New evidence of grain boundary phenomenon in Zn7Sb2O12 ceramic:: an analysis by impedance spectroscopy

Impedance spectroscopy technique was used to investigate electrical properties of Zn7Sb2O12, a new electroceramic. Electric measurements were performed in the frequency range from 5 Hz to 13 MHz and from room temperature to 600 degreesC. Zinc antimoniate Zn7Sb2O12 phase, an inverse spinel, was synthesized by the polymeric precursors method. Ceramic with a relative density of 95% of the theoretical density was prepared by sintering via constant heating rate, in air atmosphere. The date interpretation was realized by analysis of complex plane diagrams. Grain and grain boundary contributions to electrical response were identified. The conduction mechanism is of type electron hopping being the carrier of electron hole. Based on the electron hole presence and nanometric crystallites, the possibility of quantum confinement effect, e.g. photoluiminescence, in this material is proposed. (C) 2001 Elsevier Science B.V. All rights reserved.