Polar Nanoregions and Dielectric Properties of BaTiO₃‐Based Y5V Multilayer Ceramic Capacitors

Abstract

Commercial EIA-Y5V base-metal-electrode multilayer ceramic capacitors (BME-MLCCs) made of (CaO+ZrO 2 )-doped BaTiO 3 are analyzed for the microstructure and investigated for its relation to dielectric properties. The characteristic diffuse scattering (DS) intensities observed in BaTiO 3 ceramics and the featureless "solid-solution" grains in Y5V capacitor chips are originated from multiple Ti sites in the dynamic BaTiO 3 structure. The pseudo-cubic (PC)-grains retaining the overall cubic (C-) symmetry metastably at room temperature are embedded with polar nanoregions (PNRs) in the ferroelectric (FE) tetragonal (T-), and rhombohedral (R-) phases, as revealed by high-resolution transmission electron microscopy (HRTEM). The presence of PNRs contributes effectively to large relative permittivity e r % 13 200 at 25°C. The FE T-domains grow from within PC-grains at the expense of embedded PNRs after prolonged annealing by extending "oxidizing firing" at 950°C in pO 2 = 10 -7 atm. These domains contain less Zr with otherwise homogeneously distributed solutes in PNR-dispersed PC-grains. Although preserving the relaxors characteristics, e r is reduced to~11 000 after 12 h, and then to~9000 after 24 h annealing. The reduction in e r is attributed to the annealing-induced FE T-domains grown at the expense of PNRs in PC-grains. The V€ ogel-Fulcher analysis indicates that Y5V ceramics are in the relaxor FE category, containing PNRs derived from polarization frustration.C. Alan Randall-contributing editor Manuscript No. 34036. J ournaldispersion of e r were investigated for the crystalline phases using X-ray diffractometry (XRD). The microstructure and microanalysis were determined using scanning and transmission electron microscopy (SEM and TEM).

Structure and electrical properties of IrO2-doped 0.5Ba0.7Ca0.3TiO3–0.5BaTi0.8Zr0.2O3 ceramics via low-temperature sintering

“…The T C values of the samples remained unchanged, indicating that T C was independent of x. The detected DC/C values (-35 % to 0) and low tan d satisfied the Y5Y and X7R specifications of Electronic Industries Association standards at high temperatures ([T C ) [31,32]. Additionally, the subtle change in the DC/C values was attributed to the large internal stress [33].…”

Polarization Response and Thermally Stimulated Depolarization Current of BaTiO3‐based Y5V Ceramic Multilayer Capacitors

“…BaTiO 3 ‐based dielectrics are extremely important and MLCC based on BaTiO 3 are being extensively used in commercial applications, due to their superior electrical properties . The rapid development of digital electronic equipment demands thinner dielectric layers to enable more stacking layers per unit height and higher capacitance per layer . The reduction in dielectric layer thickness causes an increase in the electric field applied to the dielectrics, and the application environment also causes MLCC devices to be stressed under DC field for extended durations .…”

“…Although the reoxidation step is adopted in N 2 atmosphere contained a low O 2 pressure to reduce oxygen vacancies, oxygen vacancies and other defects will still inevitably occur in dielectrics. The structure and properties of BaTiO 3 and related BaTiO 3 ‐based dielectrics have been extensively investigated by many researchers . The MLCC samples used in this study were commercial products with Y5V characteristics.…”

“…According to the Electron Industries Association (EIA) standard, the capacitance of Y5V specification must be within +22% or −82% of the value at 25°C from −30°C to +85°C . The dielectric constant‐temperature curve of BaTiO 3 ‐based materials can be purposely modified to be flat enough to meet the X7R, Y5V, or other specifications of EIA by optimizing the compositions and microstructures . The X7R‐type MLCC show usually the typical “core‐shell” microstructure in grains.…”

“…The X7R‐type MLCC show usually the typical “core‐shell” microstructure in grains. However, the Y5V microstructures show the “solid‐solution” grains . Although the microstructure and properties of X7R MLCC has been investigated by many researchers, there are still few articles concerning the BaTiO 3 ‐based Y5V MLCC with ultra‐thin dielectric layers with a thickness less than 4 μm.…”