Experimental and theoretical investigation on tunable optical property of nanocrystalline Ca-doped CeB6

Nanocrystalline Ca-doped CeB6 powders have been synthesized via a solid-state reaction of CaO and CeO2 with NaBH4 under a vacuum condition. The Ca doping effects on phase composition, grain morphology and optical absorption properties of nanocrystalline CeB6 were investigated. As a result, all the synthesized nanocrystalline hexaborides are composed by single phase of CsCl-type structure. The grain size and morphology are very sensitive to the reaction temperature. The optical absorption result indicates that the absorption valley of nanocrystalline CeB6 shows a red-shift from 619 nm to 685 nm with increasing Ca doping content, which means the tunable optical absorption of nanocrystalline Ca-doped CeB6. In addition, a first-principles calculation has been used to reveal the origin of the tunable optical properties. It is found that Ca doping reduces the total kinetic energy of the electrons of CeB6 and leads to the absorption valleys shift to longer wavelength direction