Dielectric, thermal, compositional and microstructural characterization of copper doped LiZnPO4 ceramics for ULTCC terahertz applications

Dynamic development of high speed communication systems requires implementation of new materials with well tailored dielectric properties and improved miniaturization and integration potential. In this work, LiZn 1-x Cu x PO 4 (x=0, 0.06, 0.08, 0.1, 0.12) materials were synthesized via solid state reactions. Their applicability for ultra low temperature cofired ceramics was confirmed by fabrication of green tapes and test substrates. Measurements carried out using time domain spectroscopy demonstrated very good dielectric properties of substrates at terahertz frequencies. The undoped and copper doped LiZnPO 4 ceramics exhibited promising properties for ULTCC submillimeter wave applications – low sintering temperatures of 700-750°C, compatibility with Ag thick film pastes, low and frequency stable relative permittivity and high quality factor in the THz range. The addition of 10 mol% CuO resulted in the best dielectric properties – a relative permittivity of 5.1 which is temperature stable in the 20-70°C range and a loss tangent of 0.007 at 1 THz.