LOW-TEMPERATURE DIELECTRIC-PROPERTIES OF CANDIDATE SUBSTRATES FOR HIGH-TEMPERATURE SUPERCONDUCTORS - LAALO3 AND ZRO2-9.5 MOL-PERCENT-Y2O3

The effects of temperature (4-400 K), hydrostatic pressure and frequency on the dielectric constant, ε', and dielectric loss of single crystals of LaAlO3 and cubic yttria(9.5 mol %)-stabilized zirconia (ZrO 2) were investigated. Both crystals are relatively low-loss, low-dispersion dielectrics in the temperature range (T<150 K) of most interest for high-temperature superconductors. The pressure results make it possible to evaluate the various contributions to the temperature dependence of ε'. It is found that this dependence is dominated by the change of polarizability with volume. The dielectric properties of the two crystals are compared with those of other candidate substrate materials.