新型导电陶瓷Sm0.9Sr0.1Al0.5Mn0.5O3-δ的制备及其电性能研究

采用有机凝胶法结合固相烧结技术制备了Sm0.9Sr0.1Al0.5Mn0.5O3－δ (SSAM9155)新型导电陶瓷. 通过TG/DTA, FTIR, XRD, SEM和直流四引线法系统研究了凝胶前驱体的热分解及其相转化过程和烧结体的结构、相稳定性、微观形貌、电导率以及电输运机制. 结果表明, 凝胶前驱体在900 ℃焙烧5 h可以形成完全晶化的四方钙钛矿相纳米粉体; 高温烧结制得的SSAM9155陶瓷的电导率取决于p型电导, 电导率随温度的升高而增大, 导电行为符合p型小极化子跳跃机制; 随烧结温度的升高或保温时间的延长, SSAM9155陶瓷的电导率和相对密度都先增大后减小, 1600 ℃烧结10 h制得的SSAM9155陶瓷具有最高的电导率和相对密度(98%), 该样品在空气和氢气气氛中850 ℃时的电导率分别为8.21和1.26 S•cm－1, 表观活化能分别为0.265和0.465 eV. 具有较高电导率的Sr, Mn掺杂的SmAlO3导电陶瓷有望成为一种新型的固体氧化物燃料电池(SOFC)阳极材料.

Preparation and electrical properties of a new type of conducting ceramics Sm0.9Sr0.1Al0.5Mn0.5O3-δ

A novel conducting ceramics Sm0.9Sr0.1Al0.5Mn0.5O3－δ (SSAM9155) was prepared by the organic gel method combined with a solid state sintering technique. The thermal decomposition and phase inversion processes of the gel precursors, crystal structure, phase stability against reduction and microscopic morphology of the sinters were studied by using TG/DTA, FTIR, XRD and SEM. The electrical conductivities of sintered ceramics in both air and H2 were measured by the direct current four-wire method, and the electronic transport mechanism in this conducting ceramic was investigated. The experimental results show that the well-crystallized nanopowders with tetragonal perovskite structure can be obtained by calcining the gel precursors at 900 ℃ for 5 h. The electrical conductivity of SSAM9155 ceramics is dominated by P-type electronic conduction and increases with temperature, indicating that the mechanism of electronic transport is the hopping of p-type small polaron. With increasing calcination temperature and prolonging soaking time, both the electrical conductivity and relative density of SSAM9155 ceramics become larger initially and then decrease. The sample sintered at 1600 ℃ for 10 h has the highest relative density of 98% with electrical conductivity reaching 8.21 S•cm－1 in air and 1.26 S•cm－1 in H2 at 850 ℃. The apparent activation energies for SSAM9155 in air and H2 were calculated to be 0.265 and 0.465 eV, respectively. The Sr- and Mn-doped SmAlO3 with relatively high conductivity may be used as a potential anode material for solid oxide fuel cell (SOFC).