Conductive and dielectric properties of functional ceramic composites
|Valeriy V. Skorokhod|
Frantsevich Institute for Problems of Materials Science (IPMS), 3, Krzhizhanivsky Str., Kiev 03680, Ukraine
Usually ceramic functional materials are multi-phase systems where the physical properties of isolated phases are differed greatly. For example, relatively small amounts of conductive phase as spheroid, elongate or flattened inclusions are usually added to ceramic resistive composites with dielectric non-conductive matrix. In this case difference in absolute values of electrical resistivity for matrix and such inclusions achieve 10-15 orders depending on type of conductivity and operating temperature.
For the ferroelectrics differences in the values of dielectric permeability for ferroelectric (ε = 103 – 104) and paraelectric impurity ( ε about some units) reach 3-4 orders. Furthermore sometimes small amount of conductive phase (theoretically ε = ∞) are added for the increasing of dielectric permeability.
Within the framework of self-consistent field the dependence of conductivity and dielectric permeability effective values from the volume phase concentration under the condition of major difference in properties is a result of solution of simplified quadratic equation where some terms of equation are ignored. The analysis of such solutions allows qualitative evaluating of the influence of phase geometry in ceramic composite both on the effective values of its conducting and dielectric properties and on its some critical parameters determining extreme conditions of its performance.
Presentation: Invited oral at E-MRS Fall Meeting 2008, Symposium I, by Valeriy V. Skorokhod
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-12 15:31 Revised: 2009-06-07 00:48