Preparation and Characterization of Semi-Conducting (Ba,Sr)TiO3 Powders by a Wet Chemical Route

2007 ◽  
Vol 280-283 ◽  
pp. 657-660 ◽  
Author(s):  
Zhi Ping Zheng ◽  
Dong Xiang Zhou ◽  
Shu Ping Gong ◽  
Yun Xiang Hu ◽  
Guo Hua Huang
Keyword(s):  
Positive Temperature Coefficient ◽  
Polyacrylamide Gel ◽  
Sintering Behavior ◽  
Positive Temperature ◽  
Chemical Route ◽  
Sintering Aid ◽  
Phase Coating ◽  
Wet Chemical ◽  
Physical And Chemical

Ultrafine (Ba,Sr)TiO3-based powders used for making positive temperature coefficient of resistance (PTCR) were synthesized by two chemical steps: polyacrylamide gel process and liquid phase coating process. First, donor doped (Ba,Sr)TiO3 powders were synthesized by polyacrylamide gel process at rather low temperature, and the physical and chemical characteristics of the gels and the precursorpowders were investigated by DSC, TG, XRD and TEM. Secondly, acceptor and sintering aid were coated by an aqueous solution containing acceptor (Mn) and additive (Si). The characterization and sintering behavior of the semi-conducting powders and the PTC effect of ceramic samples prepared by the as-obtained powders were investigated.

Synthesis and characterization of Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 by wet chemical route

Rare Metals ◽  
2009 ◽  
Vol 28 (2) ◽  
pp. 122-126 ◽  
Author(s):  
Xianming Wu ◽  
Runxiu Li ◽  
Shang Chen ◽  
Zeqiang He
Keyword(s):  
Synthesis And Characterization ◽  
Chemical Route ◽  
Wet Chemical ◽  
Wet Chemical Route

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.

Research on the Fabrication of BaTiO3-Based PTCR Materials and Thermistors by Polyacrylamide Gel Process

2006 ◽  
Vol 45 ◽  
pp. 2371-2375
Author(s):  
Zhi Ping Zheng ◽  
Shu Ping Gong ◽  
Dong Xiang Zhou
Keyword(s):  
Theoretical Foundation ◽  
Sintering Temperature ◽  
Positive Temperature Coefficient ◽  
Precursor Powder ◽  
Polyacrylamide Gel ◽  
Positive Temperature ◽  
Temperature Coefficient Of Resistance ◽  
Synthesis Conditions ◽  
Average Grain Size ◽  
Xrd And Tem

BaTiO3-based powders used for positive temperature coefficient of resistance (PTCR) were synthesized by polyacrylamide gel process. The effect of synthesis conditions such as the pH of the citrate solutions and the reticulation of the polyacrylamide gel on the objection phase was investigated. The results showed that when the citrate solutions had a neutrality pH of 7~8 and the polyacrylamide gel was hard reticulated, precursor powder with pure and completely crystallized objection phase was obtained at calcination temperature of more than 700°C. The results of XRD and TEM revealed that precursor powder had an average grain size of about 50 nm. Compared with those prepared by solid-state reaction, PTCR ceramics prepared by polyacrylamide gel process have one magnitude higher ratio of maximum to minimum of resistance and low sintering temperature, which provides a practical and theoretical foundation for preparing multilayer PTCR thermistors by co-firing of semiconducting BaTiO3 ceramics and electrode.

