Browsing by Author Nguyen, Viet Tuyen

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  • 21.pdf.jpg
  • Article


  • Authors: Nguyen, Viet Tuyen; Tran, Thi Hai; Nguyen, Thi Hong; Phan, Thi Thanh Hong; Ho, Khac Hieu (2017)

  • The anharmonic correlated Debye model has been developed to investigate the pressure effects on the extended X-ray absorption fine structure (EXAFS) Debye-Waller factors of metals. The recent well-established Grüneisen parameter expressions have been applied to formulate the pressure-dependent analytical expressions of the effective spring constant, correlated Debye frequency and temperature. Combing with the anharmonic correlated Debye model, the expression of EXAFS Debye–Waller factor under pressure can be derived. Numerical calculations, performed for Fe and Cu metals show reasonable agreement with experiments.

  • 98.pdf.jpg
  • Article


  • Authors: Ta, Dinh Canh; Nguyen, Viet Tuyen; Nguyen, Ngoc Long (2009)

  • A simple and rapid process has been developed for preparation of nanometer-sized ZnO powders via microwave irradiation, by which ZnO powders with an average particle size of 10-12 nm and narrow size distribution can be synthesized in a short time. We have synthesized ZnO nanoparticles by precipitation from zinc acetate (Zn(CH2COO)2.6H2O) in different solvents: distilled water, absolute ethanol (C2H5OH), and isopropanol (C3H7OH). The ZnO nanopowders structure was characterized by X-ray powder diffraction (XRD). Raman scattering studies confirm that the as-synthesized nanopowders are of high crystalline quality. High-resolution transmission electron microscopy analysis reveals that the ...

  • 113.pdf.jpg
  • Article


  • Authors: Ta, Dinh Canh; Nguyen, Viet Tuyen; Nguyen, Ngoc Long; Vo, Ly Thanh Ha (2010)

  • n-ZnO:hVp-Si heterojunctions have been fabricated by sputter deposition of nZnO:ln on p-Si substrates. The lowest resistivity n-ZnO:In film was obtained at a substrate temperature of 150oC using a ZnO target doped with 2 wt% In2O3. At substrate temperature above 300oC the resistivity of the film increases as the carrier concentration decreases. This implies a significant decrease in the donor impurity, which is ascribed to evaporation of the indium during film growth. The wavelength dependent properties of the photo-response for the heterojunction were investigated in detail by studying the effect of light illumination on current - voltage (I-V) characteristic, photocurrent spectra ...

  • TL2.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Bui, Thi Huyen; Nguyen, Viet Tuyen (2016)

  • Well-aligned CuO nanorods were successfully prepared by thermal oxidation method. The effect of annealing time and annealing temperature on the morphology of the nanorods were studied by scanning electron microscopy. The results show that annealing temperature plays a more critical role in affecting the diameter and density of nanorods. Besides SEM images, the effect of annealing time and temperatures on the structure of the product were also studied by X-ray diffraction and Raman spectroscopy. The diameter of CuO nanorods varies from 30 nm to above 100 nm when annealing temperature changes from 400 °C to 600 °C, while the length of the rods is up to several tens of micrometers. The...

  • 7.pdf.jpg
  • Article


  • Authors: Mai, Hong Hanh; Nguyen, Viet Tuyen; Pham, Van Thanh; Hoang, Chi Hieu (2017)

  • High quality, high density, and well-aligned zinc oxide (ZnO) nanorods have been synthesized on cost-effective printed circuit board (PCB) substrates via a simple, seedless, one-step, low-temperature hydrothermal method based galvanic cell structure. It was found that the outer diameters of the ZnO nanorods range from 50 nm to 400 nm. The as-grown ZnO nanorods prefer to grow along the c axis. The morphologies of the ZnO nanorods were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The crystallinity properties were characterized by Raman spectroscopy and photoluminescence (PL) spectroscopy.

