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.
A novel synthesis approach for scandia doped rhenium–tungsten mixed nanoparticles using a sol–gel method was developed by dissolving tungsten and rhenium powder in hydrogen peroxide.
The characterization result showed that the complete formation of the spherical shape, homogeneously mixed, phase pure nanoparticle with an average diameter of 100 nm without any contamination by other materials.
Shrinkage effect of tungsten pellet made out of nanoparticles was reduced.
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Shukla, S.K., Singh, A.K. & Barik, R.K. Synthesis of Rhenium–Scandia doped tungsten nanoparticles for shrinkage investigation. J Sol-Gel Sci Technol 95, 384–392 (2020). https://doi.org/10.1007/s10971-020-05253-8
- Dispenser cathode, rhenium doped tungsten nanoparticle
- Nanoparticle synthesis
- Sol–gel process
- Nano-Scandate Cathode (NSC)
- Pressing and sintering