Characterization of (Zr1 − xCex)0.84Y0.16O2 −δ ceramics (0 ≤ x ≤ 0.1) derived by a wet chemical route

2005 ◽  
Vol 40 (16) ◽  
pp. 4395-4397
Author(s):  
T. S. Zhang ◽  
J. Ma ◽  
Y. Z. Chen ◽  
S. H. Chan
Keyword(s):  
Chemical Route ◽  
Wet Chemical ◽  
Wet Chemical Route

scholarly journals Characterization of Ternary CuNiCo Metallic Nanoparticles Produced by Hydrogen Reduction

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6006
Author(s):  
Eliana Paola Marín Castaño ◽  
José Brant de Campos ◽  
Ivan Guillermo Solórzano-Naranjo ◽  
Eduardo de Albuquerque Brocchi
Keyword(s):  
Electron Microscopy ◽  
Metallic Nanoparticles ◽  
Hydrogen Reduction ◽  
Homogeneous Distribution ◽  
Homogeneous Material ◽  
Chemical Route ◽  
Alloy Particles ◽  
Lower Temperature ◽  
Physical And Chemical

Different methods of producing nanostructured materials at the laboratory scale have been studied using a variety of physical and chemical techniques, though the challenge here is the homogeneous distribution of the elements which also depends on the precursor elements. This work thus focused on the micro-analytical characterization of Cu–Ni–Co metallic nanoparticles produced by an alternative chemical route aiming to produce solid solution nanoparticles. This method was based on two steps: the co-formation of oxides by nitrates’ decomposition followed by their hydrogen reduction. Based on the initial composition of precursor nitrates, three homogeneous ternaries of the Ni, Cu and Co final alloy products were pre-established. Thus, the compositions in %wt of the synthesized alloy particles studied in this work are 24Cu–64Ni–12Co, 12Cu–64Ni–24Co and 10Cu–80Ni–10Co. Both precursor oxides and metallic powders were characterized by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM/EDS) and transmission electron microscopy (TEM). The results show that the synthesis procedure was successful since it produced a homogeneous material distributed in different particle sizes depending on the temperature applied in the reducing process. The final composition of the metallic product was consistent with what was theoretically expected. Resulting from reduction at the lower temperature of 300 ∘C, the main powder product consisted of particles with a spheroidal and eventually facetted morphology of 50 nm on average, which shared the same FCC crystal structure. Particles smaller than 100 nm in the Cu–Ni–Co alloy agglomerates were also observed. At a higher reduction temperature, the ternary powder developed robust particles of 1 micron in size, which are, in fact, the result of the coarsening of several nanoparticles.

scholarly journals Development and Characterization of a DC-Driven Thermal Oscillator Using Acrylate-Based Composites

2020 ◽  
Vol 10 (11) ◽  
pp. 3825
Author(s):  
Mingxin Xu ◽  
Chao-Chi Yeh ◽  
Syuan-Wen Chen ◽  
Yao-Joe Yang
Keyword(s):  
Temperature Sensor ◽  
Transient Behavior ◽  
Positive Temperature Coefficient ◽  
Electrode Pair ◽  
Positive Temperature ◽  
Temperature Drift ◽  
Acrylate Copolymer ◽  
Sensing Material ◽  
Order Of Magnitude

This paper presents the design, fabrication, and characterization of a thermal oscillator driven by fixed DC voltages. The proposed device consists of a miniaturized ultra-sensitive temperature sensor and a microheater. The temperature sensor was fabricated by depositing acrylate-based temperature sensing material with a positive temperature coefficient (PTC) effect on an interdigital electrode pair, and this was the key component that enabled oscillations by periodically switching the microheater on and off. The acrylate-based material, which was prepared by dispersing an acrylate copolymer with graphite particles, exhibits an order-of-magnitude variation in resistivity over a temperature change of a few degrees. The transient behavior of the fabricated device was measured, and the effects on different driving conditions with active cooling were measured and discussed. In addition, the measurement results also show that the temperature drift is not obvious in long-term testing, which indicates that the acrylate composite is quite reliable during repeated phase transition.

Preparation and Characterization of Semi-Conducting (Ba,Sr)TiO3 Powders by a Wet Chemical Route

2007 ◽  
pp. 657-660
Author(s):  
Zhi Ping Zheng ◽  
Dong Xiang Zhou ◽  
Shu Ping Gong ◽  
Yun Xiang Hu ◽  
Guo Hua Huang
Keyword(s):  
Chemical Route ◽  
Wet Chemical ◽  
Wet Chemical Route
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