Microstructures and Electrical Properties of BaTiO3 PTC Ceramics

2013 ◽  
Vol 804 ◽  
pp. 118-122 ◽  
Author(s):  
Myoung Pyo Chun ◽  
Hyo Soon Shin ◽  
Sang Il Hyun ◽  
Byung Ik Kim
Keyword(s):  
Electron Microscope ◽  
Pressure Range ◽  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Reducing Atmosphere ◽  
Microscope Images ◽  
Ptcr Effect ◽  
The Relationship ◽  
Scanning Electron

The microstructure, especially porosity, of PTC (positive temperature coefficient) thermistor based on BaTiO3 was controlled with a forming pressure. The relationship between theirPTCR properties and microstructureswas investigated with an optical and SEM (Scanning Electron Microscope) images and digital multimeter. Disk samples were fabricated by pressinguniaxially at various pressures of 100~15000kg/cm2 and sintering at 1265°C in reducing atmosphere and finally re-oxidizing at 700°C in air. The porosity of the samples decreased rapidly from 45% to 8% with increasing the forming pressure from 100 to 1000kg/cm2andbecame 4% at 15000kg/cm2with slowdecreasing of porosity in the pressure range of 1000~15000kg/cm2.With increasing the forming pressure, the resistivity jump of samplesdecreased rapidlyfrom 0.5 to 2.9 at about1000kg/cm2that corresponds tothe porosity of 15% and was saturated above this pressure. It is considered that there is a critical amount of porosity for having PTCR effect, which was about 15% in our samples. In addition, the porosity of the sample has a greater influence on the resistivity jump than on theresistivity at room temperature, which is due to the oxidation of grain boundary through a favorable channel of oxygen such as a pore.

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.

Influence of sintering process on electrical properties and PTCR effect of laminated Ba1.005(Ti1−xNbx)O3 ceramics fired in a reducing atmosphere

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744061
Author(s):  
Xuxin Cheng ◽  
Xiaoxia Li ◽  
Xiaoming Chen ◽  
Haining Cui
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Dopant Concentration ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Sintering Process ◽  
Dopant Content ◽  
Reducing Atmosphere ◽  
Ptcr Effect ◽  
Different Temperatures

This study investigates the influence of dopant content and firing conditions on electrical properties and positive temperature coefficient of resistance (PTCR) effect of Ba[Formula: see text](Ti[Formula: see text]Nb[Formula: see text]O3 (BTN) ceramics sintered at different temperatures from 1070[Formula: see text]C to 1220[Formula: see text]C for 2 h in a reducing atmosphere and reoxidized within the temperature range of 600[Formula: see text]–[Formula: see text]750[Formula: see text]C for 0.5[Formula: see text]–[Formula: see text]8 h. The results indicate that the room-temperature (RT) resistance of the laminated BTN specimens initially decreased and then increased as a function of the dopant concentration. Moreover, the resistance jump exhibited a contrasting tendency. Furthermore, the RT resistance of the BTN samples rapidly decreased at first and then gradually decreased with increasing sintering temperature. Meanwhile, the resistance jump of the samples increased first and then decreased. In addition, the influence of reoxidation times on the PTCR characteristics of ceramics was investigated.

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.

Influence of Ba/Ti ratio on PTCR effect of Bam(Ti1−xNbx)O3 ceramics prepared by the reduction sintering-reoxidation method

2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840071
Author(s):  
Xuxin Cheng ◽  
Xiaoming Chen ◽  
Xiaoxia Li ◽  
Haining Cui ◽  
Chao Xiong
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Temperature Coefficient Of Resistance ◽  
Reducing Atmosphere ◽  
Sintering Time ◽  
Ptcr Effect ◽  
Sintering Conditions ◽  
Average Sample

In this work, we investigate the influences of Ba/Ti ratio and sintering conditions on the characteristics of positive temperature coefficient of resistance (PTCR) and electrical properties of Ba[Formula: see text](Ti[Formula: see text]Nb[Formula: see text])O3 (BTN) ceramics. The ceramics were fired at 1190[Formula: see text]C for 0.5–6.0 h in a reducing atmosphere and then reoxidized at 600–650[Formula: see text]C for 0–8 h. The Ba/Ti ratio [Formula: see text] affected the electrical properties and PTCR effect of the BTN specimens. The room-temperature (RT) resistance of the BTN samples initially decreased [Formula: see text] and then increased [Formula: see text] as the Ba/Ti ratio increased. Moreover, BTN ceramics exhibit a pronounced PTCR effect, with a resistance jump greater by 3.0 orders of magnitude and a low 0.1 [Formula: see text] RT resistance at a low reoxidation temperature of 600[Formula: see text]C after sintering under a reducing atmosphere. Furthermore, the average sample grain size increased along with the Ba/Ti ratio. In addition, the influence of the sintering time and the reoxidation time on the electrical properties and the PTCR effect were also investigated.

