Microstructure analysis of the Y5V multilayer ceramic capacitors based on BaTiO3

Abstract

The Y5V-1206 base-metal electrode (BME) multilayer ceramic capacitor (MLCC) chips have been characterised for crystalline phases using X-ray diffractometry (XRD), and microstructure using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The microstructure features found in the Ni electrode and the BaTiO 3 dielectric layer are discussed in terms of the tensile backstresses induced upon firing due to constrained sintering heterogeneously. The chemical compositions containing BaO-excess and additives CaO and ZrO 2 , determined for BaTiO 3 grains by energydispersive spectroscopy (EDS) equipped in the TEM are also reported. However, no rare-earth oxides were found in the grains. The representative microstructure of BaTiO 3 grains containing dislocations is the "solid-solution" type distinctive from the "core-shell" of the X7R compositions. The fact that no ferroelectric domains were detected suggests that the BaTiO 3 grains are pseudo-cubic with the c/a ratio ≈ 1.0.

Anisotropic Permittivity of Tetragonal BaTiO3: A First-Principles Study

“…1) The tetragonal phase of perovskitestructured BaTiO 3 is widely used as a dielectric material in multi-layer ceramic capacitors (MLCCs) [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] on account of its exceptionally large permittivity at room temperature. The ferroelectric phase-transition mechanism can be explained in terms of the successive freezing of the triply degenerate polar soft-mode phonon at the À point in the high symmetry Pm " 3m structure.…”

High dielectric constant of (Ba0.96Ca0.04)(Ti0.85Zr0.15)O3 multilayer ceramic capacitors with Cu doped Ni electrodes

“…3(a and b), it can be seen that the continuity of the internal electrodes in the MLCC was about 88% with a lay down of approximately 0.6 mg/cm 2 . The dielectric film thickness after sintering was approximately 17 m and the electrode thickness was approximately 2.0 m. However, the continuity of internal 6 electrodes in commercial MLCCs is below 80% in general with particular reference to the Y5V-1206 MLCCs rated 1 F and manufactured by Yageo Co. [17]. Pure BaTiO 3 powders are often added to the metal electrode so as to decrease the coefficient mismatch of thermal expansion and increase the sintering match with the dielectric layers.…”

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

“…The EIA‐rated X7R and X5R BME‐MLCCs with ε r ≈ 1000–5000, Z5U and Y5V with ε r > 8000 are now categorized as class II capacitors. G av in X7R is usually less than 1.2 μm, some being much smaller at ~250–400 nm, whereas those of Y5V and Z5U ranging between ~3 and 10 μm (3–5 μm) are at least several times larger. The latter two have much higher relative permittivity, ε r ≈ 18 000 for Y5V and <14 000 for Z5U.…”

“…Both X7R and Y5V formulations include aliovalent ions as dopants, but X7R's ε r at ~1000–5000 is significantly lower . The Y5V microstructure is usually referred to as consisting of “solid‐solution” grains with solutes Ca and Zr distributed homogeneously in the grains. It appears that rather than the average grain size the doping system determines the high relative permittivity in BaTiO 3 ‐based mixed crystal.…”