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4 Materials Science Poland

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Synthesis of nanocrystalline metal molybdates using cyclic microwave radiation

100%

Phuruangrat A. , Thongtem T. , Thongtem S.

tom Vol. 28, No. 2

557--563

Nanocrystalline compounds MMoO4 (M = Ca, Sr and Ba) were synthesized in propylene glycol using cyclic microwave radiation. XRD, TEM, SAED and EDX analyses revealed the presence of nanocrystallites of the phases containing the corresponding alkaline earth metals, Mo and O. The calculated lattice parameters and the crystallite sizes both increased with the increase in the atomic masses and the ionic radii of the divalent metals. Six different vibrations were detected using Raman spectroscopy, and very strong Mo-O stretching mode of [MoO4]2- tetrahedrons was observed using FTIR.

Characterization of nanocrystalline LiNi1-xCoxVO4 prepared by the polymerized complex method

100%

Thongtem W. T. , Phuruangrat A. , Thongtem S.

tom Vol. 27, No. 1

43--49

Nanocrystalline LiNi1-xCoxVO4 (x = 0.00, 0.25, 0.50, 0.75 and 1.00) was prepared from Li2CO3, Ni(NO3)2.6H2O, Co(NO3)2.6H2O and NH4VO3, using tartaric acid as a complexing agent, followed by 450 °C calcination for 12 h. TGA results show that nanocrystallites started to form at 450-550 °C. Inverse spinel LiNi1-xCoxVO4 was detected using the XRD and SAED methods. The calculated lattice parameter increased upon increasing Co concentration. It was in accordance with the increase in the particle size determined using TEM images. A stretching band of VO4 tetrahedra was detected at 651-820 cm-1 using FTIR. V-O vibrational bands analyzed with a Raman spectrometer were shifted to the lower wavenumbers, due to the increase of Co concentration. The selected elements were also analyzed using EDX and AAS to determine the stoichiometric values (x) of the oxides.

Deposition of Au, Au-V and Au-VOx on Si wafers by co-sputtering technique

88%

Narksitipan S. , Bannuru T. , Brown W. L. , Vinci R. P. , Thongtem S.

tom Vol. 27, No. 2

484--491

Au, Au-V and Au-VOx thin films were deposited on Si wafers by a co-sputtering technique. A fourpoint probe shows that the electrical resistivity of pure Au thin film on Si wafer without annealing is 7.2 m?ocm. The resistivities of thin films deposited on Si wafers, with or without annealing, tended to increase with the increase in the V and VOx concentrations, and were attributable to the inhibited drift mobility of charge carriers within the films. By using the nanoindentation technique, the hardness in all cases also tended to increase with the increase in the V and VOx concentrations. The hardness of pure Au, without annealing, was 2.52 GPa. It decreased to 1.80 GPa and 1.75 GPa after annealing at 200 °C and 400 °C, respectively. SEM and TEM analyses revealed the presence of nanosized particles on the surfaces of the thin films. XRD analysis of Au-4.00% VOx film deposited on Si wafer detected the presence of Au, VO and Si. However, SAED analysis only detected the presence of Au on the film.

Effect of lead salts on phase, morphologies and photoluminescence of nanocrystalline PbMoO4 and PbWO4 synthesized by microwave radiation

75%

Phuruangrat A. , Kuntalue B. , Artkla S. , Promnopas S. , Promnopas W. , Thongtem S. , Thongtem T.

Materials Science Poland

2016

tom Vol. 34, No. 3

529--533

PbMoO4 and PbWO4 were successfully synthesized by microwave radiation using different lead salts (acetate, chloride, nitrate and sulfate) and Na2MO4 (M = Mo, W) in propylene glycol. The products were characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), Fourier transform infrared (FT-IR), Raman spectroscopy and photoluminescence (PL) spectroscopy. In this research, morphologies, crystallization and photoluminescence of the products were influenced by the kinetics of anions, including the detection of M–O (M = Mo, W) stretching modes in the (MO4)2 tetrahedrons. Photoluminescence of PbMoO4 synthesized from Pb(NO3)2 and of PbWO4 synthesized from PbCl2 showed the strongest blue emission due to the electronic diffusion in tetrahedrons at room temperature.