2024-02-152024-02-152021FERREIRA, K. D. et al. Phase stability and properties of Bi6Te2O13+δ (δ = 0 or 2). Physica B: condensed matter, Amsterdam, v. 605, e412780, 2021. DOI: 10.1016/j.physb.2020.412780. Disponível em: https://www.sciencedirect.com/science/article/pii/S0921452620307535. Acesso em: 6 fev. 2024.0921-4526e- 1873-2135https://www.sciencedirect.com/science/article/pii/S0921452620307535The crystalline Bi6Te2O15 and Bi6Te2O13 phases with orthorhombic and cubic symmetries, respectively, were synthesized by solid-state reaction synthesis. A study of the thermal stability of both phases was carried out, being verified that the high temperature cubic phase can be kept at room temperature in a metastable condition during long time. The Raman scattering spectrum, optical reflectivity and photoluminescence emission of these phases were measured for the first time. The optical band gaps Eg = 3.29eV, for the orthorhombic phase, and Eg = 3.08eV, for the cubic phase, were calculated from the reflectivity spectra. Using the brick-layer model the electrical conductivity of a dense ceramic of Bi6Te2O15 was measured, taking in account the grain and grain-boundary effects.engAcesso RestritoBismuth tellurateBi6Te2O15Bi6Te2O13Cubic phaseThermal stabilityArtigo10.1016/j.physb.2020.412780