The effect of hydrostatic pressure on the dielectric constants, and their temperature dependences, of phosphate and tellurite glasses |
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Authors: | R N Hampton I T Collier H A A Sidek and G A Saunders |
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Institution: | School of Physics, Bath University, Bath, Avon, BA2 7AY, England |
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Abstract: | Measurements of the pressure dependence of the static dielectric constant of tellurite (pure TeO2 and 67%TeO2 + 33%WO3) and samarium phosphate (5%Sm2O3 + 95%P2O5 and 15%Sm2O3 + 85%P2O5) glasses at elevated pressures (0–70 kbar) for a range of temperatures (77–380 K) are reported. The electrical properties under pressure have been determined from the low-frequency complex plane analysis of glass discs contained within a Bridgman opposed anvil cell. The most notable observation is that the pressure dependence of the static dielectric constant, of all glasses studied, is positive, for example for vitreous TeO2 ln ε/P is equal to 4.41 × 10?11 (Pa?1) at 293 K. Behaviour of this type is common to a number of materials (plastics and chalcogenide glasses) for which it is not possible to define any long-range order. It is in direct contrast with the behaviour of crystalline insulators, for which ε/P is usually negative. The effect of pressure on the dielectric constant has been analysed using two different approaches based on the macroscopic Clausius-Mossotti equation. The effects of high pressure on the dielectric constant have been correlated with the temperature dependence of the dielectric constant at atmospheric pressure. |
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