Growth and structure of strontium-doped LaGaO3

Abstract

A series of La1-xSrxGaO3 solid solution single crystal with x equals 0, 0.04 and 0.12 were grown by the Czochralski method and with x equals 0.01, 0.06 and 0.1 by the floating zone method. The segregation coefficient of Sr in LaGaO3 has been found to be keff (Sr) equals 1.25. The crystals were grown from the melt with stoichiometric Ga2O3 amount at a growth rate ranging from 2.5 mm/h for pure LaGaO3 to 1.2 mm/h for La0.88Sr0.12GaO3. The structure of these crystals was investigated by x- ray powder diffraction technique using CuK(alpha ) radiation. The diffraction patterns were analyzed by Rietveld refinement method. Crystals with strontium concentrations from x equals 0 to 0.1 crystallizes adopting Pbnm structure. It was found that deviation from the ideal perovskite structure decreases with rising strontium concentration, finally reaching centrosymmetric Ibmm structure at x equals 0.12. Orthorombic unit cell parameters c and b decreases whereas a increases with x. Thermal analysis proved that the temperature of the first order phase transition observed in pure LaGaO3 at 150 degrees falls to 126 degrees at x equals 0.01 and remains almost constant at higher x.