SPINEL-STRUCTURE MAGNETIC SEMICONDUCTORS - SYNTHESIS AND CRYSTAL-GROWTH

The physicochemical principles of the synthesis and crystal growth of A(1-x)B(x)Cr(2)X(4) (A, B = Cu, Zn, Sn, Cd, Hg, Fe, Co; X = S, Se) cha lcogenide spinels are examined. The conditions for solid-state synthes is of chalcogenide spinels from elemental mixtures and binary compound s are optimized. The conditions for flux growth are chosen based on th e phase-diagram data for spinel-solvent systems, and the kinetics of m ass transport in chemical transport systems are examined. The effects of high temperatures and pressures on the structure and properties of chalcogenide spinels are studied. The stability fields of compounds cl ose in properties to the corresponding single crystals are mapped out. The purity of the starting materials is found to influence the photof erromagnetic effect in the magnetic semiconductor CdCr2Se4. The effect of annealing in various ambients on the physical properties of CdCr2S e4 crystals is examined. The results show that the properties of magne tic semiconductor crystals can be varied ire a controlled manner.