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(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Impedance spectroscopy and microstructure of lithium conductor Li1+x[Al xGe2-x(PO4 )3] glass ceramics

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Author(s):
A. M. Cruz [1] ; A. C. M. Rodrigues [2]
Total Authors: 2
Affiliation:
[1] Universidade Federal de S. Carlos. Departamento de Engenharia de Materiais. Laboratório de Materiais Vítreos
[2] Universidade Federal de S. Carlos. Departamento de Engenharia de Materiais. Laboratório de Materiais Vítreos
Total Affiliations: 2
Document type: Journal article
Source: Cerâmica; v. 53, n. 326, p. 180-186, 2007-06-00.
Abstract

The highly conductive Li1.5[Al0.5Ge1.5(PO4) 3] phase was obtained by a glass-ceramic route. To achieve different microstructures, the parent Li2O-Al2O3-GeO2-P 2O5 glass was submitted to double heat treatments. Glasses were first nucleated for different periods of time at the temperature of glass transition and then subsequently fully crystallized at 571 ºC. A glass-ceramic was also obtained by simple heat treatment at 618 ºC for 30 min. X-Ray diffraction analyses show that, after crystallization, the NASICON phase is the unique phase present. Electrical characterization was carried out by impedance spectroscopy, from room temperature to 120 ºC. Impedance complex plane plots of some samples reveal two semicircles, enabling the identification of two contributions to the total electrical conductivity, which was close to 10-5 S/cm at room temperature. Activation energy varied from 0.36 eV to 0.49 eV. Scanning electron microscopy analysis confirms that heat treatments with shorter nucleation time lead to samples with higher grain size. Moreover, electrical measurements show that samples with larger grain size present a higher ionic conductivity. (AU)