X-ray photoelectron spectroscopy (XPS) and FTIR studies of vanadium barium phosphate glasses

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• 作者：Abdelilah Majjane ; Abdelkrim Chahine ; Mohamed Et-tabirou ; Bousselham Echchahed ; Trong-On Do ; Peter Mc Breen
• 关键词：Glasses ; Differential scanning calorimetry (DSC) ; Fourier transform infrared spectroscopy (FTIR) ; X-ray photo-emission spectroscopy (XPS)
• 刊名：Materials Chemistry and Physics
• 出版年：15 January, 2014
• 年：2014
• 卷：143
• 期：2
• 页码：779-787
• 全文大小：1549 K

文摘

Barium vanadophosphate glasses, having composition 50BaO-xV₂O₅-(50聽鈭捖?em>x)P₂O₅, (x聽=聽0-50聽mol%), were prepared by conventional melt quench method. Density, molar volume and glass transition temperature (T_g) were measured as a function of V₂O₅ content. Structural investigation was done using XPS and FTIR spectroscopy. First, substitution of the P₂O₅ by the V₂O₅ in the metaphosphate 50BaO-50P₂O₅ glass increases the density and T_g and decreases the molar volume. When the amount of V₂O₅ increases, all these properties show a reverse trend. XPS measurement found in the O1s, P2p, and V2p core level spectra indicate the presence of primarily P-O-P, P-O-V and V-O-V structural bonds, the asymmetry in the P 2p spectra indeed arises from the spin-orbit splitting of P 2p core level, and more than one valence state of V ions being present. IR spectroscopy reveals the depolymerization of the phosphate glass network by systematic conversion of metaphosphate chains into pyrophosphate groups and then orthophosphate groups. Even though metaphosphate to pyrophosphate conversion is taking place due to breaking of P-O-P linkages, formation of P-O-V and P-O-Ba linkages provide cross linking between short P-structural units, which make the glass network more rigid. Above 10-20聽mol% V₂O₅ content, network is highly depolymerized due to the formation of orthophosphate units and V-O-V bridge bonds, resulting in poor cross-linking, making the glass network less rigid.