Abstract
Thermionic energy conversion is an ideal way of converting concentrated solar energy into electricity. Developing suitable emitter/collector materials, with optimum work functions whilst being able to withstand elevated temperatures under high vacuum conditions, is a major challenge. Rare-earth hexaborides have great potential as thermionic emitters due to their superior chemical stability and low work function values, lanthanum hexaboride (ϕ~2.60eV) and cerium hexaboride (ϕ~2.60eV). This study forms part of a series of investigations aimed at developing rare-earth hexaboride cathode materials. Methods used to synthesise, characterise and fabricate these materials are discussed together with electron emission results
Highlights
Using present state-of-art technologies, solar energy alone has the potential to generate 580TW to meet our energy demand [1]
A preliminary investigation was carried out to see the effect of excess boron on the quality of synthesised products
XRD patterns show that pure LaB6 was prepared at a temperature as low as 1250°C, whereas, pure CeB6 was produced at 1200°C
Summary
Using present state-of-art technologies, solar energy alone has the potential to generate 580TW to meet our energy demand [1]. They can be prepared by a simple borothermal method in which their oxides are reduced by boron [5, 6] This solid-state reaction process requires very high temperatures (1500-1700°C) and produces coarsegrained LaB6 and CeB6. The preparation of pure LaB6 or CeB6 at temperatures below 1300°C without any post-synthesis treatments using simple solid-state reactions is considered to represent a significant contribution to the present state-of-the-art approaches. The results are compared to those obtained for LaB6 in previous studies
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