M. Khaleeq-ur-rahman - Academia.edu (original) (raw)

Papers by M. Khaleeq-ur-rahman

Fine polished samples of p-silicon were irradiated in ambient air using Excimer Laser and Spectro... more Fine polished samples of p-silicon were irradiated in ambient air using Excimer Laser and Spectroscopic Ellipsometry was employed to investigate their various optical properties. The changes in optical constants (refractive index and extinction coefficient) and optical band gap energy were noticed in incident wavelength range 500–1000 nm. Both refractive index and extinction coefficient decrease exponentially before and after irradiation. A fall in the optical band gap energy of p-silicon was also observed after laser exposure, which makes the materials suitable for variety of optoelectronics applications.

Materials Chemistry and Physics

Journal of Materials Science, 2010

... Quesnel DJ, Sato A, Meshii M (1975) Mater Sci Eng 19:199 18. Butt MZ, Khaleeq-ur-Rahman M, Al... more ... Quesnel DJ, Sato A, Meshii M (1975) Mater Sci Eng 19:199 18. Butt MZ, Khaleeq-ur-Rahman M, Ali D (2009) J Phys D 42:035405 19. Werner M (1987) Phys Status Solidi A 104:63 20.Arsenault RJ (1967) Acta Metall 15:501 21. Little EA (1976) J Aust Inst Metals 21:50 ...

IEEE Transactions on Magnetics, 2018

Giant magnetoresistance (GMR) behavior in electrodeposited N[Fe/Cu/Ni] multilayered (ML) structur... more Giant magnetoresistance (GMR) behavior in electrodeposited N[Fe/Cu/Ni] multilayered (ML) structures is investigated as a function of non-magnetic (Cu) and ferromagnetic (Fe and Ni) layers' thicknesses. Detailed structural and magnetic analyses of the ML structures are studied before looking into the GMR behavior. Structural analyses reveal that all peaks are well matched with Ni (face-centered cubic) being the top most layer during ML deposition. Shifting of preferred orientation, between (220) and (111) planes, is observed with the thickest layer of copper spacer. Refined structural parameters are calculated and details of fittings are discussed with reference to layer thicknesses. Crystallite size, dislocation density, stacking fault probability, and strain all show oscillatory behavior with variation in thicknesses. Magnetic behavior shows strong dependence of magnetization on thickness of each layer. Saturation magnetization (M s) increases up to a value of 10.12 emu/cm 3 with increasing Fe and Ni layer thicknesses. Whereas, oscillatory behavior of magnetization is observed with variation in Cu layer thickness. Magnetoresistance (MR) measurements show oscillatory GMR behavior as a function of intervening layer thickness. Highest value of GMR ∼12% is observed at a Cu layer thickness of 9.6 nm. Structural, magnetic, and MR properties of N[Fe/Cu/Fe] are observed on the basis of variation of thicknesses of non-magnetic (Cu) and ferromagnetic (Fe and Ni) layers. It is observed that layer thicknesses play a dominant effect on the nature (i.e., oscillatory) and on the value of GMR.

4 Abstract: Air quality of Lahore, a heavily populated city of the Punjab, was determined collect... more 4 Abstract: Air quality of Lahore, a heavily populated city of the Punjab, was determined collecting samples of different types. Indoor suspended particles using AC filters were also collected along with dust from room carpets. Eight-hourly average loading of outdoor suspended particulate matter (SPM) was found to be in the range of 670 to1523 ug/m . Twenty-four hourly bulk deposition of free fall dust was found to be varying from 3 (SPM, free-fall dust, indoor suspended particles samples and carpet dust) using the Powder method. Elemental loadings of all samples were determined employing the atomic absorption spectroscopy. Cu, Ni, Cd, Zn and Pb were detected in all the samples. Since there are no ambient air quality standards enacted in Pakistan, a comparison with ambient air quality standards (WHO, USA and Europe) showed that loading of airborne particulate matter were several times higher than the maximum permissible limits accepted there as standard. In this study the Pb concent...

$Research paper thumbnail of Structural, morphological and optical changes in periodic fractal nanosymmetries of Ni doped chromium oxide ceramic nanostructures$

