Flux growth of (Ca,Ge) -substituted rare−earth iron garnets in the regular solution approximation

Abstract

The solubility parameters concept of regular solution theory has been extended to the growth from a PbO/B2O3 flux of (Ca,Ge) - substituted rare-earth iron garnets. Solubility parameters have been calculated for various oxides which are present in melts prepared for the LPE growth of these magnetic garnets. An excellent correlation is found between the logarithm of the distribution coefficient of a cation on the garnet dodecahedral sublattice ln Ki and the calculated partial molar heat of mixing of its oxide and the flux. The variation of the melt saturation temperature with type and quantity of solute oxide has also been calculated, as well as the variation of the saturation temperature with changes in flux composition. The small effect of La2O3 additions on the saturation temperature of PbO/B2O3 fluxed melts is easily understood in this thermochemical approach to LPE.