Synthesis, vacuum sintering and dielectric characterization of zirconia (t-ZrO2) nanopowder

Phase pure zirconium oxide powders have been synthesized using the single step auto-ignition combustion method, the particles were nanometer sized (20 nm) and the size distribution was very narrow (3.4 nm). Systematic structural characterization revealed the t-ZrO2 and indexed for its tetragonal structure (a = 3.5975 Å and c = 5.1649 Å). Calculated microstrain in most of the plane indicated the presence of compressive stress (65–288 MPa) along various planes of the particles. Observed space group (P42/nmc) revealed the presence of cations in the 8e positions (0.75, 0.25, 0.75) and the anions in the 16 h positions (0.25, 0.25, 0.4534). The metal-oxide (Zr–O) band observed at the low wavenumber region further confirmed the phase purity of the as-prepared ZrO2 nanopowders. Peaks at the binding energy positions 2.042 and 0.525 keV in the energy dispersive X-ray spectrum revealed oxygen deficient zirconia. The particle size estimated by TEM was in good agreement with the results obtained through X-ray line broadening (20.81 nm) measurements. The nanopowders were sintered to above 98% of the theoretical density by using vacuum sintering technique at a relatively low temperature of 1300 °C. Stable tetragonal ZrO2 experimentally yield the permittivity value of about 28 at 10 MHz.

► A single step auto-igniting combustion synthesis was employed for the preparation of nanocrystalline ZrO2. ► Detailed structural analysis was carried out using XRD and FT-IR techniques. ► Micro strain analysis of the asprepared nanocrystalline ZrO2 was carried out. ► A sintered density of above 98% of the theoretical value was obtained using vacuum sintering techniques. ► The dielectric properties of vacuum sintered ZrO2 were measured for a frequency range from 10 KHz to 10 MHz.