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.

Preparation of High-Conductive High-Temperature PTC Resistor Ba1-x SrxPb1+yO3+z

1992 ◽  
Vol 290 ◽  
Author(s):  
H. Nagamoto ◽  
H. Kagotani ◽  
T. Koya
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Perovskite Structure ◽  
Positive Temperature Coefficient ◽  
Preparation Condition ◽  
Positive Temperature ◽  
Ptcr Effect ◽  
Higher Temperature ◽  
Temperature Coefficient Of Resistivity ◽  
A Site

AbstractThe positive temperature coefficient of resistivity (PTCR) effect in Ba1-xSrxPb1+yO3+z has been systematically studied. The effect of the PTC resistivity was strongly influenced by the preparation condition. The PTCR effect in metallic-conducting BaPb1+yO3+z. is confirmed around 700 °C, and the temperature where the PTCR effect starts can be successfully shifted to higher temperature range by substituting strontium for the A-site barium. The magnitude of the PTCR effect was increased and the resistibility was reduced by the enhancement of the sintering. In addition to Pb(IV) in the perovskite structure, Pb(II) is detected at the grain boundary in the sintered body.

scholarly journals β-Li0.37Na0.63Fe(MoO4)2

2014 ◽  
Vol 70 (2) ◽  
pp. i9-i10 ◽  
Author(s):  
Amira Souilem ◽  
Mohamed Faouzi Zid ◽  
Ahmed Driss
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Solid State Reaction ◽  
Title Compound ◽  
General Position ◽  
Site Occupancy ◽  
The Other ◽  
Main Structure ◽  
Axis Direction ◽  
A Site

The title compound, lithium/sodium iron(III) bis[orthomolybdate(VI)], was obtained by a solid-state reaction. The main structure units are an FeO6octahedron, a distorted MoO6octahedron and an MoO4tetrahedron sharing corners. The crystal structure is composed of infinite double MoFeO11chains along theb-axis direction linked by corner-sharing to MoO4tetrahedra so as to form Fe2Mo3O19ribbons. The cohesion between ribbonsviamixed Mo—O—Fe bridges leads to layers arranged parallel to thebcplane. Adjacent layers are linked by corners shared between MoO4tetrahedra of one layer and FeO6octahedra of the other layer. The Na+and Li+ions partially occupy the same general position, with a site-occupancy ratio of 0.631 (9):0.369 (1). A comparison is made withAFe(MoO4)2(A= Li, Na, K and Cs) structures.

scholarly journals Sintered body characteristics of LAS by addition of CaCO3and ZrO2using a solid-state reaction

2011 ◽  
Vol 21 (5) ◽  
pp. 218-224 ◽  
Author(s):  
Sang-Hun Kim ◽  
Eun-Tae Kang ◽  
Ung-Soo Kim ◽  
Kwang-Taek Hwang ◽  
Woo-Seok Cho
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Sintered Body

scholarly journals Effect of Bi2O3 content on the microstructure and electrical properties of SrBi2Nb2O9 piezoelectric ceramics

RSC Advances ◽  
2018 ◽  
Vol 8 (28) ◽  
pp. 15613-15620 ◽  
Author(s):  
Xiaochun He ◽  
Ruiqing Chu ◽  
Zhijun Xu ◽  
Zhongran Yao ◽  
Jigong Hao
Keyword(s):  
Solid State ◽  
Electrical Properties ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Molar Ratio ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Lead Free Ceramics ◽  
Bi2o3 Content

Lead-free ceramics, SrBi2Nb2O9–xBi2O3 (SBN–xBi), with different Bi contents of which the molar ratio, n(Sr) : n(Bi) : n(Nb), is 1 : 2(1 + x/2) : 2 (x = −0.05, 0.0, 0.05, 0.10), were prepared by conventional solid-state reaction method.

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.

Photocatalytic Degradation of Methyl Orange on Iron Niobate Prepared by Solid-State Reaction

2010 ◽  
Vol 113-116 ◽  
pp. 2021-2024 ◽  
Author(s):  
Wen Jie Zhang ◽  
Xin Sun ◽  
Bai Han Chen
Keyword(s):  
Methyl Orange ◽  
Solid State ◽  
Photocatalytic Degradation ◽  
Solid State Reaction ◽  
Irradiation Time ◽  
Molar Ratio ◽  
Preparation Conditions ◽  
New Type ◽  
Iron Niobate ◽  
Degradation Of Methyl Orange

Iron niobate photocatalyst as a new type of photocatalyst was prepared by solid-state reaction of Fe3O4 and Nb2O5 and its activity was evaluated using photocatalytic degradation of methyl orange. Preparation conditions such as calcination temperature and time, and irradiation time were investigated according to photocatalytic efficiencies. FeNb2O6 was produced during calcination below 700 oC and FeNbO4 was produced above 800 oC. Iron niobate with optimum activity could be prepared after calcination at 700 oC for 8 h when Fe:Nb molar ratio was 0.8:1. Methyl orange degradation rate was 72.7% after 180 min of irradiation at photocatalyst concentration of 4 g/l.

Solid state synthesis, characterization, optical properties and cooperative catalytic performance of bismuth vanadate nanocatalyst for Biginelli reactions

RSC Advances ◽  
2015 ◽  
Vol 5 (31) ◽  
pp. 24313-24318 ◽  
Author(s):  
Shahin Khademinia ◽  
Mahdi Behzad ◽  
Hamideh Samari Jahromi
Keyword(s):  
Optical Properties ◽  
Solid State ◽  
Solid State Reaction ◽  
Raw Materials ◽  
Catalytic Performance ◽  
Bismuth Vanadate ◽  
Solid State Synthesis ◽  
Molar Ratio ◽  
Biginelli Reactions

Bi2V2O7 nano powders were synthesized via a solid state reaction at 500 °C for 8 h using Bi(NO3)3 and VO(acac)2 at stoichiometric 1 : 1 Bi : V molar ratio as raw materials.

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.

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