Browsing by Author Bach, Thanh Cong

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  • Alkali metal-substituted bismuth-based perovskite compounds_ A DFT study.pdf.jpg
  • Article


  • Authors: Nguyen, Hoang Linh; Nguyen, Hoang Tuan; Dang, Duc Dung; Phung, Quoc Bao; Bach, Thanh Cong; Le, Thi Hai Thanh (2019)

  • In this study, we have performed density functional theory based calculations to investigate the effect of alkali substituents M on the structure and electronic properties of (Bi0.5M0.5)TiO3 compounds with M ¼ Li, Na and K. When the ionic radius of the substituting M cation increases, the corresponding direct band gap of (Bi0.5M0.5)TiO3 also increases. The same trend is found for the O-deficient Bi0.5M0.5TiO3- d compounds, which were investigated by removing one Oxygen atom from the super cell creating an Ovacancy in it. The presence of the O-vacancy breaks the local symmetry of the crystal structures and generates excess electrons in the O-deficient compounds. This results in t...

  • Effect of Annealing Temperature on Cu2O Thin Films Prepared by Thermal Oxidation Method.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Nguyen, Thi Huyen Trang; Bach, Thanh Cong; Nguyen, Thi Dieu Thu; Nguyen, Thanh Binh; Nguyen, Viet Tuyen; Pham, Nguyen Hai (2020)

  • We report a facile process to fabricate cuprous thin films by thermal oxidation of copper substrates. Structure and phase identification were studied by X-ray diffraction measurement and Raman spectroscopy. Scanning electron microscopy was utilized to study surface morphology of the as-fabricated thin films and optical properties of the samples were investigated by diffused reflectance spectroscopy. The study shows that cuprous thin films could be obtained by controlling annealing temperature in the region of 200-300 oC.

  • Effect of Next Nearest Neighbor Interaction on Thermodynamic Properties of Ultrathin Magnetic Films.pdf.jpg
  • Article


  • Authors: Nguyen, Tu Niem; Bach, Thanh Cong (2019)

  • This work studies on the thermodynamic properties of the ultra-thin magnetic films within the framework of a transverse Ising model. Equations for free energy, entropy and specific heat of spin system are obtained by using the mean field approximation. We also analyze the effect of the next nearest neighbor interaction on critical temperature, layer magnetization and specific heat of the thin films.

  • 4218-97-8100-1-10-20171016.pdf.jpg
  • Article


  • Authors: Pham, Ba Duy; Nguyen, Duy Huy; Bach, Thanh Cong (2017)

  • First-principles calculations based on the density functional theory are used to study the electronic structure of LaNiO3 perovskite for application of cathode material in solid oxide fuel cell. Our results show that bulk LaNiO3 exhibits metallic behavior. For 1x1x1 LaNiO3 unit cell, increasing in-plane strain leads to the increase in the density of states (DOS) at the Fermi level. On the other hand, the DOS at the Fermi level for 2x2x2 LaNiO3 supercell first increases with the strain up to 3% and then decreases for larger values of the strain. The difference between the electronic structure of the 2x2x2 supercell and that of the 1x1x1 unit cell is attributed to the rotations of NiO6 ...

  • 172.pdf.jpg
  • Article


  • Authors: Do, Ngoc Son; Bach, Thanh Cong (2007)

  • Using Greens function method and the equation of motion approach, we have investigated the electronic transport properties of an Aharonov-Bohm (AB) ring in the presence of a magnetic field with a quantum dot inserted in one arm of the ring. In particular, we consider the electron-electron Coulomb interaction within the quantum dot. We find that the current through the system is dependent on the magnetic flux via the AB phase and the Coulomb interaction within the quantum dot, in agreement with experiments. Furthermore, the intradot Coulomb interaction induces dephasing.

  • 52.pdf.jpg
  • Article


  • Authors: Tran, Van Nam; Nguyen, Thuy Trang; Bach, Thanh Cong (2012)

  • Recently, there has been a renewed interest in TiO2 anatase as charge transfer layer in dye-sensitized solar cells (DSSC). In this work, the electronic structure of Mg-doped TiO2 anatase was explored in the framework of density functional theory (DFT). The results showed that the substitution of Mg2+ ions for Ti4+ ions was quite easy in comparison with non metalic doping case. It induced small lattice expansions about 0.3% along a and b axis and 0.1% along c axis which can be explained in terms of internal stress around the impurity site and the anisotropic softy of the material. The effects of Mg impurity on the bulk and surface electronic structures were also discussed in details. I...

  • Order-disorder-phase-transitions-in-thin-films-described-by-transverse-Ising-model_2016_Journal-of-Science-Advanced-Materials-and-Devices.pdf.jpg
  • Article


  • Authors: Nguyen, Tu Niem; Bach, Huong Giang; Bach, Thanh Cong (2016)

  • The order-disorder phase transition in thin films at finite temperature and zero temperature (quantum phase transition) is discussed within the transverse Ising model using molecular field approximation. Experimentally, it is shown that the Curie temperature TC of perovskite PbTiO3 ultra-thin film decreases with decreasing film thickness. We obtain an equation for TC of thin film in external magnetic and transverse fields. Our equation explains well for the case of strong transverse strain field this behaviour.