Ceramics International, 2016

Undoped and Nickel doped chromium dioxide (Ni+2:Cr2O3) bulk ceramic nanostructures were prepared ... more Undoped and Nickel doped chromium dioxide (Ni+2:Cr2O3) bulk ceramic nanostructures were prepared by standard solid state reaction method. We have studied the structural, surface morphological and optical properties of samples using X-ray diffraction (XRD), Raman spectroscopy, and Scanning electron microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM/EDX), and Photo luminescence (PL). This study is based on the idea that main factors influencing the disorder in structural and morphological properties of compounds are the radius, valency and charge mismatch of the substituent which plays a critical role in the growth of nanostructured ceramics. X-ray diffraction results reveal rhombohedral crystal structure with peak broadening and shoulder indicating the successful incorporation of Ni upto 5 wt% doping. Raman results exhibited shift in vibration modes associated with Cr2O3 due to Ni content. The strongest band at 551 cm−1 is of A1g symmetry, the others with Eg symmetry were observed in all NCO samples. The presence of transition metal ions introduced blue shift for 353 cm−1 mode in NCO-3% while red shift for 556 cm−1 mode in NCO-1% sample. Dynamical architectural changes in fractal type nanotriangles and nanosheets were observed in the SEM micrographs of Ni doped chromium oxide ceramics. Nanodiamond like octahedrons were also observed in 10 wt% Ni doping ratio which resulted from periodic arrangement of Sierpinski triangles. EDX results revealed that only Cr, O and Ni were present in the samples with dominance of oxygen while proportion of Cr, Ni and O constituents in each sample were not stiochiometric. PL results show dominant violet–blue emission was appeared at 416 nm and 437 nm and at around 450 nm broad band emission occurred. The highest PL intensity for NCO-4% is attributed to the defects and metamorphic growth related to appearance of new symmetries, nano Sierpinski triangle and nano sheets.

SCIENCE …, 2006

ABSTRACT soft x-rays produced by the interaction of 1.06um, 12ns, Nd:YAG laser pulsed with graphi... more ABSTRACT soft x-rays produced by the interaction of 1.06um, 12ns, Nd:YAG laser pulsed with graphite target have been detected by a modified BPX-65 PIN photodiode. the transmission spectra of X-rays through metallic filters of Al (12um, 24um thickness) and Cu (12um thickness) were recorded at 500MHz degital osciloscope. Experiments were both in air and under~ 10-3 torr. experimental results revealed the fundamentals properties of the x-rays such as broad band continuum and short pulses. The spectral response of the diode is to be strongly dependent on the choice of the filters as well as the atomic number of the filters. time resolved analysis of the signals reveals that soft x-rays emission duration loss for ~ 40ns. This information obtained from x-ray emission represents a primary tool for the identification and exploration of various phenomena occuring in plasma.

Vacuum, 2010

Significant propulsion parameters, specific impulse and coupling coefficient for the different me... more Significant propulsion parameters, specific impulse and coupling coefficient for the different metallic pendulums are presented. 4 N (99.99%) pure, solid targets are in the form of foils of aluminium, copper and gold. The targets are irradiated by Q-switched pulsed Nd:YAG laser (1064 nm, 10 mJ, 1.1 MW, 9-14 ns) under standard conditions of temperature and pressure. Plasma plume of these targets is also observed by employing CCD (BOSCH LTC0510, monochrome camera) based, computer controlled image capturing system and it was seen that expansion of plasma plume for oscillating targets is anisotropic in air. The results reveal that not only very high exhaust velocity of propellant 10 6 m/s is achieved but also very specific impulse values of Al, Cu and Au targets (3.14 Â 10 6 s, 1.37 Â 10 7 s, 7.16 Â 10 5 s respectively) are obtained. Coupling coefficients are for Al, Cu and Au were 1.54 Â 10 3 (N-s/J), 1.88 Â 10 3 (N-s/J), and 1.08 Â 10 3 (N-s/J) respectively.

Korean Journal of Chemical Engineering, 2013

Synthesis of Magnesium oxide (MgO) nanoparticles and zinc deposited magnesium oxide (Zn/MgO) nano... more Synthesis of Magnesium oxide (MgO) nanoparticles and zinc deposited magnesium oxide (Zn/MgO) nanoparticles was carried out using hydrothermal and deposition-precipitation method with the variation of 1-Propanol (organic solvent) concentration, sodium hydroxide and urea concentration. The nanoparticles were characterized by using FTIR, TGA, SEM-EDX, TEM and XRD. The photocatalytic efficiency of MgO and Zn/MgO nanoparticles was studied by degradation of 2,4,6-trinitrophenol (TNP), which is highly acute and toxic and causes skin and eyes diseases, liver malfunction and tumor formation. Photodegradation of TNP was carried out under UV irradiation and confirmed by using HPLC and GC-MS. MgO and Zn/MgO nanoparticles that were synthesized by using urea showed higher firstorder rate constant (k) value and percentage degradation as compared to nanoparticles that were synthesized using NaOH. It was observed that the concentration of solvent has direct relation with the k value of degradation of TNP.

Ceramics International, 2019

One dimensional (1-D) signatures of nanopillars and nanowires in niobium doped zinc oxide (NZO) t... more One dimensional (1-D) signatures of nanopillars and nanowires in niobium doped zinc oxide (NZO) thin films prepared by aerosol assisted chemical vapour deposition (AACVD),

ijens.org

A Comparison between dynamics of Liquid Nitrogen and Water plasma is under taken. A Q-switched Nd... more A Comparison between dynamics of Liquid Nitrogen and Water plasma is under taken. A Q-switched Nd: YAG laser (1064 nm, 9-14ns and 1.1 MW) is focused on the Liquid-Nitrogen-jet in air to generate plasma. The images captured by CCD based computer controlled image capturing system are analyzed by obtaining contours, intensity profiles etc. Intensity profiles show that the average intensity is same for both targets, where as intensity for Liquid Nitrogen plasma is little higher than Water plasma in central region. The central region of Liquid Nitrogen plasma is larger as compared to other (intermediate & outer) regions whereas in case of Water plasma all three regions (central, intermediate & outer) have comparable intensity ratio. In Liquid Nitrogen plasma intensity decreases abruptly from central to intermediate region, whereas in case of Water plasma intensity decreases gradually through different regions.

