Dielectric Effect of Distributed Curie Temperature in a Model of Cubic Core-Shell Grain
Abstract: A model of cubic core-shell grain with the distribution of the Curie temperature is proposed for simulation of the polyhedron core-shell structure to obtain the size related dielectrics. When the shell is a very thin layer with low dielectric constant, the shell has the grain-size effect: dielectric constant decreases and the peak moves to low temperature. When the shell is thick with different dielectric peak from the core one, the contribution of the core to the dielectric constant is a linear relation to the square of it size. The distribution of the Curie temperature will move dielectric peak to high temperature with dropping dielectric constant, and the temperature relation of im-permeability in paraelectric phase can not be expressed by the power-law. Ferroelectrics will have high stability of relation of dielectric constant with temperature for the combination of the shell in linear distribution and the core in Gaussian distribution. It is the square of spontaneous polariza-tion in ferroelectrics that has the same function as dipole in dielectrics for contribution to the complex dielectric constant, and therefore a temperature dependent dielectric loss of the distri-bution of the Curie temperature is derived.
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