Electrical Properties of Ag-In-(Yb,Ca) Quasicrystals and Their Approximants

Abstract

We report the electrical resistivity of the ternary Ag-In-(Yb,Ca) quasicrystals (QCs) together with those of their 1/1 and 2/1 cubic approximants. The temperature coefficient of the resistivity (TCR) is negative and nearly the same for the QCs and the 2/1 approximants suggesting that the coherence length of the conduction electrons in the QCs is comparable to the lattice parameter of the 2/1 approximants, i.e., ~2.5 nm. On the other hand, both positive and negative values of TCR are observed for the 1/1 approximants depending on the annealing temperature. Taking into consideration the occurrence of positive TCR in the binary Cd-(Yb,Ca) 1/1 approximant, the latter phenomenon suggests that the negative TCR of the ternary 1/1 approximants is due to chemical disorder between Ag and In, and the chemical disorder is possibly reduced when annealed at low temperatures.