Influence of Chromium Ions on the Dielectric Properties of the PbO-Ga2O3-P2O5 Glass System

2007 ◽  
Vol 62 (5-6) ◽  
pp. 315-323 ◽  
Author(s):  
Gnanaprakasm Little Flower ◽  
Maddireddy Srinivasa Reddy ◽  
Musugu Venkata Ramana Reddy ◽  
Nalluri Veeraiah
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Dielectric Properties ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Oxidation States ◽  
Optical Absorption Spectra ◽  
Dielectric Breakdown Strength ◽  
Chromium Ions ◽  
Wide Range

PbO-Ga2O3-P2O5 glasses containing different amounts of Cr2O3, ranging from 0 to 1.0 mol%, were prepared. The dielectric properties (viz., constant ε’, loss tanδ , ac conductivity σac over a wide range of frequencies and temperatures, dielectric breakdown strength) have been studied as a function of the concentration of chromium ions. An anomaly has been observed in the dielectric properties of these glasses, when the concentration of Cr2O3 is about 0.4 mol%. This anomaly has been explained in the light of different oxidation states of chromium ions with the aid of data of differential thermal analysis and optical absorption spectra of these glasses.

Dielectric Breakdown Strength and Microwave Dielectric Properties of Alumina Ceramics with CaO-SiO2- MgO, Yb2O3 and ZrO2 Additives

2018 ◽  
Vol 281 ◽  
pp. 640-645
Author(s):  
Gui Fen Fan ◽  
Hao Yuan Deng ◽  
Meng Meng Hao ◽  
Kai Wang ◽  
Yu Sheng Shi ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Alumina Ceramics ◽  
Conventional Solid State Reaction ◽  
Dielectric Breakdown Strength ◽  
Microwave Dielectric ◽  
Maximum Value

Al2O3 ceramics with CaO-SiO2-MgO (CMS), Yb2O3 and ZrO2 additives were fabricated by a conventional solid-state reaction method. The effects of ZrO2 dopant on phase compositions, microwave dielectric properties and dielectric breakdown strength of Al2O3 ceramics were studied. XRD demonstrated that CaAl2Si2O8 and Zr &Y compound phases co-existed with alumina. SEM exhibited that ZrO2 dopant could refine the grain of alumina ceramics and improve its relative density. With ZrO2 content increasing from 1wt% to 5wt% εr increased from 9.8 to 10.25, but Q×f decreased from 52823GHz to 35922GHz. The breakdown strength increased initially and reached the maximum value at ZrO2=3wt%. When ZrO2 content is 3wt%, the comprehensive performances were the best: Eb= 37.37kV/mm for 1mm samples and 17.26kV/mm for 3mm samples, Q×f = 37044 GHz, εr = 10.01, and τf = -52 ppm/°C.

scholarly journals Dielectric Breakdown Strength and Energy Storage Density of CCTO-ZBS Electroceramic

2020 ◽  
Vol 596 ◽  
pp. 012006
Author(s):  
Muhammad Qusyairie Saari ◽  
Julie Juliewatty Mohamed ◽  
Muhammad Azwadi Sulaiman ◽  
Mohd Fariz Abd Rahman ◽  
Zainal Arifin Ahmad ◽  
...  
Keyword(s):  
Energy Storage ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Energy Storage Density ◽  
Dielectric Breakdown Strength ◽  
Storage Density

scholarly journals Effects of Ambient Conditions on the Dielectric Properties of Thermally Sprayed Ceramic Coating

2018 ◽  
Author(s):  
M Niittymäki ◽  
B. Rotthier ◽  
K. Lahti ◽  
T. Suhonen ◽  
J Metsäjoki
Keyword(s):  
Dielectric Properties ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Thermal Spraying ◽  
Ceramic Coatings ◽  
Alumina Coating ◽  
Ambient Conditions ◽  
Coating Materials ◽  
Sprayed Coating ◽  
Thermally Sprayed

<p>Thermal spraying techniques are used to manufacture insulating coatings especially for demanding applications like fuel cells where normal insulating materials cannot be used. In electrical insulation applications, the mostly used coating materials are aluminum oxide (Al2O3), magnesium oxide (MgO) and magnesium aluminate (MgAl2O4). Dielectric properties of thermally sprayed ceramic coatings are strongly affected by ambient conditions, and in addition to this they are not well documented in the literature. In this paper the effects of environmental conditions on certain dielectric properties of a thermally sprayed coating are studied. DC resistivity as well as permittivity and losses at different frequencies at relative humidities of 20 % and 45 % at temperature of 20 °C, 40 °C and 60 °C will be reported in the paper for Al2O3 samples sprayed using HVOF (High Velocity Oxygen Fuel) technique. DC dielectric breakdown strength is also studied for the HVOF alumina coating at temperature of 20 °C and relative humidity of 20 %. Effects of ambient conditions and coating material composition are also analyzed.</p>

Dielectric Breakdown Mechanism of Perovskite-Structured Ceramics

2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000116-000120 ◽  
Author(s):  
Takuya Hoshina ◽  
Mikio Yamazaki ◽  
Hiroaki Takeda ◽  
Takaaki Tsurumi
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Dielectric Breakdown ◽  
Breakdown Strength ◽  
Dielectric Breakdown Strength ◽  
Breakdown Mechanism ◽  
High Dielectric ◽  
Measurement Efficiency ◽  
Breakdown Model

We precisely measured the dielectric breakdown strength of SrTiO3, CaTiO3, and CaZrO3 ceramics as a function of temperature, and revealed the dielectric breakdown mechanism of the ceramics. For the dielectric breakdown test, ceramics specimens with a lot of round-bottom holes were prepared. Using the specimens, the breakdown positions were stabilized and a reliability of breakdown strength was improved as well as the measurement efficiency. As a result of the dielectric breakdown tests, it was found that the dielectric breakdown strength decreased with increasing permittivity at room temperature and the permittivity dependence of breakdown strength obeyed Griffith type energy release rate model. At high temperature above 100ºC, the dielectric breakdown mechanism of SrTiO3 and CaTiO3 ceramics was explained by an intrinsic breakdown model. In contrast, an intrinsic dielectric breakdown of CaZrO3 ceramics didn't occur in the measurement temperature range up to 210ºC. To obtain a high dielectric breakdown strength at high temperature, the dielectric permittivity is required to be low to some extent and the defect concentration of oxygen vacancies should be minimized in the perovskite-structured oxide.

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