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Now showing items 1 - 16 of 105

  • Microwave Assisted Iron Oxide Nanoparticles—Structural and Magnetic Properties

    Riaz, Saira   Ashraf, Robina   Akbar, Aseya   Naseem, Shahzad  

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  • Magnetic and Magnetization Properties of Iron Aluminum Oxide Thin Films Prepared by Sol-Gel

    Riaz, Saira   Azam, Muhammad   Ashraf, Robina   Naseem, Shahzad  

    Amongst various spinels of the form MAl2O4 (where M = Fe, Co, Mg and so on), FeAl2O4 exhibits exceptional chemical and physical properties including high flexibility and ductility. Reports on magnetic properties of these spinels are limited especially in the form of thin films. Structural and magnetic properties of iron aluminium oxide thin films prepared by Sol-Gel and spin coating method have been reported in this work. The ratio of Fe/Al is varied as 0.4, 0.45, 0.5, 0.55, and 0.6. Films are annealed in the presence of vacuum at 300 degrees C under 500 Oe applied magnetic field. Peaks of FeAl2O4 are observed for Fe/Al of 0.4. However, Fe2O3 peaks appear along with iron aluminium oxide peaks for rest of the ratios. M-H curves show enhanced magnetic properties of films having 42.325 emu/cm(3) saturation magnetization (M-s), 10 emu/cm(3) remnant magnetization (M-r), and 430.19 Oe coercivity (H-c). Conductivity measurements show transition in electrical properties at a temperature of 127 K. Room temperature magnetoresistance similar to 10% is observed for iron aluminum oxide thin films with Fe/Al of 0.4.
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  • Role of co-doping on structural, optical and magnetic properties of nano-crystalline ZnO thin films

    Kayani, Zohra Nazir Nazir   Iram, Saima   Riaz, Saira   Naseem, Shahzad  

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  • Ferromagnetic Effects in Cr-Doped Fe2O3 Thin Films

    Riaz, Saira   Akbar, Aseya   Naseem, Shahzad  

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  • Grown of highly porous ZnO-nanoparticles by pulsed laser ablation in liquid technique for sensing applications

    Islam, Shumaila   Bakhtiar, Hazri   Abbas, Khaldoon N.   Riaz, Saira   Naseem, Shahzad   Johari, Abdul Rahman Bin  

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  • Effect of Bi/Fe Ratio on the Structural and Magnetic Properties of BiFeO3 Thin Films by Sol-Gel

    Riaz, Saira   Shah, S. M. H.   Akbar, Aseya   Kayani, Zohra Nazir   Naseem, Shahzad  

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  • Free Growth of Iron Oxide Nanostructures by Sol-Gel Spin Coating Technique—Structural and Magnetic Properties

    Riaz, Saira   Ashraf, Robina   Akbar, Aseya   Naseem, Shahzad  

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  • Mesoporous anatase based opto-chemical sensor

    Islam, Shumaila   Bakhtiar, Hazri   Aziz, Madzlan   Riaz, Saira   Naseem, Shahzad  

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  • Enhanced microwave absorption properties of CTAB assisted Pr-Cu substituted nanomaterial

    Sadiq, Imran   Naseem, Shahzad   Riaz, Saira   Khan, Hasan M.   Ashiq, Muhammad Naeem   Hussain, S. Sajjad   Rana, Mazhar  

    In this study, the rare earth Pr3+ and divalent Cu2+ elements substituted Sr1-xPrxMn2Fe16-yCuyO27 (x=3D0, 0.02, 0.06, 0.1 and y=3D0, 0.1, 0.3, 0.5) W-type hexagonal ferrites were prepared by Sol-Gel method. TGA and DSC analysis of as prepared material was carried out to confirm the temperature at which required phase can be obtained. The XRD patterns exhibit the single phase for all the samples and the lattice parameters were changed with the additives. The absorption bands at wave number 636 and 554 cm(-1) in FTIR spectrum indicate the stretching vibration of metal-oxygen ions which also ratifies the single phase for the prepared material. Microstructural analysis confirms the agglomeration of nanograins which leads to formation of platelet like structure which cause in the enhancement of the microwave absorption properties of material. The minimum reflection loss of -59.8 dB at 9.34 GHz frequency was observed makes the prepared material good candidate to be used in super high frequency application. The attenuation constant and reflectivity results are also in good agreement with minimum reflection losses results. (C) 2016 Elsevier B.V. All rights reserved.
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  • A comparative study of graphene growth by APCVD, LPCVD and PECVD

    Ullah, Zaka   Riaz, Saira   Li, Qi   Atiq, Shahid   Saleem, Muhammad   Azhar, Muhammad   Naseem, Shahzad   Liu, Liwei  

