Application of Direct Current and Temperature Stresses of Low-Voltage ZnO Based Varistor Ceramics

Sabri, M. G. M.; Azmi, B. Z.; Rizwan, Zahid; Halimah, M.K.; Hashim, Mansor; Sidek, H.A.A.

doi:10.3844/ajassp.2009.1591.1595

Cited by 10 publications

(7 citation statements)

References 13 publications

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“…shows that, addition of Mn increases the formation of interstitial atoms and Zn-Mn complex, which is likely to increase the insulating region near the grain boundary mostly by segregation [37,38]. The frequency dependence of tand (loss) for different frequencies obtained for different dopant concentration of Mn in ZnO is shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Structural, electrical and magnetic behavior in high-temperature sintered Zn1–x Mn x O

et al. 2015

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Nanocrystalline Mn-doped ZnO of compositions Zn 1-x Mn x O (0 B x B 0.08) has been synthesised by chemical route for uniform substitution of Mn in Zn site and then sintered at 1300°C. Systematic investigations show the effect of Mn doping level and the sintering temperature on the structural, electrical and magnetic properties of ZnO. The average size of the nanocrystalline particles is in the order of 30-50 nm, whereas the grain sizes of the sintered specimen are of the order of few microns. Substitution of Mn in ZnO has been confirmed from the X-ray diffraction peak shift. A few peaks related to secondary phases of MnO have been observed in the X-ray diffraction patterns of the doped samples. ZnO and Mn-doped ZnO show Ohmic behavior and increased resistivity value with the increasing concentration of Mn. Effect of Mn concentration in ZnO has also been reflected in the dielectric constant and dielectric loss values. All the sintered samples show paramagnetic behavior even though the presence of MnO with oxygen vacancies is evident in X-ray photoelectron spectroscopic study.

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Section: Resultsmentioning

confidence: 99%

Structural, electrical and magnetic behavior in high-temperature sintered Zn1–x Mn x O

et al. 2015

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“…Generally an exponential tail (in region-B) for crystalline semiconductors can be characterized by:

C o is the exponential tail parameter of the order of unity and < U 2 > T is the thermal average of the square of the displacement of the atoms from their equilibrium positions. The term < U 2 > T expresses the energy of displacement of atoms [ 17 , 18 ].…”

Section: Resultsmentioning

confidence: 99%

Photopyroelectric Spectroscopic Studies of ZnO-MnO2-Co3O4-V2O5 Ceramics

Rizwan

Zakaria

Ghazali

2011

IJMS

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Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO2 + 0.4Co3O4 + xV2O5), x = 0–1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300–800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (Eg) was 2.11 eV for 0.3 mol% V2O5 at a sintering temperature of 1025 °C as determined from the plot (ρhυ)2 versus hυ. With a further increase in V2O5, the value of Eg was found to be 2.59 eV. Steepness factor ‘σA’ and ‘σB’, which characterize the slope of exponential optical absorption, is discussed with reference to the variation of Eg. XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.

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“…This indicates that the pores increase with the increase of sintering temperature. The pores are trapped between the large grains in the ceramics at high sintering temperature [20]. …”

Section: Resultsmentioning

confidence: 99%

Use of a Reflectance Spectroscopy Accessory for Optical Characterization of ZnO-Bi2O3-TiO2 Ceramics

Ghazali

Zakaria

Rizwan

et al. 2011

IJMS

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The optical band-gap energy (Eg) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. Eg of the ceramic ZnO + xBi2O3 + xTiO2, where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. Eg was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature.

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Application of Direct Current and Temperature Stresses of Low-Voltage ZnO Based Varistor Ceramics

Cited by 10 publications

References 13 publications

Structural, electrical and magnetic behavior in high-temperature sintered Zn1–x Mn x O

Structural, electrical and magnetic behavior in high-temperature sintered Zn1–x Mn x O

Photopyroelectric Spectroscopic Studies of ZnO-MnO2-Co3O4-V2O5 Ceramics

Use of a Reflectance Spectroscopy Accessory for Optical Characterization of ZnO-Bi2O3-TiO2 Ceramics

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