The influence of grain boundary impedances on the electrical properties of CaCu_3Ti_4O_(12) ceramics.

摘要

There has been a lot of speculation regarding the electrical properties of an unusual perovskite (ABO_3)-type material,CaCu_3Ti_4O_(12) which contains Ca and Cu(+II) ions on the A-site and Ti(+IV) on the B-site.Fixed frequency capacitance measurements in the kHz-MHz region show a dramatic decrease in permittivity from values as high as approx350,000 at room temperature to approx100 below approx100-150 K.CaCu_3Ti_4O_(12) is centrosymmetric at room temperature (space group Im3) and does not exhibit any subambient crystallographic phase changes down to -35K.