钆掺杂氧化铈纳米材料的碳酸盐共沉淀法合成及导电性能研究

Carbonate Co-precipitation synthesis and Ionic conducting properties of Gd-doped CeO_2

采用碳酸氢铵共沉淀法合成了Ce0.8Gd0.2O2-δ(GDC)纳米材料,并用交流阻抗谱技术研究其氧离子导电性能。XRD研究结果表明,经过600℃的热处理,共沉淀产物转变为具有单一立方萤石结构的CeO2超细粉体。在300MPa下将其压制成陶瓷坯体,分别在1150～1300℃下等温烧结4h。研究发现,1250℃烧结4h后,相对密度达到96.7%,其电导率在所有烧结样品中最高,600℃下氧离子电导率为1.1×10-2S/cm,在350～600℃温度范围内其氧离子电导活化能为0.63eV。对于碳酸氢铵共沉淀法制备的GDC纳米材料,1250℃致密化烧结是一个比较适宜的温度,烧结温度过高电导率反而下降。

The solid electrolyte, Ce0.8 Gd0.2 O2.0-δ （GDC） was successfully prepared via a carbonate co-precipitation reaction using ammonium hydrogen carbonate as precipitant. XRD revealed that the co-precipitation powder had a single cubic fluorite structure of ceria after calcined at 600℃ for 2 h. Ceramics with different densities and grain sizes were obtained after sintered at different temperatures. A relative density of 96.7% was obtained after sintered at 1250℃ for 4h. AC impedance spectroscopy results revealed that the 1250℃ sintered GDC ceramic provided the highest oxygen ionic conductivity of 1.1 × 10^-2 S/cm at measuring temperature of 600℃ in all sampies, together with the lowest activation energy of conductance of 0.63 eV in the measuring temperature range of 350-600℃. 1250℃ was an appropriate sintering temperature for GDC nano-materials synthesized via a carbonate co-precipitation method, further higher sintering temperature would lower the ionic conductivity.