Synthesis of GdB6 nanostructures using nanosecond (Nd: YAG) laser: field emission investigation
We herein report field emission characteristics of GdB6 nanostructures grown directly on a pellet via laser processing (laser fluence ~ 6 J/cm2). The laser processed GdB6 pellet was characterized by X-ray diffraction, which revealed no change in phase upon laser processing. The values of the turn-on field required to draw emission current density of 1 μA/cm2 is found to be ~ 2.95 V/μm, for the laser processed GdB6 emitter. Furthermore, the Fowler-Nordheim (F-N) plot exhibits nonlinear behavior over the entire range of applied field and the field enhancement factor (β) calculated from slope of the F-N plot (low field region) was found to be ~ 543. The emission current stability over a period of 3h was observed to be fairly good. The observed results demonstrate that laser processing can be efficiently used to make GdB6 nanostructure emitter having potential for practical applications.
Single Step, Low-Temperature Synthesis of Submicron-Sized Rare Earth Hexaborides
The first ever synthesis of submicron-sized rare earth hexaborides (RB6; R = La, Ce, Nd, Sm, Eu, and Gd) with a cubic morphology has been obtained by the single-step synthesis of the RAPET (reaction under autogenic pressure at elevated temperature) technique at a relatively low temperature of 900 °C using metal acetate precursors. The synthesized materials have been characterized for their structural (XRD, XPS, and Raman) and morphological (TEM, HRTEM, and FESEM) properties. The XRD pattern confirms the phase purity and the formation of a single phase compound of rare earth hexaborides. Raman spectra elucidate the active vibrational modes of the hexaborides. The TEM and FESEM images clearly show that the hexaborides are submicron in size with a cubic morphology. The SAED patterns reveal the single crystalline nature of the products.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.