Ca₂ PbGa₈ O₁₅ : Rational Design, Synthesis, and Structure Determination of a Purely Tetrahedra-Based Intergrowth...

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 Ca₂ PbGa₈ O₁₅ ((Ca_0.5 Pb_0.5 Ga₂ O₄ )₂ (CaGa₄ O₇ )) 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.