Bombardment Induced Transport of Rb+ through a K+ Conducting Glass vs. K+ Transport through a Rb+ Conducting Glass

Abstract

Abstract The transport of rubidium ions and potassium ions respectively through rubidium and potassium ion conducting glasses has been investigated by means of the recently developed low energy bombardment induced ion transport (BIIT) approach. Here, the combination of a bombarder ion M1 (Rb+,K+) and a charge carrier ion M2 (Rb+,K+), in short M1@M2, defines a 2 × 2 matrix where the diagonal elements refer to the native ion transport, Rb+@Rb+ and K+@K+, while the off-diagonal elements refer to foreign ion transport, Rb+@K+ and K+@Rb+. The latter corresponds to the transport of rubidium ions through a potassium ion conductor and vice versa. The native ion BIIT yields the intrinsic ionic conductivities and activation energies for ion hopping in line with impedance spectroscopic data also presented. The foreign ion BIIT leads to the generation of diffusion profiles up to 100 nm into the glass sample as revealed by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The analysis of such depth profiles by means of Nernst–Planck-Poisson theory provides access to the concentration dependence of the diffusion coefficients. The concentration dependence of the potassium ion diffusion coefficient, D(K+), is markedly different for the rubidium glass vs. the potassium glass matrix. Within the error bars the concentration dependence of the rubidium ion diffusion coefficient, D(Rb+), is negligible in both glasses.