Effect of germanium doping on pyroelectric and piezoelectric properties of Sn(2)P(2)S(6) single crystal.

The results of the search for dopants to optimize the ferroelectric phase transition temperature and pyroelectric and piezoelectric properties of Sn(2)P(2)S(6) crystals are reported. Among all dopants only germanium causes a pronounced shift of the phase transition toward higher temperatures. The highest Curie temperature achieved by Ge doping is as high as 88 degrees C. The major advantage of the Ge-doped crystals as compared to pure Sn(2)P(2)S(6) is that the hydrostatic piezoelectric and pyroelectric response is kept high in a wider temperature range with much lower temperature dependence. The effects of the doping on pyroelectric and piezoelectric properties, characterizing the sensitivity of the material to thermal and hydroacoustic excitation, are discussed.