In this work we have developed and fabricated a compositionally stratified multilayered Ba1 -xSrxTiO3(BST) thin film heterostructure with a systematically varied stiochoimetric composition from Ba0.60Sr0.40TiO3 to Ba0.90Sr0.10TiO3. The optimized material design was characterized for structural, microstructural, dielectric (100 kHz and 0.5-10 GHz), and temperature stability properties. Experimental results demonstrated that the compositionally stratified thin film heterostructure possessed low loss (tan = 0.012), and high tunability (65.5% at 444 kV/cm). In addition, the BST heterostructure exhibited minimal dielectric dispersion in the temperature range of 90 to -10°C, showing a 6.4% decrease in permittivity (corresponding to a temperature coefficient of capacitance TCC20-90 = -0.921) as the temperature was elevated from 20 to 90°C and only a 2.1 increase in permittivity (TCC20 - (- 10) = -0.716) as the temperature was lowered from 20 to -10°C. Our results suggest that the compositionally stratified BST heterostructure, with its enhanced tunability and excellent temperature stability, is an excellent candidate for the next generation of tunable devices operating in harsh, i.e., temperature extreme, environments.
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Document Type: Research Article
Weapons & Materials Research Directorate, Active Materials Research Group, U.S.A. Army Research Laboratory, Aberdeen Proving Ground, MD
Materials Science and Engineering Program and Institute of Materials Science, University of Connecticut, Storrs, CT, U.S.A.
Publication date: 01 January 2008
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