Acta Physica Polonica A, 2013

In this study, tin lm was thermally evaporated onto a stainless steel substrate in an argon atmos... more In this study, tin lm was thermally evaporated onto a stainless steel substrate in an argon atmosphere. The tin lms were then subjected to a DC plasma oxidation process using an oxygen/argon gas mixture. Three dierent substrate temperatures (100 • C, 150 • C, and 200 • C) and three dierent oxygen partial pressures (12.5%, 25%, and 50%) were used to investigate the physical and microstructural properties of the lms. The surface properties were studied by scanning electron microscopy, X-ray diraction, atomic force microscopy and a four-point probe electrical resistivity measurement. The grain size and texture coecient of the tin oxide lms were calculated. Both SnO and SnO2 lms with grain sizes of 1343 nm were produced, depending on the oxygen partial pressure. SnO lms have ower-and ake-like nanostructures, and SnO2 lms have grape-like structures with nanograins. The resistivity values for the SnO2 phase were found to be as low as 10 −5 Ω cm and were observed to decrease with increasing substrate temperature.

Abstract: Influence of external magnetic field on space and time resolved X-ray emission from las... more Abstract: Influence of external magnetic field on space and time resolved X-ray emission from laser plasma is investigated. 4 N pure Copper target (2 x 2 x 0.2 cm 3) is irradiated with Nd: YAG Laser. Magnetic field of strength 1.2 Tesla (T) is applied perpendicular to the target normal. A computer controlled pinhole CCD based image capturing system was employed for space resolved X-Rays imaging. PIN photodiode connected to digital storage oscilloscope through a biasing circuit was employed for storing time resolved x-rays signals. The results reveal that the X-rays emission intensity as well as energy enhances under the influence of external magnetic field.

Laser Physics

We report the use of pulsed laser deposition (PLD) to grow manganese oxide thin films at a fixed ... more We report the use of pulsed laser deposition (PLD) to grow manganese oxide thin films at a fixed low oxygen pressure at different temperatures on silicon (1 0 0) substrates. Structural properties of the thin films were examined using x-ray diffraction and Fourier transform infrared spectroscopy. Surface morphology and topography of the films was determined using atomic force microscopy and optical microscopy, while optical properties of the thin films were studied using spectroscopic ellipsometry. It was found that PLD is a convenient technique to deposit different phases of manganese oxide by tuning the deposition temperature. All measured physical properties such as morphology, topography, crystallite size, and optical band gap were clearly dependent on the substrate temperature chosen.

NiO thin films are fabricated on n-type Si (111) substrate at different laser fluence (1.1J/cm2 -... more NiO thin films are fabricated on n-type Si (111) substrate at different laser fluence (1.1J/cm2 - 1.4J/cm2) at a temperature of 200o C by using pulsed laser deposition technique (PLD). The structural and topographical properties of deposited thin films are examined. The films are characterized by employing the diagnostics XRD and AFM. The crystallinity of the deposited films under vacuum (~10-6 torr) and in ambient O2 (~3.75x10-2 torr) at different laser fluence is verified through x-ray diffractometry. RMS roughness decreases at higher fluence (1.4J/cm2) as exhibited by AFM micrographs. The deposition of films in air shows amorphous behavior.

Russian Journal of Physical Chemistry A, 2015

Calcium oxide (CaO) and tin oxide (SnO2) with nanodimension have attracted significant attention ... more Calcium oxide (CaO) and tin oxide (SnO2) with nanodimension have attracted significant attention as effective chemosorbents for toxic compounds. Hydrothermal method was used for the synthesis of highly porous CaO-SnO2 nanocomposites by using sodium dodecylsulfate surfactant as a templating agent. Effect of concentration of surfactant as well as its critical micelle concentration (CMC) on the particle size of the nanocomposites was investigated. X-ray diffraction (XRD) was used to determine the crystal phases of these nanocomposites and particle size and morphology was identified by using transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray (SEM/EDX) respectively. Furthermore thermo gravimetric analysis (TGA) and fourier transform infrared (FTIR) spectroscopy techniques were also used to characterize the CaO-SnO2 nanocomposites.

Nanoparticles were found having applications in various fields of life but recently in diagnostic... more Nanoparticles were found having applications in various fields of life but recently in diagnostic and therapeutic fields of medicine. Iron oxide-tin oxide (Fe2O3-SnO2) nanoparticles were synthesized via hydrothermal method with various concentrations of sodium dodecyl sulfate (SDS) surfactant. Their characterization was done by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) powder techniques. Antibacterial activities of these metal oxides nanoparticles were determined and they were found active against gram-positive B. subtilis and B. lichniformis and gram-negative E. coli, P. aeruginosa and K. pneumonia.