Monophasic mullite （3Al2O3？2SiO2） samples doped with 0.002 M, 0.02 M, 0.1 M, 0.15 M and 0.2 M of cobalt were prepared by a sol-gel process. Prepared gels were then dried, grinded, pressed into pellets and sintered ...Monophasic mullite （3Al2O3？2SiO2） samples doped with 0.002 M, 0.02 M, 0.1 M, 0.15 M and 0.2 M of cobalt were prepared by a sol-gel process. Prepared gels were then dried, grinded, pressed into pellets and sintered at 1 000 °C and 1 300 °C for 4 h. Phase formation and densification behavior has been investigated as a function of the cobalt content and sintering temperature. Mullite densification behavior was analyzed .The density of the sintered ceramics was measured using Archimedes method. CoO and Co related compounds were detected by the analysis for G3, G4 and G5 doping levels. The mullite X-ray diffraction suggests predominant incorporation of Co in the glassy phase, whose quantity increased with the doping level.展开更多
Highly crystallized mullite has been achieved at temperatures of 1100℃and 1400℃by sol-gel technique in presence of titanium and strontium ions of different concentrations:G_(0)=0 M,G_(1)=0.002 M,G_(2)=0.01 M,G_(3)=0...Highly crystallized mullite has been achieved at temperatures of 1100℃and 1400℃by sol-gel technique in presence of titanium and strontium ions of different concentrations:G_(0)=0 M,G_(1)=0.002 M,G_(2)=0.01 M,G_(3)=0.02 M,G_(4)=0.1 M,G_(5)=0.2 M and G6=0.5 M.X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),LCR meter characterized the samples.Mullite formation was found to depend on the concentration of the ions.The dielectric properties(dielectric constant,loss tangent and AC conductivity)of the composites have been measured,and their variation with increasing frequency and concentration of the doped metals was investigated.All the experiments were performed at room temperature.The composites showed maximum dielectric constants of 24.42 and 37.6 at 1400℃of 0.01 M concentration for titanium and strontium ions at 2 MHz,respectively.Due to the perfect nature of the doped mullite,it can be used for the fabrication of high charge storing capacitors and also as ceramic capacitors in the pico range.展开更多
文摘Monophasic mullite （3Al2O3？2SiO2） samples doped with 0.002 M, 0.02 M, 0.1 M, 0.15 M and 0.2 M of cobalt were prepared by a sol-gel process. Prepared gels were then dried, grinded, pressed into pellets and sintered at 1 000 °C and 1 300 °C for 4 h. Phase formation and densification behavior has been investigated as a function of the cobalt content and sintering temperature. Mullite densification behavior was analyzed .The density of the sintered ceramics was measured using Archimedes method. CoO and Co related compounds were detected by the analysis for G3, G4 and G5 doping levels. The mullite X-ray diffraction suggests predominant incorporation of Co in the glassy phase, whose quantity increased with the doping level.
基金We are grateful to DST and UGC(PURSE program),Government of India,for the financial assistance.
文摘Highly crystallized mullite has been achieved at temperatures of 1100℃and 1400℃by sol-gel technique in presence of titanium and strontium ions of different concentrations:G_(0)=0 M,G_(1)=0.002 M,G_(2)=0.01 M,G_(3)=0.02 M,G_(4)=0.1 M,G_(5)=0.2 M and G6=0.5 M.X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),LCR meter characterized the samples.Mullite formation was found to depend on the concentration of the ions.The dielectric properties(dielectric constant,loss tangent and AC conductivity)of the composites have been measured,and their variation with increasing frequency and concentration of the doped metals was investigated.All the experiments were performed at room temperature.The composites showed maximum dielectric constants of 24.42 and 37.6 at 1400℃of 0.01 M concentration for titanium and strontium ions at 2 MHz,respectively.Due to the perfect nature of the doped mullite,it can be used for the fabrication of high charge storing capacitors and also as ceramic capacitors in the pico range.
