PTC Behavior and Microstructure of Zn-Ni-Ti-O Ceramics

2010 ◽  
Vol 146-147 ◽  
pp. 1013-1016
Author(s):  
Yong Ping Pu ◽  
Yu Qin Mao ◽  
Ji Feng Wei
Keyword(s):  
Room Temperature ◽  
Spinel Phase ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Clear Cut ◽  
Temperature Coefficient Of Resistivity ◽  
Synthetic Routes ◽  
Temperature Resistivity

Zn-Ni-Ti-O system ceramics were prepared by solid state reaction method using two different routes. The positive temperature coefficient of resistivity (PTCR) behavior and microstructure were investigated in terms of different composition and synthetic routes. It was found that using ZnO, NiO and TiO2 as the starting materials (route A), the prepared ceramics exhibited low room temperature resistivity (ρRT was ~102 Ω•cm) and inferior resistivity jump (ρmax/ρmin<50) starting at the temperature when it began to rise. However, using ZnOss (Zn0.95Ni0.05O), NiOss (Ni0.55Zn0.45O) and spinel phase (ZnNiTiO4) as starting materials (route B), the ceramics revealed ρRT >103 Ω•cm and marked resistivity jump (ρmax/ρmin was ~102) starting at ~200 °C. The microstructure showed that the ceramics prepared by route B possessed clear-cut grain boundaries but the grains of ceramics prepared by route A were irregular shape and distribution.

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.

Electrical Properties of Nb-Doped and Nb-Mn-Codoped BaTiO3-(Bi0.5Na0.5)TiO3 Lead-Free PTCR Ceramics

2010 ◽  
Vol 67 ◽  
pp. 134-142
Author(s):  
Guo Rong Li ◽  
Sen Lin Leng ◽  
Liao Ying Zheng ◽  
Jiang Tao Zeng ◽  
Zhi Jun Xu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Lead Free ◽  
High Resistivity ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Conventional Solid State Reaction ◽  
Xrd Patterns ◽  
Temperature Resistivity

Nb-doped and Nb-Mn-codoped (1-xmol%)BaTiO3-xmol%(Bi0.5Na0.5)TiO3 (BBNTx) lead-free positive temperature coefficient of resistivity (PTCR) ceramics were prepared by the conventional solid state reaction method. The XRD patterns indicated that all BBNTx samples formed a single perovskite structure with tetragonal phase. 0.25 mol% Nb doped BBNT1 ceramic, sintered at 1330°C for 1h in air, had low room-temperature resistivity (ρ25) of 80 Ω•cm and a high resistivity jump (maximum resistivity [ρmax]/minimum resistivity [ρmin]) of 4.2 orders of magnitude with Tc about 152°C. The Nb-doped BBNTx (10≤x≤60) ceramics also showed distinct PTC effect with Tc between 185 and 232°C by sintering in N2, which was shut off when samples were cooled to a low temperature. In addition, The Nb-Mn-codoped BBNT1 ceramics exhibited higher resistivity jump than the single Nb-doped ones, with increasing the room-temperature resistivity.

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.

Electrical properties of polyethylene highly filled with carbon

1996 ◽  
Vol 11 (11) ◽  
pp. 2889-2894 ◽  
Author(s):  
F. A. Modine ◽  
A. R. Duggal ◽  
D. N. Robinson ◽  
E. L. Churnetski ◽  
M. Bartkowiak ◽  
...  
Keyword(s):  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Melting Transition ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Resistance Change ◽  
Carbon Blacks ◽  
Low Resistivity ◽  
Trade Offs ◽  
Temperature Coefficient Of Resistivity

Carbon-filled polyethylene composites were fabricated and tested to establish the practical lower limit of their electrical resistivity at room temperature and to investigate the trade-offs between low resistivity and the magnitude of the resistance anomaly (i.e., a large positive temperature coefficient of resistivity) that appears when such composites are heated through the polyethylene crystalline melting transition. Carbon blacks with large particle size and low surface area provided low-resistivity composites having large resistance anomalies. The largest resistance anomalies were found in composites that were well mixed, but the room-temperature resistivity also increased in composites that were cycled repetitively through the crystalline-melting transition. A mixture of carbon blacks of two different sizes provided a lower resistance than was found in a material with the same fill of only the coarser black. By controlling the composition and the processing, composites were made with room-temperature resistivities lower than 0.2 ohm cm and resistance changes of at least 2 orders of magnitude. A resistance change of as much as 5 orders of magnitude was obtained for composites with room-temperature resistivities of only 1 ohm cm.

