| A series of new low expansion conductive oxide ceramics, including ZrO2(TiO2)-Ta2O5,Sb2O3(Ta2O5, Cr2O3)-SnO2,R2O3-TiO2-Cr2O3 systems are studied in this paper. These low expansion conductive oxide ceramics are synthesized by solid sintering method. The conductivity, thermal expansibility, rnicostructure morphology are investigated by insulated resistance device, thermal dilatometer (TD), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanism of low expansion and the influence of composition and structure on conductivity are discussed. Results are indicated as follow:In Ta2O5 matrix conductive ceramics, the ZrO2-Ta2O5 ceramic system displays low thermal expansibility. When X (the metal atom mole percent) increases from 13% to 66.6%, thermal expansion coefficient changes from 0.82 to 6.22×10-6K-1 which increases as X increases; The ceramics display negative thermal expansibility when X is smaller than 13%. When X is between 2.0% and 10%, the thermal expansibility ranges from -3.231×10-6K-1 to -4.730×10-7K-1.Ga2O3-Ta2O5 ceramics show negative thermal expansion when X changes from 4.0% to 10%, its thermal expansibility changes from -1.43×10-7K-1 to -2.41×10-6K-1. The TiO2-Ta2O5 sysytem has low thermal expansibility which is smaller than 2.5×10-6K-1 when X ranges from 2.0% to 20%.Conductivity of the ZrO2-Ta2O5 ceramic at 820℃increases before X gets to 16% and reaches a peak value of 0.385×10-3S/cm at X=16%. The conductivity reduces when X gets bigger. The activation energy from 200℃to 820℃at this point is 0.90eV.Conductivity of the TiO2-Ta2O5 sysytem at 820℃increases first and then decreases when X ranges from 2.0% to 20%. It changes from 0.261 to 2.422×10-3S/cm in this area and gets to a highest value at X=4.2%. The activation energy from 200℃to 820℃at this point is 0.77eV.In SnO2 matrix conductive ceramics, the Sb2O3-SnO2 system has conductivities between 0.25 and 3.013×10-3S/cm at 820℃when X ranges from 0.5% to 3%. Its conductivity reaches a peak value of 3.013×10-3S/cm at X=1.70%. The activation energy from 30℃to 400℃is 0.04eV and it is 0.22eV from 400℃to 800℃at this point. The thermal expansion of this system ranges between 4.0 and 4.7×10-6K-1. Conductivity of the Ta2O5-SnO2 system at 820℃ranges from 0.44 to 9.42×10-3S/cm. When X equals to 1.6%, the conductivity gets to 9.42×10-3S/cm which is the highest value. The thermal expansion of this system ranges between 2.81 and 4.42×10-6K-1.The conductivity of the Cr2O3-SnO2 system at 820℃first increases and then decreases between 0.22 and 3.37×10-3S/cm as X ranges from 15% to 83%. The peak value is 3.37×10-3S/cm when X is 55.56% and the activation energy from 200℃to 820℃at this point is 0.99eV. Its thermal expansion ranges from 4.5 to 6.7×10-6K-1.The TiO2-Cr2O3 system has high conductivity at 820℃. The value ranges from 1.1 to 62.7×10-3S/cm when X changes from 5% to 95%. When X equals to 29.41%, the conductivity reaches a peak value of 62.7×10-3S/cm. Its thermal expansion ranges between 5.8 and 8.5×10-6K-1.In the R2O3-TiO2-Cr2O3 system, Al2O3, Y2O3,La2O3 are doped to take the place of TiO2 at 20%, 40%, 60% and 80%. Its conductivity at 820℃ranges from 0.29 to 4.75×10-3S/cm and the thermal expansion changes from 5.78 to 7.35×10-6K-1.In the Ta2O5-Sb2O3-SnO2 system, Ta2O5 and Sb2O3 are doped equally in percentage from 0.5% to 2.5%. Its conductivity at 820℃ranges from 0.34 to 1.78×10-4S/cm and the thermal expansion changes from 4.17 to 4.75×10-6K-1.The conductivity at 820℃of the Sb2O3/CuO-Cr2O3-SnO2 system ranges from 0.06 to 4.17×10-3S/cm and thermal expansion changes from 3.74 to 6.29×10-6K-1.
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