An effective way to detect the secondary phase in Sr-doped LaInO3

Sr-doped LaInO3 and SrIn2O4 were synthesized using conventional solid-state reaction technique. The structures of La1-xSrxInO3-delta with different do pant concentration and La1-xSrxInO3-delta after annealing in reducing atmos pheres have been investigated using X-ray powder diffraction, Raman spectro scopy and electron diffraction. The XRD patterns of Sr-doped LaInO3 show mi nor changes and the intensities of the weak peaks related to secondary phas e increase with the dopant concentration. Raman spectra of Sr-doped LaInO3 exhibit obvious changes when Sr dopant concentration is greater than 10 mol %. Compared with the Raman spectrum of SrIn2O4, the appearance of new Raman -active modes in La1-xSrxInO3-delta originates from the appearance of SrIn2 O4. The effect of annealing in an oxygen partial pressure P-O2 = 10(-17) at m on Raman spectra of La0.9Sr0.1InO3-delta is equivalent to that of Sr-dopi ng at a high level, indicating the appearance of SrIn2O4 at this oxygen par tial pressure, whereas the information is not clear in the XRD pattern. It is suggested that Raman spectroscopy is much more sensitive than XRD. Elect ron diffraction study reveals that La0.9Sr0.1InO3-delta, calcined in low ox ygen partial pressure has a normal perovskite lattice, and indicates that t he absence of oxygen vacancy clusters, and defects are randomly distributed . In addition, a standard Raman spectrum of SrIn2O4 was obtained. (C) 2001 Elsevier Science Ltd. All rights reserved.