BACKGROUND OF THE INVENTION

The present invention relates to a dielectric composition and an electronic component.

There is a high demand for higher performance of mobile communication devices represented by smartphones. For example, the number of frequency bands to be used is increasing for achieving high-speed large-capacity communication. The frequency band to be used is a high frequency band (e.g., GHz band). Among high frequency components that function in such a high frequency band (e.g., baluns, couplers, filters, duplexers combining filters, diplexers combining filters), there is one utilizing a dielectric material as a resonator. Such a dielectric material is demanded to have a small dielectric loss and selectively pass a specific frequency in high frequency band.

The mobile communication devices are exposed to temperature change due to usage environment, heat generation of parts used in the devices, etc. Meanwhile, capacitance of high frequency components changes depending on temperature, and temperature dependency of capacitance, that is, temperature coefficient of capacitance thereby needs to be small within a predetermined temperature range in high frequency components.

Thus, dielectric materials applicable to the high frequency components are required to have small dielectric loss and temperature coefficient of capacitance. The reciprocal of dielectric loss can be represented as a quality factor (Q factor). In other words, thereby desired is a dielectric material having a high quality factor (Q factor) in high frequency band and a small temperature coefficient of capacitance in a predetermined temperature range.

To correspond with analysis of vehicle information and vehicle travel information, autonomous driving, etc., connected cars with always-on internet connection are being developed. An in-vehicle communication equipment mounted on the connected cars is also a type of the mobile communication devices and is required to be communicable at high speed with large capacity. The in-vehicle communication equipment may be disposed in engine room or its surroundings, which become high temperature, and is thereby particularly required to be reliable at high temperature. Thus, the high frequency components to be mounted on in-vehicle communication equipment are also required to be reliable at high temperature.

In accordance with higher performance of the mobile communication devices and the in-vehicle communication equipment, the number of electronic components mounted on one communication device tends to increase, and the electronic components are simultaneously required to be downsized for maintaining the size of the communication devices. Electrode area needs to be small for downsizing the high frequency components utilizing the dielectric materials. To compensate for the consequent decrease in capacitance, the dielectric materials are required to have a high relative permittivity in high frequency band.

By the way, capacitance of the high frequency components utilizing the dielectric materials changes depending on relative permittivity of the dielectric materials, electrode area, and distance between electrodes. In other words, their changes can adjust capacitance of the high frequency components. Meanwhile, when the performance of the high frequency components utilizing the dielectric materials is changed according to the purpose of communication devices to be mounted and so on, it may be required to correspond with change in performance of the high frequency components by adjusting relative permittivity of the dielectric materials without changing a mounting area of the high frequency components. In this case, it is more preferred that dielectric materials having the same composition system exhibit a relative permittivity corresponding to the performance of the high frequency components than the composition system of the dielectric materials is changed based on a required relative permittivity.

That is, dielectric characteristics required for dielectric materials are diversified for meeting various needs relating to the high frequency components.

Bi—Zn—Nb—O based oxides are conventionally known as materials having predetermined dielectric characteristics in high frequency band. For example, Patent Document 1 discloses a mixture of Bi3NbO7phase and Bi2(Zn2/3Nb4/3)O7phase, and Patent Document 2 discloses a sintered body obtained by mixing Bi2O3, ZnO, and Nb2O5and firing this mixture.Patent Document 1: JP2009537444 (A)Patent Document 2: JPH04285046 (A)

BRIEF SUMMARY OF INVENTION

However, Patent Document 1 discloses that an absolute value of temperature coefficient of permittivity of a mixture where Bi3NbO7phase and Bi2(Zn2/3Nb4/3)O7phase are mixed by 1:1 is 10 ppm or less. However, this mixture has a relative permittivity of less than 100, and the dielectric quality factor Q at 1 GHz is about 1000. Thus, the dielectric characteristics in high frequency band are not enough for advancing the downsizing of the high frequency components.

From the viewpoint of not changing the mounting area of the high frequency components, since the permittivity of this mixture is too large, capacitance cannot sufficiently be adjusted even if it is tried to be adjusted by electrode area, thickness of dielectric material, or the like in manufacturing the high frequency components with the same shape, and low capacitance cannot be achieved in the same composition system.

Patent Document 2 discloses that an absolute value of temperature coefficient of permittivity of a sintered body obtained by mixing and firing Bi2O3, ZnO, and Nb2O5at a predetermined proportion is 100 ppm or less. However, this sintered body has a no-load Q factor of 400 or less at 1 GHz, and dielectric characteristics in high frequency band are not thereby enough.

It is a first object of the present invention to provide a dielectric composition having a high quality factor (Q factor) in high frequency band, a small absolute value of temperature coefficient of capacitance Tcc in a predetermined temperature range, a relative permittivity εr within a predetermined range, and a high reliability at high temperature and an electronic component including this dielectric composition.

It is a second object of the present invention to provide a dielectric composition having predetermined values or more of relative permittivity εr and quality factor (Q factor) in high frequency band, a small absolute value of temperature coefficient of capacitance Tcc in a predetermined temperature range, and a high reliability at high temperature and an electronic component including this dielectric composition.

To achieve the first object, the present invention is:

[1] a dielectric composition including a complex oxide containing bismuth, zinc, and niobium, wherein

x+y+z=1.00,x<0.20,0.20≤y≤0.50, and0.25≤x/z,

in which the complex oxide is represented by a composition formula of BixZnyNbzO1.75+δ.

To achieve the second object, the present invention is:

[2] a dielectric composition including a complex oxide containing bismuth, zinc, and niobium, wherein

x+y+z=1.00,0.20≤y≤0.50,1.5<x/z≤3.0, andz<0.25,

in which the complex oxide is represented by a composition formula of BixZnyNbzO1.75+δ.

[3] An electronic component including a dielectric layer containing the dielectric composition according to [1] or [2].

Advantageous Effects of Invention

The present invention can provide a dielectric composition having a high quality factor (Q factor) in high frequency band, a small absolute value of temperature coefficient of capacitance Tcc in a predetermined temperature range, a relative permittivity εr within a predetermined range, and a high reliability at high temperature and an electronic component including this dielectric composition.

The present invention can provide a dielectric composition having predetermined values or more of relative permittivity εr and quality factor (Q factor) in high frequency band, a small absolute value of temperature coefficient of capacitance Tcc in a predetermined temperature range, and a high reliability at high temperature and an electronic component including this dielectric composition.

