Now showing items 11-29 of 29

    • First principles phase diagram calculations for the wurtzite-structure systems AlN-GaN, GaN-InN, and AlN-InN 

      Burton, Bejnamin P.; van de Walle, Axel; kattner, Ursula (2014-11-20)
      First principles phase diagram calculations were performed for the wurtzite-structure quasibinary systems AlN–GaN, GaN–InN, and AlN–InN. Cluster expansion Hamiltonians that excluded, and included, excess vibrational ...
    • GeTe-PbTe PbS-PbTe PbSe-PbS PbTe-PbSe PbTe-SnTe SnTe-GeTe mixing and coherency strain energies 

      Doak, Jeff W.; Wolverton, C. (2012-10-15)
      Nanostructures formed by phase separation improve the thermoelectric figure of merit in lead chalcogenide semiconductor alloys, with coherent nanostructures giving larger improvements than incoherent nanostructures. However, ...
    • Hf-Ox First principles phase diagram calculations for the octahedral-interstitial system 

      Burton, Benjamin P. (2013-04-03)
      The group IV hexagonal closest packed (hcp) suboxides MOX (M = Ti, Zr or Hf) all exhibit octahedral interstitial ordering of oxygen, O, and vacancies, in solid solutions of the form View the MathML source, 0≤X≤1/2. By far, ...
    • Li-Ni-Mn-Co-Ti-O Voltage Profile 

      Markus, Isaac M; Asta, Mark (2014-08-11)
      The performance enhancements associated with Ti substitution of Co in the layered cathode material Li1(NixMnxCo1-2x)O2 were investigated using density functional theory calculations. Examining the structural and electronic ...
    • MoS2-MoTe2 

      Burton, Benjamin P; Singh, Arunima
      A first principles phase diagram calculation, that included van der Waals interactions, was performed for the system (1-X)$\cdot$MoS$_{2}$-(X)$\cdot$MoTe$_{2}$. Surprisingly, the predicted phase diagram has at least ...
    • NaCl-KCl 

      Burton, Bejnamin P.; van de Walle, Axel
      First principles phase diagram calculations were performed for the system NaCl-KCl. Planewave pseudopotential calculations of formation energies were used as a basis for fitting cluster expansion Hamiltonians, both with- ...
    • NaCl–KCl: The role of excess vibrational entropy 

      Burton, Benjamin P. (2013-04-08)
      First principles phase diagram calculations were performed for the system NaCl–KCl. Plane-wave pseudopotential calculations of formation energies were used as a basis for fitting cluster expansion Hamiltonians, both with ...
    • NaNbO3–KNbO3: Can spinodal decomposition generate relaxor ferroelectricity? 

      Burton, Benjamin P. (2013-04-08)
      First principles based phase diagram calculations were performed for the system (1−X) NaNbO3–(X) KNbO3. Plane wave pseudopotential calculations of formation energies were used as a basis for fitting a cluster expansion ...
    • Np incorporation into metal organic frameworks 

      Saha, Saumitra; Becker, Udo (2014-08-11)
    • PbTiO3: Dipole moment of a Pb-O vacancy pair 

      Burton, Benjamin P. (2013-04-08)
      The polarization of a nearest-neighbor (nn) Pb-O vacancy pair [(VPb-VO)nn] in PbTiO3 is calculated, using the modern theory of polarization, implemented in the density-functional-theory ultrasoft pseudopotential formalism. ...
    • SiC-AlN, SiC-GaN and SiC-InN: wurtzite-structure quasibinary systems 

      Burton, Benjamin P. (2013-04-08)
      The cluster-expansion method was used to perform first principles phase diagram calculations for the wurtzite-structure quasibinary systems (SiC)1-X(AlN)X, (SiC)1-X (GaN)X and (SiC)1-X(InN)X; and to model variations of ...
    • Ta Melting Point Calculation by Small-cell Coexistence Method 

      Hong, Qijun; van de Walle, Axel (2014-08-16)
      We calculate the melting temperature of Tantalum, by employing the small-size coexistence solid-liquid coexistence method. Two pseudo-potentials are employed, namely Ta_v (5d^3 6s^2) and Ta_pv (5p^6 5d^3 6s^2). Results ...
    • Ti-O-M interaction between oxygen and metal (M) substitution in titanium for oxygen diffusion change 

      Wu, Henry H. (2013-05-28)
      We calculate first-principles interaction energies between substitutional solutes and oxygen interstitials in α-titanium and predict the effect of solutes on oxygen diffusion from those interactions. Interaction between ...
    • Ti-X (X=Al, V, Nb, Ta, Mo, Zr, and Sn) impurity diffusion coefficients from first-principles calculations 

      Xu, Weiwei; Shang, ShunLi; Zhou, Bi-Cheng; Wang, Yi; Liu, Xingjun; Wang, Cuiping; Liu, Zi-Kui
      Knowledge of diffusivity is fundamental to our understanding of diffusion mechanism and design of materials. Despite various elements dissolved in industrial Ti alloys to improve their performance, diffusion coefficients ...
    • TiO2: On the possibility of ferromagnetism 

      Yang, Kesong (2013-04-08)
      To see if ferromagnetism can occur in C-doped anatase TiO2, we performed first-principles calculations for a number of C-doped structures in which C atoms substitute O atoms. Our study shows that each C has spin-polarized ...
    • TiO_X 

      Burton, Bejnamin P.; van de Walle, Axel (2014-09-29)
      First principles based phase diagram calculations were performed for the hexagonal closest packed octahedral-interstitial solid solution system aTiOX, or aTi½ 1 XOX ([ ]¼Vacancy; 0rXr1=2), by the cluster expansion (CE) ...
    • ZrO-X 

      Burton, Benjamin (2013-04-08)
    • ZrSiO4-HfSiO4 

      Burton, Benjamin (2013-05-09)
      ZrSiO4 and HfSiO4 are of considerable interest because of their low thermal expansions, thermal conductivities, and the optical properties of HfSiO4. In addition, silicate phases of both are studied as model radioactive ...