Cooperative phenomena of random electric dipoles in an amorphous matrix |
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Authors: | R. Braunstein K. Bärner |
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Affiliation: | Department of Physics, University of California, Los Angeles, CA 90024, U.S.A. |
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Abstract: | A ferroelectric phase transition has been observed for the first time in a series of glasses containing WO6-octahedra. The techniques of thermally stimulated depolarization currents were used to observe the transition from independent dipole behavior to cooperative behavior in this amorphous system as a function of concentration. These measurements yielded the activation energy ΔE=1.2eV, the pre-exponential τ0=2 × 10-22sec, and the dipole moment p?=1.3 × 10?15 esu cm for WO3 in Li2B4O7. A dipole moment bearing species due to Li2B4O7 was observed with ΔE=0.44eV and pre-exponential τ0=5 × 10?8 sec. The depolarization peaks of WO3 occur in the temperature range 265–275 K depending upon WO3 concentration and are pressure dependent with an initial slope of 2 × 10?5K dyne?1 cm2. A model was developed for a possible phase transition associated with a random “pseudo-spin” system in an amorphous matrix. |
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