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Study on Synthesize and Modification of BaTiO3-Bi (Mg1/2Ti1/2)O3 Ceramics with High Temperature Stability Over Wide Range

Author: XiongBo
Tutor: HaoHua
School: Wuhan University of Technology
Course: New Energy Material
Keywords: Multilayer ceramic capacitors Permittivity Yung temperature and the rate of change Core - shell structure
CLC: TQ174.1
Type: Master's thesis
Year: 2011
Downloads: 65
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Abstract


Multilayer Ceramic Capacitors ( MLCC ) is an important electronic components, and can be applied to almost all of the electronics industry . Due to having a high dielectric constant insulating properties and long life , barium titanate (BaTiO3) is the most widely used perovskite ferroelectrics, therefore , barium titanate-based ceramic materials have been the focus of research in MLCC . However , the Curie point of the barium titanate only ~ 130 ° C , limits the upper temperature limit for it to work in the the XNR ceramic compound , stability requirements can not satisfy the higher temperature dielectric properties . The papers address the problem , ( 1 - x ) BaTiO3 - XBI ( Mg1/2Ti1/2 , ) O3 ( BT - BMT ) system as the research object , focus on exploration ( 1 - x ) the BT - xBMT ( x = 0.01 to 0.60 ) the structure of the ceramic dielectric performance and relaxation phenomena . The study found that , The BMT 's added to make the BT -based ceramics exhibit obvious frequency dispersion and diffuse phase transition characteristics , dielectric constant peak is down , the dielectric temperature peak of the spectrum becomes more flat , BMT BT solution is only 7 mol% . Referral temperature curve shows that the nominal composition of the lower Tm 0.85BT-0.15BMT , temperature stability , has good adjustability may applied to XnR type MLCC material , doping modification . Nb2O5, Co2O3 doped BT system can effectively enhance the stability of the temperature of the system , but the type of the process will lead to changes in the structure of the ceramic microstructure . This thesis focused on the Nb , Co doping mechanism of the formation of the core-shell structure in the BT - BMT system . Two different dopant is added sequentially processes result in different micro- structure, but can be obtained to meet the the X8R ??requirements ceramic medium . Dielectric properties : dielectric constant to 1000 , the loss is less than 1.5% , the capacity temperature change rate ≤ ± 15 % of the temperature range -55 to 155 ° C . By the the the BT base shell - core structure and dielectric properties of the relationship between the design and synthesis of a multi- shell structure ceramic , to expand system capacity temperature rate of change ≤ ± 15 % of the temperature range . The paper analyzes the impact of each step of the process on the structure and properties of ceramic . The experiments show that sequentially by the sol - gel coated and solid - phase mixing of ultrafine powder to give the desired multi - shell structure , adjust the molar ratio of the shell and the core and sintering parameters , ns: nx = 1:8 for optimum component , its performance : dielectric constant to 1800 , the loss is less than 1.5% , Yung temperature rate of change ≤ ± 15 % of the temperature range -55 to 150 ° C .

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CLC: > Industrial Technology > Chemical Industry > Silicate > Ceramic Industry > Basic theory
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