Low K dielectrics in sintered Al–Zr oxide composites processed by thermal plasma heating

A simple and low cost heating technique based on extended arc thermal plasma heating (EATPH) source has been developed to sinter high temperature Alx–Zr100−x (x=0, 10, 20, …, 100) oxides. Structure and morphology of sintered Al–Zr oxide samples were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). Interesting result pertaining to the reduction of dielectric constant (K) and dielectric loss (tan δ) were noted in thermal plasma sintered specimen as compared to the conventional sintered sample using resistive heating. It is observed that values of K are reduced up to 40% (maximum) w.r.t. conventional sintering. This low K behavior observed in thermal plasma sintered sample may be attributed to the incorporation of dynamic inclusion in different defect form during thermal plasma heating within a short sintering time. It is also further observed from the frequency and temperature variation of K and tan δ that surface charge polarization along with dipole screening play an important role at high frequencies and temperatures which can be explained by dipole pinning and depinning mechanisms.