Synthesis of Rhenium–Scandia doped tungsten nanoparticles for shrinkage investigation

Abstract

Scandate cathode made out of tungsten nanoparticles have several advantages such as high current density, uniform emission, and long life over conventional cathode. Fabrication of porous tungsten pellet out of tungsten nanoparticles by pressing and sintering is a critical challenge. Cold pressing followed by sintering of nanoparticles results shrinkage of pellet size and uncontrolled porosity, which motivate us to work on sintering of nanoparticle. A new chemical synthesis approach was adopted for precisely controlling the powder particle parameters. The present technology relates to the preparation of an ultra-fine nano-scandate powder using chemical route, dissolving tungsten, and rhenium powder in special solvent under ultra-agitation, wherein the other constituents (such as Ba, Ca, Sc, and alumina) are uniformly distributed throughout the powder. Dissolving tungsten and rhenium in the solution, and further sol–gel process, resulted in the formation of spherical shaped particles. Nanoparticles were characterized using: (1) X-ray diffraction (XRD) for phase purity of powder, (2) Field Emission Scanning Electron Microscopy (FE-SEM) for particle size and distribution, (3) Scanning Electron Microscopy (SEM) to study the surface micro-features such as pore dimension and pore distribution and (d) Energy Dispersive Analysis of X-rays (EDAX) for elemental composition. The results showed that the powder has uniform grain size with an average particle diameter of ~100 nm. In this proposed work, rhenium has been co-doped with scandia doped tungsten nanoparticles in order to improve shrinkage. Addition of rhenium in scandia doped tungsten nanoparticles showed about 10% less shrinkage compared with scandia doped tungsten nanoparticle.