Thermal transformation and ionic conductivity of ammonium ion-exchanger prepared from Na-4-mica

Ammonium ion exchange of Na-4-mica and thermal transformation of the ion-exchanger were investigated and the conductivities of the heated ion-exchangers were estimated. More than 95.4% of Na+ ions in the interlayer of the Na-4-mica could be substituted by NH4+ ions after repeating ion exchange four times. Almost of NH4+ ions remained in the interlayer at 700 degrees C and they were completely decomposed into protons at 900 degrees C. The conductivities of the ion-exchangers heated at 700-900 degrees C were 10(-7)-10(-6) S/cm at 700 degrees C. The conduction mechanism of the ion-exchangers heated at 700 and 800 degrees C was NH4+ ion migration in the interlayer and that of the ion-exchanger heated at 900 degrees C was proton migration. However, the contribution of residual Na+ ions to the conduction cannot be excluded. (C) 2010 Elsevier B.V. All rights reserved.ArticleMaterials Science and Engineering: B. 173(1-3):271-274 (2010)journal articl