Effect of Ni Electrode on the Characteristics of BaTiO3 Based PTCR Ceramics

2011 ◽  
Vol 415-417 ◽  
pp. 1000-1004
Author(s):  
Huan Liu ◽  
Rong Zhu ◽  
Zhi Ping Zheng ◽  
Dong Xiang Zhou ◽  
Qiu Yun Fu
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Heating Temperature ◽  
Single Layer ◽  
Volume Ratio ◽  
Cost Effective ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Ni Powder ◽  
Ptcr Effect

In order to achieve cost-effective inner electrodes for the multilayer BaTiO3-based ceramics having a positive temperature coefficient of resistivity (PTCR), we fabricated Ni paste based on Ni powder and investigated the effect of Ni electrode on the performance of semiconducting BaTiO3 ceramics. We adjusted the particle size of Ni powder (0.2μm, 0.6μm and 1μm) and incorporated them as the electrodes into both single-layer and laminated BaTiO3 PTCR devices. The device samples were sintered at 1200oC for 30min in reducing atmosphere consisting of N2 and H2 (97:3 by volume ratio), and went through a post-sintering in-air heat treatment at 700-900oC in air which is necessary for the PTCR effect. The results indicate that Ni powder with lager particle size are more stable against post-sintering heat treatment, and the heating temperature needs to be optimized to overcome the trade-off between ohmic behaviors of Ni electrodes and the PTCR effect of BaTiO3-based semiconducting ceramics.

scholarly journals Effect of Semiconductor Element Substitution on the Electric Properties of Barium Titanate Ceramics

2016 ◽  
Vol 61 (2) ◽  
pp. 887-890 ◽  
Author(s):  
B. Garbarz-Glos ◽  
A. Lisińska-Czekaj ◽  
D. Czekaj ◽  
W. Bąk
Keyword(s):  
Activation Energy ◽  
Barium Titanate ◽  
Structural Phase ◽  
Rhombohedral Phase ◽  
Positive Temperature Coefficient ◽  
Quantitative Composition ◽  
Positive Temperature ◽  
Ptcr Effect ◽  
Ion Substitution ◽  
Titanate Ceramics

Abstract The investigated ceramics were prepared by a solid-state reaction from simple oxides and carbonates with the use of a mixed oxide method (MOM). The morphology of BaTi0.96Si0.04O3 (BTSi04) ceramics was characterised by means of a scanning electron microscopy (SEM). It was found that Si+4 ion substitution supported the grain growth process in BT-based ceramics. The EDS results confirmed the high purity and expected quantitative composition of the synthesized material. The dielectric properties of the ceramics were also determined within the temperature range (ΔT=130-500K). It was found that the substitution of Si+4 ions had a significant influence on temperature behavior of the real (ε’) and imaginary (ε”) parts of electric permittivity as well as the temperature dependence of a.c. conductivity. Temperature regions of PTCR effect (positive temperature coefficient of resistivity) were determined for BTSi04 ceramics in the vicinity of structural phase transitions typical for barium titanate. No distinct maximum indicating a low-temperature structural transition to a rhombohedral phase in BTSi04 was found. The activation energy of conductivity was determined from the Arrhenius plots. It was found that substitution of Si ions in amount of 4wt.% caused almost 50% decrease in an activation energy value.

Semiconducting BaTiO3 ceramic prepared by low temperature liquid phase sintering

1998 ◽  
Vol 13 (3) ◽  
pp. 660-664 ◽  
Author(s):  
I. Zajc ◽  
M. Drofenik
Keyword(s):  
Liquid Phase ◽  
Grain Boundary ◽  
Sintering Temperature ◽  
Positive Temperature Coefficient ◽  
Liquid Phase Sintering ◽  
Positive Temperature ◽  
Sintering Aid ◽  
Ptcr Effect ◽  
Temperature Coefficient Of Resistivity ◽  
Temperature Liquid

Donor-doped BaTiO3 ceramics were prepared by adding PbO B2O3 SiO2 as a sintering aid. Semiconducting BaTiO3 was obtained at a sintering temperature of 1100 °C. The sintered samples exhibit the Positive Temperature Coefficient of Resistivity (PTCR) effect, which depends on the amount of liquid phase, the concentration of the donor-dopant, and the sintering temperature. The cold resistivity of the samples decreases when the sintering temperature increases. The increase of the grain boundary resistivity and hence of the cold resistivity at lower sintering temperatures was explained by applying the diffusion grain boundary layer model.

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.

