- Cr doped ferrite prepared by self combustion
- Annealed as prepared sample at 1000 K and 1200 K for 24 hours separately
- Dielectric constant of 1000 K annealed sample found to be greater than that of 1200 K annealed sample.
- Why dielectric constants decreases?
can you provide the values by which it shows increase or graph for the same?
It is reported in the literature that the dielectric constant is directly proportional to the
grain size[12]. While grain size decreases with chromium content resulting corresponding decrease in dielectric constant. Such variation of grain size was also reported in the literature.
The study of dielectric behavior reveals that dielectric constant and dielectric loss tangent shows dispersion with frequency for Mg-Cd ferrites and Cr3+ substituted Mg-Cd ferrites, which is attributed to interfacial polarization. The dielectric polarization depends on composition and found increasing with Cd2+content whereas decrease with Cr3+ substitution. Substituted Cr3+ ion reduces the conduction resulting in the decrement of dielectric constant and dielectric loss tangent.
Dielectric constant of 1000 K annealed sample found to be greater than that of 1200 K annealed sample because of the fact that the high temperature annealing resulted larger grain size that the lower temperature annealing. The grain growth is a natural process because that results reduction in Global Gibbs free energy of the system due to the concurrent reductions in surface free energy .
One can easily show that dGT/dr = 0 when ro = -2 Gs/Gv, and GT < 0 when r> ro. Where Gv
Ravikiran sir,
magnitude of dielectric constant decreases with increase in annealing temperature from 1000 to 1200 K about one order of magnitude(101 ) at lower frequency (2 Hz) and shows almost same value at 100 Hz,
Dear Sijo, the following paper might help you even though there are some inconsistency whether the increase in resistivity could affect the dielectric constant as much as the grain boundaries and sizes! Best regards
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