BiInO3:: A polar oxide with GdFeO3-type perovskite structure

A new oxide, BiInO3, was prepared using a high-pressure high-temperature technique at 6 GPa and 1273 K. BiInO3 has the GdFeO3-type perovskite structure, but crystallizes in the polar space group Pna2(1). Structure parameters of BiInO3 were refined from laboratory X-ray powder diffraction data (Z = 4; a = 5.95463(7) angstrom, b = 5.60182(7) angstrom, and c = 8.38631(11) angstrom). BiInO3 shows a second-harmonic generation signal of about 120-140 times that of quartz. BiInO3 decomposes at ambient pressure on heating above 873 K to give In2O3 and Bi25InO39. No phase transitions were found between 140 and 873 K using differential scanning calorimetry and differential thermal analysis. Vibrational properties of BiInO3 were studied by Raman spectroscopy.