Features of conductivity of the intermetallic semiconductor $n$-ZrNiSn heavily doped with a Bi donor impurity

The crystal structure, distribution of the electron density of states, and the energy, kinetic, and magnetic properties of the intermetallic semiconductor $n$-ZrNiSn heavily doped with a Bi donor impurity have been investigated in the ranges $T$ = 80–400 K, $N^{\mathrm{Bi}}_D\approx$ 9.5 $\times$ 10$^{19}$ cm$^{-3}$ ($x$ = 0.005)–1.9 $\times$ 10$^{21}$ cm$^{-3}$ ($x$ = 0.10), and $H\le$ 0.5 T. It has been established that such doping generates two types of donor-like structural defects in the crystal, which manifest themselves in both the dependence of the variation in the unit cell parameter $a(x)$ and temperature dependence of resistivity $\ln\rho(1/T)$ of ZrNiSn$_{1-x}$Bi$_x$ ($x$ = 0.005). It is shown that ZrNiSn$_{1-x}$Bi$_x$ is a new promising thermoelectric material, which converts thermal energy to electric energy much more effectively as compared to $n$-ZrNiSn. The results obtained are discussed within the Shklovskii–Efros model of a heavily doped and strongly compensated semiconductor.