Microwave characterization of dielectric materials in the temperature range of 90–450 K

Grupo de Cerâmicas Ferroelétricas Departamento de Física, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, São Carlos, SP, 13565-905, Brazil

Corresponding author: santos@df.ufscar.br

Received: 28 April 2006
Revised: 4 July 2006
Accepted: 28 July 2006
Published online: 6 October 2006

Abstract

In this article, a pressure-controlled sample holder for microwave dielectric measurements in the temperature range from 90–450 K is presented. The experimental set-up involves a coaxial line used to couple a microwave frequency network analyzer and an adapted sample holder in order to obtain dielectric characterization as a function of the temperature. The main innovation of the present work is the technical adaptation in the pressure control of the sample for low temperature measurements. The system was tested characterizing the complex dielectric constant of a Ca modified strontium titanate (SrTiO₃) quantum paraelectric-type ceramic material, for which the main physical dielectric properties (orientational or relaxation polarization) in the high frequency region are interesting to be investigated mainly at low temperatures.