KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Settings

Author: search.filters.author.Wattanawikkam, ChakkaphanSubject: search.filters.subject.Magnetic properties

Search Results

Now showing 1 - 2 of 2
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    X-ray absorption spectroscopy analysis and magnetic properties of M-doped TiO2 nanoparticles (M=Co, Mn, Ni and Zn) prepared by co-precipitation method
    (2017-08-01)
    Wattanawikkam, Chakkaphan
    ;
    Pecharapa, Wisanu
    ;
    Ishihara, Keiichi N.
    M-doped TiO<inf>2</inf> nanoparticles (M=Co, Mn, Ni and Zn) were synthesized by co-precipitation method combined with annealing at 500 °C for 2 h. X-ray diffraction (XRD) was used to identify their structural phases. X-ray absorption near edge structure (XANES) was conducted to probe the chemical state and crystal atomic structure of prepared samples. Magnetic properties of all samples were characterized by vibrating sample magnetrometer (VSM). The XRD analyses reveal that all samples crystallize in anatase tetragonal structure with no additional peaks. The XANES spectra exhibit triple pre-edge fingerprint of Ti4+ of oxidation state with six-fold octahedral coordinate structure. Co-, Ni- and Zn- K-edge results indicate that the Co, Ni and Zn ions in M-doped TiO<inf>2</inf> are in 2+ formal oxidation state. Meanwhile, Mn-doped TiO<inf>2</inf> sample contains the different oxidation states of 3+ and 4+. The amount of each oxidation state is confirmed by using linear combination fitting method. The magnetic measurement illustrates the paramagnetic behavior for Co-, Mn- and Ni- doped samples that strongly depend on the doping content and no hysteresis loop is observed in undoped and Zn-doped samples.
  • Loading...
    Thumbnail Image
    Some of the metrics are blocked by your 
    consent settings
    Item type:Publication,
    Structural, optical and magnetic properties of diluted magnetic perovskite ZnTiO3 doped with Co and Mn prepared by sonochemical method
    (2017-01-01)
    Wattanawikkam, Chakkaphan
    ;
    Phoohinkong, Weerachon
    ;
    Pecharapa, Wisanu
    We employed a sonochemical method to fabricate transition metal ion doped perovskite ZnTiO<inf>3</inf> (M-ZnTiO<inf>3</inf>) nanoparticles, including individual Co and Mn ions. The Zn:Ti was mixed in molar ratio of 1:1 to obtain starting precursor for ZnTiO<inf>3</inf>. The different concentrations of Co (5-10 mol%) and Mn (3-7 mol%) were doped in ZnTiO<inf>3</inf>, then the mixing solution were irradiated in high frequency ultrasound of a sonometer (20 kHz, 750 W) at room temperature to obtain the as-prepared samples. The final products were calcined at 800°C for 3 h to improve the crystallinity. We confirmed formation structures of M-ZnTiO<inf>3</inf> nanoparticles by X-ray diffraction (XRD), and used X-ray absorption near edge spectroscopy (XANES) and X-ray photoelectron spectroscopy (XPS) technique to investigate the crystal structure and valence states of the sample. Meanwhile, we studied their optical properties by diffuse reflectance spectroscopy, and evaluated magnetic properties of the samples at room temperature by vibrating sample magnetometer (VSM). Magnetization measurements revealed the paramagnetic behavior for Co-ZnTiO<inf>3</inf> and weak ferromagnetic behavior for Mn-ZnTiO<inf>3</inf>. We also investigated and discussed the effect of metal ion doping concentration on the structural, optical and magnetic properties.