Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestab...Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.展开更多
The effect of （Ba（0.6）Sr（0.4））TiO3（BST） addition on dielectric properties of CaCu3Ti4O（12） （CCTO） ceramic was investigated. Ceramic samples with the chemical formula （1-x）CaCu3Ti4O（12） ＋ x（Ba（0.6）...The effect of （Ba（0.6）Sr（0.4））TiO3（BST） addition on dielectric properties of CaCu3Ti4O（12） （CCTO） ceramic was investigated. Ceramic samples with the chemical formula （1-x）CaCu3Ti4O（12） ＋ x（Ba（0.6）,Sr（0.4））TiO3 （x=0, 0.05, 0.1, and 0.2） were synthesized from high purity oxide powders by the conventional solid-state synthesis method. X-ray diffraction （XRD） analysis showed the existence of BST as a secondary phase alongside CCTO. Scanning electron microscopy （SEM） investigation showed a slight decrease in grain size of doped CCTO samples. Density measurements showed that porosity content increased with increasing BST addition indicating low densification due to high melting point secondary phase addition. Dielectric constant of undoped CCTO （x=0） showed lack of stability with frequency which dropped drastically between 104 and 105Hz and accompanied by high dielectric loss. Addition of BST into CCTO caused the dielectric constant to slightly decrease but improved stability with frequency compared to the undoped sample. The decrease in dielectric constant of doped CCTO samples was suggested to be partly due to the decrease in average grain size and increase in porosity with BST addition. Nevertheless, a high value of dielectric constant was still maintained around ～104 range for all doped samples. The dielectric loss （tanδ） of all BST-doped samples was lower than that of pure CCTO sample at the frequency range of 103 to 105 Hz probably due to the increase of grains boundary resistivity. The activation energy of grains boundary （E（gb）） showed higher values as compared to the activation energy of grains （Eg ） for all samples and conforms to the internal barrier layer capacitor （IBLC） model.展开更多
Influence of the coupling agent on microstructure and dielectric properties of ceramic-polymer composites is systematically studied using CaCu_(3)Ti_(4)O_(12)(CCTO)as the filler,trichloro-(1H,1H,2H,2H-perfluorooctyl)-...Influence of the coupling agent on microstructure and dielectric properties of ceramic-polymer composites is systematically studied using CaCu_(3)Ti_(4)O_(12)(CCTO)as the filler,trichloro-(1H,1H,2H,2H-perfluorooctyl)-silane(Cl_(3)-silane)as coupling agent,and P(VDF-CTFE)88/12 mol.%copolymer as the matrix.It is demonstrated that Cl_(3)-silane molecules can be attached onto CCTO surface using a simple process.The experimental results show that coating CCTO with Cl_(3)-silane can improve the microstructure uniformity of the composites due to the good wettability between Cl_(3)-silane and P(VDF-CTFE),which also significantly improves the electric breakdown field of the composites.It is found that the composites using CCTO coated with 1.0 wt.%Cl_(3)-silane exhibit a higher dielectric constant with a higher electric breakdown field.For the composites with 15 vol.%CCTO that is coated with 1.0 wt.%Cl_(3)-silane,an electric breakdown field of more than 240 MV/m is obtained with an energy density of more than 4.5 J/cm^(3).It is also experimentally found that the dielectric constant can be used to easily identify the optimized content of coupling agent.展开更多
基金supported by the Universiti Sains Malaysia(USM) fellowship(APEX 91002/JHEA/ATSG4001)fundamental research grant scheme(FRGS) under grant number of 203/PBAHAN/6071263
文摘Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.
基金supported by the Malaysian Ministry of Science, Technology and Innovation under Fundamental Research Grant Scheme Nos. UiTM-600-RMI/ST/FRGS5/3/FST (18/2010) and 600-RMI/ST/FRGS 5/3/FST(203/2010)
文摘The effect of （Ba（0.6）Sr（0.4））TiO3（BST） addition on dielectric properties of CaCu3Ti4O（12） （CCTO） ceramic was investigated. Ceramic samples with the chemical formula （1-x）CaCu3Ti4O（12） ＋ x（Ba（0.6）,Sr（0.4））TiO3 （x=0, 0.05, 0.1, and 0.2） were synthesized from high purity oxide powders by the conventional solid-state synthesis method. X-ray diffraction （XRD） analysis showed the existence of BST as a secondary phase alongside CCTO. Scanning electron microscopy （SEM） investigation showed a slight decrease in grain size of doped CCTO samples. Density measurements showed that porosity content increased with increasing BST addition indicating low densification due to high melting point secondary phase addition. Dielectric constant of undoped CCTO （x=0） showed lack of stability with frequency which dropped drastically between 104 and 105Hz and accompanied by high dielectric loss. Addition of BST into CCTO caused the dielectric constant to slightly decrease but improved stability with frequency compared to the undoped sample. The decrease in dielectric constant of doped CCTO samples was suggested to be partly due to the decrease in average grain size and increase in porosity with BST addition. Nevertheless, a high value of dielectric constant was still maintained around ～104 range for all doped samples. The dielectric loss （tanδ） of all BST-doped samples was lower than that of pure CCTO sample at the frequency range of 103 to 105 Hz probably due to the increase of grains boundary resistivity. The activation energy of grains boundary （E（gb）） showed higher values as compared to the activation energy of grains （Eg ） for all samples and conforms to the internal barrier layer capacitor （IBLC） model.
文摘Influence of the coupling agent on microstructure and dielectric properties of ceramic-polymer composites is systematically studied using CaCu_(3)Ti_(4)O_(12)(CCTO)as the filler,trichloro-(1H,1H,2H,2H-perfluorooctyl)-silane(Cl_(3)-silane)as coupling agent,and P(VDF-CTFE)88/12 mol.%copolymer as the matrix.It is demonstrated that Cl_(3)-silane molecules can be attached onto CCTO surface using a simple process.The experimental results show that coating CCTO with Cl_(3)-silane can improve the microstructure uniformity of the composites due to the good wettability between Cl_(3)-silane and P(VDF-CTFE),which also significantly improves the electric breakdown field of the composites.It is found that the composites using CCTO coated with 1.0 wt.%Cl_(3)-silane exhibit a higher dielectric constant with a higher electric breakdown field.For the composites with 15 vol.%CCTO that is coated with 1.0 wt.%Cl_(3)-silane,an electric breakdown field of more than 240 MV/m is obtained with an energy density of more than 4.5 J/cm^(3).It is also experimentally found that the dielectric constant can be used to easily identify the optimized content of coupling agent.
