The preparation and composition design of boron-rich lanthanum hexaboride target for sputtering

Abstract

Lanthanum Hexaboride (LaB6) nano-film has been proved to be promising transparent thermal insulation material, while its properties are limited on purity and composition. High-purity LaB6 polycrystalline powder was prepared through boron carbide reduction method in this work. A series of techniques such as scanning electron microscopy, X-ray diffraction, laser particle analyzer and inductively coupled plasma emission spectrometer were employed to characterize LaB6 powder. As raising the content of La2O3 in reactants, more uniform, finer (2.686μm) and purer (99.5139wt%) LaB6 powder is prepared, with only 0.4434wt% residual B4C. The density of targets increases with the rise of sintering temperature and the extension of sintering time, while crystallite size increases simultaneously with the extension of sintering time. The introduction of B powder in target is conductive to sintering process, increasing hardness and flexural strength of targets. X-ray photoelectron spectrometer was used to characterize the composition and microstructure of LaB6 nano-film which is tentatively considered to be composed of LaB6 nanocrystalline and amorphous microstructure of La and B atoms. The film LaB6.0627±0.02 was obtained when the ratio of B and La of sputtering target reached 12.5. The thickness and deposition rate decrease with the increase of B content in targets.