Low temperature synthesis of rare-earth hexaborides for solar energy conversion

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 (⏀~2.60eV) and cerium hexaboride (⏀~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.