Structural and optical characterization of crystals obtained via solid state reactions in the In2O3–TiO2–Al2O3 pseudoternary system

Abstract

In this article, a synthesis of the compound In2O3–TiO2–Al2O3 (molar relation 3:4:1 and 5:8:1) at 1350 °C by solid-state reactions is described. The compounds were obtained after heat treatment at 1350 °C for two days. X-ray diffraction patterns indicate that the synthesized samples belong to the monoclinic crystal system with the space group C 2/m. An agglomeration of the crystals was observed by scanning electron microscopy for the heat-treated samples of either composition (S1HT and S2HT). Atomic quantitative analysis showed variations of the two compositions presented and TEM analyses confirmed that In3Ti2AlO10 crystals were formed. Partial nanocrystallization and irregularities can be observed in the micrographs. Both samples were polymorphic and presented chain discontinuities attributed to oxygen vacancies and/or distortions in the structure. UV–vis measurements were performed obtaining a band gap ~ 3.2 eV for all the samples analyzed. XPS analysis for S1HT and S2HT confirmed the expected oxidation of the compounds.