Electronic device, dielectric ceramic composition and the production method

• US 20060223692A1
• Filed: 03/28/2006
• Published: 10/05/2006
• Est. Priority Date: 04/04/2005
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Sato, Akira, Ito, Kazushige
• Granted Patent: US 7,439,203 B2
• Time in Patent Office: Days
• US Class Current: 501/139
• CPC Class Codes: B32B 2311/22 Nickel or cobalt
• CPC Class Codes: C04B 2235/3203 Lithium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3205 Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3239 Vanadium oxides, vanadates or oxide forming salts thereof, e.g. magnesium vanadate
• CPC Class Codes: C04B 2235/3241 Chromium oxides, chromates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3249 containing also titanium oxide or titanates, e.g. lead zirconate titanate (PZT)
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• CPC Class Codes: C04B 2235/3258 Tungsten oxides, tungstates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/3409 Boron oxide, borates, boric acids, or oxide forming salts thereof, e.g. borax
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
• CPC Class Codes: C04B 2235/3436 Alkaline earth metal silicates, e.g. barium silicate
• CPC Class Codes: C04B 2235/3454 : Calcium silicates, e.g. wollastonite
• CPC Class Codes: C04B 2235/6582 : Hydrogen containing atmosphere
• CPC Class Codes: C04B 2235/6584 : at an oxygen percentage below that of air
• CPC Class Codes: C04B 2235/6588 : Water vapor containing atmospheres
• CPC Class Codes: C04B 2235/663 : Oxidative annealing
• CPC Class Codes: C04B 2237/346 : Titania or titanates
• CPC Class Codes: C04B 2237/405 : Iron metal group, e.g. Co or Ni
• CPC Class Codes: C04B 35/4682 : based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/62685 : characterised by the order of addition of constituents or additives
• CPC Class Codes: C04B 35/628 : Coating the powders or the macroscopic reinforcing agents
• CPC Class Codes: C04B 35/62813 : Alumina or aluminates
• CPC Class Codes: C04B 35/6303 : Inorganic additives
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: H01G 4/1227 : based on alkaline earth titanates
• CPC Class Codes: H01G 4/30 : Stacked capacitors H01G4/33 takes precedence
• CPC Class Codes: Y10T 428/2993 : Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

A dielectric ceramic composition comprising a main component including barium titanate and an oxide of Al, wherein the dielectric ceramic composition includes a plurality of dielectric particles, concentration of Al in each of the dielectric particles becomes lower from a particle surface to inside thereof, and each of the dielectric particles has an Al non-dispersed region substantially not including Al at least at a center portion of the particle.

Claims

1. A dielectric ceramic composition comprising a main component including barium titanate and an oxide of Al, wherein:

said dielectric ceramic composition includes a plurality of dielectric particles; and

concentration of Al in each of said dielectric particles becomes lower from a particle surface to inside thereof.

2. The dielectric ceramic composition as set forth in claim 1, wherein each of said dielectric particles has an Al non-dispersed region substantially not including Al at least at a center portion of the particle.

3. The dielectric ceramic composition as set forth in claim 2, wherein each of said dielectric particles has Al dispersed region substantially including Al dispersing from the particle surface to inside thereof;

and

when assuming that a particle diameter of said dielectric particle is D, a depth T_Al of said Al dispersed region from the particle surface is 5 to 45% of said particle diameter D.

4. The dielectric ceramic composition as set forth in claim 3, wherein:

said dielectric ceramic composition has a plurality of said dielectric particles and crystal grain boundaries existing between said dielectric particles next to each other; and

a rate of Al content at a depth T₅ as a depth from the particle surface being 5% of said particle diameter D is 20 to 80% when a rate of Al content at said crystal grain boundaries is 100%.

5. The dielectric ceramic composition as set forth in claim 1, wherein a content of an oxide of said Al is 0 to 4.0 moles (note that 0 is not included) with respect to 100 moles of said main component in terms of Al₂O₃.

6. The dielectric ceramic composition as set forth in claim 1, furthermore comprising:

a first subcomponent including at least one kind selected from MgO, CaO, BaO, SrO and Cr₂O₃;

a second subcomponent including oxide silicon as a main component;

a third subcomponent including at least one kind selected from V₂O₅, MoO₃ and WO₃;

a fifth subcomponent including CaZrO₃ or CaO+ZrO₂;

a sixth subcomponent including an oxide of R2 (note that R2 is at least one kind selected from Y, Dy, Ho, Tb, Gd and Eu); and

a seventh subcomponent including MnO;

wherein ratios of the respective subcomponents with respect to 100 moles of said main component are

first subcomponent;

0.1 to 3 moles,

second subcomponent;

2 to 10 moles,

third subcomponent;

0.01 to 0.5 mole,

fifth subcomponent;

larger than 0 mole but not larger than 5 moles,

sixth subcomponent;

larger than 0 mole but not larger than 9 moles (note that number of moles of the sixth subcomponent is a rate in terms of an R2 element), and

seventh subcomponent;

larger than 0 mole but not larger than 0.5 mole.

7. The dielectric ceramic composition as set forth in claim 6, furthermore comprising a fourth subcomponent including an oxide of R1 (note that R1 is at least one kind selected from Sc, Er, Tm, Yb and Lu);

wherein a content of said fourth subcomponent is 0.5 to 7 moles with respect to 100 moles of said main component in terms of an R1 element.

8. A production method of the dielectric ceramic composition as set forth in claim 1, comprising a step of performing calcining on a main component and at least a part of an oxide of Al to be included in said dielectric ceramic composition.

9. An electronic device comprising a dielectric layer formed by the dielectric ceramic composition as set forth in claim 1.

10. A multilayer ceramic capacitor comprising a capacitor element body obtained by alternately stacking dielectric layers formed by the dielectric ceramic composition as set forth in claim 1 and internal electrode layers.