Na2CaV4O12: A low-temperature-firing dielectric with lightweight, low relative permittivity, and dielectric anomaly around 515 °C

摘要

A low temperature fired Na2CaV4O12 ceramic was synthesized via a solid-state reaction route at a temperature range of 350-550 degrees C. The Thermal analysis confirmed the densification and melting temperature of Na2CaV4O12 to be 530 degrees C and 580 degrees C, respectively. Dielectric properties together with the electrical conductivity were characterized at a broad frequency and temperature range. A super-low relative permittivity of epsilon(r) = 7.72 and loss tangent of tan delta = 0.06 were obtained at 1 MHz at room temperature. A dielectric anomaly peak took place around 515 degrees C, which was associated with the phase transition from P4/nbm to P (4) over bar b2. Ac impedance spectrum coupled with complex modulus plots unveiled the electrical conduction mechanism, which was dominated by the short-range movement of the charge carriers at low temperatures (T <= 220 degrees C) however long-range migration of charge carriers emerged at higher temperatures.

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