Effect of a restricted geometry on thermal and dielectric properties of NH4HSO4 ferroelectric

Abstract

Heat capacity, thermal dilatation, sensitivity to pressure and permittivity of NH4HSO4 embedded into glass matrices with a pore size of 320nm and 46nm were studied. Large difference in the thermal expansion of both glass and ferroelectric leads to a “clamped” state of NH4HSO4 in nanocomposites and to the phase transition temperatures change. The restricted geometry does not effect on the order of successive transformations in NH4HSO4 but is accompanied by a significant reduction in entropy of phase transitions. The behavior of DTA-signal and permittivity show the expansion of the temperature range of the ferroelectric phase under hydrostatic pressure.