X-ray diffraction, optical birefringence, and87Rb nuclear magnetic resonance spectroscopy of the paraelectric and antiferroelectric phases of Rb3DxH1-x(SO4)2

The antiferroelectric (AFE) phase transition of Rb3DxH1-x(SO4)2 was studied using x-ray diffraction, optical birefringence, and nuclear magnetic resonance. The orientation dependence of the resonance lines deduced from the quadrupole-perturbed 87Rb nuclear magnetic resonance of Rb3D(SO4)2 single crystals indicates slight deviations from the monoclinic symmetry in the paraelectric and the AFE phases. The dynamical critical exponents as deduced from measurements of the spin-lattice relaxation times depend on the deuteron concentration. Additionally, we have carried out x-ray single-crystal diffraction as well as optical birefringence measurements and find clear evidence for a structural phase…