Grain size-dependent electrical resistivity of bulk nanocrystalline Gd metals

The electrical resistivity of the as-consolidated and coarse-grained bulk gadolinium (Gd) metals was studied in the temperature range of 3-315 K. The experimental results showed that with decrease in the grain size of Gd grains from micrometer to nanometer range, the room temperature electrical resistivity increased from 209.7 to 333.0 mO cm, while the electrical resistivity at the low temperature of 3 K was found to increase surprisingly from 16.5 to 126.3 mO cm. The room temperature coefficient resistivity (TCR) values were obtained as 39.2 ? 10-3, 5.51 ? 10-3 and 33.7 ? 10-3 K?1. The ratios of room temperature to residual resistivity [RRR ? r(300 K)/r(3 K)] are 2.64, 11.0, respectively, for the as-consolidated samples at 280 1C and 700 1C with respect to that of the coarse-grained sample. All results indicate the remarkable influence of the nanostructure on the electrical resistivity of Gd due to the finite size effect and large fraction of grain boundaries.