Dielectric, NMR and X-ray diffraction study of pseudo-one-dimensional Cs_1−x(NH₄)_xH₂PO₄

Abstract

Mixed crystals Cs_1−x (NH₄) _x H₂PO₄ of the ferroelectric CsH₂PO₄ (CDP) and the antiferroelectric NH₄H₂PO₄ were grown with x = 0.2 (CADP0.2) in solution. The structural properties of the crystal were analyzed by means of X-ray diffraction. Dielectric measurements at several temperatures and frequencies have been performed along the three crystallographic axes in this sample and also in the fully deuterated CADP0.2 sample (DCADP0.2). Dielectric and NMR experiments in a powdered sample were also performed. The shift of the transition temperature as a function of x and deuteration, and the changes in the properties of the different phases together with, the thermally-activated conductivity found in the paraelectric phase will be discussed and related with the several relaxation mechanisms measured in the NMR experiments.

Key Words:

• Phase transitions
• mixed crystals
• CADP