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.

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.

Investigation of PTCR characteristics in Nb2O5-doped BaTiO3-based chip-type ceramics prepared by reduction sintering-reoxidation method

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040047
Author(s):  
Xuxin Cheng ◽  
Xiaoming Chen ◽  
Haining Cui ◽  
Yuxin Wang ◽  
Chao Xiong
Keyword(s):  
Electrical Properties ◽  
Temperature Coefficient ◽  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Firing Time ◽  
Temperature Coefficient Of Resistance ◽  
Reducing Atmosphere ◽  
Chip Type ◽  
Sintering Conditions

This study investigates the influence of sintering conditions on electrical properties and positive temperature coefficient of resistance (PTCR) of [Formula: see text] (BTNO) ceramics, fired at [Formula: see text]C for different times from 1 to 6 h in a reducing atmosphere and reoxidised within the temperature range of [Formula: see text]–[Formula: see text]C for 1 h. The results showed that the room-temperature (RT) resistance and the resistance jump of the multilayer BTNO ceramics decreased with an increase in the firing time. Furthermore, the RT resistance of the BTNO samples gradually increased at first and then rapidly increased with increasing reoxidation temperature. In addition, the influence of sintering times on the microstructure of ceramics was also investigated.

Effect of Trace Strontium Addition on Microstructure and Room Temperature Fracture Toughness of Nb-12Si-22Ti Alloys

2016 ◽  
Vol 849 ◽  
pp. 603-608 ◽  
Author(s):  
Mei Ling Wu ◽  
Feng Wei Guo ◽  
Ming Li ◽  
Ya Fang Han
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Fracture ◽  
The Relationship ◽  
Scanning Electron

The effect of strontium (Sr) addition (0.2 at.%) on the microstructure and mechanical properties of Nb-12Si-22Ti alloys were studied. Microstructure of the alloys was observed by scanning electron microscope, and their phase compositions were analyzed with X-ray diffraction and Electro-Probe Microanalyzer. The room temperature fracture toughness was measured. The results indicated that the phases of Nbss and Nb3Si were presented in Nb-12Si-22Ti alloys. However, with the Al and Sr addition, the alloys were composed of Nbss and β-Nb5Si3. Compared with the Nb-12Si-22Ti alloys, the value of room temperature fracture toughness increased about 46% and 73% with the addition of Al and Sr alloy, respectively. The relationship between the microstructure and the mechanical properties was discussed.

scholarly journals Dielectric and Electrical Properties of BLT Ceramics Modified by Fe Ions

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5623
Author(s):  
Beata Wodecka-Dus ◽  
Tomasz Goryczka ◽  
Małgorzata Adamczyk-Habrajska ◽  
Mateusz Bara ◽  
Jolanta Dzik ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Iron Content ◽  
Room Temperature ◽  
Positive Temperature Coefficient ◽  
Elementary Cell ◽  
Positive Temperature ◽  
Weiss Temperature ◽  
Transition Area ◽  
Ptcr Effect

The solid solution of the perovskite type structure Ba0.996La0.004Ti1−yFeyO3 (BLTF) for varying iron content (y = 0.1−0.4 mol.%) was obtained as a result of a solid state reaction using the conventional method. At room temperature (Tr < TC), the as-received ceramics reveals a single-phase, tetragonal structure and a P4mm space group. An increase in the iron content causes a slight decrease in the volume of the elementary cell. In addition, this admixture significantly reduces the maximum permittivity value (εm) and the shift of the phase transition temperature (TC) towards lower temperatures. The BLTF solid solution shows a classical phase transition and low values of dielectric loss tangent (tgδ), both at room temperature and in the phase transition area. The Curie–Weiss temperature (T0) and Curie constant (C) were also determined on the basis of the dielectric measurements results. The analysis of temperature changes in DC conductivity revealed presence of the positive temperature coefficient of resistivity (PTCR) effect in the phase transition area.

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