The Influence of Donor-Doped Content on PTC Effect of Ba-Excess BaTiO3 Based Ceramics Fired in Reducing Atmosphere

2014 ◽  
Vol 1015 ◽  
pp. 425-429
Author(s):  
Xu Xin Cheng ◽  
Hai Ning Cui ◽  
Dong Xiang Zhou ◽  
Qiu Yun Fu
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Ptc Effect ◽  
Reducing Atmosphere ◽  
Donor Dopant ◽  
Temperature Resistivity

We investigated the influence of the Sm-doped contentration on the electrical properties and PTC effect of Ba-excess BaTiO3Based Ceramics, which were fired at 1300 °C for 30 min in a reducing atmosphere and then reoxidized at 850 °C for 1 h. The results showed that the donor dopant affected PTC characteristics and the electrical properties of the BSMT ceramics, whose room temperature resistivity first decreased and then increased with an increase in the Sm3+-doped content across the range from 0.1 to 0.5 mol%. The BSMT specimens exhibited a remarkable PTC effect, with a resistance jump greater by 2.7 orders of magnitude, along with a low room temperature resistivity of 128.6 Ω∙cm at the donor-doped content of 0.3 mol%. The influence of the donor dopant on the grain size of the as-fired samples has been also investigated.

Preparation of Ni/BaTiO3 Composites and PTC Effect

2007 ◽  
Vol 280-283 ◽  
pp. 341-344
Author(s):  
Xiao Lei Li ◽  
Yuan Fang Qu ◽  
Wei Bing Ma ◽  
Zhan Shen Zheng
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Ptc Effect ◽  
Reducing Atmosphere ◽  
Prepared Composite ◽  
Temperature Resistivity ◽  
Ntc Effect

Ni/BaTiO3 composite was prepared by decomposition of NiC2O4·2H2O/BaTiO3 precursor, which was prepared by precipitating of nickel in the form of oxalate into the BaTiO3 slurry. The composite must be sintered in reducing atmosphere. Otherwise NTC effect would be introduced. The prepared composite almost had no PTC effect. But PTC effect of the Ni/BaTiO3 composite can be effectively renewed by heat-treatment in air. Under a proper composition and method, the composite shows low room-temperature resistivity (ρRT=6.0 Ω·cm) and obvious PTC effect (ρmax/ρmin=102).

The Influence of Sintering Atmosphere and Reoxidation Temperature on the Electrical Properties of the Chip-Type Ba1-xSmxTiO3 Based Ceramics

2014 ◽  
Vol 900 ◽  
pp. 134-137
Author(s):  
Xu Xin Cheng ◽  
Dong Xiang Zhou ◽  
Qi Jun Xiao ◽  
Zhao Xiong Zhao
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Sintering Atmosphere ◽  
Reducing Atmosphere ◽  
Chip Type ◽  
Ptcr Effect ◽  
Temperature Resistivity

The PTCR characteristics of (Ba1-xSmx)TiO3(BSMT) with different donor-doped concentration (x) sintered in a reducing atmosphere and reoxidized in air are investigated. The results reveal that the room temperature resistivity (ρRT) of the semiconducting BSMT ceramics first decreases and then increases with increasing of thexvalues, especially whenxis 0.004, the semiconducting BSMT ceramics reoxidized at 850oC for 1 h after sintering at 1300 °C for 30 min in a reducing atmosphere achieve a lower room temperature resisitivity of 82.6 Ωcm. in addition, the doped 0.1 mol% Sm3+BSMT samples fired at 1300 °C for 30 min in air exhibit remarkable PTCR effect with a resistance jumping ratio of 3.4 orders magnitude; moreover, a lower ρRTof the BSMT specimens sintered in a reducing atmosphere is obtained.

