Abstract
The transparent willemite, Zn2SiO4 (ZS) glass–ceramic nanocomposites were prepared from melt-quench derived ZnO–Al2O3–B2O3–SiO2 (ZABS) precursor glass by an isothermal heat-treatment process. The generation of willemite crystal phase, size and morphology with increase in heat-treatment time was examined by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. The average calculated crystallite size obtained from XRD is found to be in the range 80–120nm. The decreased refractive index with increase in heat-treatment time attributed to partial replacement of ZnO4 units of willemite nanocrystals by AlO4 units and simultaneous generation of vacancies in the Zn-site. Fourier transform infrared (FTIR) reflection spectroscopy exhibits the structural evolution of willemite glass–ceramics. The photoluminescence spectra of Sm3+ ions exhibit emission transitions of 4G5/2→6HJ (J=5/2, 7/2, 9/2, 11/2) and its excitation spectra shows an intense absorption band at 402nm. These spectra reveal that the luminescence performance of the glass–ceramic nanocomposites is enhanced up to 14-fold with crystallization into willemite.
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