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.

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.

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.

Study on the Effects of (Bi1/2Na1/2)TiO3 Content on the Curie Temperature of (Bi1/2Na1/2)TiO3-BaTiO3 PTCR Ceramics

2011 ◽  
Vol 687 ◽  
pp. 411-415
Author(s):  
Long Xing Yang ◽  
Xing Wen Zhu ◽  
Li Zhe Li ◽  
Wen Zhong Jiang ◽  
Xiao Zhou
Keyword(s):  
Curie Temperature ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Positive Temperature Coefficient ◽  
Lead Free ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Resistivity

Perovskite-structured (Bi1/2Na1/2)TiO3 (BNT) ferroelectric with Curie temperature about 320°C is considered to be a good candidate of high temperature lead-free materials with a positive temperature coefficient of resistance (PTCR). In this study, lead-free PTCR ceramics with compositions of (1-x)BaTiO3-x(Bi1/2Na1/2)TiO3 (BT-BNT x=0.5-55mol%) were successfully prepared without any additional donor or acceptor dopants. The effects of BNT content on the Curie temperature Tc and the PTC effect of the ceramic materials were investigated. The X-ray diffraction data indicated that BT phase and BNT phase formed a solid solution during sintering even though the x value was up to 55mol%. The Curie temperature Tc of the samples increased from ~130°C to ~216°C with the increase of the BNT amount (x value) from 0.5mol% to 40mol%. However, it decreased when excess BNT was added (x value increased from 40mol% up to 55mol%), which was resulted from the volatile effects of Bi3+ and Na+ ions during sintering. The sample of 0.6BaTiO3- 0.4(Bi1/2Na1/2)TiO3 with Tc =216°C, room-temperature resistivity 104 Ω·cm and Rmax/Rmin= 102.7 was obtained. There is a relationship between the Curie temperature and the cell volume of the perovskite structured lattice.

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.

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.

Investigation of PTCR effect and microdefects in Nb2O5-doped BaTiO3-based ceramics by positron annihilation techniques

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744060
Author(s):  
Xuxin Cheng ◽  
Haining Cui ◽  
Xiaoxia Li ◽  
Wen Deng
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Doppler Broadening ◽  
Temperature Coefficient Of Resistance ◽  
Ptcr Effect ◽  
Temperature Resistivity ◽  
Coincidence Doppler Broadening

The influence of Nb2O5-doped concentration on the positive temperature coefficient of resistance (PTCR) effect, electrical properties and microdefects of (Ba[Formula: see text]Sr[Formula: see text])(TiNb[Formula: see text])O3 (BSTN) ceramics were investigated. Firing was conducted at 1350[Formula: see text]C for 2 h in air. The donor-doped content affected the electrical properties, PTCR effect and formation of the microdefect type of the BSTN samples. The room temperature resistivity of the BSTN specimens first decreased and then increased with increasing donor-doped content in the range of 0.2 mol.% Nb[Formula: see text] to 0.5 mol.% Nb[Formula: see text]. Moreover, the information on microdefects in BSTN ceramics was demonstrated by coincidence Doppler broadening spectrum. The influence of the defects on the PTCR characteristics of the ceramics was also revealed.

Electrical and thermal properties of a (Ba1-x-ySrxCay)TiO3-based PTC thermistor for preheating light oil

2018 ◽  
Vol 11 (05) ◽  
pp. 1850076 ◽  
Author(s):  
Joonsoo Kim
Keyword(s):  
Thermal Properties ◽  
Electrical Properties ◽  
Solid State Reaction Method ◽  
Positive Temperature Coefficient ◽  
Room Temperature Resistivity ◽  
Positive Temperature ◽  
Conventional Solid State Reaction ◽  
Heater Element ◽  
Light Oil ◽  
Cartridge Heater

The electrical properties of a (Ba[Formula: see text]SrxCay)TiO3-based positive temperature coefficient (PTC) thermistor were determined by measuring resistivity with increasing temperature, and its thermal properties were measured with a cartridge heater made of a (Ba[Formula: see text]Sr[Formula: see text]Ca[Formula: see text])TiO3-based PTC thermistor. The (Ba[Formula: see text]SrxCay)TiO3-based PTC thermistor were fabricated by a conventional solid-state reaction method with Sb2O3, BaTiO3, SrTiO3, SiO2, and CaTiO3. Their electrical properties were determined by room temperature resistivity ([Formula: see text]C), minimum resistivity ([Formula: see text]), maximum resistivity ([Formula: see text]), resistivity jump rate (log [Formula: see text]/[Formula: see text]), Curie temperature ([Formula: see text]), and withstanding voltage. The effect of the microstructure on the electrical properties was investigated to improve the withstand voltage. The cartridge heater was fabricated with the (Ba[Formula: see text]Sr[Formula: see text]Ca[Formula: see text])TiO3-based PTC thermistor and its thermal properties were determined by the temperature of light oil in a 100 cc beaker. The temperature of light oil was maintained at 60[Formula: see text]C without fluctuations in temperature after reaching 60[Formula: see text]C at 220[Formula: see text]V, and thus (Ba[Formula: see text]SrxCay)TiO3-based PTC thermistor was able to operate as a self-regulating heater element for preheating light oil.

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.

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