Effect of germanium doping on pyroelectric and piezoelectric properties ofSn2P2S6 single crystal

The results of the search for dopants to optimize the ferroelectric phase t ransition temperature and pyroelectric and piezoelectric properties of Sn2P 2S6 crystals are reported. Among all dopants only germanium causes a pronou nced shift of the phase transition toward higher temperatures. The highest Curie temperature achieved by Ge doping is as high as 88 degrees C. The maj or advantage of the Ge-doped crystals as compared to pure Sn2P2S6 is that t he hydrostatic piezoelectric and pyroelectric response is kept high in a wi der temperature range with much lower temperature dependence. The effects o f the doping on pyroelectric and piezoelectric properties, characterizing t he sensitivity of the material to thermal and hydroacoustic excitation, are discussed.