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Published byImogen Gertrude Jefferson Modified over 9 years ago
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SiC-based Boundary Layer Capacitors Rui Zhang Zhengzhou University zhangray@zzu.edu.cn
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Outlines 1. Backgrounds for SiC-based BLCs 2. Preparation of the SiC-based BLCs 3. Characteristics of the SiC-based BLCs 4. Summary
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1. Backgrounds for SiC-based BLCs Traditionally, SiC is not suitable for capacitor applications Ferroelectrics with perovskite structure BaTiO 3 -1vol%SiC 300,000 La-PbTiO 3 450,000 compounds SiC10 BaTiO310000 SrTiO3320 PbTiO3350 PbZrO 3 110 Pb(Mg 1/3 Nb 2/3 )O 3 15000 Pb(Ni 1/3 Nb 2/3 )O 3 4000 Pb(Zn 1/3 Nb 2/3 )O 3 22000 Pb(Fe 1/2 Nb 1/2 )O 3 12000 Pb(Fe 2/3 W 1/3 )O 3 9000 PFN-PFW21000 If we modify grain boundary of SiC Composites, How about the dielectric properties?
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2. Preparation of the SiC-based BLCs Semi-conductive SiC particles Al 2 O 3 -MgO-SiO 2 Mixing Hot Pressing Microstructure characterization Dielectric properties measurement Impedance detection
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3. Characteristics of the SiC-based BLCs Microstructure Width of grain boundary 200 nm Amorphous grain boundary Insulation phase
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Nano grains of new phases Increasing the interface area
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Dielectric properties At 500 o C, increases sharply At 590 – 730 o C Higher temperature increases the conductivity of samplessamples at 700 o C
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Complex impedance R decreases from 1.4 M to 0.08 M at 190 o C and 500 o C, respectively Perfect semi-circle at 190 o CTail appears at low frequency at 500 o C Space charge polarization phenomena
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Space charge polarization Higher T leads to much lower R Tails at low f grow with T Highest space charge polarization appears at around 700 o Cappears More charge carriers are generated in SiC improving the C and apparent Indicating enhancing space charge behavior It is the space charge behavior that gives rise to the extremely high Charge carriers accumulate at the insulation boundary to form space charge region
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The space charge behavior also determines the lowering tan lowering tan Maximum tan occurs at the initial T of space charge polarization
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Surface potential induction Atomic Force Microscope system Sub sequential DC pulse at: 5 V, 10 V, 0 V, - 5 V, - 10 V
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(a)(b)(c) Potential image 5 V 10 V0 V Space charge behavior does appear for the SiC-based capacitors
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4. Summary Space charge behavior appears with temperature for the SiC-based BLCs The space charge behavior leads to the extremely high , and lowers the tan
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Thank you for your attention
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