Simulation of the Grain Boundary Effects in PTCR Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1692-1694
Author(s):  
Chao Fang ◽  
Dong Xiang Zhou ◽  
Hu An Liu ◽  
Shu Ping Gong
Keyword(s):  
Differential Equation ◽  
Grain Boundary ◽  
Fermi Level ◽  
Boundary Effect ◽  
Positive Temperature Coefficient ◽  
Boundary Effects ◽  
Positive Temperature ◽  
Potential Well ◽  
Temperature Coefficient Of Resistivity ◽  
Grain Boundary Effect

The positive temperature coefficient of resistivity (PTCR) behavior of semiconductive BaTiO3 ceramics is often explained by the Heywang model. However, Heywang model couldn’t explain some experimental phenomena of jump range more than 106. This paper considered that the migration of donors, electrons and holes has important influence on grain boundary effect. A differential equation about Fermi level was established on the base of Heywang model. By solving the equation the jump range can be calculated quantitatively. It was found that a potential well exists on the edge of grain due to the donor ionization, and the experimental phenomena of PTC jump range more than 106 could be explained.

Grain boundary effects in NTC-PTC composite thermistor materials

1999 ◽  
Vol 14 (1) ◽  
pp. 120-123 ◽  
Author(s):  
D. J. Wang ◽  
J. Qiu ◽  
Y. C. Guo ◽  
Z. L. Gui ◽  
L. T. Li
Keyword(s):  
Energy Level ◽  
Grain Boundary ◽  
Boundary Effect ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Impedance Analysis ◽  
Composite Effect ◽  
Complex Impedance Analysis ◽  
Temperature Coefficient Of Resistivity ◽  
Grain Boundary Effect

Yttrium-doped (Sr0.45Pb0.55)TiO3 ceramics have been studied by complex impedance analysis. As a sort of NTC-PTC composite thermistor, it exhibited a significantly large negative temperature coefficient of resistivity below Tc in addition to the ordinary PTC characteristics above Tc. It is found that the NTC effect in NTC-PTC materials was not originated from the deep energy level of donor (bulk behavior), but from the electrical behavior of the grain boundary. Therefore, the NTC-PTC composite effect was assumed to be a grain boundary effect, and yttrium was a donor at shallow energy level. The NTC-PTC ceramics were grain boundary controlled 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.

scholarly journals Grain boundary effects on piezoelectric properties of the core–shell-structured BaTiO3@TiO2 ceramics

2018 ◽  
Vol 08 (06) ◽  
pp. 1850044 ◽  
Author(s):  
Xixi Li ◽  
Zhonghua Yao ◽  
Juan Xie ◽  
Zongxin Li ◽  
Hua Hao ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Boundary Effect ◽  
Ferroelectric Properties ◽  
Critical Role ◽  
Impedance Analysis ◽  
Ferroelectric Materials ◽  
Boundary Effects ◽  
Grain Boundary Effects ◽  
Grain Boundary Effect

Grain boundary effect on BaTiO3 has been widely investigated for several decades. However, all of them tailored the grain boundary by grain size of BaTiO3. In this case, a direct way was introduced to modify the grain boundary by coating technique to investigate the role of grain boundary in ferroelectric materials. Nonferroelectric phase TiO2 was employed to investigate grain boundary effects on the electrical properties of BaTiO3 piezoelectric ceramics. TiO2 coating can result in the reduction of piezoelectric and ferroelectric properties and the annealing process in oxygen can increase piezoelectric behavior of pure BaTiO3 due to valence state of Ti ions while that remains for Ti-modified composition possibly due to the increased grain boundary effect by impedance analysis. Compared with ferroelectric grain, grain boundary plays a critical role to impact the electrical properties of perovskite-type ferroelectric materials.

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.

Complex Impedance Spectroscopy Studies of BaTiO3 Ceramic with 10% BaFe12O19 Substitution

2015 ◽  
Vol 1107 ◽  
pp. 14-19 ◽  
Author(s):  
Zainuddin Zalita ◽  
S.N. Anuar ◽  
Roslinda Shamsudin ◽  
M.N. Idris
Keyword(s):  
Impedance Spectroscopy ◽  
Grain Boundary ◽  
Complex Impedance ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Impedance Spectroscopy Study ◽  
Different Temperatures ◽  
Temperature Coefficient Of Resistivity ◽  
Lower Temperature ◽  
Spectroscopy Studies

Barium titanate with 10% barium ferrite substitution (BaTiO3-BaFe12O19) has been synthesized by the solid state reaction route. Formation of the BaFe12O19 phase confirmed its existence in the composite. Impedance spectroscopy study of the composite sample was performed at different temperatures of 25, 40, 80, 120 and 160 °C. BaFe12O19 substituted sample shows a single semicircle at lower temperature and two overlapped arcs at 120 and 160 °C due to grain and grain boundary. The impedance plots were fitted based on a parallel R-CPE circuit. The grain boundary resistance behaves like the positive temperature coefficient of resistivity (PTCR) for donor-doped BaTiO3 semiconductor. The highest capacitance is contributed by the grain boundary at 80 °C.

Piezoresistivity modeling of grain‐boundary junctions in positive temperature coefficient of resistivity BaTiO3

1995 ◽  
Vol 77 (10) ◽  
pp. 5322-5334 ◽  
Author(s):  
Aldo B. Alles ◽  
Michael W. Murphy ◽  
Jesse J. Symanski ◽  
Christine L. Tremper ◽  
Walter A. Schulze
Keyword(s):  
Grain Boundary ◽  
Temperature Coefficient ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Temperature Coefficient Of Resistivity

scholarly journals Mapping grain boundary heterogeneity at the nanoscale in a positive temperature coefficient of resistivity ceramic

APL Materials ◽  
2017 ◽  
Vol 5 (6) ◽  
pp. 066105 ◽  
Author(s):  
Kristina M. Holsgrove ◽  
Demie M. Kepaptsoglou ◽  
Alan M. Douglas ◽  
Quentin M. Ramasse ◽  
Eric Prestat ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Temperature Coefficient ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Temperature Coefficient Of Resistivity
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