Effect of Rare-Earth Doping on the Temperature-Capacitance Characteristics of MLCCs with Ni electrodes

概要

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The doping effect of rare-earths on the temperature-capacitance characteristics of MLCCs with Ni electrodes has been investigated for a BaTiO3-MgO-Rare-earth system. The temperature dependence of capacitance was reduced with smaller radii ions such as Ho, Er, Tm, Yb, and Lu, with Tm, Yb, and Lu being especially effective. The Curie temperature also shifted towards a higher temperature by the doping of smaller ionic radii rare-earth elements. On the other hand, the temperature dependence of capacitance increased and a decrease in the insulation resistance was observed for the larger ionic radii rare earth elements such as Tb and Gd. Ionic radii of rare-earth dopants can be an important factor in controlling the temperature-capacitance characteristics as well as improving the reliability. The reason for the increase in Curie temperature originates form the residual tensile stress generated by the mismatch in the lattice constant between the BaTiO3 core and diffused aria. Ni electrode MLCCs with X8R characteristic specification for automotive use have been developed using rare-earth dopants with smaller ionic radii such as Tm, Yb, Lu.
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