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Synthesis and Characterization of Nano-hydroxyapatite Powder Using Wet Chemical Precipitation Reaction

Journal of Materials Science & Technology 2014年第4期30卷 307-310页

作者： Syed Sibte Asghar Abidi qasim murtaza Centre of Excellence in Materials Science(Nanomaterials) Aligarh Muslim University Mechanical and Production Engineering Department Delhi Technology University(Formerly Delhi College of Engineering)

Hydroxyapatite （HA） nano-powder was synthesized via wet chemical technique in a used precipitation reaction, in which Ca（OH）2 and H3PO4 were used as precursors. Deionised water was used as a diluting media for the reaction and ammonia was used to adjust the pH. The synthetic HA nano-powder has some medical applications such as a coating material in orthopaedic implants and in dental. HA powder has been studied at different temperatures from 100 to 800 ℃ to achieve the stoichiometric Ca/P ratio 1.667. The optimum temperature was found to be 600 ℃. Above this temperature, the HA powder decomposed to CaO. The crystallite size of HA powder was found to be in the range of 8.47-24.47 nm. The crystallographic properties were evaluated by X-ray diffraction, Fourier transform infrared spectroscopy, energy dispersive X- ray spectroscopy and scanning electron microscopy. The results show that, high purity of nano-hydroxyapatite powders could be obtained at low temperatures, and the crystallinity, crystallite size and Ca/P ratio of the resulting nanoparticles were found to be dependent on the calcination temperature. When Ca/P ratio exceeded 1.75, formation of CaO phase was observed.

关键词： Hydroxyapatite Nano-powder Synthesis Characterization

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Room Temperature Ferromagnetism in Ga1-xHoxN （x=0.0 and 0.05） Diluted Magnetic Semiconductor Thin Films

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Chinese Journal of Chemical Physics 2012年第3期25卷 313-317,373,374页

作者： Ghulam murtaza Rai Muhammad Azhar Iqbal Yong-bing Xu lain Gordon Will qasim Mahmood Department of Physics University of the Punjab Lahore 54590 Pakistan Spintronics Laboratory Department of Electronics The University of York York Y010 5DD UK

Holmium doped GaN diluted magnetic semiconductor thin films have been prepared by thermal evaporation technique and subsequent ammonia annealing. X-ray diffraction mea- surements reveal all peaks belong to the purely hexagonal wurtzite structure. Surface mor- phology and composition analysis were carried out by scanning electron microscopy and energy dispersive spectroscopy respectively. The room temperature ferromagnetic proper- ties of Gal-xHoxN （x=0.0, 0.05） films were analyzed using vibrating sample magnetometer at room temperature. Magnetic measurements showed that the undoped films （i.e. GaN） exhibited diamagnetic behavior, while the Ho-doped （Gao.95Hoo.05N） film exhibited a ferro- magnetic behavior.

关键词： Diluted magnetic semiconductor Holmium doping X-ray diffraction Scan-ning electron microscopy Room temperature ferromagnetism

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Optical spin-symmetry breaking for high-efficiency directional helicity-multiplexed metaholograms

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Microsystems & Nanoengineering 2021年第2期7卷 71-79页

作者： Muhammad Ashar Naveed Muhammad Afnan Ansari Inki Kim Trevon Badloe Joohoon Kim Dong Kyo Oh Kashif Riaz Tauseef Tauqeer Usman Younis murtaza Saleem Muhammad Sabieh Anwar Muhammad Zubair Muhammad qasim Mehmood Junsuk Rho NanoTech Lab Department of Electrical EngineeringInformation Technology University(ITU)of the PunjabFerozepur RoadLahore54600Pakistan Department of Mechanical Engineering Pohang University of Science and Technology(POSTECH)Pohang37673Republic of Korea Department of Physics Lahore University of Management Sciences(LUMS)Lahore54792Pakistan Department of Chemical Engineering Pohang University of Science and Technology(POSTECH)Pohang37673Republic of Korea National Institute of Nanomaterials and Technology(NINT) Pohang37673Republic of Korea

Helicity-multiplexed metasurfaces based on symmetric spin–orbit interactions (SOIs) have practical limits because they cannot provide central-symmetric holographic imaging. Asymmetric SOIs can effectively address such limitations, with several exciting applications in various fields ranging from asymmetric data inscription in communications to dual side displays in smart mobile devices. Low-loss dielectric materials provide an excellent platform for realizing such exotic phenomena efficiently. In this paper, we demonstrate an asymmetric SOI-dependent transmission-type metasurface in the visible domain using hydrogenated amorphous silicon (a-Si:H) nanoresonators. The proposed design approach is equipped with an additional degree of freedom in designing bi-directional helicity-multiplexed metasurfaces by breaking the conventional limit imposed by the symmetric SOI in half employment of metasurfaces for one circular handedness. Two on-axis, distinct wavefronts are produced with high transmission efficiencies, demonstrating the concept of asymmetric wavefront generation in two antiparallel directions. Additionally, the CMOS compatibility of a-Si:H makes it a cost-effective alternative to gallium nitride (GaN) and titanium dioxide (TiO2) for visible light. The cost-effective fabrication and simplicity of the proposed design technique provide an excellent candidate for high-efficiency, multifunctional, and chip-integrated demonstration of various phenomena.

关键词： directional breaking visible

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