Hexagonal type barium titanate powder, producing method thereof, dielectric ceramic composition and electronic component
To provide a hexagonal type barium titanate powder having a fine and uniform particle size and contributing to a thinner dielectric layer. A hexagonal type barium titanate powder according to the present invention has the following characteristics that a maximum particle diameter is 1.0 μm or less, a ratio of 90% accumulated particle diameter and 50% accumulated particle diameter is 3.0 or less, and a hexagonal ratio is 50% or more.
1. A hexagonal type barium titanate powder, wherein a maximum particle diameter is 1.0 μm or less,
a ratio (D90/D50) of 90% accumulated particle diameter (D90) and 50% accumulated particle diameter (D50) is 3.0 or less,
a hexagonal ratio is 50% or more,
an average particle diameter is 0.1 to 0.5 μm,
the powder is shown by Ba A (Ti 1-α M α ) B O 3 , wherein
M is a trivalent metal ion having an effective ionic radius in the range from 0.58 to 0.64 Å, a ratio A/B is in the range from 0.900 to 1,040, and α is in the range from 0.03 to 0.2, and
M is a trivalent metal ion selected from the group consisting of Cr, Ga and Co.
2. The hexagonal type barium titanate powder as set forth in claim 1 , wherein the hexagonal type barium titanate powder has a specific surface area of 2.0 m 2 /g or more when measured by a BET method.
3. The hexagonal type barium titanate powder as set forth in claim 1 , wherein the hexagonal type barium titanate powder has a specific surface area of 3.0 m 2 /g or more when measured by a BET method.
4. The hexagonal type barium titanate powder as set forth in claim 1 , wherein the hexagonal type barium titanate powder has a specific surface area ranging from 2.8 m 2 /g to 5.5 m 2 /g when measured by a BET method.
5. A dielectric ceramic composition comprising a sintered compact of barium titanate powder as set forth in claim 1 as a main component.
6. An electronic component comprising a dielectric layer composed of the dielectric ceramic composition as set forth in claim 5 and an internal electrode layer.
7. A method of producing the hexagonal type barium titanate powder according to claim 1 , comprising steps of:
preparing a mixed powder including a barium carbonate powder with a specific surface area of 20 m 2 /g or more, a titanium dioxide powder with a specific surface area of 30 m 2 /g or more and a powder comprising M element (M is the element which effective ionic radius of the trivalent ion is in the range from 0.58 to 0.64 Å) with a specific surface area of 5.0 m 2 /g or more, and
heat-treating the mixed powder at 900° C. or higher and less than 1300° C.