【摘要】 采用短时固相反应和放电等离子烧结(SR-SPS)方法,制备了单相多晶Ca3Co2O6陶瓷块,系统研究了制备条件及烧结工艺对Ca3Co2O6陶瓷块显微结构及热电性能的影响。研究表明,950℃下固相反应2 h即能得到单相树枝状,尺寸约1~3μm的Ca3Co2O6粉末,延长焙烧时间虽然对物相影响不大,但会引起粉末颗粒长大,不利于SPS烧结;SPS烧结温度强烈影响着Ca3Co2O6陶瓷块的制备,本实验范围内,Ca3Co2O6陶瓷块体的最佳制备条件为950℃固相反应2 h,SPS 900℃保温5 min,此时Ca3Co2O6陶瓷块具有p型半导体特性,电阻率ρ随温度的升高急剧下降,然后趋于平缓(高于600℃);Seebeck系数S随温度(100℃以上)升高稍有下降,热导率κ表现为先下降后增加,在500℃时仅为1.73 W.m-1.K-1。综合电性能与热性能结果,其无量纲因子ZT随温度升高呈上升趋势,在本实验范围内,于700℃下达到最高值0.02。更多还原

【Abstract】 Short-time solid reaction and spark plasma sintering method（SR-SPS） was used to prepare single-phase polycrystalline Ca₃Co₂O₆ ceramic bulk,and effects of preparation condition and sintering technology were investigated in detail.Single-phase dendritic Ca₃Co₂O₆ powders with grain size of about 1～3 μm were obtained under 950 ℃ for 2 h by solid-state reaction process,and prolonged reaction time could hardly influence phase structure,but it could make grain size growth,which is harmful for SPS sintering.Temperature of SPS strongly affects the preparation of Ca₃Co₂O₆ ceramic bulk.In our experimental range,the best condition for Ca₃Co₂O₆ ceramic bulk is to react under 950 ℃ for 2 h,and then sinter under 900 ℃ for 5 min by SPS.The bulk obtained by above technology shows character of p-type semiconductor,electrical resistivity ρ decrease sharply and then slightly,Seebeck coefficient S reduces,thermal conductivity κ decreases and then increases with increasing temperature,the minimum value of κ is 1.73(W·m^-1·K^-1) at 500 ℃.As a result,the figureless factor of merit ZT shows increasing trend and the maximum value of ZT reaches 0.02 at 700 ℃ in our experimental range.更多还原