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Room temperature XRD patterns of different BP15 glass samples. BPP15A: as-quenched sample; BPP15B: sample treated at for ; BPP15C: sample electrically treated at with a dc voltage for ; BPP15D: sample electrically treated at with a dc voltage, now for .
Typical impedance dispersions measured on (a) BPP00 and (b) BPP10 glass samples at with a ac voltage.
Typical impedance dispersions observed especially for (a) BPP10 and (b) BPP15 glass samples after subsequent measurements at with the ac voltage. After a time period of about of electric field applied, a second semicircle appeared at intermediate frequencies, besides the spikelike electrode effect at the lowest ones.
Morphological aspects of a BPP15 glass sample after remaining subjected to a dc voltage at . Surface crystallization was observed and identified to correspond to a phase formation.
(a) Resistivity values measured at (using the dc electrometer) for while subjecting a BPP15 sample to a dc voltage (open symbols). (b) Subsequent impedance dispersions measured at with a ac voltage, just after switching off the above dc voltage. In (a), the behavior of the resistivity values corresponding to is also shown (closed symbols). Quantitative difference between the open-symbols curve versus the initial material resistivity (star symbol) at and the closed-symbols curve at especially includes, among other possible effects, the additional electrode contribution for the data with open symbols.
Glass transition and crystallization temperatures ( and ) extracted from the DSC analysis for all the studied glass compositions.
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