Voltage dependence of resistivity(VDR)is a widely existing phenomenon insemiconducting ceramics, but there is no quantitative study on this phenomenon. Inthis note, the quantitative results of voltage dependence of re...Voltage dependence of resistivity(VDR)is a widely existing phenomenon insemiconducting ceramics, but there is no quantitative study on this phenomenon. Inthis note, the quantitative results of voltage dependence of resistivity insemiconducting ceramics are obtained from the grain boundary barrier model, andthe methods to decrease the voltage dependence of resistivity in sendconductingceramics are proposed.展开更多
The CeO2 modified SrTiO3 ceramics were prepared by conventional ceramic process. The SrTiO3 matrix and CeO2 additive were combined in following system:SrTiO3 +x(CeO2·TiO2), where x is the weight percent , of whic...The CeO2 modified SrTiO3 ceramics were prepared by conventional ceramic process. The SrTiO3 matrix and CeO2 additive were combined in following system:SrTiO3 +x(CeO2·TiO2), where x is the weight percent , of which x (wt%)=2,5, 10, 15, 20,25, and 30. The samples were sintered at 1400℃ for an hour in air. The Ce element in SrTiO3 ceramics is used as an impurity donor. The scanning electron microscopic (SEM) analysis and X-ray diffractive examination of SrTiO3 ceramics containing CeO2 indicated that there exists a Ce2O3 secondary phase (viz. glass phase) and it had solid solution solubility for impurities which decrease the semiconductive property of SrTiO3 ceramics , and weaken the oxidation of the surface of grain and thus increase the conductivity of the grains. The semiconducting ceramics process lightly distorted cubic structure at room temperature. This paper mainly gives a study of the conductivity of CeO2 modified SrTiO3 ceramics.展开更多
The constitution and firing-technology of Ni paste were experimentally investigated. The experimental resalts show that the contact resistance could be lowered by adding glass powder and Boron powder, respectively use...The constitution and firing-technology of Ni paste were experimentally investigated. The experimental resalts show that the contact resistance could be lowered by adding glass powder and Boron powder, respectively used as adhesive and antioxidant when the content of Ni powder is higher than 65wt% . By firing at 810 ℃ , Ni paste obtained could form a good ohmic contact to PTC ceramics, as shown by SEM iamges. In addition, we compared the electrical properties of PTCR ceramics measured with various electrodes and found that fired- Ni contact is superior to contacts made by fired-Al and sputtered-Ni.展开更多
Grain boundary barrier layer （GBBL） capacitors are widely used for their excellent physical properties. But since the invention of BaTiO<sub>3</sub> GBBL capacitor in the 1960s, no theory can quantitativ...Grain boundary barrier layer （GBBL） capacitors are widely used for their excellent physical properties. But since the invention of BaTiO<sub>3</sub> GBBL capacitor in the 1960s, no theory can quantitatively describe their physical properties, which has resulted in many problems in the design and manufacture of GBBL capacitors. In this note, on the basis of grain-boundary-barrier model, we quantitatively analyze the physical properties and their limits of GBBL capacitors, and thus make designs and study the methods to improve the properties of GBBL capacitors.展开更多
文摘Voltage dependence of resistivity(VDR)is a widely existing phenomenon insemiconducting ceramics, but there is no quantitative study on this phenomenon. Inthis note, the quantitative results of voltage dependence of resistivity insemiconducting ceramics are obtained from the grain boundary barrier model, andthe methods to decrease the voltage dependence of resistivity in sendconductingceramics are proposed.
文摘The CeO2 modified SrTiO3 ceramics were prepared by conventional ceramic process. The SrTiO3 matrix and CeO2 additive were combined in following system:SrTiO3 +x(CeO2·TiO2), where x is the weight percent , of which x (wt%)=2,5, 10, 15, 20,25, and 30. The samples were sintered at 1400℃ for an hour in air. The Ce element in SrTiO3 ceramics is used as an impurity donor. The scanning electron microscopic (SEM) analysis and X-ray diffractive examination of SrTiO3 ceramics containing CeO2 indicated that there exists a Ce2O3 secondary phase (viz. glass phase) and it had solid solution solubility for impurities which decrease the semiconductive property of SrTiO3 ceramics , and weaken the oxidation of the surface of grain and thus increase the conductivity of the grains. The semiconducting ceramics process lightly distorted cubic structure at room temperature. This paper mainly gives a study of the conductivity of CeO2 modified SrTiO3 ceramics.
文摘The constitution and firing-technology of Ni paste were experimentally investigated. The experimental resalts show that the contact resistance could be lowered by adding glass powder and Boron powder, respectively used as adhesive and antioxidant when the content of Ni powder is higher than 65wt% . By firing at 810 ℃ , Ni paste obtained could form a good ohmic contact to PTC ceramics, as shown by SEM iamges. In addition, we compared the electrical properties of PTCR ceramics measured with various electrodes and found that fired- Ni contact is superior to contacts made by fired-Al and sputtered-Ni.
基金Project supported by the Educational Commission of Zhejiang Province
文摘Grain boundary barrier layer （GBBL） capacitors are widely used for their excellent physical properties. But since the invention of BaTiO<sub>3</sub> GBBL capacitor in the 1960s, no theory can quantitatively describe their physical properties, which has resulted in many problems in the design and manufacture of GBBL capacitors. In this note, on the basis of grain-boundary-barrier model, we quantitatively analyze the physical properties and their limits of GBBL capacitors, and thus make designs and study the methods to improve the properties of GBBL capacitors.
