Specific heat of ferroelectric schultenites

Abstract
Specific heat of PbHPO4, PbHAsO4, PbDPO4 and PbDAsO4 has been measured in 200 K. temperature ranges including the ferroelectric phase transition. Entropy change connected with the onset of spontaneous polarization is estimated and compared with the value calculated from dielectric measurements. PbHPO4 crystals grown by different methods differ very little in their thermal properties.