No abstract

Intergrowth oxides, like Aurivillius, Ruddlesden–Popper phase, comprise functional layers and exhibit interesting physical properties. The hitherto known intergrowth structures mainly were composed of closed‐packing of oxygen ions, and it is very challenging to develop new types of intergrowth structures. We proposed the possible match between the tridymite and grossite, both of which are purely tetrahedra‐based structures. We synthesized Ca2PbGa8O15 ((Ca0.5Pb0.5Ga2O4)2(CaGa4O7)) and its structure was solved by ab‐initio method. Pb2+ is vitally important to stabilize this first example of tetrahedra‐based intergrowth oxide. The appropriate size difference between Pb2+ and Ca2+ causes the layered type cationic ordering, and reduced the thermodynamic potential, in addition, the high hybridization between Pb 6s6p and O 2p orbitals further consolidate the covalency of the tetrahedra‐base framework.

Stuffed tridymites AM 2 O 4 composed of a condensed MO 4 -tetrahedra-based framework have been widely investigated due to their structural diversity and rich physical properties. Herein, the strategy of stuffing mixed Ca 2+ and Sr 2+ cations into the [Ga 2 O 4 ] 2− framework in (Ca 1−x Sr x )Ga 2 O 4 (CSGO, 0 ≤ x ≤ 1) is utilized to manipulate the phase formation behavior with different structure types at particular annealing temperatures. Five derivatives, including αand β-CaGa 2 O 4 , βand γ-SrGa 2 O 4 , 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 GaO 4 -tetrahedra with respect to the plane grids, in a ratio of 2:1. Single-phase α-Ca 1−x Sr x Ga 2 O 4 (x < 0.2) and γ-Ca 1−x Sr x Ga 2 O 4 (x > 0.67) could be obtained at low temperatures. Biphasic regions, including α-Ca 1−x Sr x Ga 2 O 4 /CSGO (0.2 ≤ x ≤ 0.67), γ-Ca 1−x Sr x Ga 2 O 4 /CSGO (0.67 < x ≤ 0.8), and β-Ca 1−x Sr x Ga 2 O 4 /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 Bi 3+ activators to advance the development and applications of stuffed tridymites.

Intergrowth oxides, like Aurivillius, Ruddlesden–Popper phase, comprise functional layers and exhibit interesting physical properties. The hitherto known intergrowth structures mainly were composed of closed‐packing of oxygen ions, and it is very challenging to develop new types of intergrowth structures. We proposed the possible match between the tridymite and grossite, both of which are purely tetrahedra‐based structures. We synthesized Ca2PbGa8O15 ((Ca0.5Pb0.5Ga2O4)2(CaGa4O7)) and its structure was solved by ab‐initio method. Pb2+ is vitally important to stabilize this first example of tetrahedra‐based intergrowth oxide. The appropriate size difference between Pb2+ and Ca2+ causes the layered type cationic ordering, and reduced the thermodynamic potential, in addition, the high hybridization between Pb 6s6p and O 2p orbitals further consolidate the covalency of the tetrahedra‐base framework.