Study of ferroelectric–paraelectric phase transition of RbH2AsO4 single crystals by 87Rb NMR relaxation time measurements

The temperature dependences of the resonance frequency, line width, and spin–lattice relaxation time T 1 of the ferroelectric and paraelectric phases of RbH 2 AsO 4 crystals are investigated. The 87 Rb NMR line at the phase transition temperature T C (=110 K) splits into two lines, which indicates the occurrence of phase transition from tetragonal to orthorhombic phase. In addition, T 1 for the 87 Rb nucleus undergoes remarkable changes near T C , which indicates drastic alterations of the spin dynamics at T C . At T C , changes occur in the resonance frequency and T 1 , which are related to variations in the symmetry of the environments of the 87 Rb ions.