To transform maifanite powders from insulators to conductors by Sm gaseous penetration technology

Abstract

For the preparation of low-cost and eco-friendly conductive powders, a novel rare earth gaseous penetration technology was applied to modify maifanite powders. After 5-h penetration at 600 °C, the resistivity of Sm-modified maifanite powders has been greatly reduced from 1.95 × 1010 Ω m to 3.67 Ω m. And the resistivity characteristics of grain interior and grain boundary were discussed by analyzing the Nyquist plots and the impedance frequency characteristic curves. After penetration, the grain resistance and grain boundary resistance of maifanite were reduced to 50 Ω and 900 Ω, respectively. Furtherly, the composition and structure of Sm-modified maifanite powders were analyzed; then, the conductive mechanism of the materials was discussed in detail. SEM patterns showed that the fine particles in Sm-modified maifanite powders increased after penetration, which indicates that rare earth ions have a crushing effect on maifanite powders and improve the conductive properties of maifanite powders. XRD and XPS patterns showed that Ca2+ and Na+ ions were successfully replaced by Sm3+ ions, which is the main reason for improving the electrical conductivity of maifanite powders. Moreover, thermogravimetric analysis displays that Sm-modified maifanite powders have excellent thermal stability, which indicates their widely application prospect in electronic industry.