Browsing by Author Bach, Thanh Cong

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 7 of 7
  • Alkali metal-substituted bismuth-based perovskite compounds_ A DFT study.pdf.jpg
  • Article


  • Authors: Nguyen, Hoang Linh; Nguyen, Hoang Tuan; Dang, Duc Dung; Phung, Quoc Bao; Bach, Thanh Cong; Le, Thi Hai Thanh (2019)

  • In this study, we have performed density functional theory based calculations to investigate the effect of alkali substituents M on the structure and electronic properties of (Bi0.5M0.5)TiO3 compounds with M ¼ Li, Na and K. When the ionic radius of the substituting M cation increases, the corresponding direct band gap of (Bi0.5M0.5)TiO3 also increases. The same trend is found for the O-deficient Bi0.5M0.5TiO3- d compounds, which were investigated by removing one Oxygen atom from the super cell creating an Ovacancy in it. The presence of the O-vacancy breaks the local symmetry of the crystal structures and generates excess electrons in the O-deficient compounds. This results in t...

  • Effect of Annealing Temperature on Cu2O Thin Films Prepared by Thermal Oxidation Method.pdf.jpg
  • Article


  • Authors: Tran, Thi Ha; Nguyen, Thi Huyen Trang; Bach, Thanh Cong; Nguyen, Thi Dieu Thu; Nguyen, Thanh Binh; Nguyen, Viet Tuyen; Pham, Nguyen Hai (2020)

  • We report a facile process to fabricate cuprous thin films by thermal oxidation of copper substrates. Structure and phase identification were studied by X-ray diffraction measurement and Raman spectroscopy. Scanning electron microscopy was utilized to study surface morphology of the as-fabricated thin films and optical properties of the samples were investigated by diffused reflectance spectroscopy. The study shows that cuprous thin films could be obtained by controlling annealing temperature in the region of 200-300 oC.

  • Effect of Next Nearest Neighbor Interaction on Thermodynamic Properties of Ultrathin Magnetic Films.pdf.jpg
  • Article


  • Authors: Nguyen, Tu Niem; Bach, Thanh Cong (2019)

  • This work studies on the thermodynamic properties of the ultra-thin magnetic films within the framework of a transverse Ising model. Equations for free energy, entropy and specific heat of spin system are obtained by using the mean field approximation. We also analyze the effect of the next nearest neighbor interaction on critical temperature, layer magnetization and specific heat of the thin films.

  • 4218-97-8100-1-10-20171016.pdf.jpg
  • Article


  • Authors: Pham, Ba Duy; Nguyen, Duy Huy; Bach, Thanh Cong (2017)

  • First-principles calculations based on the density functional theory are used to study the electronic structure of LaNiO3 perovskite for application of cathode material in solid oxide fuel cell. Our results show that bulk LaNiO3 exhibits metallic behavior. For 1x1x1 LaNiO3 unit cell, increasing in-plane strain leads to the increase in the density of states (DOS) at the Fermi level. On the other hand, the DOS at the Fermi level for 2x2x2 LaNiO3 supercell first increases with the strain up to 3% and then decreases for larger values of the strain. The difference between the electronic structure of the 2x2x2 supercell and that of the 1x1x1 unit cell is attributed to the rotations of NiO6 ...

  • 172.pdf.jpg
  • Article


  • Authors: Do, Ngoc Son; Bach, Thanh Cong (2007)

  • Using Greens function method and the equation of motion approach, we have investigated the electronic transport properties of an Aharonov-Bohm (AB) ring in the presence of a magnetic field with a quantum dot inserted in one arm of the ring. In particular, we consider the electron-electron Coulomb interaction within the quantum dot. We find that the current through the system is dependent on the magnetic flux via the AB phase and the Coulomb interaction within the quantum dot, in agreement with experiments. Furthermore, the intradot Coulomb interaction induces dephasing.

  • 52.pdf.jpg
  • Article


  • Authors: Tran, Van Nam; Nguyen, Thuy Trang; Bach, Thanh Cong (2012)

  • Recently, there has been a renewed interest in TiO2 anatase as charge transfer layer in dye-sensitized solar cells (DSSC). In this work, the electronic structure of Mg-doped TiO2 anatase was explored in the framework of density functional theory (DFT). The results showed that the substitution of Mg2+ ions for Ti4+ ions was quite easy in comparison with non metalic doping case. It induced small lattice expansions about 0.3% along a and b axis and 0.1% along c axis which can be explained in terms of internal stress around the impurity site and the anisotropic softy of the material. The effects of Mg impurity on the bulk and surface electronic structures were also discussed in details. I...

  • Order-disorder-phase-transitions-in-thin-films-described-by-transverse-Ising-model_2016_Journal-of-Science-Advanced-Materials-and-Devices.pdf.jpg
  • Article


  • Authors: Nguyen, Tu Niem; Bach, Huong Giang; Bach, Thanh Cong (2016)

  • The order-disorder phase transition in thin films at finite temperature and zero temperature (quantum phase transition) is discussed within the transverse Ising model using molecular field approximation. Experimentally, it is shown that the Curie temperature TC of perovskite PbTiO3 ultra-thin film decreases with decreasing film thickness. We obtain an equation for TC of thin film in external magnetic and transverse fields. Our equation explains well for the case of strong transverse strain field this behaviour.