NASICON SOLID ELECTROLYTES .3. SODIUM CONDUCTIVITY ENHANCEMENT ALONG DOMAIN AND GRAIN-BOUNDARIES

Bulk, grain, and domain boundary sodium ion conductivity data are presented for NASICON single crystals and ceramics of composition Na//1// plus //x// plus //4//yZr//2// minus //ySi//xP//3// minus //xO//1//2 (x equals 0-3, y equals 0-0. 2). For silicate-rich compositions the 'crystals' are built out of domains and the conductance of the resulting domain boundaries are shown to determine the macroscopically observed conductivity. Grain boundaries in ceramics behave in a similar way. A structural explanation of the observed phenomena is suggested.