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RISS 인기검색어
- 검색키워드
- 저자 : Ameer Azam (검색결과 5 건)
- 무료
- 기관 내 무료
- 유료
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Fabrication of Co-Doped ZnO Nanorods for Spintronic Devices
Ameer Azam,Faheem Ahmed,Sami S. Habib,Zishan H. Khan,Numan A. Salah 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.4
Herein, single-crystalline Zn1-xCoxO (0.0≤x≤0.10) nanorods were prepared using a facile microwave irradiation method. Structural analyses by X-ray diffraction and transmission electron microscopy revealed the incorporation of Co2+ in the lattice position of Zn2+ ions into the ZnO matrix. Field emission scanning electron microscopy and TEM micrographs revealed that the length and diameter of the undoped ZnO nanorods were about ~2 μm and ~200 nm, respectively. For Co-doped ZnO, the length and diameter were found to increase with an increase of Co doping. The selected area electron diffraction pattern indicated that the Zn1-xCoxO (0.0≤x≤0.10) nanorods had a single phase nature with the preferential growth direction along the [0 0 1] plane. Raman scattering spectra confirmed the shift of the E2high mode toward a lower wave number, suggested successful doping of Co ions at Zn site into the ZnO. Magnetic studies showed that Co doped ZnO nanorods exhibited room temperature ferromagnetism and the magnetization value increased with an increase in Co doping. The synthesis method presented here is a simple approach to prepare ZnO based diluted magnetic semiconductors nanostructures for practical application to spintronic devices.
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Mohammad Jahir Khan,Qayyum Husain,Ameer Azam 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.2
Enzymes play a pivotal role in catalyzing diverse reactions. However, their instability upon repetitive/prolonged use, as well as their inhibition by high substrates and product concentration, remains an area of concern. In this study, porcine pancreatic α-amylase was immobilized on magnetic Fe2O3 nanoparticles (Fe2O3-NPs) in order to hydrolyze starch. The magnetic nanoparticle bound enzymes retained 94% of their initial enzyme activity. X-ray diffraction and atomic force microscopy analyses showed that the prepared matrix had advantageous microenvironment and a large surface area for binding significant amounts of protein. Functional groups present in enzyme and support were monitored by Fourier transform infrared spectroscopy. Immobilized enzyme exhibited lowered pH optimum (pH 6.0) to a greater degree than its soluble counterpart (pH 7.0). Optimum temperature for the immobilized enzyme shifted towards higher temperatures. The immobilized enzyme was significantly more resistant to inactivation caused by various metal ions and chemical denaturants. Immobilized α-amylase hydrolyzed 92% starch in a batch process, after 8 h at 40oC; while the free enzyme could hydrolyze only 73% starch under similar experimental conditions. A reusability experiment demonstrated that the immobilized enzyme retained 83% of its original activity even after its 8th repeated use.
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Influence of Cr incorporation on structural, dielectric and optical properties of ZnO nanoparticles
M. Mehedi Hassan,Wasi Khan,Ameer Azam,A. H. Naqvi 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
This study demonstrated the effect of Cr doping on structural, dielectric and optical behavior of ZnOnanoparticles synthesized through sol–gel method. Characteristic investigations have been carried outby X-ray diffraction, Field emission scanning electron microscope, Energy dispersive X-ray spectrometry,and Transmission electron microscope. The results confirmed the formation of nanoparticles inpolycrystalline single phase with hexagonal wurtzite structure. The crystallite size has been found tovary around 20 nm. Dielectric studies were carried out by Impedance spectroscopy. The decrease effectof dielectric parameters with increase in dopant has been explained on the basis of Maxwell–Wagnermodel and Koops phenomenological theory. The impedance analysis suggested that the contribution ofgrain boundaries is dominating over grain contribution. A red shift in UV–vis spectra signified that bandgap can be tuned by Cr doping from 3.32 to 3.22 eV because of the s–d and p–d exchange interactions.
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Rani Bushra,Mu. Naushad,Gaurav Sharma,Ameer Azam,Zeid Abdullah ALOthman 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.7
A composite material polyaniline-Zr(IV) phosphoborate (PZPB) was synthesized via sol-gel method by the combination of Zr(IV) phosphoborate and polyaniline. The PZPB composite material was characterized by various analytical techniques. The PZPB composite material was found to be selective for Hg2+ metal ion due to the high distribution coefficient values for Hg2+ metal ion in all mediums. The PZPB composite material was used for Hg2+ removal under different experimental conditions. The antibacterial activity of PZPB composite material was also studied against E. coli.
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Ahmed, Faheem,Arshi, Nishat,Anwar, M. S.,Alsharaeh, Edreese,Koo, Bon Heun,Azam, Ameer American Scientific Publishers 2018 Science Of Advanced Materials Vol.10 No.1
<P>In this work, mono-disperse hematite iron oxide (alpha-Fe2O3) nanoparticles with continuously tunable sizes from 2 to 11 nm by using Sb doping in alpha-Fe2O3 were synthesized by a sonication method at room temperature followed by calcination. By varying the concentration of the Sb, precise control on the size of the alpha-Fe2O3 nanoparticles could be established. The X-ray diffraction (XRD), and high resolution transmission electron microscopy (HR-TEM) studies confirmed that the prepared nanoparticles were hematite with high crystallinity. The optical measurements showed that the band gap of the Sb-doped alpha-Fe2O3 nanoparticles increased with Sb doping. Transmission electron microscopy (TEM) results showed that the alpha-Fe2O3 nanoparticles appeared as spherical dots, and the size decreased from 11 to 2 nm with Sb doping. Magnetic studies revealed that all the Sb doped samples were superparamagnetic at 300 K, and the increase in Sb doping can controllably decreased the blocking temperature from 248 K for pure alpha-Fe2O3 nanoparticles to 209 K for 5% Sb doped, respectively. The presented method might be useful for controlling the diverse size of crystalline inorganic materials for a variety of applications.</P>
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