Element allotropes and polyanion compounds of pnicogenes and chalcogenes: stability, mechanisms of formation, controlled synthesis and characterization

The application of the EnPhaSyn (theoretical Energy diagrams, experimental Phase formation, Syn-thesis and characterisation) concept is reviewed with respect to prediction of structures and stability of ele-ment allotropes and compound polymorphs, their phase formation and transition processes, and their directed synthesis, respectively. Therein, the relative energeti-cal stability (En) of target compounds and possible decomposition are determined from quantum chemical DFT calculations. Phase formation and transition (Pha) is probed by a gas balance method, developed as high temperature gas balance concept. It helped to study the synthe-sis and stability range of several compounds experimentally. Applications of the concept and synthesis principles (Syn) of non-equilibrium phases are pre-sented for allotropes of P, As, P1-x As (x), as well as binaryand ternary compounds including the Zintl and Laves like phases IrPTe, NiP 2, CoSbS, NiBiSe, Li (0.2) CdP (2), Cu3Cd-CuP10, and Cd (4) Cu (7) As.