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Yuan C.L.,Guilin University of Electronic Technology | Luo Y.,Guilin Academy of Air Force | Zhou X.J.,Guilin University of Electronic Technology | Zhou C.R.,Guilin University of Electronic Technology | And 2 more authors.
Advances in Applied Ceramics | Year: 2013

The polycrystalline Ba1-xBixFe 0·9Sn0·1O3 (x50·1, 0·2, 0·3, 0·4 and 0·5) ceramics were prepared using a solid state reaction process, and the effect of Bi substitution on the microstructures and the electrical properties is investigated. The as sintered Ba1-xBixFe0·9Sn 0·1O3 ceramics showed the cubic perovskite structure with small amount of spinel BaFe2O4 and some residual Fe 2O3. As the Bi concentration increased, the ceramic grain size decreased and the pores or holes were reduced for the ceramics. The values of room temperature resistivity, thermistor constant and activation energy of the Ba1-xBixFe0·9Sn 0·1O3 thermistor ceramics, increasing with the rise of Bi content, were in the range of 1-1290 kΩ cm, 4469-7328 K and 0·385-0·632 eV respectively. The electrical properties of Ba 1-xBixFe0·9Sn0·1O 3 thermistor ceramics are mainly attributed to the contribution of grains, grain shells and grain boundaries by the impedance analysis. © 2013 Institute of Materials, Minerals and Mining. Source


Yuan C.-L.,Guilin University of Electronic Technology | Liu X.-Y.,Guilin University of Electronic Technology | Liu X.-Y.,Central South University | Chen G.-H.,Guilin University of Electronic Technology | And 3 more authors.
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2014

CuO and BaCo0.02 IICo0.04 III Bi0.94O3 co-doped Ba0.5Bi0.5Fe0.9 Sn0.1O3 thick films were fabricated by screen-printing technology. The phases, surface topologies and electrical properties of the thick films were characterized by X-ray diffraction, scanning electronic microscopy and AC impedance analyzer. The added CuO in thick films led to the decomposition of BaCo0.02 IICo0.04 III Bi0.94O3 compound and then the formation of non-perovskite bismuth barium oxides. A number of particle chains were observed in the thick-film thermistors and each particle in chains was composed of fine-grain Ba0.5Bi0.5Fe0.9 Sn0.1O3 and coarse-grain BaCo0.02 IICo0.04 III Bi0.94O3 with low melting. A lowest value of room-temperature resistivity was obtained for the thick-film composition containing 10% CuO. The resistivity drift of 2.3% with duration time about 300 h at aging temperature 150°C was observed for the film containing 4% CuO. The electrical properties of thick films were mainly attributed to the contribution of grain boundaries which showed the oxygen-vacancy conduction in low measured temperature range, and electron and oxygen-vacancy coupling conduction in high measured temperature region. Source


Yuan C.,Guilin University of Electronic Technology | Yang T.,Guilin University of Electronic Technology | Luo Y.,Guilin Academy of Air Force | Zhou C.,Guilin University of Electronic Technology | And 2 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2014

The thick film NTC thermistor of compositions Sr0.6Bi 0.4Fe0.6Sn0.4O3 + BaCo II 0.02CoIII 0.04Bi 0.94O3, synthesized by solid state reaction, were prepared by screen-printing on alumina substrate. The microstructures, composition dependent, impedance characteristics, self-heating behaviours and thermistor properties were investigated. The relation between logarithm of resistivity and reciprocal of absolute temperature for the thick film thermistor was almost linear for all the compositions studied. The room-temperature resistivity, thermistor constant and activation energy of the films decreased with increasing BaCoII 0.02CoIII 0.04Bi 0.94O3 content and were in the range of 18.2-945.7 Ω cm, 1,753-2,649 K and 0.151-0.228 eV, respectively. The thick films showed the nearest-neighbor hopping or variable-range hopping model depended on the compositions. Impedance analysis indicated that the resistivity value of the thick films was mainly ascribed to the contribution of grains. At higher BaCoII 0.02CoIII 0.04Bi 0.94O3 content, a good self-heating effect of one thermistor film was observed. © 2014 Springer Science+Business Media New York. Source


Yuan C.,Guilin University of Electronic Technology | Yang Y.,Guilin University of Electronic Technology | Luo Y.,Guilin Academy of Air Force | Yang L.,Guilin University of Electronic Technology | And 2 more authors.
Bulletin of Materials Science | Year: 2014

A novel (1-x)Ba0.7Bi0.3Fe0.9Sn 0.1O3-xBaCoII 0.02CoIII 0.04Bi0.94O3 (0.2 = x = 0.9) negative temperature coefficient (NTC) thick film thermistors with high thermistor constant was prepared by screen printing. The values of room-temperature resistivity, thermistor constant and activation energy of the thick film thermistors, increasing with the addition of Ba0.7Bi 0.3Fe0.9Sn0.1O3, are in the range of 35.5 ω.cm-1.34 Mω.cm, 2067-6139 K and 0.177- 0.527 eV, respectively. This means that the electrical properties of the thick films are adjustable at a wide range, depending on the compositions. Impedance analysis shows that the magnitude of thick film bulk resistance is mainly attributed to the contribution of grain boundary. © Indian Academy of Sciences. Source


Cheng J.,Guilin University of Electronic Technology | Yuan C.-L.,Guilin University of Electronic Technology | Luo Y.,Guilin Academy of Air Force | Yang Y.,Guilin University of Electronic Technology | And 2 more authors.
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2014

BaCo0.02 IICo0.04 III Bi0.94O3-BaSb0.04 Sn0.96O3 composite thick films were prepared by screen-printing technology. The microstructures and electrical properties of the thick films were characterized by X-ray diffractometry(XRD), scanning electron microscopy(SEM) and a digital multimeter. The results indicate that the composite thermistor films are still composed of perovskite-type BaCo0.02 IICo0.04 III Bi0.94O3 and BaSb0.04Sn0.96O3 phases. The denser and more even film surface was observed as the BaCo0.02 IICo0.04 III Bi0.94O3 content increasing. The sintering temperatures, room-temperature resistivity(ρ25), thermistor constant (β25/85) and activation energy (Ea) of the composite films, decreased as the BaCo0.02 IICo0.04 III Bi0.94O3 content increasing, are in the range of 870-1000 °C, 2.5 kΩ·cm-2.35 M Ω·cm, 2764-4030 K and 0.238-0.348 eV, respectively. Source

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