Single-phase polycrystalline CoSb3 skutterudite thermoelectric compounds have been synthesized by spark plasma sintering (SPS) and the thermoelectric properties including Seebeck coefficient, electrical resistivity and thermal conductivity are measured from room temperature to 800 K. The CoSb3 compound with relative density of 97.4% and grain size of about 100 nm is achieved under the sintering condition of 873 K for 5 min, and a maximum thermoelectric dimensionless figure of merit value of 0.095 is obtained at about 673 K.

The secondary electron emission properties of rare-earth-doped molybdenum emitter made by aqueous solution-solid doping method, its microstructure and surface behavior are discussed in this paper. The experimental results show that adding rare-earth oxides La2O3,Y2O3 and Gd2O3 into molybdenum raises the maximum secondary electron yield dm from 1.25 of clean Mo to 2.0-3.24 of doped molybdenum when heated to 1100-1600 8C in vacuum. With increasing percentage content of doped rare-earth oxide dm is enhanced in some extent. dm remains nearly constant during 1000h of test period when cathodes are operated at 1100 8C and under primary electron bombardment with bombarding energy of 1000 eVand bombarding power of 300W/cm2. This demonstrates such cathodes have good anti-bombing insensitivity. A work function of about 2.7-2.8 eV is obtained from Richardson lines. SEM observations and EDS analysis show that distribution of rare-earth oxides in the cathode body is inhomogeneous and tends to aggregate at molybdenum grain boundaries. By AES analysis it is found, that atomic concentrations of La and Yon the surface are about 2.5 times higher than in the bulk for a sintered body and further increase after activation.We believe the rare-earth atoms segregated at the grain boundaries diffuse along the grain boundary during the process of cathode activation. Therefore, the surface of the cathode is covered by a certain amount of rare-earth oxide. As a result, the secondary electron yield is improved.

用溶胶-凝胶（Sol-Gel）法制备了RE（RE=La，Y）-Mo复合氧化物粉末，工艺条件：初始溶液pH值=1，于550℃分解胶体，500℃，900℃2次还原粉末。采用XRD，TEM对还原后粉末的相组成、形貌、粒度进行分析。结果表明：500℃还原后，单质Mo衍射峰出现，RE以非晶态RE-O-Mo存在；900℃2次还原后，RE 以氧化物形式存在。红外光谱（FT-IR）分析结果表明，La和Y通过O与Mo键合，削弱Mo=O键，使稀土钼复合氧化物可还原性增强。TEM分析表明，还原后稀土钼粉末粒径在70nm左右。