Structural Diversity And Incompatibility Induced Complex Phase Formation Behavior In The Stuffed Tridymites Ca1-Xsrxga2o4

Stuffed tridymites AM(2)O(4) composed of a con- densed MO4-tetrahedra-based framework have been widely investigated due to their structural diversity and rich physical properties. Herein, the strategy of stuffing mixed Ca2+ and Sr2+ cations into the [Ga2O4](2-) framework in (Ca1-xSrx )Ga2O4 (CSGO, 0 <= x <= 1) is utilized to manipulate the phase formation behavior with different structure types at particular annealing temperatures. Five derivatives, including alpha- and beta-CaGa2O4, beta- and gamma-SrGa2O4, and new CSGO-type structures, were observed. The distinctive feature of the CSGO-structure is the coexistence of UUDDUD- and UDUDUD-type six-membered rings, where U (up) and D (down) denote the orientations of GaO4-tetrahedra with respect to the plane grids, in a ratio of 2:1. Single-phase alpha-Ca1-xSrxGa2O4 (x < 0.2) and gamma-Ca1-xSrxGa2O4(x > 0.67) could be obtained at low temperatures. Biphasic regions, including alpha-Ca1-xSrxGa2O4 / CSGO (0.2 <= x <= 0.67), gamma-Ca1-xSrxGa2O4/CSGO (0.67 < x <= 0.8), and beta-Ca1-xSrxGa2O4/CSGO (0.8 < x < 1), were observed at the intermediate temperature region and evolve irreversibly into the CSGO single-phase region upon elevating the temperature. Moreover, the structure-property relationship of the new CSGO-phase was further studied by doping coordinationsensitive BOl activators to advance the development and applications of stuffed tridymites.