We have developed a dry transfer method that allows graphene to be transferred from polymer- thyl-methacrylate (PMMA)/Si (silicon) substrates on commercially available hexagonal boron ni- tride (hBN) crystals. With th...We have developed a dry transfer method that allows graphene to be transferred from polymer- thyl-methacrylate (PMMA)/Si (silicon) substrates on commercially available hexagonal boron ni- tride (hBN) crystals. With this method we are able to fabricate graphene devices with little wrin- kles and bubbles in graphene sheets, but that do not degrade the electronic quality more than the SiO2 substrate does. For hBN to perform the function described above substrate cleanliness is critical to get high quality graphene devices. Using hBN as a substrate, graphene exhibits enhanced mobility, reduced carrier inhomogeneity, and reduced intrinsic doping compared to graphene on SiO2 substrate.展开更多
Ni WO4 was prepared using the polymeric precursor method and studied in terms of physical and chemical properties to verify its stability for industrial applications as pigments.The characterization was accomplished u...Ni WO4 was prepared using the polymeric precursor method and studied in terms of physical and chemical properties to verify its stability for industrial applications as pigments.The characterization was accomplished using thermal analyses,X-ray diffraction(XRD),scanning electron microscopy(SEM),photoluminescence(PL)and UV–Vis spectroscopies,colorimetric coordinates,and Raman spectra.Increasing the temperature,successive exothermic reactions were observed and they are related with thermal decomposition of the organic compound.The stability was reached at^700℃.The material is verified to become completely free of second phase at^800℃.The end Ni WO4 powders showed an intense charge transfer(CT)-related tail centered in the ultraviolet region,resulting in a yellow product.In addition,the powders exhibited broad excitation band and broad deep blue–green emission band,which were enhanced with increasing powders’crystallinity.展开更多
文摘We have developed a dry transfer method that allows graphene to be transferred from polymer- thyl-methacrylate (PMMA)/Si (silicon) substrates on commercially available hexagonal boron ni- tride (hBN) crystals. With this method we are able to fabricate graphene devices with little wrin- kles and bubbles in graphene sheets, but that do not degrade the electronic quality more than the SiO2 substrate does. For hBN to perform the function described above substrate cleanliness is critical to get high quality graphene devices. Using hBN as a substrate, graphene exhibits enhanced mobility, reduced carrier inhomogeneity, and reduced intrinsic doping compared to graphene on SiO2 substrate.
基金the financial support from Brazilian research funding agencies,namely,FAPESP(Grant Nos.2013/07909-4 and 2013/07296-2)CAPESCNPq(Grant No.470069/2013-9)。
文摘Ni WO4 was prepared using the polymeric precursor method and studied in terms of physical and chemical properties to verify its stability for industrial applications as pigments.The characterization was accomplished using thermal analyses,X-ray diffraction(XRD),scanning electron microscopy(SEM),photoluminescence(PL)and UV–Vis spectroscopies,colorimetric coordinates,and Raman spectra.Increasing the temperature,successive exothermic reactions were observed and they are related with thermal decomposition of the organic compound.The stability was reached at^700℃.The material is verified to become completely free of second phase at^800℃.The end Ni WO4 powders showed an intense charge transfer(CT)-related tail centered in the ultraviolet region,resulting in a yellow product.In addition,the powders exhibited broad excitation band and broad deep blue–green emission band,which were enhanced with increasing powders’crystallinity.
