Phase stability and properties of Bi6Te2O13+delta (delta=0 or 2)

• Autor(a) principal: Ferreira, K. D.
• Data de Publicação: 2021
• Outros Autores: Gasparotto, G., Maia, L. J. Q., Reis, S. P. [UNESP], Araujo, E. B. [UNESP], Carvalho, J. F.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• DOI: 10.1016/j.physb.2020.412780
• Texto Completo: http://dx.doi.org/10.1016/j.physb.2020.412780; http://hdl.handle.net/11449/209214
• topic: Bismuth tellurate; Bi6Te2O15; Bi6Te2O13; Cubic phase; Thermal stability

The 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 E-g = 3.29eV, for the orthorhombic phase, and E-g = 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.