dc-Electrical Degradation of the BT-Based Material for Multilayer Ceramic Capacitor with Ni internal Electrode: Impedance Analysis and Microstructure

Abstract

The impedance of a BaTiO3 (BT)-based multilayer ceramic capacitor with a nickel internal electrode (Ni-MLCC) was investigated by measuring the frequency domain at various temperatures. All the obtained impedance data could be successfully fitted to a 4-RC section electrical equivalent network. The 4-RC section electrical equivalent network was successfully correlated to the microstructure: the core, the shell, the grain boundary, and the ceramic/internal electrode interface regions. Based on this electrical equivalent network, the electrical properties including the Curie-Weiss law, the current-voltage characteristics, and dc electrical degradation, were well explained. A model for the degradation behavior for BT-based Ni-MLCC with thin active layer thickness was proposed.

Effects of Ca and Zr additions and stoichiometry on the electrical properties of barium titanate-based ceramics

“…Some reports have indicated that the breakdown of MLCCs in the High Accelerated Life Test (HALT) was caused by the accumulation of oxygen vacancies at the cathodes. 7), 8) To depress this oxygen migration in the HALT, a coreshell structure, comprising an inner core of almost pure BaTiO 3 with a shell of the relaxor-like BaTiO 3 , is incorporated in the dielectrcs. 9),10) Grain boundaries also play an important role alongside the shell to depress the oxygen vacancy migration under electric fields.…”

“…Recently, the thickness of dielectric layers in MLCCs has reached below 1¯m to increase the volume density of capacitance, but each dielectric layer still requires 56 grains to have a sufficient number of grain boundaries for preventing oxygen vacancy migration. 7) This means that the grain size of BaTiO 3 should be decreased with the dielectric layer thickness, which is a notable disadvantage in high-capacitance MLCCs, because BaTiO 3 loses its dielectric permittivity (¾ r ) with grain sizes of less than 1¯m. 11)16) Tsurumi et al showed the limit of capacitance density of current MLCCs by computer simulation and predicted that there would be no advantage in utilizing BaTiO 3 with grains sizes of less than 80 nm to increase the volume density of capacitance of MLCCs.…”

Effect of Cr additions on the electrical properties of Ni–BaTiO3 ultra-thin multilayer capacitors

“…Generally, the total impedance of actual MLCCs is modeled by a series of leaky capacitive components for the dielectric-electrode interfaces (E), dielectric grains (G) and dielectric grain boundaries (GB) [5,16,22,23]. The corresponding resistance for each element at low AC field (~50 mV), was calculated using this model and is summarized in Table 1.…”

“…We also know that charged defects, like oxygen vacancies, can migrate toward the dielectric-electrode interface when DC-bias is applied and accumulate at the electrode regions [15][16][17]. In this case the formation of tunneling current through the Schottky barrier is possible, which will lead to significant suppression of interfacial contact resistance and degradation of total electrical properties [8,10].…”

Photocurrent Characteristics for Mn-doped Barium Titanate Ferroelectric Single Crystals

“…There exist lots of works on the control of its polarization and piezoelectric properties by the doping of acceptor-type impurities such as aluminum (Al), iron (Fe), or manganese (Mn), etc. [16][17][18][19][20][21][22][23][24] Mn-doped barium titanate has especially attracted research interests because of (1) the multivalent character of Mn ions (Mn 4+ , Mn 3+ and Mn…”