کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1483023 | 1510492 | 2010 | 6 صفحه PDF | دانلود رایگان |

Oxyfluoride glass samples in the system SiO2–Al2O3–CaF2–SmF3 were produced by using the melt-quenched technique and the kinetics of non-isothermal crystallization of CaF2 nano-crystals has been investigated. Differential thermal analysis (DTA) has shown an exothermic peak at about 700 °C which was assigned to the CaF2 nano-crystals precipitation within the glass matrix as was identified by X-ray diffraction (XRD) analysis of the annealed glass samples. It was shown the Ozawa model is most suitable for describing the behaviour of non-isothermal crystallization of CaF2 nano-crystals within the glass matrix. The mean value of the Avrami exponent was found 1.16 which indicates the diffusion-controlled growth process of nano-particles in the glass system with zero nucleation rate as the single operative mechanism; the activation energy of the crystallization is Ed = 379 ± 25 kJ/mol (3.93 ± 0.26 eV). The activation energy of the nano-crystals growth was computed within the same model and agrees very well with the activation energy of the crystallization.
Journal: Journal of Non-Crystalline Solids - Volume 356, Issues 33–34, 15 July 2010, Pages 1631–1636