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Md. Sohel Rana,Sujan Kumar Das,Md. Obaidur Rahman,Farid Ahmed,Md. Abul Hossain 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.5
Vanadium (V) doped zinc sulfi de (ZnS) nanoparticles have been synthesized in the doping concentration of 0.2, 0.4, 0.6, 0.8, and 1 wt% by chemical co-precipitation method, where de-ionized water was used as solvent and the precursors were Zn(CH3COO)2·2H2O, Na2S and V2O5. The synthesized nanoparticles have been characterized by XRD, UV–Vis spectroscopy, FTIR spectroscopy and precision impedance analyzer (PIA). XRD studies revealed that all the samples exhibit cubic structure and confi rmed the incorporation of V into ZnS lattice. The calculated average crystallite size was varied in the range of 2.16–2.82 nm. The red shifting of the absorption edge was observed from the UV–Vis study and the direct optical band gap (Eg ) was decreased from 3.63 to 3.35 eV with increasing the doping concentrations. The various vibrational modes were observed by the FTIR spectroscopy. The characteristic vibrational peaks were found near at 666, 615 and 478 cm −1 . The PIA study showed that frequency dependent dielectric constant, loss tangent and ac resistivity were high at the lower frequency, while the ac conductivity was low at higher frequency. The bandgap tuning behavior of ZnS nanoparticles with V-doping concentrations may find interesting applications in optoelectronic devices.
Formation mechanism of self-organized nano-ripples on quartz surface using femtosecond laser pulses
Ahsan, Md. Shamim,Lee, Man Seop,Hasan, Mohammad Khairul,Noh, Young-Chul,Sohn, Ik-Bu,Ahmed, Farid,Jun, Martin B.G. Elsevier 2015 OPTIK -STUTTGART- Vol.126 No.24
<P><B>Abstract</B></P> <P>This article demonstrates the formation of self-organized nano-ripples on a quartz surface by irradiation of femtosecond laser pulses. Self-oriented nano-ripples are printed on the quartz surface by controlling various laser parameters: average pulse energy, pulse width, and number of laser pulses on each irradiated spot. We validate that the direction of the self-organized nano-ripples are oriented perpendicularly to the laser polarization direction. We also investigate and analyze the dependency of nano-ripples period on various laser parameters including the pulse energy, number of laser pulses, and pulse width. The nano-ripples show increasing trend with the increase of laser energy and pulse width, whereas show decreasing trend with the increase of irradiated laser pulses. We also explain, qualitatively, the formation mechanism of the self-organized nano-ripples on quartz surface.</P>
Effect of Ni-doping on coloring and photocatalytic performance of MgTi2O5 nanoceramics
Moksodur Rahman,Md. Lutfor Rahman,Bristy Biswas,Md. Farid Ahmed,Md. Aftab Ali Shaikh,Shirin Akter Jahan,Nahid Sharmin 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-
The Ni-doped MgTi2O5 has been synthesized by sol–gel method and investigated the effect of sinteringwith %Ni content. The heat inspection of intermediate products was done at 1000–1400 C. The structuralproperties of synthesized samples were studied by various methods viz. simultaneous thermal analysis(TGA-DTG), Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), Scanningelectron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), Zeta Sizer, and UV–VisNIR spectroscopy. The crystallite size of the obtained samples was determined from PXRD analysis usingClassical Scherrer formulae, modified Scherrer model, Williamson–Hall method, and size-strain plotequation. Unit cell parameter was determined precisely from PXRD data based on Rietveld refinementanalysis, which confirmed insertion of Ni2+ ions into the MgTi2O5 structure by decreasing unit cell parameters. Particle size was measured using dynamic light scattering and laser diffraction techniques. Opticalparameter analysis reveals that nano-pigments with narrow bandgap energy were suitable for photocatalysis. Ni0.6Mg0.4Ti2O5 sintered at 1400 C exhibits highest photocatalytic activity (93%) within120 min solar light irradiation. Color properties of the samples were determined from DRS measurementusing CIE-L*a*b* software. The obtained outcomes confirmed that the optical, photocatalytic and colorproperties of prepared samples improved with increasing Ni-contents.
Mohammad Mahfuzur Rahman,Md. Abdullah Al Mahmud,Farid Uddin Ahmed 한국산림과학회 2017 Forest Science And Technology Vol.13 No.3
Lack ofnon-forestry incomesources for the forest-dependent community was oneof the major causes of continued biodiversity loss in Chunati Wildlife Sanctuary (CWS). A livelihood support program was implemented from July 2012 through June 2015 to reduce people’s forest-dependence for their livelihoods. We evaluated the efficacy of this program in enhancing the biodiversity health of CWS. An Ordinary Least Square regression framework was used to estimate the difference in difference of the income between the control and the treatment households. Alongside, the biodiversity attributes of the CWS were measured in 2012 and 2015 and were compared. The intervention increased a treatment household’s monthly non-forestry income by BDT11,781 and decreased its monthly forest income by BDT2128. In contrast, with increased natural regeneration of 8.43%, 12 out of the 16 major species at CWS showed increased importance value index (IVI). The IVI increased by 48.03% for Acacia auriculiformis and decreased by 56.30% and 31.76% for Dipterocarpus turbinatus and Tectona grandis, respectively. As confirmed by the households, this biodiversity improvement could be attributed to the livelihood intervention program at CWS. Continued monitoring is important to sustain the successes of the program.