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A 55ZrF 4 ·17BaF 2 ·23NaF·5EuF 3 glass was densified under 1.5, 3.0, 4.5, 6.0, and 9.0 GPa at 250°C by using a 6–8 multi-anvil-type high-pressure apparatus. The densities of permanently densified glasses increased until exhibiting a maximum value around 3.0 GPa and then gradually decreased with further increasing pressure. Local structures around Zr 4+ , Eu 3+ , and Ba 2+ in the undensified and densified glasses were investigated by means of Raman spectroscopy, Eu 3+ fluorescence spectroscopy, and Zr–K, Eu–L III , and Ba–L III EXAFS spectroscopy. The EXAFS analyses revealed that the local structure around Ba 2+ changed remarkably with applied pressure, giving a pressure dependence similar to that of density, while the local structures around Zr 4+ and Eu 3+ hardly changed. Therefore, it is concluded that the structural change around Ba 2+ , which is explained by a structural relaxation in the F − coordination environments around Ba 2+ under releasing applied pressure, is an origin of a peculiar high-pressure behavior observed in the present glass. |
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