Crystal structure evolution and temperature-dependent phase transition of solid solutions are much desired for the understanding of the optimization of functional properties.Herein,the NASICON-type NaZr_(2)(PO_(4))_(3...Crystal structure evolution and temperature-dependent phase transition of solid solutions are much desired for the understanding of the optimization of functional properties.Herein,the NASICON-type NaZr_(2)(PO_(4))_(3)–SrZr_(4)(PO_(4))_(6)solid solutions with the formula Na(2−2x)Srx[]xZr_(4)(PO_(4))_(6)(0≤x≤1),where[]represents the vacancy,were prepared by the sol–gel method,and their crystal structures,phase transitions and thermal expansion properties were investigated in detail.In the range of x=0.3–0.35,there is a reversible structural phase transition R3¯c↔R3¯and the different structural models of the R3¯phase and R3¯c phase were built to better understand the phase transition mechanism.We determined the phase transition boundary between the R3¯c and R3¯structures and predicted the phase transition temperature of Na_((2−2x))Srx[]_(x)Zr_(4)(PO_(4))_(6)with any x for further investigation of controlled physical properties.The results indicated that Na_(0.5)Sr_(0.75)[]_(0.75)Zr_(4)(PO_(4))_(6)showed a near zero thermal expansion in the temperature range of 450–600 K,which can find potential applications.展开更多
基金supported by the National Natural Science Foundation of China(Grants 91622125,51722202 and 51572023)the Natural Science Foundations of Beijing(2172036)support of the Russian Foundation for Basic Research(17-52-53031).
文摘Crystal structure evolution and temperature-dependent phase transition of solid solutions are much desired for the understanding of the optimization of functional properties.Herein,the NASICON-type NaZr_(2)(PO_(4))_(3)–SrZr_(4)(PO_(4))_(6)solid solutions with the formula Na(2−2x)Srx[]xZr_(4)(PO_(4))_(6)(0≤x≤1),where[]represents the vacancy,were prepared by the sol–gel method,and their crystal structures,phase transitions and thermal expansion properties were investigated in detail.In the range of x=0.3–0.35,there is a reversible structural phase transition R3¯c↔R3¯and the different structural models of the R3¯phase and R3¯c phase were built to better understand the phase transition mechanism.We determined the phase transition boundary between the R3¯c and R3¯structures and predicted the phase transition temperature of Na_((2−2x))Srx[]_(x)Zr_(4)(PO_(4))_(6)with any x for further investigation of controlled physical properties.The results indicated that Na_(0.5)Sr_(0.75)[]_(0.75)Zr_(4)(PO_(4))_(6)showed a near zero thermal expansion in the temperature range of 450–600 K,which can find potential applications.
