Ac conductivity and dielectric relaxation studies in the polycrystalline compound KYHP3O10

Polycrystalline samples of KYHP3O10 were obtained by heating a mixture containing K2CO3, Y2O3 and H3PO4 for 12 h at 553 K. The samples were characterized by X-ray diffraction and examined by impedance spectroscopy technique. Ac conductivity and dielectric relaxation in this compound have been evaluated. A break was observed in the curve of log sigma T versus 1000/T, accompanied at high temperature by a decreasing of activation energy and increasing of conductivity about 10 times higher than that of KDyHP3O10. These evolutions are strongly coupled to the structure modification. Dielectric relaxation is examined using the modulus formalism. The suitability of stretched exponential relaxation function has been investigated. The activation energies obtained from the impedance and modulus spectra are close, suggesting that the ionic transport in the material investigated is due to a hopping mechanism. (C) 1999 Elsevier Science Ltd. All rights reserved.