The Influence of Donor-Doped Content on PTCR Effect of (Ba1-xSmx)TiO3 Based Ceramics Prepared by the Reduction Sintering-Reoxidation Method

2014 ◽  
Vol 1015 ◽  
pp. 517-520
Author(s):  
Xu Xin Cheng ◽  
Zhao Xiong Zhao ◽  
Dong Xiang Zhou ◽  
Qiu Yun Fu
Keyword(s):  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Dopant Content ◽  
Reducing Atmosphere ◽  
Donor Dopant ◽  
Ptcr Effect ◽  
Temperature Coefficient Of Resistivity ◽  
Temperature Resistivity

We investigated the effect of the donor-doped content on the positive temperature coefficient of resistivity (PTCR) of (Ba1-xSmx)TiO3(BST) Based Ceramics that were sintered at 1300 °C for 30 min in a reducing atmosphere and re-oxidized at 850 °C for 1 h. The results indicated that the resistance jump first increased and then decreased with an increase of the donor-doped concentration. Moreover, the specimens achieved a low room temperature resistivity of 383.1 Ω·cm at a donor-doped content and exhibited a pronounced PTCR characteristics with a resistance jump of 3.1 orders of magnitude. Furthermore, the RT reisistivity of the samples reduced and increased with the increasing of the donor-dopant content in the range of 0.1−0.5 mol% Sm3+. In addition, the effect of the Sm3+-doped concentration on the grain size of the ceramics was investigated in our paper.

The Influence of Donor-Doped Concentration on the PTCR Characteristics of the Ban-xSmxTiO3 Based Ceramics Sintered in Reducing Atmosphere

2014 ◽  
Vol 881-883 ◽  
pp. 1031-1034
Author(s):  
Xu Xin Cheng ◽  
Dong Xiang Zhou ◽  
Zhao Xiong Zhao ◽  
Qiu Yun Fu
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Positive Temperature Coefficient ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Reducing Atmosphere ◽  
Ptcr Effect ◽  
Temperature Coefficient Of Resistivity ◽  
Temperature Resistivity

Positive temperature coefficient of resistivity (PTCR) effect and electrical properties of (Ban-xSmx)TiO3(BSMT ) samples with different Ba-site/Ti-site ratio (n) and various concentration of the donor-doped Sm3+(x) sintered in a reducing atmosphere and reoxidized in air are investigated. The results show that the room temperature resistivity (ρRT) of the semiconducting BSMT ceramics first decreases and then increases with increasing of concentration of the donor-doped Sm3+, especially whenxis 0.005 mol, the ρRTof the BSMT ceramics is the lowest. Moreover, the ρRTof the Ba-excess BSMT (n= 1.01) specimens reoxidized at 800 oC for 1 h after sintering at 1270 °C for 30 min in a reducing atmosphere is lower than the Ti-excess ones (n= 0.99), in addition, the ρRTof the BSMT specimens increases with an increase of both sintering temperature and reoxidized time.

Characterization of 6H-SiC Single Crystals Grown by PVT Method Using Different Source Materials and Open or Closed Seed Backside

2009 ◽  
Vol 615-617 ◽  
pp. 19-22 ◽  
Author(s):  
Katarzyna Racka ◽  
Emil Tymicki ◽  
Marcin Raczkiewicz ◽  
Krzysztof Grasza ◽  
Michal Kozubal ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Single Crystals ◽  
Room Temperature ◽  
Experimental Methods ◽  
Room Temperature Resistivity ◽  
P Type ◽  
Source Materials ◽  
Type Crystal ◽  
Temperature Resistivity

n- and p-type 6H-SiC single crystals grown by PVT method using different charge materials – poly-SiC sinter or fresh SiC powder – have been studied. An open or closed seed backside during the growth processes have been applied. In the former, a distinct decrease backside etching of the seed was observed. Crystals have been extensively characterized with respect to their purity, quality and electrical properties using complex experimental methods. For the n-type boule an axially and radially homogeneous resistivity ~0.11 cm at 300 K was observed. Electrical properties of the p-type crystal, i.e., high room-temperature resistivity of 239 cm, were affected by compensation effects between residual donors (nitrogen and oxygen) and acceptors (mainly boron).

