Growth and structural investigations of La1-xPrxCaO3 solid solution single crystals

Abstract

Growth of single crystals in the pseudobinary LaGaO3-PrGaO3 system by the Czochralski and floating-zone methods was investigated. It has been found that solid solution crystals La1-xPrxGaO3 exist in the whole concentration range x, The segregation coefficients of Pr in LaGaO3 and La in PrGaO3 have been found to be k(eff)(Pr) approximate to 0.84 and k(eff)(La) approximate to 1.19. The structure of the crystals was investigated by X-ray diffraction method. With increasing Pr concentration x, the lattice parameters a and c decrease, whereas b remains almost constant, the volume of the unit-cell decreases. At x = 0.51 parameters a and b become equal and the crystal adopts a pseudo-tetragonal structure. The differential thermal analysis proved that the temperature of the first-order phase transition observed in LaGaO3 at similar to 150 degreesC rises linearly with Pr concentration I at the rate of 13.3 degreesC/Pr mol%. (C) 2001 Elsevier Science B.V. All rights reserved