Structure and microwave dielectric properties of epitaxial 0.7CaTiO3 0.3NdAlO3 dielectric thin films deposited by pulsed laser deposition
Abstract High quality epitaxial 0.7CaTiO3 0.3NdAlO3 (CTNA) dielectric thin films with complex perovskite structure are deposited on SrTiO3 substrates by pulsed laser deposition. In a combination with XRD and aberration corrected TEM, the strain state and oxygen octahedral rotation are analyzed in detail. The substrate temperature dependence of microwave dielectric properties has been investigated by a split post dielectric resonator method. The dielectric constant and dielectric loss tangent of the CTNA thin film deposited at 700 degC are 417 and 0.048 at 10 GHz, respectively. The dielectric response of CTNA films derived from far infrared reflectance spectroscopy shows that the frequency of phonon mode TO1 centered at 174.5 cm 1 is shifted to 176.6 cm 1 with increasing substrate temperature. In contrast, the damping factor decreases with increasing substrate temperature. The substrate temperature dependence of dielectric response mainly results from the strain induced oxygen octahedral rotation.
Ceramics International