Composites of poly(methyl methacrylate)(PMMA)and Sr_(2) TiMnO_(6)(STMO)were fabricated via melt mixing followed by hot pressing technique.These were characterized using X-ray diffraction(XRD),thermo gravimetric analys...Composites of poly(methyl methacrylate)(PMMA)and Sr_(2) TiMnO_(6)(STMO)were fabricated via melt mixing followed by hot pressing technique.These were characterized using X-ray diffraction(XRD),thermo gravimetric analysis(TGA),differential scanning calorimetry(DSC),thermo mechanical analysis(TMA)and impedance analyser for their structural,thermal and dielectric properties.The coefficient of thermal expansion(CTE)was measured between 40℃ and 100℃ for pure PMMA is 115.2ppm/℃,which was decreased to 78.58ppm/℃ when the STMO content was increased to 50 wt.%in PMMA.There was no difference in the glass transition(T g)temperature of the PMMA polymer and their composites.However,the FTIR analysis indicated possible interaction between the PMMA and STMO.The density and the hardness were increased as the STMO content increased in the PMMA matrix.Permittivity was found to be as high as 30.9 at 100Hz for the PMMAþSTMO-50 wt.%composites,indicating the possibility of using these materials for capacitor applications.The thermal stability of polymer was enhanced by incorporation of STMO fillers.展开更多
CaCu_(3)Ti_(4)O_(12)(CCTO)ceramics which has perovskite structure gained considerable attention due to its giant permittivity.But it has high tan(0.1 at 1 kHz)at room temperature,which needs to be minimized to the le...CaCu_(3)Ti_(4)O_(12)(CCTO)ceramics which has perovskite structure gained considerable attention due to its giant permittivity.But it has high tan(0.1 at 1 kHz)at room temperature,which needs to be minimized to the level of practical applications.Hence,TeO_(2) which is a good glass former has been deliberately added to CCTO nanoceramic(derived from the oxalate precursor route)to explore the possibility of reducing the dielectric loss while maintaining the high permittivity.The structural,morphological and dielectric properties of the pure CCTO and TeO_(2) added ceramics were studied using X-ray diffraction,Scanning Electron Microscope along with Energy Dispersive X-ray Analysis(EDX),spectroscopy and Impedance analyzer.For the 2.0 wt.%TeO_(2) added ceramics,there is a remarkable difference in the microstructural features as compared to that of pure CCTO ceramics.This sample exhibited permittivity values as high as 7387 at 10 KHz and low dielectric loss value of 0.037 at 10 kHz,which can be exploited for the high frequency capacitors application.展开更多
The glasses in the system(100-x)TeO_(2)-xCaCu_(3)Ti_(4)O_(12),(x=0.25 mol.%to 3 mol.%)were fabricated.The color varied from olive green to brown as the CaCu_(3)Ti_(4)O_(12)(CCTO)content increased in TeO_(2) matrix.The...The glasses in the system(100-x)TeO_(2)-xCaCu_(3)Ti_(4)O_(12),(x=0.25 mol.%to 3 mol.%)were fabricated.The color varied from olive green to brown as the CaCu_(3)Ti_(4)O_(12)(CCTO)content increased in TeO_(2) matrix.The X-ray powder diffraction and differential scanning calorimetric analyses that were carried out on the as-quenched samples confirmed their amorphous and glassy nature respectively.The dielectric constant and loss in the 100Hz1MHz frequency range were monitored as a function of temperature(50-400℃).The dielectric constant(ε′_(τ))and the loss(D)increased as the CCTO content increased in TeO_(2) at all the frequencies and temperatures under investigation.Further,the ε′_(τ) and D were found to be frequency-independent in the 50-200℃ temperature range.The value obtained for the loss at 1MHz was 0.0019 which was typical of low loss materials,and exhibited near constant loss(NCL)in the 100Hz-1MHz frequency range.The electrical relaxation was rationalized using the electric modulus formalism.These glasses may be of considerable interest as substrates for high frequency circuit elements in conventional semiconductor industries owing to their high thermal stability.展开更多
基金The management of Central Power Research Institute is acknowledged for the financial support(CPRI Project no.R-DMD-01/1415).
文摘Composites of poly(methyl methacrylate)(PMMA)and Sr_(2) TiMnO_(6)(STMO)were fabricated via melt mixing followed by hot pressing technique.These were characterized using X-ray diffraction(XRD),thermo gravimetric analysis(TGA),differential scanning calorimetry(DSC),thermo mechanical analysis(TMA)and impedance analyser for their structural,thermal and dielectric properties.The coefficient of thermal expansion(CTE)was measured between 40℃ and 100℃ for pure PMMA is 115.2ppm/℃,which was decreased to 78.58ppm/℃ when the STMO content was increased to 50 wt.%in PMMA.There was no difference in the glass transition(T g)temperature of the PMMA polymer and their composites.However,the FTIR analysis indicated possible interaction between the PMMA and STMO.The density and the hardness were increased as the STMO content increased in the PMMA matrix.Permittivity was found to be as high as 30.9 at 100Hz for the PMMAþSTMO-50 wt.%composites,indicating the possibility of using these materials for capacitor applications.The thermal stability of polymer was enhanced by incorporation of STMO fillers.
基金The management of Central Power Research Institute is acknowledged for the financial support(CPRI Project No.R-DMD-01/1415).
文摘CaCu_(3)Ti_(4)O_(12)(CCTO)ceramics which has perovskite structure gained considerable attention due to its giant permittivity.But it has high tan(0.1 at 1 kHz)at room temperature,which needs to be minimized to the level of practical applications.Hence,TeO_(2) which is a good glass former has been deliberately added to CCTO nanoceramic(derived from the oxalate precursor route)to explore the possibility of reducing the dielectric loss while maintaining the high permittivity.The structural,morphological and dielectric properties of the pure CCTO and TeO_(2) added ceramics were studied using X-ray diffraction,Scanning Electron Microscope along with Energy Dispersive X-ray Analysis(EDX),spectroscopy and Impedance analyzer.For the 2.0 wt.%TeO_(2) added ceramics,there is a remarkable difference in the microstructural features as compared to that of pure CCTO ceramics.This sample exhibited permittivity values as high as 7387 at 10 KHz and low dielectric loss value of 0.037 at 10 kHz,which can be exploited for the high frequency capacitors application.
基金The management of Central Power Research Institute is acknowledged for the financial support(CPRI Project No.R-DMD-01/1415).
文摘The glasses in the system(100-x)TeO_(2)-xCaCu_(3)Ti_(4)O_(12),(x=0.25 mol.%to 3 mol.%)were fabricated.The color varied from olive green to brown as the CaCu_(3)Ti_(4)O_(12)(CCTO)content increased in TeO_(2) matrix.The X-ray powder diffraction and differential scanning calorimetric analyses that were carried out on the as-quenched samples confirmed their amorphous and glassy nature respectively.The dielectric constant and loss in the 100Hz1MHz frequency range were monitored as a function of temperature(50-400℃).The dielectric constant(ε′_(τ))and the loss(D)increased as the CCTO content increased in TeO_(2) at all the frequencies and temperatures under investigation.Further,the ε′_(τ) and D were found to be frequency-independent in the 50-200℃ temperature range.The value obtained for the loss at 1MHz was 0.0019 which was typical of low loss materials,and exhibited near constant loss(NCL)in the 100Hz-1MHz frequency range.The electrical relaxation was rationalized using the electric modulus formalism.These glasses may be of considerable interest as substrates for high frequency circuit elements in conventional semiconductor industries owing to their high thermal stability.
