Micro-Structure and Vibrational Mode of Complex Double Perovskite Oxides xLaAlO3 – (1-x)Ba(Mg1/2 W1/2 )O3

Abstract

The micro-structures and vibrational modes of complex double perovskite oxides xLaAlO3 – (1-x)Ba(Mg1/2 W1/2 )O3[LABMW] have been characterized for different values of x (0.10, 0.25, 0.50, 0.75 and 0.90). The materials are synthesized by the solid state reaction technique. The Rietveld refinement of the XRD patterns shows rhombohedral R3􀴤C(161) phase for LaAlO3 and cubic Fm3m (225) phases for Ba(Mg1/2W1/2)O3. XRD patterns show that with increasing the doping concentration ‘x’, rhombohedral phase gradually increases and cubic phase gradually decreases. A meticulous comparison of crystal structures and vibrational degrees of freedom in the light of change in doping concentration ‘x’ for LA-BMW has been carried out for accurate identification of crystal symmetry and distortions. From room-temperature comparative Raman spectra of the samples, different vibrational phonon modes have been assigned using group theoretical analysis together with experimental literature survey.