Preparation, Characterization, and Ionic Conductivity of Novel Crystalline, Microporous Germanates, M3HGe7O16-xH2O, M = NH4+, Li+, K+, Rb+, Cs+; x = 4-6. 2

Shouhua Feng, Martha Greenblatt

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44 Scopus citations

Abstract

A series of crystalline, microporous germanates, M3HGe7O16.xH2O, M = NH4+, Li+, x = 6; M = K+, Rb+, Cs+, x = 4, were synthesized hydrothermally and characterized by powder X-ray diffraction, differential thermal analysis, and thermogravimetric analysis. Ionic conductivity in both hydrated and dehydrated samples was investigated by ac impedance in the temperature range 25-550 °C. The protonic conductivity is highest in (NH4)3HGe7O16.6H2O, 3.1 X 10−4(Ω cm)−1at 144 °C. The best ionic conductivity was found in Cs3HGe7O16, 2.0 X 10−3(Ω cm)−1at 400 °C. The ionic conductivity of dehydrated M3HGe7O16 increases and the activation energy decreases with increasing cation radius from room temperature to 500) °C. This behavior is consistent with a reduced Coulombic attraction between the mixed tetrahedral-octahedral (GeO4-GeO6) anion framework structure of the germanates and the cations located in their channels, compared with that in other zeolite-type compounds.

Original languageEnglish (US)
Pages (from-to)462-468
Number of pages7
JournalChemistry of Materials
Volume4
Issue number2
DOIs
StatePublished - Feb 1 1992

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry

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