Optical studies of ferroelastic domain structures of LaGaO3and NdGaO3

Abstract

Abstract Crystal structures of rare-earth gallium oxide perovskites RGaO3, (R = La, Nd) have been studied by powder neutron diffraction and X-ray single crystal diffraction. The single crystals were grown by the Czochralski method. From power neutron diffraction we know that lanthanum gallium oxide, LaGaO3, is orthorhombic with space group Pbnm at room temperature and shows a first order phase transition at 425 K to a rhombohedral phase (R3c). The room temperature structure of neodymium gallium oxide, NdGaO3, has been determined by X-ray diffraction on a single domain crystal. The compound is orthorhombic with space group Pbnm. Polished samples with different thickness were studied by polarized light microscopy. The birefringence δn has been measured by orthoscopy and conoscopy versus wavelength and temperature. The orientation of the indicatrix has been correlated with the chemical unit cell. Further the absorption spectrum of Nd3+ in NdGaO3, at room temperature in the range of 400 nm ≤ Λ ≤ 800 nm was me...