Browsing by Author Nguyen, Viet Tuyen

Jump to: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
or enter first few letters:  
Showing results 1 to 5 of 5
  • 21.pdf.jpg
  • Article


  • Authors: Nguyen, Viet Tuyen; Tran, Thi Hai; Nguyen, Thi Hong; Phan, Thi Thanh Hong; Ho, Khac Hieu (2017)

  • The anharmonic correlated Debye model has been developed to investigate the pressure effects on the extended X-ray absorption fine structure (EXAFS) Debye-Waller factors of metals. The recent well-established Grüneisen parameter expressions have been applied to formulate the pressure-dependent analytical expressions of the effective spring constant, correlated Debye frequency and temperature. Combing with the anharmonic correlated Debye model, the expression of EXAFS Debye–Waller factor under pressure can be derived. Numerical calculations, performed for Fe and Cu metals show reasonable agreement with experiments.

  • 98.pdf.jpg
  • Article


  • Authors: Ta, Dinh Canh; Nguyen, Viet Tuyen; Nguyen, Ngoc Long (2009)

  • A simple and rapid process has been developed for preparation of nanometer-sized ZnO powders via microwave irradiation, by which ZnO powders with an average particle size of 10-12 nm and narrow size distribution can be synthesized in a short time. We have synthesized ZnO nanoparticles by precipitation from zinc acetate (Zn(CH2COO)2.6H2O) in different solvents: distilled water, absolute ethanol (C2H5OH), and isopropanol (C3H7OH). The ZnO nanopowders structure was characterized by X-ray powder diffraction (XRD). Raman scattering studies confirm that the as-synthesized nanopowders are of high crystalline quality. High-resolution transmission electron microscopy analysis reveals that the ...

  • 113.pdf.jpg
  • Article


  • Authors: Ta, Dinh Canh; Nguyen, Viet Tuyen; Nguyen, Ngoc Long; Vo, Ly Thanh Ha (2010)

  • n-ZnO:hVp-Si heterojunctions have been fabricated by sputter deposition of nZnO:ln on p-Si substrates. The lowest resistivity n-ZnO:In film was obtained at a substrate temperature of 150oC using a ZnO target doped with 2 wt% In2O3. At substrate temperature above 300oC the resistivity of the film increases as the carrier concentration decreases. This implies a significant decrease in the donor impurity, which is ascribed to evaporation of the indium during film growth. The wavelength dependent properties of the photo-response for the heterojunction were investigated in detail by studying the effect of light illumination on current - voltage (I-V) characteristic, photocurrent spectra ...

  • TL2.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Bui, Thi Huyen; Nguyen, Viet Tuyen (2016)

  • Well-aligned CuO nanorods were successfully prepared by thermal oxidation method. The effect of annealing time and annealing temperature on the morphology of the nanorods were studied by scanning electron microscopy. The results show that annealing temperature plays a more critical role in affecting the diameter and density of nanorods. Besides SEM images, the effect of annealing time and temperatures on the structure of the product were also studied by X-ray diffraction and Raman spectroscopy. The diameter of CuO nanorods varies from 30 nm to above 100 nm when annealing temperature changes from 400 °C to 600 °C, while the length of the rods is up to several tens of micrometers. The...

  • 7.pdf.jpg
  • Article


  • Authors: Mai, Hong Hanh; Nguyen, Viet Tuyen; Pham, Van Thanh; Hoang, Chi Hieu (2017)

  • High quality, high density, and well-aligned zinc oxide (ZnO) nanorods have been synthesized on cost-effective printed circuit board (PCB) substrates via a simple, seedless, one-step, low-temperature hydrothermal method based galvanic cell structure. It was found that the outer diameters of the ZnO nanorods range from 50 nm to 400 nm. The as-grown ZnO nanorods prefer to grow along the c axis. The morphologies of the ZnO nanorods were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). The crystallinity properties were characterized by Raman spectroscopy and photoluminescence (PL) spectroscopy.