On the microwave conductivity of α-AgI part I: The effect of sample preparation
Abstract Differing microwave conductivity spectra of α-AgI have been measured and published by different authors. In the present paper, we report experimental evidence for the conclusion that this discrepancy is entirely due to different ways of sample preparation. In particular we confirm that α-AgI formed directly from the melt exhibits its d.c. conductivity, σ(0), at microwave frequencies. On the other hand, samples machined to their requisite shapes at room temperature and subsequently heated into the α-phase show a characteristic frequency dependence, σ(ω), which reflects surface properties of these samples. For an analysis of the electrical bulk properties of fast ionic conductors at microwave frequencies we therefore generally recommend the use of samples formed directly from the melt.