Crystal Chemistry of Lithium Intermetallic Compounds: A Survey

The structural chemistry of lithium intermetallic compounds that are formed in Li–М binary systems where М = Ca, Sr, Ba, Mg, Zn, Cd, and Hg is surveyed. It is for the first time that the crystal structures of intermetallic compounds are classified in terms of polyhedral precursor metal clusters (in the program package ToposPro). The precursor metal clusters of crystal structures are identified using the algorithms of partitioning structural graphs into cluster structures and via the design of the basal 3D network of the structure in the form of a graph whose nodes correspond to the positions of the centers of precursor clusters. Tetrahedral precursor metal clusters M₄ are identified for the crystal structures LiZn₃-oC4, LiMg₃-hP2, LiCd₃-hP2, LiHg₃-hP8, (LiMg₃)(Li₂Mg₂)-tI16, Li₂Zn₂-cF16, Li₂Cd₂-cF16, Li₂Hg₂-cP2, Li₃Cd-cF4, and Li₃Hg-cF16; tetrahedral metal clusters M₄ are found for the framework structures with spacer atoms Sr(Li₂Sr₂)-tP20, Ca₂(Li₄)-cF24, and Ca₂(Li₄)-cP12; tetrahedral metal clusters M₄ and rings M₆, for framework structures Ba₃Li₂(Li₁₀)-hP30 and Ba₃Li₂(Li₄In₆)-hP30; icosahedral metal clusters M13 for the framework structure Li(Zn₁₃)-cF112; bilayer tetrahedral metal clusters 0@М₄@M₂₂ for the framework structure Li₂₃Sr₆-cF116; and deltahedra М₁₇ and deltahedra М₃₀, for framework structures Sr₄Li₁₄ Sr(Sr₄Li₁₂)] (Sr₂ (Sr₈Li₁₈)]-tI252 and Ba₄Li₁₄ Ba(Ba₄Li₁₂)](Ba₂ (Ba₈Li₁₈)]-tI252. The scenario of crystal structure self-assembly from precursor metal clusters S₃⁰ in intermetallic compounds is reconstituted as: primary chain S₃¹→ microlayer S₃²→ microframework S₃³.