scholarly journals Effect of intergranular glass films on the electrical conductivity of 3Y-TZP

1994 ◽  
Vol 9 (5) ◽  
pp. 1228-1240 ◽  
Author(s):  
M. Gödickemeier ◽  
B. Michel ◽  
A. Orliukas ◽  
P. Bohac ◽  
K. Sasaki ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Grain Boundary ◽  
Characteristic Temperature ◽  
Complex Impedance ◽  
Layer Model ◽  
Total Electrical Conductivity ◽  
Intergranular Films ◽  
Brick Layer Model ◽  
Equilibrium Thickness ◽  
Glass Films

The electrical conductivity of 3Y-TZP ceramics containing SiO2 and Al2O3 has been investigated by complex impedance spectroscopy between 500 and 1270 K. At low temperatures, the total electrical conductivity is suppressed by the grain boundary glass films. The equilibrium thickness of intergranular films is 1-2 nm, as derived using the “brick-layer” model and measured by HRTEM. A change in the slope of the conductivity Arrhenius plots occurs at the characteristic temperature Tb at which the macroscopic grain boundary resistivity has the same value as the resistivity of the grains. The temperature dependence of the conductivity is discussed in terms of a series combination of RC elements.

Grain boundary conductivity and microstructure study of 4% Y2O3 doped CeO2 thin films

1996 ◽  
Vol 453 ◽  
Author(s):  
Chunyan Tian ◽  
Siu-Wai Chan
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Complex Impedance ◽  
Preexponential Factor ◽  
X Ray Diffraction ◽  
Ac Impedance Spectroscopy ◽  
Boundary Conductivity ◽  
Transmission Electron ◽  
Brick Layer Model ◽  
Beam Deposition

AbstractThe thin films of 4% Y2O3 doped CeO2 have been deposited on different substrates of Pd film/(001) LaAlO3, Pd film/r-cut sapphire, and Pd film/Quartz using an e-beam deposition technique. The microstructures and electrical properties of the films were investigated by means of x-ray diffraction, transmission electron microscopy, and ac impedance spectroscopy. Both textured and polycrystalline films were produced on different substrates. A brick layer model was adopted to correlate the micro structure and electrical property of the films. Only the grain boundary arc was observed in the film complex impedance plots. The conductivities of the films were similar to the conductivity of 6% Y2O3 doped CeO2 bulk grain boundary because of lower preexponential factor, although the activation energies were smaller than that of bulk grain boundary. The resistive gram boundaries were found to dominate the conductivities of the films.

Impedance/Dielectric Spectroscopy of Electroceramics in the Nanograin Regime

2002 ◽  
Vol 756 ◽  
Author(s):  
N. J. Kidner ◽  
B. J. Ingram ◽  
Z. J. Homrighaus ◽  
T. O. Mason ◽  
E. J. Garboczi
Keyword(s):  
Finite Difference ◽  
Grain Boundary ◽  
Boundary Layers ◽  
Volume Fraction ◽  
Layer Model ◽  
Grain Sizes ◽  
Brick Layer Model ◽  
Polycrystalline Ceramics ◽  
Gradient Effects ◽  
Grain Core

ABSTRACTIn the microcrystalline regime, the behavior of grain boundary-controlled electroceramics is well described by the “brick layer model” (BLM). In the nanocrystalline regime, however, grain boundary layers can represent a significant volume fraction of the overall microstructure and simple layer models are no longer valid. This work describes the development of a pixel-based finite-difference approach to treat a “nested cube model” (NCM), which more accurately calculates the current distribution in polycrystalline ceramics when grain core and grain boundary dimensions become comparable. Furthermore, the NCM approaches layer model behavior as the volume fraction of grain cores approaches unity (thin boundary layers) and it matches standard effective medium treatments as the volume fraction of grain cores approaches zero. Therefore, the NCM can model electroceramic behavior at all grain sizes, from nanoscale to microscale. It can also be modified to handle multi-layer grain boundaries and property gradient effects (e.g., due to space charge regions).

