Abstract

Cobalt Alumino Silicate Ceramic (CASC) composites, with different molar weight concentration (i.e. G0=0, G1=0.4, G2=0.6, G3=0.8, G4=1.0, and G5=1.2 (M.W.)) of cobaltus acetate are prepared via sol-gel route. XRD shows mullite and cobalt aluminate phase which is found to depend on the concentrations of Co+2 ions. Field emission scanning electron microscope (FESEM) images show for all samples of CASC nanocomposites after sintering at 1400oC, nano sized cobalt aluminate grains are embedded in evenly spread mullite grains; but in case of G0, there are only evenly spread mullite grains. The study of dielectric property of the composite samples at room temperature shows that at all concentration (G1, G2, G3, G4 and G5) the dielectric constant is higher than pure mullite (G0) and there is a critical concentration of cobaltus acetate (G3) where there is maximum enhancement of dielectric constant in the higher frequency range from 40 KHz to 2 MHz. The dielectric constant varies from 44.77 to 37.75 for G3 and from 29.8 to 24.12 for G0 respectively. The tangent loss of composite with G3 has the lowest value than that of other concentrations including pure mullite in the frequency range 40 KHz to 2MHz. Due to high dielectric constant and low tangent loss, the composite with specific concentration and in the high frequency range has great importance as an electronic material.

Highlights

  • During past decades Alumino silicate ceramic composite was used as an advanced structural ceramics and it is well known as a promising electronic material with some great properties such as high melting point, antierosion, better chemical stability to oxidation as well as good resistance to most chemical attack, great coercivity, good electrical resistance, good mechanical strength, low thermal expansion coefficient, very good high temperature strength and a low cost material [1,2,3,4]

  • The dielectric constant of all Cobalt Alumino Silicate Ceramic (CASC) nanocomposites is higher than alumino-silicate composite throughout the frequency range 40 KHz to 2 MHz and there is a critical concentration i.e. G3 (0.8M.W.%) of metal ions (Co+2) where the dielectric constant is maximum

  • The tangent loss of G3 (0.8M.W.%) composites is lower than pure alumino-silicate composite in the frequency range 50 KHz and sample G3 has minimum tangent loss in that frequency range

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Summary

Introduction

During past decades Alumino silicate ceramic composite was used as an advanced structural ceramics and it is well known as a promising electronic material with some great properties such as high melting point, antierosion, better chemical stability to oxidation as well as good resistance to most chemical attack, great coercivity, good electrical resistance, good mechanical strength, low thermal expansion coefficient, very good high temperature strength and a low cost material [1,2,3,4] This composite have been increasingly gaining importance for high frequency circuit packaging and electronic substrate application due to their low dielectric constant[1,5,6,7] since last few decades. Cobalt aluminate composite behaves like an outstanding dielectric material due to so cobalt aluminate mullite ceramic composites have been studied widely because of its potential applications such as in high charge storage multilayer ceramics capacitors (MLCC), transducer because of its high polarization, high permittivity and very low tangent loss and can be promising candidate in Microelectronic industries, interconnect technology

Experimental
XRD Analysis
Dielectric Constant Behavior
Conclusions
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