Alumina densification at low temperatures using CaV2O6 for LTCC application

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AbstractLow‐temperature densification of alumina using calcium vanadate (CaV2O6, CV) having a similar dielectric constant as a liquid‐forming additive has been studied. The alumina‒CV composites containing 20‒40 vol.% CV achieve ∼94% of theoretical density at low temperatures of 1100°C‒900°C by liquid‐phase sintering. A reduction in the average size of grains from .87 to .42 µm with a surge in CV amount from 20 to 40 vol.% is observed. The permittivity decreases from 9.2 to 8.90, and the dielectric loss increases from 2.154 × 10‒3 to 4.761 × 10‒3 when the amount of CV in the alumina‒CV composite rises from 20 to 40 vol.%. The temperature coefficient of resonance frequency, thermal expansion coefficient, and thermal conductivity of the alumina‒CV composites are observed in the ranges of ‒54 to ‒72 ppm °C‒1, 6.94‒7.32 ppm °C‒1, and 13.78‒8.02 W m‒1 K‒1, respectively. The compatibility of the composites with Ag for low‐temperature co‐fired ceramics (LTCC) application is established through co‐sintering and energy‐Dispersive X‐ray spectroscopy line spectra analysis. The low‐temperature densification, acceptable range of dielectric and thermal properties, and silver compatibility make the alumina‒CV composite a candidate for LTCC application.