PHASE-TRANSITION IN C3H7NH3H2PO4 SINGLE-CRYSTAL

The ferroelastic phase transition in C3H7NH3H2PO4 (abbreviated as C(3) ADP) single crystal has been investigated by measurements of dielectri c constant, spontaneous polarization, far-infrared transmittance and R aman scattering. It has turned out that the ferroelastic phase transit ion in C(3)ADP occurs at 101.1 degrees C, and the point groups in the high and low temperature phases are mmm and 2/m, respectively. It is c onjectured that C(3)ADP single crystal belongs to the space group of P 2(1)/m or P2(1)/n (Z = 8) in the room temperature phase.