JPH031261B2 - - Google Patents

Description

Detailed Description of the Invention "Field of Industrial Application" The alumina ceramic composition of the present invention can be used for dielectric resonators,
It can be suitably used in the field of telecommunications, such as microwave waveguides, microwave capacitors, and microwave IC boards, or in the field of nuclear fusion-related equipment, such as microwave transmission windows. ``Conventional technology'' With the development of communication networks in recent years, the frequency range used has expanded to include microwaves. In connection with this, dielectric ceramics are applied to dielectric resonators, microwave integrated circuit boards, and impedance matching of various microwave circuits in the microwave frequency region.
Especially recently, a large number of filters, guns, or FET microwave oscillators are required to stabilize the frequency, and the demand for them is increasing. The size of this microwave circuit is based on the wavelength of electromagnetic waves, and when an electromagnetic plate propagates in a three-dimensional microwave circuit using a dielectric, the wavelength is λο compared to the wavelength in vacuum. Letting the dielectric constant be ε, it becomes λο/ε.
On the other hand, alumina porcelain has high mechanical strength, low dielectric loss, and low cost, so it is expected to be used in the above-mentioned telecommunications field. “Problems to be solved by the invention” However, conventional alumina porcelain has a dielectric constant of ε
Since the temperature coefficient τε of is large at approximately +110ppm/℃,
Its uses were extremely limited. "Means for Solving the Problems" The present invention solves the above problems and provides 1MHz to 7G
The purpose is to provide alumina porcelain with a dielectric power factor tan8 of 10×10 ^-5 or less at Hz and an absolute value of the temperature coefficient of permittivity τε of 40 ppm/℃ or less, and the means thereof are as follows.
Al ₂ O ₃ SnO ₂ TiO ₂ point P 0.95 0.025 0.025 Point Q 0.70 0.225 0.075 Point R 0.70 0.075 0.225 [Unit: mole fraction] in the ternary composition diagram of the Al ₂ O ₃ −SnO ₂ −TiO ₂ system is the peak. Within the area of triangle PQR (including on the sides)
It is in the composition. "Effect" By the above means, the dielectric power factor at 1MHz to 7GHz
The tan δ is 10 × 10 ^-5 or less, and the absolute value of the temperature coefficient of dielectric constant τε is 40 ppm/°C or less, making it possible to use it in a wide range of telecommunications fields in the high frequency range. When Al ₂ O ₃ is in excess, τε takes a positive value with an excessive absolute value, and when Al 2 O 3 is insufficient, τε takes a negative value with an excessive absolute value.
tan8 becomes excessive. Even if the alumina content is within the above range, if the content ratio of SnO ₂ to TiO ₂ exceeds the above range, tan δ becomes excessive. "Example" Alumina with an average particle size of 0.5 μm and a purity of 99.995%, reagent special grade tin oxide, and reagent special grade titanium oxide are blended in the composition shown in the table for details in the proportions dotted inside and outside the range of triangle PQR in the attached composition diagram, Add 200g of deionized water and 3g of polyvinyl alcohol to 300g of the compound to produce 1Kg of alumina coccule with a diameter of 15mm and a purity of 99.9%.
The mixture was placed in a polyethylene bottom mill with an inner volume of 1, wet mixed at 120 rpm for 48 hours, freeze-dried, passed through a 42-mesh sieve, and then subjected to a pressure of 1500 kg/cm ^2.
Alumina porcelain compositions No. 1 to No. 13 having a size of 15 φ x 8 mm were manufactured by press molding with a mold, firing at the temperature shown in the table, and polishing. Alumina porcelain compositions No. 1 to No. 13 were ultrasonically cleaned with chlorocene and deionized water for 20 minutes each, air-dried, and dried in a desiccator containing silica gel for 15 hours, and then dielectric properties were measured under the following conditions. The results are shown in the table. Measurement conditions Method: Dielectric cylindrical resonator method Equipment: Yokogawa Huret Packard 8410C network analyzer system Frequency: 7GHz [Table]

[Brief explanation of the drawing]

The drawing shows the components of the alumina porcelain composition of the present invention.
It is a ternary composition diagram showing the contents of Al ₂ O ₃ , SnO ₂ and TiO ₂ .

Claims (1)

[Claims] 1 _{Al 2} O ₃ SnO ₂ TiO _{2 point} P 0.95 0.025 0.025 Point Q 0.70 0.225 0.075 Point _{R 0.70} 0.075 0.225 [Unit: moles] Fraction〕 Within the area of triangle PQR with vertices (including on the sides)
Alumina porcelain composition with composition.