Structural Behaviour of Solid Solutions in the NdAlO3-SrTiO3 System

Single-phase mixed aluminates-titanates Nd1-xSrxAl1-xTixO3 (x = 0.3 / 0.9) were prepared from stoichiometric amounts of constituent oxides Nd2O3, Al2O3, TiO2 and strontium carbonate SrCO3 by solid-state reaction technique in air at 1773 K. Crystal structure parameters of Nd1-xSrxAl1-xTixO3 were refined by full-profile Rietveld refinement in space groups R (3) over bar c (x = 0.3, 0.5, 0.7 and 0.8) and Pm (3) over bar m (x = 0.9). Comparison of the obtained structural parameters with the literature data for the end members of the system NdAlO3 and SrTiO3 revealed formation of two kinds of solid solutions Nd1-xSrxAl1-xTixO3 with the cubic and rhombohedral perovskite structure. Morphotropic rhombohedral-to-cubic phase transition in Nd1-xSrxAl1-xTixO3 series occurs at x = 0.84. Based on the results obtained as well as the literature data for the parent compounds, the tentative phase diagram of the NdAlO3-SrTiO3 pseudo-binary system have been constructed.