Phase transition in caesium dihydrogen phosphate crystal with thallium impurities

Abstract

A mixed crystal between two one-dimensional hydrogen bonding crystals of caesium dihydrogen phosphate (CDP) and thallium dihydrogen phosphate (TDP), TDP, was studied by dielectric constant measurements of phase transition characteristics. Dielectric constant dependence on temperature in the TDP crystal was best fitted by a power-law equation of the form with = 1.43 for CDP, and = 1.39 and = 1.34 for TDP mixed crystals of x = 0.003 and x = 0.008 respectively. A quasi-one-dimensional Ising model was employed to explain the experimental observations in terms of the decrease in the intrachain interaction constant, , and the increase in the interchain interaction constant, , with increasing TDP impurity concentration x.