Investigation of a high-temperature phase of 3Bi2O3·2TeO2 binary oxide

Phase Formation and Dielectric Characterization of the Bi2O3–TeO2 System Prepared in an Oxygen Atmosphere

“…Reinvestigations of the thermal behavior have shown the decomposition temperature to be 815°-827°C, with the melting point at 920°C. 17,18 Using Mössbauer spectroscopy, the tellurium has been found to be exclusively in the 6ϩ oxidation state below 815°C. In the temperature range between 815°and 900°C, the existence of an oxygen-deficient fluorite structure, Bi 6 Te 2 O 13 , which is similar to ␦-Bi 2 O 3 , has been revealed, and the 4ϩ oxidation state of tellurium has been indicated.…”

“…In the temperature range between 815°and 900°C, the existence of an oxygen-deficient fluorite structure, Bi 6 Te 2 O 13 , which is similar to ␦-Bi 2 O 3 , has been revealed, and the 4ϩ oxidation state of tellurium has been indicated. 18 A further review of studies on the Bi 2 O 3 -TeO 2 system reveals several inconsistencies. Room-temperature phases Bi 12 TeO 20 and Bi 16 Te 5 O 34 are reported to have been prepared under vacuum; 8 however, neither of the phases is included in the corresponding phase diagram.…”

Crystal structure and thermal behavior of Bi$$_6$$Te$$_2$$O$$_{15}$$: investigation of synthetic and natural pingguite

“…The compound Bi 6 Te 2 O 15 was prepared by solid-state reaction adapting the method reported previously (Sakai et al 1994). Starting materials were Bi 2 O 3 and TeO 2 (99.9% purity).…”

Bi6Te2-xRxO13 (R=Ti, Si, Ce) Systems: A Investigation for Fuel Cell Applications

“…The Bi2O3:TeO2 binary system presents many phases reported in the literature, although that for most of them there are no sufficient physical and chemical characterization. In particular, for the 3Bi2O3:2TeO2 composition there are two reported phases, the Bi6Te2O15 orthorhombic one, stable at room temperature, and the high temperature cubic phase Bi6Te2O13 [6,11,12]. This cubic-orthorhombic phase transition is accompanied by the oxidation of Te 4+ ions to Te 6+ ions, assimilating oxygen [11][12].…”

“…In particular, for the 3Bi2O3:2TeO2 composition there are two reported phases, the Bi6Te2O15 orthorhombic one, stable at room temperature, and the high temperature cubic phase Bi6Te2O13 [6,11,12]. This cubic-orthorhombic phase transition is accompanied by the oxidation of Te 4+ ions to Te 6+ ions, assimilating oxygen [11][12]. Ferreira et al reports that the cubic phase can be kept at temperatures up to approximately 500°C during long time in a metastable condition due to the imposition of kinetic mechanisms [12].…”