scholarly journals Electrical properties of magnesium titanate ceramics post-sintered by hot isostatic pressing

2017 ◽  
Vol 49 (4) ◽  
pp. 373-380
Author(s):  
Antonije Djordjevic ◽  
Dragan Olcan ◽  
Nina Obradovic ◽  
Vesna Paunovic ◽  
Suzana Filipovic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Negative Temperature Coefficient ◽  
Sintered Material ◽  
Hot Isostatic Pressing ◽  
Negative Temperature ◽  
Frequency Range ◽  
Free Atmosphere ◽  
Magnesium Titanate ◽  
Isostatic Pressing ◽  
Titanate Ceramics

Post-sintering of magnesium titanate ceramics by hot isostatic pressing (HIP) in an oxygen-free atmosphere significantly alters various electrical properties of the product. In particular, the sintered material becomes a semiconductor. The aims of this paper are: to extend our investigations of the electrical properties of this material by expanding the frequency range of measurements, to design interpolation formulas for the frequency dependence of the complex relative permittivity, and to propose HIP-sintered magnesium titanate as a material for thermistors that have a negative-temperature-coefficient resistance (NTCR), as well as for varistors.

scholarly journals Structure-Property Correlation in Ir Transparent Zinc Sulphide (Zns) Ceramics Under Chemical Vapour Deposited & Hot Iso-Statically Pressed Conditions

2019 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Grain Size ◽  
Hot Isostatic Pressing ◽  
Chemical Vapour ◽  
Complex Impedance ◽  
Ac Impedance ◽  
Spectroscopic Studies ◽  
Structure Property ◽  
Frequency Range ◽  
Equivalent Circuit Analysis ◽  
Isostatic Pressing

IR Transparent ZnS ceramics processed through chemical vapour deposition were subjected to Hot Isostatic pressing and the samples in both the conditions were characterized by XRD, microstructure and high temperature impedance spectroscopic studies for the dielectric and electrical properties. Both the samples have shown cubic sphalerite phase with enhanced orientation along (111) plane as a result of hot isostatic pressing as revealed by XRD.HIP treatment to ZnS facilitated the enhancement of the homogeneity of microstructure and enhancement in the grain size from 10μm to 50μm. The electrical behavior of both the samples was investigated by AC impedance spectroscopy in the frequency range 1Hz to 1MHz from RT to 500°C in dry air. HIP has resulted in a significant increase in the dielectric constant, which can be attributed to the increase in homogeneity and the grain size. Further, the complex impedance plots exhibited two impedance semicircles identified in the frequency range is explained by the grain and grain boundary effects. An equivalent-circuit analysis of AC impedance spectra based on the brick-layer model was performed. Activation energies obtained from the conductivity plots indicates an Arrhenius type thermally activated process.

scholarly journals Structural characterization and electrical properties of sintered magnesium–titanate ceramics

2013 ◽  
Vol 555 ◽  
pp. 39-44 ◽  
Author(s):  
S. Filipović ◽  
N. Obradović ◽  
J. Krstić ◽  
M. Šćepanović ◽  
V. Pavlović ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Structural Characterization ◽  
Magnesium Titanate ◽  
Titanate Ceramics

Electrical Properties of La(Cr,Mn)O3 NTC Materials

2011 ◽  
Vol 485 ◽  
pp. 237-240 ◽  
Author(s):  
Toshiaki Fujita ◽  
Kazutaka Fujiwara ◽  
Takashi Yamaguchi
Keyword(s):  
Electrical Properties ◽  
Carrier Mobility ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Electronic Configuration ◽  
B Value ◽  
Transfer Energy ◽  
Local Lattice Distortion ◽  
Local Lattice ◽  
The Relationship

We investigated the electrical properties of the perovskite R(Cr,Mn)O3(where R is selected from various rare earth elements and Y), which is suitable for use in negative temperature coefficient (NTC) thermistors. The substitutions of Mn for Cr in La(Cr,Mn)O3and larger ions for R3+decreased both the resistivities (r) and thermistor constants (B values) estimated from measurements at 25°C and 50°C according to r = r0exp(B/T). The activation energies of the carrier number (Eg) and carrier mobility (WH) were estimated by measuring the thermoelectric power and resistivity. A change in WHcorresponded to a change in the B value. We discussed the relationship between the grand state electronic configuration of the M3+ions and the local lattice distortion around the M3+ions. The change in WHcould be qualitatively linked to the M3d– O2p transfer energy, which is corresponding to the hybridization between the M3d and O2p orbital (M: transition metal elements, O: oxygen).

Microstructure and Electrical Properties of Calcium Copper Titanate Ceramics

2007 ◽  
Vol 561-565 ◽  
pp. 551-555 ◽  
Author(s):  
Lai Jun Liu ◽  
Hui Qing Fan
Keyword(s):  
Electrical Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Cell Parameters ◽  
Grain Sizes ◽  
Calcium Copper Titanate ◽  
Titanate Ceramics

The effect of stoichiometry, i.e. Ca/Cu ratios (CaCu3xTi4O12, x = 0.8, 0.9, 1.0, 1.1 and 1.2) on the microstructure and electrical properties was investigated. The grain sizes of CaCu3xTi4O12 composition increased sharply with the increase of copper, from ~1 μm with x = 0.8 to ~50 μm with x = 1.2. The real part of dielectric permittivity changed dramatically, the pellet with x = 1.0 had the highest dielectric permittivity ~160, 000 at 1 kHz. Furthermore, the dielectric permittivity of all pellets was impressively large values (between 10, 000 to 1, 000,000 at 100 Hz) and was nearly constant over a wide frequency range between 100 Hz to ~100 MHz. However, the dielectric permittivity of CaCu3xTi4O12 composition is not consistent with the amount of copper and cell parameters and grain sizes. Impedance spectroscopy exhibited that the CaCu3xTi4O12 composition had two semicircle at least at high frequency (~ 107 Hz) and low frequency (<100 Hz), respectively. The grain and grain boundary of the compositions had different impedance and relaxation behavior.

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