MAGNETIC AND MICROSTRUCTURAL STUDIES OF CA-HEXAFERRITE BASED GLASS-CERAMICS

X-ray diffraction, magnetisation and EPR measurements have been carried out on the glass-ceramic specimens of CaO-Fe//2O//3-B//2O//3 based glass systems. The results are explained on the basis of their microstructures. In a system, 13CaO-48Fe//2O//3-39B//2O//3, CaFe//2O//4 is found to crystallise as a magnetic phase having a surprisingly large magnetisation (85 emu/g). The actual composition of this phase is believed to be Ca//0//. //6Fe//2//. //4O//4 with Fe**2** plus and Fe**3** plus ions distributed among the different available sites in a particular way. CaFe//1//2O//1//9 and Ca//3Fe//1//5O//2//5 ferrites can be crystallised with useful magnetic properties in the systems containing (1 mol%) Ag//2O or P//2O//5 as nucleating agent. Incorporation of As//2O//3 (0. 1 mol%) in the P//2O//5 system gives rise to the crystallisation of Ca//3Fe//1//5O//2//5 particles in platelet shape.