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1. Backgrounds for SiC-based BLCs
2. Preparation of the SiC-based BLCs
3. Characteristics of the SiC-based BLCs
4. Summary
1. Backgrounds for SiC-based BLCs
Traditionally, SiC is not suitable for capacitor applications
Ferroelectrics with perovskite structure
BaTiO3-1vol%SiC 300,000
La-PbTiO3 450,000
compounds
SiC 10
BaTiO3 10000
SrTiO3 320
PbTiO3 350
PbZrO3 110
Pb(Mg1/3Nb2/3)O3 15000
Pb(Ni1/3Nb2/3)O3 4000
Pb(Zn1/3Nb2/3)O3 22000
Pb(Fe1/2Nb1/2)O3 12000
Pb(Fe2/3W1/3)O3 9000
PFN-PFW 21000
If we modify grain boundary of SiC Composites,
How about the dielectric properties?
2. Preparation of the SiC-based BLCs
Semi-conductive SiC particles
Al2O3-MgO-SiO2
Mixing
Hot Pressing
Microstructure characterization
Dielectric propertiesmeasurement
Impedance detection
3. Characteristics of the SiC-based BLCs
Microstructure
Width of grain boundary
200 nm
Amorphous grain boundary
Insulation phase
Nano grains of new phases
Increasing the interface area
d
Sε C
Dielectric properties
000,20..
TR
000,910,2max
At 500oC, increases sharply
000,400,2 At 590 – 730oC
Higher temperature increases the conductivity of samples
at 700oC
Complex impedance
R decreases from 1.4 M to 0.08 M at 190oC and 500oC, respectively
Perfect semi-circle at 190oC Tail appears at low frequency at 500oC
Space charge polarization phenomena
Space charge polarization
Higher T leads to much lower R
Tails at low f grow with T
Highest space charge polarization appears at around 700oC
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
300 400 500 600 700 800 900 1000 11000
300
600
900
1200
1500
1800
1 MHz
0.1 MHz
100 Hz
Temperature (K)
tan
60
40
20
01000800600400
tan
Temperature (K)
The space charge behavior also determines the lowering tan
Maximum tan occurs at the initial T of space charge polarization
Surface potential induction
Atomic Force Microscope system
Sub sequential DC pulse at:
5 V, 10 V, 0 V, - 5 V, - 10 V
(a) (b) (c)
Potential image
5 V 10 V 0 V
Space charge behavior does appear for the SiC-based capacitors
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
Thank you for your attention
