From Ag2Sb2O6 to Cd2Sb2O7: Investigations on an anion-deficient to ideal pyrochlore solid solution

A complete solid solution between the anion-deficient pyrochlore Ag2Sb2O6 and the ideal pyrochlore Cd2Sb2O7 has been synthesized through the standard solid state ceramic method. Each composition has been characterized by various different techniques, including powder X-ray diffraction, optical spectroscopy, electron paramagnetic resonance and 121Sb Mössbauer spectroscopy. Computational methods based on density functional theory complement this investigation. Photocatalytic activity has been studied, and transport properties have been measured on pellets densified by spark plasma sintering. The analysis of the data collected from these various techniques enables a comprehensive characterization of the complete solid solution and revealed an anomalous behavior in the Cd-rich end of the solid solution, which has been proposed to arise from a possible radical O− species in small concentrations. - Graphical abstract: A complete solid solution between the anion-deficient pyrochlore Ag2Sb2O6 and the ideal pyrochlore Cd2Sb2O7 has been synthesized and investigated through various techniques including X-ray diffraction, electron paramagnetic spectroscopy, and 121Sb-Mössbauer spectroscopy. Optical and electrical measurements have been performed, and computational methods have been applied to determine the density of states. Photocatalytic activity was monitored by the degradation of Methylene Blue, and upon cadmium substitution, the degradation amount decreased, which is attributed primarily to the changing optical and electrical properties of the solid solution. Display Omitted - Highlights: • A complete solid solution between Ag2Sb2O6 and Cd2Sb2O7 has been synthesized. • XRD reveals a relatively constant lattice parameter as the series progresses. • Optical and electrical properties have been measured for the solid solution. • Computational methods have been used to determine the density of states. • Photocatalytic degradation of Methylene Blue decreased upon cadmium substitution