Selective excitation in transparent oxyfluoride glass-ceramics doped with Nd³⁺

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• 作者：G. Gorni^a ; J.J. Velá ; zquez^a ; G.C. Mather^a ; A. Durá ; n^a ; G. Chen^b ; M. Sundararajan^b ; R. Balda^c ; J. Ferná ; ndez^c ; M.J. Pascual^a ; ^{mpascual@icv.csic.es}
• 关键词：Oxyfluoride ; Transparent ; Glass-ceramics ; Neodimium ; Laser emission
• 刊名：Journal of the European Ceramic Society
• 出版年：2017
• 出版时间：April 2017
• 年：2017
• 卷：37
• 期：4
• 页码：1695-1706
• 全文大小：3850 K
• 卷排序：37

文摘

Transparent oxyfluoride nano-glass-ceramics have been prepared by melting-quenching and doped with five different Nd3+ concentrations (0.1–2 mol%) to obtain the most efficient 4F3/2 → 4I11/2,13/2 emission. It was observed by differential thermal analysis (DTA) that the addition of Nd3+ does not affect the crystallization mechanism which corresponds to a diffusion-controlled volumetric process that starts from a constant number of nuclei. Nevertheless, the presence of the dopant affects the kinetics due to the progressive increase of Tg on increasing the Nd3+ content. LaF3 crystals with a size between 9 and 12 nm are obtained after heat treatments at Tg + 20–80 °C as confirmed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM). Energy dispersive X-ray (EDX) analysis shows the incorporation of Nd3+ ions into the LaF3 nano-crystals. Judd-Ofelt analysis from the absorption spectra further demonstrate the incorporation of Nd3+ ions into the fluoride phase and the most relevant parameters such as radiative lifetime and stimulated emission cross-section are calculated. A detailed optical characterisation clearly shows that Nd3+ ions in the glass-ceramics are incorporated in both crystalline and amorphous phases. Low temperature site-selective emission and excitation spectra, together with the different lifetime values of the 4F3/2 state depending on the excitation and emission wavelengths, allow emission from Nd3+ ions in the LaF3 nanocrystals to be identified and correlated with the structural properties. As the Nd3+ concentration is increased beyond 0.1 mol%, a stronger quenching of lifetime is observed for Nd3+ ions residing in LaF3 crystals than for those dispersed in the glass matrix. This strong concentration quenching is explained by the much higher concentration of Nd3+ ions in the crystalline phase with respect to that in the glass matrix.