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Structural Diversity and Incompatibility Induced Complex Phase Formation Behavior in the Stuffed Tridymites
Yuhang Chen1, Jia Yang2, Pengfei Jiang1
1College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 401331, P. R. China.
Abstract:
Stuffed tridymites AM2O4 composed of a condensed 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-Sr)Ga2O4 (CSGO, 0 ≤ x ≤ 1) is utilized to manipulate the phase formation behavior with different structure types at particular annealing temperatures. Five derivatives, including α- and β-CaGa2O4, β- and γ-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 α-Ca1-SrGa2O4 (x < 0.2) and γ-Ca1-SrGa2O4 (x > 0.67) could be obtained at low temperatures. Biphasic regions, including α-Ca1-SrGa2O4/CSGO (0.2 ≤ x ≤ 0.67), γ-Ca1-SrGa2O4/CSGO (0.67 < x ≤ 0.8), and β-Ca1-SrGa2O4/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 coordination-sensitive Bi3+ activators to advance the development and applications of stuffed tridymites.
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