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.

scholarly journals High-Temperature Dielectric Relaxation Behaviors in Mn3O4 Polycrystals

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4026 ◽  
Author(s):  
Songwei Wang ◽  
Xin Zhang ◽  
Rong Yao ◽  
Liguo Fan ◽  
Huaiying Zhou
Keyword(s):  
High Temperature ◽  
Dielectric Relaxation ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Thermally Activated ◽  
Dielectric Relaxations ◽  
Plasma Sintering ◽  
Ptcr Effect ◽  
Temperature Relaxation ◽  
Lower Temperature

High temperature dielectric relaxation behaviors of single phase Mn3O4 polycrystalline ceramics prepared by spark plasma sintering technology have been studied. Two dielectric relaxations were observed in the temperature range of 200 K–330 K and in the frequency range of 20 Hz–10 MHz. The lower temperature relaxation is a type of thermally activated relaxation process, which mainly results from the hopping of oxygen vacancies based on the activation energy analysis. There is another abnormal dielectric phenomenon that is different from the conventional thermally activated behavior and is related to a positive temperature coefficient of resistance (PTCR) effect in the temperature region. In line with the impedance analyses, we distinguished the contributions of grains and grain boundaries. A comparison of the frequency-dependent spectra of the imaginary impedance with imaginary electric modulus suggests that both the long range conduction and the localized conduction are responsible for the dielectric relaxations in the Mn3O4 polycrystalline samples.

scholarly journals Microstructure and Magnetic Properties of Mn55Bi45 Powders Obtained by Different Ball Milling Processes

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 441 ◽  
Author(s):  
Xiang Li ◽  
Dong Pan ◽  
Zhen Xiang ◽  
Wei Lu ◽  
Dan Batalu
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Ball Milling ◽  
Melt Spinning ◽  
Positive Temperature Coefficient ◽  
Low Energy ◽  
High Coercivity ◽  
Temperature Phase ◽  
Positive Temperature ◽  
Energy Ball

Low-temperature phase (LTP) MnBi is considered as a promising rare-earth-free permanent magnetic material with high coercivity and unique positive temperature coefficient of coercivity. Mn55Bi45 ribbons with high purity of LTP MnBi phase were prepared by melt spinning. Then, Mn55Bi45 powders with different particle size were obtained by low-energy ball milling (LEBM) with and without added surfactant. The coercivity is enhanced in both cases. Microstructure characterization reveals that Mn55Bi45 powders obtained by surfactant assisted low-energy ball milling (SALEBM) have better particle size uniformity and show higher decomposition of LTP MnBi. Coercivity can achieve a value of 17.2 kOe and the saturation magnetization (Ms) is 16 emu/g when Mn55Bi45 powders milled about 10 h by SALEBM. Coercivity has achieved a maximum value of 18.2 kOe at room temperature, and 23.5 kOe at 380 K after 14 h of LEBM. Furthermore, Mn55Bi45 powders obtained by LEBM have better magnetic properties.

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.

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.

Resistivity Control by Solid-State Reaction of Perovskite-Type Oxides

1994 ◽  
Vol 365 ◽  
Author(s):  
H. Nagamoto ◽  
H. Tanaka ◽  
T. Koya
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Positive Temperature Coefficient ◽  
Sintered Body ◽  
Molar Ratio ◽  
Log P ◽  
Positive Temperature ◽  
Ptcr Effect ◽  
A Site ◽  
Perovskite Type

ABSTRACTResistivity control has been conducted by solid–state reaction of two different perovskite–type oxides. One is La0.5Ba0.5CoO3−δ (LBC) which showed metallic conduction, and its resistivity, ρ was 10−3 Ω.cm at 20 °C. The other is Ba0.998Sb0.002TiO3 (BT) which showed positive temperature coefficient of resistivity (PTCR) effect. The sintered body of the mixiure of the two oxides did not show PTCR effect. The logarithm of the resistivity of the sintered body, log ρmix was expressed using the resistivity of LBC, ρLBC, the molar ratio of BT, x, and temperature dependent constant, α(T) aslog ρmix = (l–x) log PLBC + xα(T)which holds for 0 ≤ x ≤ 0.8 at the temperature ranging from 20 to 240° C ρmix changed by about 8 orders of magnitude at room temperature. X–ray diffraction analysis suggested that metal ions at the A–site move from one perovskite–type oxide to another and that the sintered body consisted of two perovskite–type oxides different from starting ones.

Sign in / Sign up

Export Citation Format

Share Document