Very high thermal stability with excellent dielectric, and non-ohmics properties of Mg-doped CaCu_3Ti_(42)O_(12) ceramics

摘要

In this work, the nominal CaCu~(3−x)Mg~(x)Ti~(4.2)O~(12)(0.00, 0.05 and 0.10) ceramics were prepared by sintering pellets of their precursor powders obtained by a polymer pyrolysis solution method at 1100 °C for different sintering time of 8 and 12 h. Very low loss tangent (tanδ) < 0.009–0.014 and giant dielectric constant ( ε ′) ∼ 1.1 × 10_(4)–1.8 × 10_(4)with excellent temperature coefficient (Δ ε ′) less than ± 15% in a temperature range of − 60 to 210 °C were achieved. These excellent performances suggested a potent application of the ceramics for high temperature X8R and X9R capacitors. It was found that tan δ values decreased with increasing Mg_(2+)dopants due to the increase of grain boundary resistance ( R ~( gb )) caused by the very high density of grain, resulting from the substitution of small ionic radius Mg_(2+)dopants in the structure. In addition, CaCu~(3−x)Mg~(x)Ti~(4.2)O~(12)ceramics displayed non-linear characteristics with the significant enhancements of a non-linear coefficient ( α ) and a breakdown field ( E ~( b )) due to Mg_(2+)doping. The high values of ε ′ (14012), α (13.64) and E ~( b )(5977.02 V/cm) with very low tanδ value (0.009) were obtained in a CaCu~(2.90)Mg~(0.10)Ti~(4.2)O~(12)ceramic sintered at 1100 °C for 8 h.