Effect of structure and composition on the DC-conductivity in calcium phosphate glasses of the type x CaO ⋯(55 − x) M2O ⋯ 45 P2O5 (M = Na, K, Rb, Cs)

• Investigation of ionic conductivity in alkali (Na, K, Rb, Cs) — calcium–phosphate glasses
• Correlation of structural parameters (ionic radii, density) and function (Tg, σDC, Eact)
• Conductivities depend on relative ionic radii of M+ and Ca2 +.
• Large M+ ions contribute to a widening of the glass network.

The ion transport properties of calcium phosphate glasses (CaXY, X = 40,30,20; Y = Na,K,Rb,Cs) have been investigated by means of the bombardment induced ion transport (BIIT) technique. A systematic variation of the identity of the alkali ion as well as its molar content has been considered. The DC conductivity increases with increasing molar content of the alkali ion, the activation energy and the glass temperature decrease. For the Ca40Y glass the conductivity decreases in the order Na > K > Rb > Cs. For the Ca20Y glass the trend of conductivities follows the order Cs > Na > Rb > K. The effect of the identity of alkali ion is connected to its radius relative to that of the Ca2+.