Phase Relationship of CsH[sub 2]PO[sub 4]–CsPO[sub 3] System and Electrical Properties of CsPO[sub 3]

The dehydration behavior of the paraelectric phase of was investigated by thermogravimetric and X-ray diffraction analyses, and then the phase diagrams of system were established. The relationship between the onset temperature of dehydration and the partial pressure of water is below . The thermodynamically stable phase just above is the fully dehydrated product , although partially dehydrated products transiently appeared in the course of the dehydration to . Such developments allowed us to complete the temperature-humidity phase diagram and to regard the composition-temperature phase diagram as the eutectic type. This paper also reports the phase transition and electrical properties of examined by differential thermal analysis, ac impedance spectroscopy, and dc polarization measurement. The just-synthesized showed the relatively high electrical conductivity in unhumidified Ar. Ionic conductivity as high as was observed on heating from . Such high ionic conductivity disappeared after first heating up to and was explained by the proton diffusion through the absorbed . At around , a high-temperature phase of showed the electrical conductivity as high as . However, this conductivity was not purely ionic.