synthesized by solid-state reactions, and characterized by X-Ray diffraction and Raman spectroscopy. The X-Ray powder diffraction (XRD) data at room temperature shows a systematical change of structure vs. nickel content: the compound adopts a monoclinic phase with a P21/n space group with 0 ≤ x ≤ 0.18, a tetragonal structure with a I4/m space group with x = 0.25, and a tetragonal structure with a I4/mmm space group with 0.5 ≤ x ≤ 1. Further in-situ Raman study at elevated temperature (up to 555 °C) shows the pristine monoclinic phase (0 ≤ x ≤ 0.18) follows the phase path: monoclinic (P21/n) → tetragonal (I4/m) → tetragonal (I4/mmm) → cubic (Fm3¯m); for the compound Sr2Zn0.75Ni0.25WO6, it involves later two phase transitions as tetragonal (I4/m) → tetragonal (I4/mmm) → cubic (Fm3¯m); and for the 0.5 ≤ x ≤ 1 compounds, only one phase transition I4/mmm to Fm3¯m was observed. The combined investigation of composition and temperature provides us a complete understanding of chemical substitution and temperature effect on structural phase transition. Phase diagram of Sr2Zn1−xNixWO6 (0 ≤ x ≤ 1) as a function of the composition of nickel and temperature. [Display omitted] •Synthesis and characterization of new double perovskites with compositions Sr2Zn1−xNixWO6 (0 ≤ x ≤ 1).•High temperature studies of Sr2Zn1−xNixWO6 (0 ≤ x ≤ 1) double perovskite using Raman spectroscopy.•Temperature and compositions induced phase transitions in these materials.•Structural determination/refinement of these compounds as a function of composition.