A Review of Synthesis, Characterization, Properties, and Applications of Double Perovskite Oxides

Double perovskites are represented by the formula A2BB’O6 and AA’BB’O6. These materials have been synthesized using the solid-state reaction, sol–gel, Pechini, and hydrothermal methods. X-ray fluorescence, X-ray diffraction, magnetic measurements, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction, synchrotron X-ray diffraction, neutron powder diffraction, extended X-ray absorption fine structure, and Raman spectroscopy have been used for the characterization of double perovskites. X-ray diffraction, synchrotron X-ray diffraction, and neutron powder diffraction coupled with the Rietveld method determine the crystal structure of a sample. These materials present various properties and applications. The present review aims (i) to report a process to determine the symmetry, apparent size, and apparent strain using the Rietveld method; (ii) show how experimental characterization techniques complement each other in the investigation of double perovskites; (iii) describe how the synthesis method can help in the uncovering of double perovskites with improved properties; and (iv) exemplify some of the main applications of double perovskites.