Nanodiamond（ND） powder was successfully activated by wet chemical method and by exposure of UV/O3 in a chamber followed by mixing in triethylenetetramine（TETA） solution.The reinforcement role of activated ND in th...Nanodiamond（ND） powder was successfully activated by wet chemical method and by exposure of UV/O3 in a chamber followed by mixing in triethylenetetramine（TETA） solution.The reinforcement role of activated ND in the mechanical properties of epoxy matrix was studied.Both treatments,i.e.acid and UV/O3 provide ND surface with chemical functionalities for adhesion with epoxy resin.Fourier transform infrared spectroscopy was utilized to confirm the attachment of surface groups to the ND particles.The low content of acid and UV/O3 activated ND was dispersed ultrasonically in the epoxy matrix separately to make nanocomposites.The mechanical properties of the nanocomposites were investigated under three point bending.The strong interactions among activated ND particles and the epoxy resin provide efficient load transfer interfaces,which enhances the mechanical properties of the composites.It was found that the flexural strength,modulus,and toughness of 0.1 wt%ND loaded nanocomposites have been enhanced up to 85%,57%,and 39%,respectively for UV/O3 treated ND powder.It is also found that the optimum ND concentration to achieve maximum reinforcement is 0.1 wt%while higher concentrations lead to decrease in mechanical properties.The significant improvement of the mechanical properties of the ND/epoxy nanocomposites is attributed to the good dispersion of the functionalized ND in epoxy matrix.展开更多
Sm3＋/yb3＋ co-doped tellurite glasses are prepared by melt-quenching technique. The density of the glasses varies between 4.65 and 4.84 g/cm3. The optical absorption spectra consist of eight bands in the wavelength r...Sm3＋/yb3＋ co-doped tellurite glasses are prepared by melt-quenching technique. The density of the glasses varies between 4.65 and 4.84 g/cm3. The optical absorption spectra consist of eight bands in the wavelength range of 350-2 000 nm, which correspond to the transitions from ground level 6H5/2 to the various excited states of the Sm3＋ ion. Energy band gaps vary in the range of 2.73 2.91 eV, and the Urbach energy ranges from 0.21 to 0.27. Emission spectra exhibit four peaks originating from the 4G5/2 energy level centered at 576, 613, 657, and 718 nm. Quenches in emission bands may be due to the energy transfer from the Sm3＋ to Yb3＋ ions.展开更多
Zn1-xCrxO （x = 0.00, 0.01, 0.03, 0.05, 0.07, and 0.09） nanoparticles were synthesized, by an auto-com- bustion method. Structural, optical, and magnetic characteristics of Cr-doped ZnO samples calcined at 600 ℃ hav...Zn1-xCrxO （x = 0.00, 0.01, 0.03, 0.05, 0.07, and 0.09） nanoparticles were synthesized, by an auto-com- bustion method. Structural, optical, and magnetic characteristics of Cr-doped ZnO samples calcined at 600 ℃ have been analyzed by using X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM）, UV-Vis spectroscopy and vibrating sample magnetometer （VSM）. The XRD data confirmed the hexagonal wurtzite structure of pure and Cr-doped ZnO nanoparticles. The calculated values of grain size using Scherrer＇s formula are in the range of 30.7-9.2 nm. The morphology of nanopowders has been observed by FESEM, and EDS results con- firmed a systematic increase of Cr content in the samples and clearly indicate with no impurity element. The band gaps, computed by UV-Vis spectroscopy, are in the range of 2.83-2.35 eV for different doping concentrations. By analyzing VSM data, significantly enhanced room temperature ferromagnetism is identified in Cr-doped ZnO samples. The value of magnetization is a 12 times increased of the value reported by Daun et al. （2010）. Room temperature ferromagnetism of the nanoparticles is of vital prominence for spintronics applications.展开更多
基金The financial support of the Centre of Excellence for Science & Advanced Technology,and Higher Education Commission of Pakistan
文摘Nanodiamond（ND） powder was successfully activated by wet chemical method and by exposure of UV/O3 in a chamber followed by mixing in triethylenetetramine（TETA） solution.The reinforcement role of activated ND in the mechanical properties of epoxy matrix was studied.Both treatments,i.e.acid and UV/O3 provide ND surface with chemical functionalities for adhesion with epoxy resin.Fourier transform infrared spectroscopy was utilized to confirm the attachment of surface groups to the ND particles.The low content of acid and UV/O3 activated ND was dispersed ultrasonically in the epoxy matrix separately to make nanocomposites.The mechanical properties of the nanocomposites were investigated under three point bending.The strong interactions among activated ND particles and the epoxy resin provide efficient load transfer interfaces,which enhances the mechanical properties of the composites.It was found that the flexural strength,modulus,and toughness of 0.1 wt%ND loaded nanocomposites have been enhanced up to 85%,57%,and 39%,respectively for UV/O3 treated ND powder.It is also found that the optimum ND concentration to achieve maximum reinforcement is 0.1 wt%while higher concentrations lead to decrease in mechanical properties.The significant improvement of the mechanical properties of the ND/epoxy nanocomposites is attributed to the good dispersion of the functionalized ND in epoxy matrix.
基金support fromthe Research Management Centre,University Technology Malaysia (RMC,UTM) through the researchgrants (VOTE ERGS 4L032 and 07J80,MoHE)F.Nawaz extends his gratitude to the financial support by UTM through the International Doctoral Fellowship(UTM.J.10.01/13.14/1/128)
文摘Sm3＋/yb3＋ co-doped tellurite glasses are prepared by melt-quenching technique. The density of the glasses varies between 4.65 and 4.84 g/cm3. The optical absorption spectra consist of eight bands in the wavelength range of 350-2 000 nm, which correspond to the transitions from ground level 6H5/2 to the various excited states of the Sm3＋ ion. Energy band gaps vary in the range of 2.73 2.91 eV, and the Urbach energy ranges from 0.21 to 0.27. Emission spectra exhibit four peaks originating from the 4G5/2 energy level centered at 576, 613, 657, and 718 nm. Quenches in emission bands may be due to the energy transfer from the Sm3＋ to Yb3＋ ions.
基金Project supported by the Office of Research,Innovation,and Commercialization(ORIC),MUST Mirpur(AJK)
文摘Zn1-xCrxO （x = 0.00, 0.01, 0.03, 0.05, 0.07, and 0.09） nanoparticles were synthesized, by an auto-com- bustion method. Structural, optical, and magnetic characteristics of Cr-doped ZnO samples calcined at 600 ℃ have been analyzed by using X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM）, UV-Vis spectroscopy and vibrating sample magnetometer （VSM）. The XRD data confirmed the hexagonal wurtzite structure of pure and Cr-doped ZnO nanoparticles. The calculated values of grain size using Scherrer＇s formula are in the range of 30.7-9.2 nm. The morphology of nanopowders has been observed by FESEM, and EDS results con- firmed a systematic increase of Cr content in the samples and clearly indicate with no impurity element. The band gaps, computed by UV-Vis spectroscopy, are in the range of 2.83-2.35 eV for different doping concentrations. By analyzing VSM data, significantly enhanced room temperature ferromagnetism is identified in Cr-doped ZnO samples. The value of magnetization is a 12 times increased of the value reported by Daun et al. （2010）. Room temperature ferromagnetism of the nanoparticles is of vital prominence for spintronics applications.
