Significant increase of the ferroelectric phase transition temperature in partially deuterated KH2PO4 by proton irradiation

Abstract

The ferroelectric phase transition temperature was significantly raised by 5 K in partially deuterated KH2PO4 irradiated by a proton beam. Increase in the hydrogen bond length was indicated by the dielectric constant analysis. Deuteron nuclear magnetic resonance (NMR) measurements of the electric field gradient tensor showed atomic displacement after the proton irradiation, and P-31 NMR measurements of the chemical shift tensor revealed phosphorous displacement in the hydrogen-bonded direction and the PO4 tetrahedral distortion. Increase of the phase transition temperature can be closely related to the structural modification involving the hydrogen-bond geometry.