New investigation within ZnO–TeO2–Bi2O3 system in air

A glass formation region in the ZnO–TeO2–Bi2O3 system at 800 °C has been synthesized. The glass transition and crystallization temperatures were studied by direct scanning calorimetry. The identification by X-ray powder diffraction of the phases appearing during crystallization revealed γTeO2 form in TeO2–ZnO pseudo-binary for 18 mol% ZnO content which transforms into the stable αTeO2 form at 500 °C. The compositions of the glasses, in the system treated at 450 °C reveal several phases. The value of refractive index of the compositions of some glasses is about 2.2. Their densities were also obtained. The investigation in the system at 750 °C by solid state reaction technique using XRD reveals two new phases: Bi4Te5Zn3O19 and Bi2TeZnO7. They crystallize with the monoclinic and triclinic symmetry, respectively.