摘要
Triglycine sulphate （NH<sub>2</sub>CH<sub>2</sub>COOH）<sub>3</sub>·H<sub>2</sub>SO<sub>4</sub> is a well-known ferroelectric crystal widely used in pyroelectric application. Being monoclinic, its space group is P2<sub>1</sub> and its polarization direction is along the two-fold screw axis. Its Curie temperature （T<sub>c</sub>）is 49℃ and it crystallizes at room temperature. Above 49℃ the spontaneous polarization disappears
<正> Triglycine sulphate （NH2CH2COOH）3·H2SO4is a well-known ferroelectric crystal widely used in pyroelectric application. Being monoclinic, its space group is P21and its polarization direction is along the two-fold screw axis. Its Curie temperature （Tc）is 49℃ and it crystallizes at room temperature. Above 49℃ the spontaneous polarization disappears as
