The structural stabilities of the intermetallics and the solid-state phase transformations induced by lattice vibration effects in the Al–Zr system by first-principles calculations

2010 ◽  
Vol 25 (9) ◽  
pp. 1689-1694 ◽  
Author(s):  
Hui Zhang ◽  
Shaoqing Wang

We investigated the structural stabilities of the intermetallics and the solid-state phase transformations induced by lattice vibration effects in the Al–Zr system by first-principles calculations. The calculated lattice parameters of all the phases and the phonon dispersion relations for pure Al and Zr are in good agreement with the experimental data. AlZr(oC8), Al4Zr5 (hP18), and Al3Zr5 (tI32) are predicted to be the high-temperature phases. To study the structural stabilities at high temperatures, the thermodynamic properties of the intermetallics are calculated via the linear response approach within the harmonic approximation. Thanks to the calculated enthalpies of formation at high temperatures, Al3Zr5 is predicted to be stabilized above 1163 K with respect to AlZr2 and Al2Zr3, in good agreement with the phase transformation temperature (1273 K) in the experimental phase diagram.

2018 ◽  
Vol 54 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Z. Hu ◽  
C. Huang ◽  
J. Tu ◽  
Y. Huang ◽  
A. Dong

Based on an assessment of the phase equilibria and thermodynamic data in the literature, the thermodynamic modeling of the In?Sc and In?Y systems was carried out by means of the calculation of phase diagram (CALPHAD) method supported by first-principles calculations. The solution phases, i.e., liquid, (In), (?Sc), (?Sc), (?Y) and (?Y), were modeled with the substitutional regular solution model. Ten intermetallic compounds, including InSc3, InSc2, In4Sc5, InSc, In2Sc, In3Sc, InY2, InY, In5Y3, and In3Y were described as stoichiometric phases, while In3Y5 was modeled with a sublattice model with respect to its homogeneity range. The enthalpies of formation of the intermetallic compounds at 0 K were computed using firstprinciple calculations and were used as input for the thermodynamic optimization. A set of self-consistent thermodynamic parameters for both the In?Sc and In?Y systems were obtained and the calculated phase diagrams are in good agreement with the experimental data.


2015 ◽  
Vol 1735 ◽  
Author(s):  
Jingxuan Ding ◽  
Ben Xu ◽  
Yuanhua Lin

ABSTRACTThe BiCuSeO has been proved to be one of the best oxide-based thermoelectric materials in recent years. Its electric properties have been widely studied, yet the lattice thermal conductivity was only discussed roughly. Our investigation suggests that the anharmonic vibration and the interlayer-interaction plays the crucial role in reducing the intrinsic lattice thermal conductivity. The thermal conductivity has been calculated based on quasi-harmonic approximation and detailed contribution have been discussed. The calculated data have good agreement with the experimental data.


2017 ◽  
Vol 121 (40) ◽  
pp. 21877-21886 ◽  
Author(s):  
Matthew T. Dunstan ◽  
Hannah Laeverenz Schlogelhofer ◽  
John M. Griffin ◽  
Matthew S. Dyer ◽  
Michael W. Gaultois ◽  
...  

2016 ◽  
Vol 52 (45) ◽  
pp. 7186-7204 ◽  
Author(s):  
Sharon E. Ashbrook ◽  
David McKay

DFT calculations are an important tool in assigning and interpreting NMR spectra of solids: we discuss recent developments and their future potential in the context of NMR crystallography.


2017 ◽  
Vol 30 (1) ◽  
pp. 163-173 ◽  
Author(s):  
Hanmei Tang ◽  
Zhi Deng ◽  
Zhuonan Lin ◽  
Zhenbin Wang ◽  
Iek-Heng Chu ◽  
...  

2018 ◽  
Vol 6 (3) ◽  
pp. 1150-1160 ◽  
Author(s):  
Musheng Wu ◽  
Bo Xu ◽  
Xueling Lei ◽  
Kelvin Huang ◽  
Chuying Ouyang

Systematic study on bulk properties, defect chemistry and Li-ion transport mechanisms of a Li3OCl fast-ion conductor.


2010 ◽  
Vol 132 (25) ◽  
pp. 8732-8746 ◽  
Author(s):  
Karen E. Johnston ◽  
Chiu C. Tang ◽  
Julia E. Parker ◽  
Kevin S. Knight ◽  
Philip Lightfoot ◽  
...  

2004 ◽  
Vol 813 ◽  
Author(s):  
M.D. Mccluskey ◽  
S.J. Jokela

ABSTRACTZinc oxide (ZnO) has shown great promise as a wide band gap semiconductor with optical, electronic, and mechanical applications. Recent first-principles calculations and experimental studies have shown that hydrogen acts as a shallow donor in ZnO, in contrast to hydrogen's usual role as a passivating impurity. The structures of such hydrogen complexes, however, have not been determined. To address this question, we performed vibrational spectroscopy on bulk, single-crystal ZnO samples annealed in hydrogen (H2) or deuterium (D2) gas. Using infrared (IR) spectroscopy, we have observed O-H and O-D stretch modes at 3326.3 cm−1 and 2470.3 cm−1 respectively, at a sample temperature of 14 K. These frequencies are in good agreement with the theoretical predictions for hydrogen and deuterium in an antibonding configuration, although the bond-centered configuration cannot be ruled out. The IR-active hydrogen complexes are unstable, however, with a dissocation barrier on the order of 1 eV.


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