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Summary: Ionics 7 (2001) 215
Electrical Conductivity-Microstructure Correlation
in AIN-CuO Composites
Abdul-Majeed Azad* and Haw Su Cheng
Department of Physics, University Putra Malaysia
43300 UPM Serdang, Selangor, Malaysia
Abstract. Water vapor is an important constituent of any gas and in many applications is
regarded as a contaminant that needs to be monitored and controlled. A1N-CuO composites (2 % <
CuO -<50 % by weight) have been studied to exploit them as novel humidity sensors over wide
ranges of moisture levels and temperature. Development of benign microstructure with open
porosity has been attempted by varying the composition and firing conditions. The impedance data
acquired on the composites over the frequency range 5 Hz to 13 MHz, revealed a bulk response in
terms of a single semicircular relaxation in the complex Z*-plane. A systematic variation of
electrical conductivity with CuO content in the composites has been explained in the light of
percolation theory.
1. Introduction
High thermal conductivity along with good electrical and
mechanical properties, adequate permittivity, low dielec-
tric losses and low thermal expansion make aluminum
nitride a very promising substrate material in electronic
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