• Riddle, Bill
• Geyer, Richard G.
• Krupka, Jerzy
• Boatner, Lynn

Abstract

<p>Microwave dielectric properties of single-crystal incipient quantum ferroelectrics, KTa O3 and SrTi O3, have been measured at cryogenic temperatures. Cylindrical specimens were used as TE0n1 -mode and quasi- TE011 -mode dielectric resonators at temperatures ranging from 4 to 300 K. Conductive losses of the measurement resonant structures were taken into account, both as a function of frequency and temperature, so that uncertainties in the evaluated dielectric losses were ±5%. The real permittivity was measured with an accuracy of ±0.5%. The evaluated real permittivities of KTa O3 and SrTi O3 exhibit no ferroelectric transition, and remain paraelectric down to 5 K, consistent with soft-mode stabilization. Dielectric loss tangent values of KTa O3 at 3 GHz were 4.2× 10-5 at 5.4 K, 8.9× 10-5 at 77 K, and 1.4× 10-4 at 300 K, while those of SrTi O3 were 3.4× 10-3 at 5.4 K, 2.4× 10-4 at 77 K, and 3.8× 10-4 at 300 K. Results of the complex permittivity measurements are compared with theoretical predictions from a modified Devonshire phenomenological model. © 2005 American Institute of Physics.</p>

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