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

Electrical Conductivity and Structural Studies on the Binary System BiI3-Ag2SO4

2012 ◽  
Vol 584 ◽  
pp. 521-525
Author(s):  
S. Austin Suthanthiraraj ◽  
Ayesha Saleem
Keyword(s):  
Electrical Conductivity ◽  
Binary System ◽  
Ionic Conduction ◽  
Structural Characteristics ◽  
Complex Impedance ◽  
Present System ◽  
Rapid Melt Quenching ◽  
Ionic Nature ◽  
Electrochemical Devices ◽  
Silver Sulphate

A new solid-state pseudo binary system BiI3_-Ag2SO4 involving bismuth triiodide (BiI3) and a silver oxysalt namely silver sulphate (Ag2SO4) has been prepared using rapid melt-quenching technique. AC conductivity studies have been carried out on the nine different samples of the (BiI3)x –- (Ag2SO4)(1-x) system with compositions corresponding to x=0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8 and 0.9 mole fraction at temperatures ranging from room temperature (298 K) to 433K. The bulk resistance values estimated using complex impedance plots indicated that electrical conductivity of the synthesized solid specimens would vary from 2.9 x10-2 to 3.4 x10-6Scm-1 thus suggesting the present system to be ionic in nature. The extent of ionic conduction due to Ag + cation has also been analyzed using Wagner’s dc polarization technique whereas detailed structural characteristics of the various compositions derived from Fourier transform infrared (FTIR) spectroscopy and features of surface morphology of these samples obtained using scanning electron microscopy (SEM) have further supported the ionic nature of the chosen system and suggested possible application as a solid electrolyte in electrochemical devices.

Electrical Properties of Y0.06Sr0.94Ti0.6Fe0.4O3-δ-YSZ Composites as Electrode Materials

2016 ◽  
Vol 697 ◽  
pp. 327-330 ◽  
Author(s):  
Ke Shan ◽  
Xing Min Guo ◽  
Feng Rui Zhai ◽  
Zhong Zhou Yi
Keyword(s):  
Electrical Conductivity ◽  
Electrode Materials ◽  
Electronic Conductivity ◽  
Ionic Conductivities ◽  
Conductivity Measurement ◽  
Transference Numbers ◽  
Secondary Phases ◽  
Electrical Conductivity Measurement ◽  
Total Electrical Conductivity ◽  
Phase Compatibility

Y0.06Sr0.94Ti0.6Fe0.4O3-δ-YSZ composites were prepared by mixing Y, Fe co-doped SrTiO3 (Y0.06Sr0.94Ti0.6Fe0.4O3-δ known as YSTF) and 8 mol% Y2O3 stabilized ZrO2 (YSZ) in different weight fractions. The phase stability, phase compatibility, microstructure and mixed ionic-electronic conductivity of composites were investigated. Phase analysis by XRD showed no clearly detectable secondary phases. The electrical conductivity measurement on the YSTF-YSZ composites showed a drastic decrease in total electrical and ionic conductivities when more than 10 wt% of YSZ was used in the composites. The total electrical conductivity was 0.102 S/cm for Y0.06Sr0.94Ti0.6Fe0.4O3-δ and 0.043 S/cm for YSTF-20YSZ at 700 oC, respectively. The value at 700 oC is approximately 2.4 times higher than that of YSTF-20YSZ. The ionic conductivity of Y0.06Sr0.94Ti0.8Fe0.2O3-δ varies from 0.015S/cm at 700 oC to 0.02 S/cm at 800 oC, respectively. The value at 800°C is approximately 12.5 times higher than YSTF-20YSZ. The ion transference numbers of YSTF-YSZ composites vary from 0.14 to 0.28 at 800 °C.

Effect of Aging Treatment on Properties and Microstructure of an Al-7.5Zn-1.3Mg-1.4Cu-0.12Zr Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 273-278 ◽  
Author(s):  
Xi Wu Li ◽  
Bai Qing Xiong ◽  
Yon Gan Zhang ◽  
Guo Jun Wang ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Grain Boundary ◽  
Response Rate ◽  
Aging Treatment ◽  
Aging Response ◽  
Peak Aging

In this study, the effect of various aging treatment (T6 and T7 treatment) on the mechanical properties, electrical conductivity and the microstructure of an Al-7.5Zn-1.3Mg-1.4Cu-0.12Zr alloy has been investigated. The results show that with elevating the aging treatment temperatures, the aging response rate is greatly accelerated. When T6 temper is performed at 140°C for 12h, as compared to peak aging for 24h at 120°C, the UTS and the corresponding Elongation values keep the same level, whereas the TYS and the electrical conductivity obviously increase by 5% and 9%, which is up to 560 MPa and 22.6 MS/m, respectively. And there are clear PFZs along the grain boundary and slightly coarser precipitates inside the grain. GPI zones, GPII zones and η' phases are major precipitates for the alloy under T6 condition. When T7 temper is performed on the alloy, the main precipitates are GPII zones, η′ and η phases. The coarser precipitates inside the grain and discontinuous grain boundary precipitates are favorable to electrical conductivity, which decrease the strength of 5~17% compared to T6 treatment. After T76 treatment (i.e., 110°C/6 h + 160°C/6 h), the UTS, TYS, Elongation and electrical conductivity values were 540 MPa, 510 MPa, 16.7% and 23.5 MS/m, respectively.

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.

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