Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Electronic components, assemblies > Microwave transmission control components

Study on Microwave Dielectric Properties of Ba(Mg1/3Ta2/3)O3 Ceramics Doped with Nanoscaled Powder Additives

Author WangWei
Tutor WuShunHua
School Tianjin University
Course Microelectronics and Solid State Electronics
Keywords Ba (Mg1/3Ta2/3) O3 Nanopowder Microwave dielectric properties Lattice vibrational modes Wet chemical synthesis process Uniform Design Multiple linear regression analysis
Type PhD thesis
Year 2005
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Ba (Mg 1/3 Ta 2/3 ) O 3 (BMT) ceramic is the low εr class microwave dielectric ceramics in the best typical representative is the high frequency satellite communications used in the field of media materials, and thus become one of the hot spots of the international microwave dielectric ceramics research and application areas. In this thesis work, starting from the microscopic structure of the material, analysis of BMT ceramic dielectric loss and resonant frequency temperature coefficient (τ f ) intrinsic mechanisms influencing factors, as a basis by doped nano additives on BMT dielectric ceramics modified research, the main purpose is to get good sintering performance and excellent microwave dielectric properties of BMT system microwave dielectric material. BMT ceramic dielectric properties Theoretical Study analyzed: a dielectric loss material at microwave frequencies is divided into internal losses and external losses, the internal loss depending on the chemical structure of the material composition and crystal structure, the external loss mainly depends the microscopic structure of the material; the dielectric constant temperature coefficient (τ ε ), not only with the material's chemical composition concerned, but also by the impact of the material crystal structure of the reason is that the crystal structure changes directly affect the temperature dependence of the material microstructure polarization. 2. Use a variety of metal ions doping modification to the the traditional electronic ceramic technology BMT ceramic materials ion physical parameters with polar lattice vibrational modes of contact established through the classical harmonic oscillator model to explore different location replace ion Effects and regularity of the material properties: the BMT system ε of r and τ f , mainly depending on the variation in the characteristics of the material of the polarity of the low frequency region lattice vibration mode, and the system's internal loss depending on the polarity lattice phonon anharmonic effect by doping replace the the polarity lattice vibrational modes of the the adjustable original BMT system characteristics, thus improving the microwave dielectric properties of the materials. Sn 4 Mn 2 nanopowder solution doping modification BMT system ceramics with good sintering performance and excellent microwave dielectric properties of BMT-BS system microwave dielectric ceramic materials: doping 1.5 mol% Mn the 0.85BMT-0.15BS system insulation the 4h after τf approximately 0ppm ° C -1 1450 ℃, body density 7.33g/cm 3 , εr 24.9, Q × f value of 1.85 × the 10 5 GHz. 4. Liquid coated - interfacial reaction method at 800 ℃ BMT nanopowder synthesis of uniform composition, high purity, good sintering activity, cost-effectively through the uniform design and multiple linear regression to nano BMT powder as additives to improve the sintering properties of the BMT system optimization analysis, the relative density of the samples incubated at 1550 ℃ for 4h containing 8.5wt% additives BMT reached 93.80%, the microwave dielectric properties: the ε r < / sub> = 24.8; τ f = 6ppm ℃ -1 ; Q × f = 1 .24 × 10 5 GHz.

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