Band Gap Tailoring in Doped Alkaline-Earth Hexaborides: Advanced Materials for Neutron Detection Applications
HIRALES A. 1, MORTON R. 2, VASQUEZ V. 2, GRAEVE O. 1
1 University of California San Diego, La Jolla, United States; 2 University of Nevada, Reno, Reno, United States
Metal hexaborides (MB6) are a class of materials characterized by their good chemical stability, low work function, and high electron emissivity, making them excellent candidates for solar energy applications, electron emitters, coatings for electric components, refractory and high-wear resistant tools, and thermoelectric applications. Despite the numerous studies on the mechanical, electrical and thermal properties of these materials, little has been done to determine the effect of dopants on the overall electrical behavior of these ceramics. In this study, we describe the design and manufacturing of new 10B-enriched hexaborides for applications in radiation detection. The focus is principally on determination of the band gap by UV-Vis spectroscopy and conductivity with respect to dopant concentration for compounds Cax-1MxB6 and Srx-1MxB6 (x = 0, 0.1, 0.3, 0.5), where M can be Li, Na, or K dopants. Sample preparation consisted of diluting the hexaboride powders in ethanol, subjecting them to bath ultrasonication, and then performing their corresponding absorbance analysis. For such purpose, ethanol was used as a baseline comparative to determine the changes in the absorbance peak minima. The Tauc plot method was used to compare the optical bandgaps between blank and doped compounds. Results demonstrate that both the dopant type and concentration affect the band gap energies for CaB6 and SrB6, proving the feasibility of tailoring hexaboride properties under different dopant concentrations.