The ionic conductivity of alkali aluminum germanium phosphate glasses – comparison of Plasma CAIT with two electrode DC measurements

Abstract

The ionic conductivity of alkali aluminum germanium phosphates (MAGP) has been investigated by two different techniques, i.) a fs-Plasma-Charge Attachment Induced Transport (CAIT) approach and ii.) a classical two electrode DC approach. Amorphous MAGP samples of the composition M1.5Al0.5Ge1.5(PO4)3 M=(Li–Cs) have been synthesized by the melt-quenching technique. Comparison of fs-Plasma-CAIT and DC data reveal that the ionic conductivities as well as the activation energies for ion transport agree within the error margins of the experiment. While conventional expectation suggests that a DC approach should fail because of spontaneous charge carrier blocking, this work demonstrates that DC measurements are a simple tool for quantifying ionic conductivities provided that only a small amount of charge has been transported in total.

Manifestation of site energy landscapes for ion transport in borate glasses

“…impedance spectroscopy. 32,33 As a side note, D CAIT = D σ equals two times the standard tracer diffusion coefficient, D * ( cf. the ESI†).…”

“…As will be elaborated at a later point, the effective diffusion coefficients measured by the CAIT approach are identical to the diffusion coefficients D s , obtained from the low frequency limit of impedance spectroscopy. 32,33 Fig. 1 (A)-(C) Concentration profiles after the CAIT experiment Experimental concentration depth profiles (dashed lines) together with the result of NPP model calculations (solid lines) reflecting the best agreement between experiment and simulation.…”

“…The effective diffusion coefficients measured by the CAIT technique are equivalent to the diffusion coefficients, D σ , measured in the DC limit of impedance spectroscopy. 32,33 On the other hand pulsed field gradient NMR techniques rather measure a self-diffusion coefficient which is best comparable to a tracer diffusion coefficient D *. 73 Readers interested in the Haven ratio relating the tracer diffusion coefficient to D CAIT and D σ , are referred to the ESI †…”

“…As will be elaborated at a later point, the effective diffusion coefficients measured by the CAIT approach are identical to the diffusion coefficients D σ , obtained from the low frequency limit of impedance spectroscopy. 32,33…”

Energy landscapes in alkali aluminum germanium phosphate glasses as probed by alkali proton substitution

“…Three batches of alkali-aluminum-germanium-phosphate (AAGP) glasses with the general composition A 1.5 Al 0.5 Ge 1.5 (-PO 4 ) 3 (with A = Li-K) were synthesized via the melt-quenching method. 11,26 The educts of glass synthesis, A 2 CO 3 , GeO 2 , (NH 4 ) 2 HPO 4 and Al 2 O 3 were dried for 12 h at 120 °C in an oven. Stoichiometric amounts of the compounds were mixed with an agate mortar.…”