Conductivity study of a new protonic conductor Rb-1.12(NH4)(0.88)SO4 center dot Te(OH)(6)

Single crystals of Rb-1.12(NH4)(0.88)S4 . Te(OH)(6) were obtained by slow e vaporation at 300 K. Differential scanning calorimetry showed an anomaly at 418 K, two shoulders at 482 and 510 K and one strong peak at 517 K. X-ray diffraction shows that the first DSC peak at 418 K passes the material from paraelectric to ferroelectric phase. A conductivity study shows that the s houlder at 482 (which masks a second one at about 458 K) can be attributed to a superprotonic phase transition. Dielectric constant and dissipation fa ctor evolutions indicate that the peak at 458 K is probably due to a ferroe lectric-paraelectric phase transition. The strong peak at 517 K was attribu ted to the decomposition of the salt. (C) 2001 Elsevier Science B.V. All ri ghts reserved.