High dielectric microwave ceramic dielectric material and preparation method thereof

Abstract

The invention discloses a high dielectric microwave ceramic dielectric material and a preparation method thereof. The material has the following formula: (1-x) (Sm0.5Li0.5) TiO3-xCaTiO3, wherein x uses the mole fraction and satisfies the relation of 0.15<=x<=0.20; and the material is prepared from the main raw materials of CaCO3, Li2CO3, TiO2 and Sm2O3. The preparation method of the high dielectric microwave ceramic dielectric material is as below: adding the raw materials to a mill pot, conducting wet milling for 14-18 h, baking, sieving, calcining at 1090-1110 DEG C for 2-3 h, and carrying out a solid state reaction to synthesize a principal crystalline phase powder; cooling the principal crystalline phase powder, adding the principal crystalline phase powder into the mill pot, conducting wet milling again for 14-18 h, drying, sieving, and conducting compression molding at pressure of0.4 to 0.5 tons to obtain a cylindrical base substrate; placing the base substrate in a alumina square porcelain boat with a platinum foil pad, burning with cover at 1290-1300 DEG C for 2-3 h into a porcelain, so as to obtain the final product. The invention provides a high dielectric microwave ceramic dielectric material, which has high microwave dielectric constant epsilon r while ensuring a low resonant frequency temperature coefficient tau f.

Description

technical field [0001] The invention relates to a high-dielectric microwave ceramic dielectric material applied to microwave devices and a preparation method thereof, belonging to the technical field of microwave ceramic dielectric materials. Background technique [0002] Microwave ceramic dielectric material is a kind of rapidly developing functional ceramic material. It is the key material of microwave components such as microwave resonator, filter, duplexer and microwave antenna. Development plays a vital role. [0003] The main index for evaluating the performance of microwave dielectric ceramics is the dielectric constant ε r , the product Qf of the quality factor Q and the resonant frequency f, the resonant frequency temperature coefficient τ f . Among the reported high dielectric microwave ceramic materials, CaTiO 3 ε r Up to 170, Qf about 3600GHz, τ f It is +800ppm / ℃, and its sintering temperature is around 1300℃. To be in CaTiO 3 The near-zero temperature co...

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Problems solved by technology

Chinese patent, application number 201010167964.7 discloses a composition of a LaAl x o 3 -(1-a)CaTiO 3 +ywt%MO (where MO is one or more of metal oxides, 0.30≤a≤0.35, 0.98≤x≤1.06, 0.05≤y≤2) high-Q intermediate microwave ceramics and its preparation method, its medium Electrical constant ε r =43~46, Qf≈40000GHz,τ f Stable at ±10ppm / °C, but its sintering temperature is as high as 1400-1450°C

Chinese journal "Functional Materials" 2007 Supplement 38 in "La 3+ , Li 1+ to CaTiO 3 Influence of Microwave Dielectric Properties" discloses a composition of (1-y) Ca 1-x La 2x / 3 TiO 3 -yLi 1 / 2 Nd 1 / 2 TiO 3 microwave ceramic materials, although when x=0.4 and y=0.5, ceramics have better comprehensive microwave dielectric properties (τ f Reduced to within 10ppm / ℃, ε r higher than 100), but its Qf drops significantly below 1400GHz

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