Dielectric ceramic and laminated ceramic capacitor
AssigneeMurata Manufacturing Co., Ltd.
InventorKoichi BANNO
Life of this patent
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Abstract
A laminated ceramic capacitor suitable for intermediate to high voltage applications uses a dielectric ceramic represented by {100(BaTiO3+aBaZrO3)+bR+cMg+dMn+eSi} where R is a rare earth element; 0≦a≦0.2, 8.0≦b≦12.0, 1.0≦c≦10.0, 0.1≦d≦3.0, and 1.0≦e≦10.0, and includes first grains of 0.7 μm or more in grain size and an average first grain size (Aave) and area ratio of the ceramic (SA), and second grains of 0.6 μm or less in grain size and an average second grain size (Bave) and area ratio (SB), 0.8 μm≦Aave≦2.0 μm, 0.1 μm≦Bave≦0.5 μm, Aave/Bave≧3.0, 0.3≦SA≦0.9, 0.1≦SB≦0.7, and 0.8≦SA+SB≦1.0.
Claims16
A dielectric ceramic comprising a composition represented by
- 100(BaTiO3+aBaZrO3)+bR+cMg+dMn+eSi
- in which
- R represents one or more elements selected from the group consisting of Sm, Eu, Gd, Tb, Dy, and Ho,
- 0≦a≦0.2,
- 8.0≦b≦12.0,
- 1.0≦c≦10.0,
- 0.1≦d≦3.0,
- 1.0≦e≦10.0,
- having first grains A of 0.7 μm or more in grain size, the first grains A having an average grain size Aave, and second grains B of 0.6 μm or less in grain size, the second grains B having an average grain size Bave for, wherein
- 0.8 μm≦Aave≦2.0 μm,
- 0.1 μm≦Bave≦0.5 μm, and
- Aave/Bave≧3.0, and
- wherein an area ratio SA occupied by the first grains and an area ratio SB occupied by the second grains satisfy
- 0.3≦SA≦0.9,
- 0.1≦SB≦0.7, and
- 0.8≦SA+SB≦1.0.
Dependencies are inferred from the claim text.