Electrophysical properties of microalloyed alumo-silicate ceramics as active dielectric

Abstract

In this paper, electrophysical properties of porous alumo-silicate ceramics, modified by alloying with magnesium and microalloying with aluminum, were investigated. Complex multiphase system, as active microalloyed ceramics, has specific behavior under influence of external electrical field, which involves changes of dielectric losses and impedance, depending on frequency and temperature. Dielectric properties were measured in the frequency range 20 Hz - 1 MHz. Values for permittivity (εr) ranged between 140 - 430. Order of magnitude for electrical resistivity was about 106 Ωm, for impedance 104 - 108 Ω, and loss tangent had values about and greater than 0.05. Current flow through active dielectric takes place through dielectric barrier and throughout conduction bands of thin aluminum and magnesium metal films. Permittivity has nonlinear distribution and complex functional dependences because of significant nonhomogeneity of active microalloyed ceramics. Lower values of electrical resistivity are the result of complex electron and ion transfer of charge through solid phase and pores, with decreased potential barriers height, due to the influence of additives, ingredients and defects. [Projekat Ministarstva nauke Republike Srbije, br. III 45012 i br. ON 172057

Application of Minkowski layer for intergranular fractal surfaces of multiphase active microalloyed and alloyed aluminium-silicate ceramics

“…In active microalloyed ceramics, as sintered ceramics material, grain shape, their distribution and nature of contact are accessible to fractal analysis. Each microcontact point, grain boundaries and intergranular area also, can be represented with dominant electronic parameters-resistance, capacitance or inductance [3].…”

“…Fractal analysis represents a new approach for deeper examination of ceramics materials microstructure, and further, for the prognosis of materials properties. This method provides a new approach for describing, predicting and modeling the grains shape and correlations between ceramics microstructure and its electrical properties [3]. Therefore, fractal microstructure analysis allows better interpretation of electrical characteristics.…”

“…Advanced composite materials, with multiphase, amorphous-crystal, microheterogeneous, metallized, very dispersive and porous nonhomogeneous microstrucure have complex dielectric and conductive properties, as a result of micromorphology and structure significant changes and incorporation of some additives and ingredients [2]. Our previous studies have shown that changes in the ceramics microstructure and structurally sensitive properties, especially electrical and dielectric physical-chemical properties, will be gained by incorporation of Al and Mg in the structure of the solid aluminosilicate matrix [3,4]. Alloying with magnesium and microalloying with aluminium significantly change and modify micromorphology and microstructure of aluminium-silicate ceramics.…”

Synthesis and characterization of CuS nanocomposites by using alumina channel-technique

“…The value of exponent's' at different temperature is calculated by fitting the curve. Above graph shows a relationship between capacitance and LOG F .When we increase the temperature with increase of frequency capacitance decreases (at 30 °c and 50 °c capacitance shows a sharp fall i.e at higher frequency capacitance shows low value within a temperature range 150 °c to 250 °c capacitance also decreases with frequency but within a frequency range 1KHz to 50 KHz capacitance shows a constant value i.e it's independent with frequency 4,5 According to the theory capacitance of nanostructure material is primarily due to different types of polarizations present in material. Nanostructured material possesses enormous number of interfaces, and the large number of defects present in these interfaces and can cause a positive and negative space charge distribution resulting in space charge polarization.…”