engleski

A Multiple Thermal Analysis of Ammonium Heptamolybdate Tetrahydrate

Crystalline powder of ammonium heiptamolybdate tetrahydrate (AHM) was studied by use of thermally stimulated charge (TSC), differential thermal analysis (DTA), permittivity and dielectric loss measurements in the range from 113 K to 300 K. TSC performed on d.c. poied samples resulted in a homocharge release with a discontinuity in the vicinity of 200 K. TSC carr ied out in heating-cooling cycles did not confirm a recent assumption of ferroelectric activity in AHM powder. TSC of the unpoled samples showed a peak at (280 ± 10) K indicating a phase transition. A similar result was obtained by DTA showing an endothermic peak at (260±4) K. epsilon(T) and tg delta(T) increased substantially above 200 K because o which is proibably the reason for the homocharge storage in poled samples.

ammonium heptamolybdate tetrahydrate ; thermally stimulated current

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