Positive temperature coefficient of resistivity effect in Pb-doped KnbO3

2002 ◽  
Vol 17 (12) ◽  
pp. 2989-2992 ◽  
Author(s):  
Irena Pribošič ◽  
Darko Makovec ◽  
Miha Drofenik
Keyword(s):  
Phase Transition ◽  
Temperature Coefficient ◽  
Ferroelectric Material ◽  
Positive Temperature Coefficient ◽  
Cubic Phase ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Ptcr Effect ◽  
Temperature Coefficient Of Resistivity ◽  
Temperature Resistivity

KnbO3 is a ferroelectric material with a Curie temperature (TC) at 415°C, thus giving it the potential to be a material for high-temperature positive temperature coefficient of resistivity (PTCR) applications. In this study, we investigated the PTCR effect in donor-doped KnbO3 ceramics containing 0, 0.1, 0.2, and 0.3 mol% PbO. The donor-doped KnbO3 ceramics exhibited a PTCR anomaly with a relatively low room-temperature resistivity. The temperature of the tetragonal-to-cubic phase transition (TC) of the KnbO3 decreased with the amount of added PbO, while the orthorhombic-to-tetragonal phase transition (TOT) remained unchanged.

Quantitative calculation of barium vacancy formation mechanism effects on the room-temperature resistance and PTCR effect in donor-doped BaTiO3 ceramics

2016 ◽  
Vol 30 (27) ◽  
pp. 1650211
Author(s):  
Chao Fang
Keyword(s):  
Formation Mechanism ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Positive Temperature Coefficient ◽  
Vacancy Formation ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Quantitative Calculation ◽  
Ptcr Effect ◽  
Temperature Resistivity

A modified barium vacancy formation mechanism in donor-doped barium titanate (BaTiO3) ceramics is proposed. Assuming a uniform distribution of barium vacancies at sintering temperature and only oxygen partial pressure and sintering temperature related concentration of unionized barium vacancies, the electrical characteristics have been calculated by solving a differential equation about electron level. The room-temperature resistivity and positive temperature coefficient of resistivity (PTCR) behaviors of donor-doped BaTiO3 semiconducting ceramics have been quantitatively computed. The results pointed out that the room-temperature resistivity changes as a U-type curve with an increase of donor concentration. Moreover, the PTCR effect of BaTiO3 semiconductive ceramics was calculated quantitatively under different conditions. Theoretical and experimental results for BaTiO3 semiconductive ceramics are compared and discussed.

Fabrication of Lead-Free and High Tc Positive Temperature Coefficient of Resistivity Ceramics Sintered in Air

2011 ◽  
Vol 415-417 ◽  
pp. 1005-1008
Author(s):  
Jun Zhao ◽  
Hai Bo Yang ◽  
Shu Ping Gong ◽  
Dong Xiang Zhou
Keyword(s):  
Temperature Coefficient ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Lead Free ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Conventional Solid State Reaction ◽  
High Tc ◽  
C Value ◽  
Temperature Coefficient Of Resistivity

As a lead-free positive temperature coefficient of resistivity (PTCR) material, [Ba0.95-x (K0.5Bi0.5)0.05Cax]1-yNbyO3 system was prepared by the conventional solid-state reaction method. All samples sintered in air at 1300°C possess PTC characteristics as well as semi-conductivity characteristics, especially they show high Tc(130°C~160°C) value and the jump of the resistivity (maximum resistivity ρmax / minimum resistivity ρmin ) is four orders of magnitude. Samples with the composition of 0.3mol% Nb5+ have low room-temperature resistivity (ρ25°C) of ~103Ω.cm.

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.

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