    Graphene films are deposited on Cu foils through atmospheric-pressure chemical vapor deposition (APCVD), low-pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD), and their comparative analysis is performed to explore the most appropriate growth method and experimental conditions. The temperature, pressure and concentration of precursor gases inside the furnace tube are the major factors which directly affect the graphene growth, and by employing APCVD, LPCVD and PECVD, these factors are optimized to achieve the desired growth. For the deposited films, surface morphology is investigated via optical microscopy and scanning electron microscopy, quality of graphene is examined through Raman spectroscopy, transmission measurements are made by employing UV-visible spectroscopy, and sheet resistance of deposited graphene is measured using four-point probe method. In present work, most of the graphene films deposited by APCVD are multilayer, by LPCVD are a few-layer, and by PECVD are monolayer and bilayer. The graphene deposition is also achieved at reduced temperature similar to 350 degrees C using PECVD, which is still among the lowest growth temperatures in the reported literature. The study can be of great significance in achieving the desired growth of graphene and other related materials using CVD.
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  • Optically active phenolphthalein encapsulated gold nanodendrites for fiber optic pH sensing

    Islam, Shumaila   Bakhtiar, Hazri   Aziz, Madzlan   Riaz, Saira   Aziz, Muhammad Safwan Abd   Naseem, Shahzad   Elshikeri, Nada  

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  • Geographical Variations in Life Histories of House Flies, Musca domestica (Diptera: Muscidae), in Punjab, Pakistan

    Khan, Hafiz Azhar Ali   Khan, Muhammad Umer   Nasiba, Amara   Riaz, Saira   Altaf, Maria  

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  • Honey mediated microwave assisted sol-gel synthesis of stabilized zirconia nanofibers

    Bukhari, Bushra S.   Imran, M.   Bashir, Mahwish   Riaz, Saira   Naseem, Shahzad  

    Aim of the present work is to prepare zirconia nanofibers using microwave assisted sol-gel method. Both honey and microwave powers are employed as structure directing agents to improve the stability and reduce the crystallite size. Honey, acting as capping agent, prevents the particles from hard agglomeration. Soft agglomeration or less agglomeration results in smaller crystallite size that prevents the transformation of tetragonal to monoclinic phase resulting in stabilized tetragonal zirconia (t-ZrO2). Zirconium oxychloride is used as precursor of zirconium and deionized water as solvent. Effect of microwave powers, in the range of 100-900 W with interval of 200 W, on zirconia stabilization is observed. X-ray diffraction analysis shows the presence of phase pure t-ZrO2 at low microwave power similar to 100 W with crystallite size similar to 26 nm. Formation of phase pure t-ZrO2 at low microwave power is due to the presence of sufficient amount of honey to coat the zirconia crystals. Relatively higher x-ray density has been observed in case of phase pure t-ZrO2 at 100 W of microwave power. This high density and phase purity reveals the high value of hardness (similar to 1503 HV). Scanning electron microscopy analysis reveals the formation of well-separated nanofibers without agglomeration at 100 W. These nanofibers are purposed for bone implants and bone grafting. Structural transformation along with hard agglomeration is observed with increase in microwave powers from 500 W to 900 W. FTIR and Raman fundamental tetragonal bands, appearing at 490 cm(-1) and 148 cm(-1) , respectively, confirm the formation of t-ZrO2 at low microwave power. Sample with phase purity exhibits high grain boundary resistance (1.95 M Omega) along with high dielectric constant (similar to 74) and low tangent loss (at log f = 4.0). It is worth mentioning here that phase pure t-ZrO2 at very low microwave power (similar to 100 W) with high density and well-separated nanofibers has been obtained without any post heat treatment. [GRAPHICS] .
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  • Investigation of structural, optical and magnetic characteristics of Co3O4 thin films

    Kayani, Zohra Nazir   Arshad, Saliha   Riaz, Saira   Naseem, Shahzad  

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  • Antibacterial performance of glucose-fructose added MW based zirconia coatings 鈥� Possible treatment for bone infection

    Sanaullah, Ifra   Bukhari, Bushra S.   Batool, Tanzeela   Riaz, Saira   Khan, Hira N.   Sabri, Anjum N.   Naseem, Shahzad  

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  • Thermally activated variations in conductivity and activation energy in SrMnO3

    Abbas, Syed Kumail   Atiq, Shahid   Riaz, Saira   Naseem, Shahzad  

    In this paper, we present a series of strontium manganite samples, synthesized using an efficient sol-gel based auto-combustion route by optimizing the calcination temperature and time. X-ray diffraction revealed the formation of pure phase hexagonal perovskite structure in the sample calcined at 1000 A degrees C for 4 h. Tangent loss and loss factor versus frequency plots demonstrate total losses present in the material which are important parameters in determining immunity level of the materials for magneto-electric coupling potentially viable for non-volatile ferroelectric random access memories. Frequency dependent ac conductivity at different temperatures indicates that the conduction process is thermally activated. Trend of ac conductivity exhibits frequency independent and dependent regions. Correlation of the ac and dc conductivities along with hopping mechanism has also been probed. The activation energy has been calculated from an Arrhenius plot of dc conductivity and relaxation frequency.
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