Abstract
The effect of Sn O2 addition on the high-frequency dielectric properties of Ba2 Ti9 O20 ceramics has been investigated using terahertz time-domain spectroscopy, far-infrared (FIR) reflectivity, and Raman-scattering measurements. The dielectric constants determined from the terahertz and FIR spectra are smaller than that taken in the microwave frequency region. In contrast, the increase of the dielectric loss with increasing frequency is due to some resonance modes above 1 THz. Importantly, our data clearly show that the Sn O2 (2.4 mole %) addition degraded the dielectric properties of Ba2 Ti9 O20 ceramics, which is ascribed to the deterioration on the coherency of lattice vibrational characteristics for these materials. © 2006 American Institute of Physics.