Design of a bilayer ceramic capacitor with low temperature coefficient of capacitance

Abstract

We show how a simple bilayer system that combines a layer of undoped BaTiO3 (BT) with a second layer of Ba0.975Na0.025Ti0.975Nb0.025O3 (2.5NNBT) can be used to improve the temperature coefficient of capacitance (TCC) of BaTiO3-based materials for capacitor applications. The bilayer system emulates the volume ratio between a conventional core and shell phase microstructure allowing a simple resource efficient approach to optimise the system for low TCC. Optimisation was achieved with a volume ratio of 0.67 2.5NNBT with 0.33 BT and results in a TCC of ±6% over the temperature range ∼25 to 125 °C whilst maintaining a permittivity of εr ∼ 3000 and low dielectric loss.

Resource efficient exploration of ternary phase space to develop multi-layer ceramic capacitors

“…We first choose our input materials, here nine input -T profiles were selected from a single solid solution. The ceramics were prepared via the conventional solid-state route; more details are given in [30]. The -T profiles were obtained using an LCR meter (Agilent E4980 Precision LCR Meter, Agilent Technologies) for a fixed frequency of 100 kHz with an applied ac voltage of 100 mV and corrected for sample geometry.…”

“…One possible solution to impede diffusion is by the use of 'floating' electrodes between the materials to act as a physical barrier without being directly connected to the termination. Previously we have demonstrated the fabrication of a simple bilayer ceramic with an internal Au electrode to impede diffusion between sintered ceramics of undoped BaTiO3 (BT) and Ba0.975Na0.025Ti0.975Nb0.025O3 (2.5NNBT) [30]. TCC was optimised to ±6% over a ~ 100 o C temperature range from ∼25 to 125 °C whilst maintaining r ∼ 2000 with low dielectric loss over the range using a ratio of 0.59:0.41.…”

Cold‐Sintered C0G Multilayer Ceramic Capacitors

“…The ever‐increasing trend toward miniaturization of electronic systems drives the 3D integration of alternating ceramic and metallic electrode layers. Multilayer ceramic capacitors (MLCCs) are probably the best known and most successful examples of 3D integration of functional ceramics with more than two trillion manufactured every year . 3D integration demands the sintering temperature of the ceramic layers to be lower than the melting temperature of (and chemically compatible with) the metallic electrode .…”

Improved breakdown strength and energy storage density of a Ce doped strontium titanate core by silica shell coating

“…A more rigorous presentation of mathematics and assumptions behind the model has been presented here 29 . This technique has been used previously to simulate the impedance response of core-shell structures 30 , interfaces effects in lamellar devices and temperature stable capacitance bi-layers 31,32 .…”