Electrical conductivity dependence of Ni doped Sm0.95Ce0.05FeO3−δ on surface morphology and composition
Electrical conductivity dependence of Ni doped Sm0.95Ce0.05FeO3−δ on surface morphology and composition
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DOI：
10.1016/j.snb.2010.12.057
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发表时间：
2011-07
影响因子：
8.4
通讯作者：
Syed M. Bukhari;J. B. Giorgi
中科院分区：
文献类型：
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作者：
Syed M. Bukhari;J. B. Giorgi
Sm0.95Ce0.05Fe1−xNixO_3−δ材料被认为是还原气体传感的候选材料。从Ni掺杂浓度、表面形貌和相对表面原子比三个方面讨论了掺Ni的Sm0.95Ce0.05FeO3−δ钙钛矿材料的总电导率。以柠檬酸盐前驱体为原料，采用溶胶凝胶法制备了Sm0.95Ce0.05Fe1−xNixO3−δ(x=0-0.10)粉末，经单轴压制后，在1350℃下烧结4h，制得球状粉末。在新鲜球团中，Sm和Ni的相对表面原子比随镍浓度的增加而增加，而Fe和Ce的相对表面原子比随镍浓度的增加而降低，显示出Sm物种的偏析。相反，化学还原的球团显示出富铁的表面。用四探针法测量了新鲜、部分还原(700℃，5%(v/v)H2/N2下1h)和完全还原(1000℃，5%(v/v)H2/N2下1h)球团的电导率。在空气中，x=0.07和x=0.10的电导率最高。有趣的是，x=0.01-0.05的材料是n型导体，而x=0.07-0.10的材料表现出p型行为。由于表面形貌和表面元素组成的变化，1000°C下的还原处理使∼的电导率提高了5000倍。虽然相分离通常是有害的，但在这种情况下，简化的传感器在不牺牲重复性的情况下更灵敏。
Sm0.95Ce0.05Fe1−xNixO3−δmaterials are considered as candidates for sensing reducing gases. The total electrical conductivity of Ni doped Sm0.95Ce0.05FeO3−δperovskite materials is discussed in terms of Ni concentration, surface morphology and relative surface atomic ratios. Powders of formula Sm0.95Ce0.05Fe1−xNixO3−δ(x=0–0.10) were prepared from citrate precursors by using a sol gel method and were then pressed uniaxially and sintered at 1350°C for 4h to form pellets. In fresh pellets the relative surface atomic ratios of Sm and Ni increased while that of Fe and Ce decreased as a function of nickel concentration, showing the segregation of samarium species. In contrast, the chemically reduced pellets show Fe rich surfaces. The electrical conductivity of fresh, partially reduced (700°C under 5% (v/v) H2/N2for 1h) and fully reduced (1000°C under 5% (v/v) H2/N2for 1h) pellets was measured by the four probe DC method. Under air, x=0.07 and x=0.10 showed the highest electrical conductivity in the series. Interestingly the x=0.01–0.05 materials were n-type conductors while x=0.07–0.10 exhibited p-type behaviour. The reduction treatment at 1000°C enhanced electrical conductivities up to ∼5000 fold due to changes associated with surface morphology and surface elemental composition. While phase separations are usually detrimental, in this case the reduced sensors are more sensitive without sacrificing reproducibility.