YBa2 Cu(3-x)CoxOy- A Substrate Material for YBCO Superconductors

1992 ◽  
Vol 275 ◽  
Author(s):  
J. D. Vienna ◽  
U. Balachandran ◽  
W. Cermignani ◽  
R. B. Poeppel ◽  
J. A. Taylor
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Electrical Properties ◽  
Room Temperature ◽  
Substrate Material ◽  
Nominal Composition ◽  
Room Temperature Resistivity ◽  
Cobalt Substitution ◽  
Ybco Superconductors ◽  
Temperature Resistivity

ABSTRACTThe physical properties of the ceramic YBa2Cu(3-x)CoxOy have been investigated in order to evaluate its usefulness as a substrate material for YBCO superconductors. YBa2Cu(3-x)CoxOy has been found to be thermally and chemically compatible with 123 and displays adequate electrical properties for a substrate material. A material with the nominal composition of YBa2Cu2.2CO0.8O7 was investigated, extensively. The mechanical properties of this material were found to be poor, e.g., tensile strength was only 60 MPa. A semiconductor-like behavior was observed with a room-temperature resistivity of 70 mμ.cm and a resistivity equal to 4 × 106 mn.cm at 77K. [ Key words: YBa2Cu3Oy, cobalt substitution, substrate, electrical properties, thermal properties, processing]

The Influence of Ba-Ti Ratio on the Electrical Properties and Microstructures of the BaM-0.007Sm0.007TiO3 Based Ceramics Fired in Reducing Atmosphere

2011 ◽  
Vol 415-417 ◽  
pp. 1032-1037
Author(s):  
Xu Xin Cheng ◽  
Dong Xiang Zhou ◽  
Qiu Yun Fu ◽  
Shu Ping Gong
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Reducing Atmosphere ◽  
Ptcr Effect ◽  
Temperature Coefficient Of Resistivity ◽  
Bst Ceramics ◽  
Better Than

Electrical properties, positive temperature coefficient of resistivity (PTCR), and microstructures of (Bam-0.007Sm0.007)TiO3(BST) with different Ba-site/Ti-site (A/B) ratio sintered in a reducing atmosphere and reoxidized in air are investigated. The results reveal that the room temperature resistivity of the semiconducting BST ceramics first decreases and then increases with increasing of A/B ratio (m), particularly when m is equal to 1.006, the semiconducting BST ceramics which have been sintered in a reducing atmosphere and reoxidized at 800°C exhibit significant PTCR effect with a resistance jumping ratio of 3 orders magnitude, and achieve a lower room temperature resisitivity of 80.8 Ω∙cm, in addition, the grain size distribution of the Ti-excess specimens is much better than that of the Ba-excess ones.

Effects of Glass-Additives on the Properties of Ni/Ceramic PTC Composites

2007 ◽  
Vol 280-283 ◽  
pp. 337-340
Author(s):  
Yuan Fang Qu ◽  
Hua Tao Wang ◽  
Xiao Lei Li ◽  
Wei Bing Ma
Keyword(s):  
Contact Resistance ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
Room Temperature Resistivity ◽  
Sintering Aids ◽  
Ptc Effect ◽  
Suitable Amount ◽  
Interface Contact ◽  
Temperature Resistivity

The effects of glass additives on the sintering and properties of Ni/(Ba0.92Sr0.08)TiO3 composites were investigated. Due to the addition of glass additives, Ni/ceramic composites with low room-temperature resistivity and obvious PTC effect were obtained at a low sintering temperature. It was shown that glass-additives could form liquid phase that aided the solution and diffusion of solid atoms, acting as sintering aids to accelerate the sintering and lower the sintering temperature. The room-temperature resistivity decreased first and increased later with the increasing content of glassadditives, which was explained by two functions of glass-additives, decreasing interface contact resistance as sintering aids and adding volume resistance as insulators. Moreover, a suitable amount of glass-additives could enhance the PTC effect unexpectedly, which was attributed to the decrease of the contact resistance existing at the ceramic/ceramic interface.

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