Growth and structural investigations of La1-xPrxCaO3 solid solution singlecrystals

Growth of single crystals in the pseudobinary LaGaO3-PrGaO3 system by the C zochralski and floating-zone methods was investigated. It has been found th at solid solution crystals La1-xPrxGaO3 exist in the whole concentration ra nge x, The segregation coefficients of Pr in LaGaO3 and La in PrGaO3 have b een found to be k(eff)(Pr) approximate to 0.84 and k(eff)(La) approximate t o 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 d ecreases. At x = 0.51 parameters a and b become equal and the crystal adopt s a pseudo-tetragonal structure. The differential thermal analysis proved t hat the temperature of the first-order phase transition observed in LaGaO3 at similar to 150 degreesC rises linearly with Pr concentration I at the ra te of 13.3 degreesC/Pr mol%. (C) 2001 Elsevier Science B.V. All rights rese rved.