US-12626862-B2 - Dielectric composition and electronic device

Abstract

A dielectric composition includes main phases having a tungsten bronze structure and first segregation phases. The first segregation phases include Ba and Si.

Inventors

• Toshihiro Iguchi
• Kenichiro MASUDA

Assignees

• TDK CORPORATION

Dates

Publication Date

20260512

Application Date

20230427

Priority Date

20220531

Claims (6)

1. 1 . A dielectric composition comprising: main phases having a tungsten bronze structure; and first segregation phases, wherein the first segregation phases include Ba, Si and Sr, and a molar ratio of a total of Ba element and Sr element to Si element in the first segregation phases is 1.05 to 2.5.
2. 2 . The dielectric composition according to claim 1 , wherein the main phases have an average particle size of 1.5 μm or less.
3. 3 . The dielectric composition according to claim 1 , wherein a ratio of an area of the first segregation phases to an area of a predetermined field of view is 0.005 to 0.15.
4. 4 . The dielectric composition according to claim 1 , wherein the first segregation phases surrounded by three or more of the main phases are specific first segregation phases, and a ratio of an average particle size of the specific segregation phases to an average particle size of the main phases is 1 or less.
5. 5 . The dielectric composition according to claim 1 , wherein a composition of the main phases is represented by a formula of A a B b D 4 O 15+α , in which A includes at least Ba, B includes at least Zr, D includes at least Nb, a is 3.05 or more, and b is 1.01 or more.
6. 6 . An electronic device comprising the dielectric composition according to claim 1 .

Description

The present application claims a priority based on Japanese Patent Application No. 2022-088930 filed on May 31, 2022 and incorporates it into the present specification by reference to that disclosure in its entirety. BACKGROUND OF THE INVENTION The present invention relates to a dielectric composition and an electronic device including dielectric layers composed of the dielectric composition. Electronic circuits or power supply circuits incorporated in electronic equipment are equipped with a large number of electronic devices such as multilayer ceramic capacitors for utilizing dielectric characteristics of dielectrics. As materials constituting dielectrics of such electronic devices (dielectric materials), barium titanate based dielectric compositions are widely used. As a dielectric composition other than the barium titanate based dielectric compositions, Japanese Patent Application Laid-Open No. H03-274607 discloses a dielectric composition having a tungsten bronze structure, and dielectric compositions having a tungsten bronze structure and exhibiting a higher relative permittivity are demanded. BRIEF SUMMARY OF THE INVENTION The present invention has been achieved under such circumstances. It is an object of the invention to provide a dielectric composition exhibiting a high relative permittivity and an electronic device including dielectric layers composed of the dielectric composition. To achieve the above object, a dielectric composition according to the present invention comprises: main phases having a tungsten bronze structure; andfirst segregation phases,wherein the first segregation phases include Ba and Si. The dielectric composition according to the present invention can exhibit a high relative permittivity. Moreover, the dielectric composition according to the present invention can exhibit a high resistivity and can also exhibit a high strength. The first segregation phases may further include Sr. Preferably, the main phases have an average particle size of 1.5 μm or less. As a result, the dielectric composition according to the present invention exhibits a higher relative permittivity and a higher resistivity and can exhibit a higher strength. Preferably, a ratio of an area of the first segregation phases to an area of a predetermined field of view is 0.005 to 0.15. As a result, the dielectric composition according to the present invention can exhibit a higher relative permittivity. Moreover, when the ratio is within the above-mentioned range, a higher strength can be exhibited compared to when the ratio is below the above-mentioned range. Preferably, a molar ratio of a total of Ba element and Sr element to Si element in the first segregation phases is 1.05 to 2.5. As a result, the dielectric composition according to the present invention can exhibit a higher relative permittivity. Moreover, when the molar ratio is within the above-mentioned range, a higher strength can be exhibited compared to when the molar ratio is below the above-mentioned range. Preferably, the first segregation phases surrounded by three or more of the main phases are specific first segregation phases, and a ratio of an average particle size of the specific segregation phases to an average particle size of the main phases is 1 or less. As a result, the dielectric composition according to the present invention can exhibit a higher relative permittivity. A composition of the main phases may be represented by a formula of AaBbD4O15+α, in which A includes at least Ba,B includes at least Zr,D includes at least Nb,a is 3.05 or more, andb is 1.01 or more. As a result, the dielectric composition according to the present invention can exhibit a higher resistivity. An electronic device according to the present invention comprises dielectric layers composed of the above-mentioned dielectric composition. BRIEF DESCRIPTION OF THE DRAWING(S) FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention; and FIG. 2 is a schematic cross-sectional view of a dielectric composition constituting dielectric layers shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention is described based on a specific embodiment. Multilayer Ceramic Capacitor FIG. 1 shows a multilayer ceramic capacitor 1 as an example of an electronic device according to the present embodiment. The multilayer ceramic capacitor 1 includes an element body 10 consisting of dielectric layers 2 and internal electrode layers 3 alternately laminated. A pair of external electrodes 4 electrically connected to the internal electrode layers 3 alternately arranged inside the element body 10 is formed at both ends of the element body 10. The shape of the element body 10 is not limited, but is normally rectangular parallelepiped. The dimensions of the element body 10 are not limited either and are determined appropriately according to the application. The dielectric layers 2 are composed