CVT GROWTH AND CHARACTERIZATION OF ZN1-XMNXCR2O4 SINGLE-CRYSTALS

Single crystals of Zn1-xMnxCr2O4 have been grown by the chemical vapour transport (CVT) technique using chlorine as the transport agent. The zinc chromite grew with little difficulty. The presence of manganese chromite liquid caused the ampoules to crack when the crystals rich in manganese were grown. In addition, when the spinels were grown with nominal starting compositions x > 0.5, the condensation of MnCl2 caused the crystals grown to be depleted in manganese. A thermodynamic study of the closed tube system has been done in order to determine the most favourable conditions for growth and calculate the ranges of temperature and chlorine pressure most suitable to avoid the segregation of manganese. Single crystals of different compositions were analyzed by X-ray diffractometric methods. Magnetic susceptibility measurements suggest a spin-glass-like behaviour which is explained by the existence of a cluster-glass state.