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M. A. Majeed Khan,Wasi Khan,Maqusood Ahamed,M.S. Alsalhi,Tansir Ahmed 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.1
The present work describes the synthesis of indium oxide nanocubes (NCs) by a modified sol-gel method and its thin film was deposited by spray pyrolysis method. The sample was characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), field emission transmission electron microscope (FE-TEM), fourier transform infrared (FTIR) spectroscopy and photoluminescence (PL) techniques in detail. The temperature dependent resistivity of indium oxide thin film was determined in the temperature range of 77 - 350 K which exhibited semiconducting behavior of the sample. The resistivity data were fitted in the Mott's variable range hopping (VRH) model and the density of states was estimated.
Synthesis of Facial Amphiphile 3,7-Diamino-5α-cholestane Derivatives as a Molecular Receptor
Md. Wasi Ahmad,Young Mee Jung,Sharaf Nawaz Khan,김홍석 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.9
A series of facial amphiphiles 3,7-diaminocholestane were synthesized from 3,7-diketocholestane via 2 sequential reductive aminations and anion recognition was evaluated with acetate, chloride, bromide, fluoride and phosphate anions. The stereo-selective reductive amination protocol was utilized to synthesized facial amphiphiles afforded receptors in high yields. The molecular receptor 2 showed the highest binding constant with acetate in a 1:1 ratio.
Synthesis of Facial Amphiphile 3,7-Diamino-5α-cholestane Derivatives as a Molecular Receptor
Ahmad, Md. Wasi,Jung, Young-Mee,Khan, Sharaf Nawaz,Kim, Hong-Seok Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.9
A series of facial amphiphiles 3,7-diaminocholestane were synthesized from 3,7-diketocholestane via 2 sequential reductive aminations and anion recognition was evaluated with acetate, chloride, bromide, fluoride and phosphate anions. The stereo-selective reductive amination protocol was utilized to synthesized facial amphiphiles afforded receptors in high yields. The molecular receptor 2 showed the highest binding constant with acetate in a 1:1 ratio.
Abdullah A. Saad,Wasi Khan,Pooja Dhiman,A. H. Naqvi,M. Singh,유춘리 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.1
Nanoparticles (NPs) of (La1-xSrx)(Fe1-xNix)O3, (x = 0.0, 0.1 & 0.2) with orthorhombic perovskite structure was successfully prepared through the sol-gel combustion method. The structural, optical and magnetic properties of the NPs were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with an energy dispersive x-ray spectrometer (EDS), UV-Vis. Spectrometer and magnetization measurements. The crystallite size was estimated from x-ray diffraction (XRD) patterns, which decreases with increase in Sr and Ni contents and SEM images exhibit formation of agglomerated NPs for pure and doped samples. The absorbance has a tendency to increase with the increase in dopant concentration and band gap increases with Sr and Ni contents. Magnetization measurement revealed ferromagnetic nature of all samples at room temperature.
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.
M. Arshad,M. Abushad,Shahid Husain,Wasi Khan 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.4
In the present study, bulk samples of yttrium doped La0.7−xYxCa0.3MnO3 (x = 0.3 and 0.4) are prepared through solid-state reaction route. The structural, optical and electrical transport properties have been explored through various analytical techniques. The x-ray diffraction (XRD) patterns affirm single phase and polycrystalline nature of the samples. Rietveld refinement analysis of the XRD data is used to determine the various structural parameters. It reveals that both the samples belong to orthorhombic crystal system with Pnma space group. Using Scherrer’s equation, a lower value of crystallite size is found in the higher concentration of yttrium doped sample. The band gap as determined from the UV–visible DRS data by employing the Tauc’s relation is found to enhance with the increase of yttrium concentration in La0.7Ca0.3MnO3. The low temperature resistivity measurements establish semiconducting nature of the samples over the temperature range of ~ 110–300 K. Moreover, the electrical resistivity data are interpreted within the variable range hopping (VRH) model to estimate the density of states at the Fermi level N(EF), mean hopping distance Rh(T) and hopping energy Eh(T). It is observed that the electrical quantities vary gradually with the change of Y content. The conduction mechanism in this system is governed in the framework of thermally activated small polaron hopping (SPH) model and accordingly various parameters namely Debye temperature (θD), activation energy (Ep) and optical phonon frequency (νph) are evaluated. The obtained results support a strong connection between structure and electrical behavior in our samples and can be elucidated on the basis of localization of charge carriers induced by the substituting ions.