ebook img

Band structure calculations on Ti-enhanced NaAlH4 - HZG PDF

37 Pages·2006·1.73 MB·English
Save to my drive
Quick download
Download
Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.

Preview Band structure calculations on Ti-enhanced NaAlH4 - HZG

FuncHy 2006: First principles modelling for predicting and understanding novel complex hydrides Ole M. Løvvik Centre for Materials Science and Nanotechnology, University of Oslo, Norway Institute for Energy Technology, Kjeller, Norway Alanates for hydrogen storage Accessible hydrogen wt%: (cid:132) LiALliHAlH4 5.3 2.7 4 NaNAalHAlH4 3.7 1.9 4 KAKlHAlH4 2.9 1.4 4 Li LAi3lAHlH6 5.6 3 6 NaNaA3lAHlH6 3.0 3 6 K AK3lHAlH6 2.0 3 6 MMgg(A(AllHH4))2 7.0 4 2 CCa(aA(AlHlH4))2 3.0 3.0 4 2 0.0 2.0 4.0 6.0 8.0 Crystal structure predictions E.g. Na AlH : Seven representative systems (cid:132) 3 6 Full relaxation; allows to leave space group/symmetry (cid:132) Space # Type # atoms Model system group P-1 2 Triclinic 20 Ti NiS 3 6 P2 /n 14 Monoclinic 20 K Fe(CN) 1 3 6 P2 /n 14 Monoclinic 20 Na AlF (α) 1 3 6 Pna2 33 Orthorombic 40 Li AlF 1 3 6 Immm 71 Tetragonal 20 Na AlF (β) 3 6 R-3 148 Rhombohedral 20 Ti NiS 3 6 Fm-3m 225 Cubic 40 K MoF 3 6 Calculation details Band-structure DFT (cid:132) VASP (cid:132) Generalized gradient appr. (GGA) PW91 (cid:132) Projector augmented wave (PAW) method (cid:132) Spin polarization allowed (cid:132) Cut-off energy 780 eV (cid:132) Overall convergence: ~1 meV (0.01 kJ/mol)/unit cell (cid:132) Predicted crystal structures Compound Predicted Expt. O. M. Løvvik, S. M. Opalka, H. W. (cid:132) Brinks, B. C. Hauback, Phys. Rev. structure structure B 69 (2004) 134117) LiAlH P2 /c P2 /c O. M. Løvvik, O. Swang, Europhys. 4 1 1 (cid:132) Lett. 67 (2004) 607. NaAlH I4 /a I4 /a 4 1 1 O. M. Løvvik, Phys. Rev. B. 71 (cid:132) KAlH Pnma Pnma 4 (2005) 144111. Li AlH R–3 R–3 O. M. Løvvik, O. Swang, J. Alloys 3 6 (cid:132) Comp. 404-406 (2005) 757-761. Na AlH P2 /n P2 /n 3 6 1 1 O. M. Løvvik, P. N. Molin, Phys. (cid:132) K AlH P2 /n Rev. B. 72 (2005) 073201. 3 6 1 Mg(AlH ) P–3m1 P–3m1 O. M. Løvvik, O. Swang, S. M. (cid:132) 4 2 Opalka, J. Mater. Res. 20 (2005) Ca(AlH ) Pbca 3199 (Invited paper). 4 2 Thermodynamic stability Formation enthalpy: (cid:132) H (M AlH ) = form n (n+3) E(M AlH ) – n E(M) – E(Al) – (n+3)/2 E(H ) n (n+3) 2 Compound LiAlH NaAlH KAlH Li AlH Na AlH K AlH 4 4 4 3 6 3 6 3 6 Formation (kJ/mol H ) -55.5 -54.9 -70.0 -102.8 -69.9 -78.5 enthalpy 2 Ca(AlH ) 4 2 Non-layered structure AlH tetrahedra, 4 Al-H distance 162 pm Ca Al Ca 8-coordinated, Ca-H distance 220 pm H H wt. density: 5.9% H vol density: 70 kg/m3 Space group: Pbca • O. M. Løvvik, Phys. Rev. B. 71 (2005) 144111. Ca(AlH ) density of states (DOS) 4 2 1 3 Ca Al 2 0.5 1 S O 0 0 D H Total DOS 0.2 100 0.1 50 0 0 -5 0 5 -5 0 5 E (eV) E (eV)

Description:
Calculation details. ▫ Band-structure DFT. ▫ VASP. ▫ Generalized gradient appr. (GGA) PW91. ▫ Projector augmented wave (PAW) method. ▫ Spin polarization
See more

The list of books you might like

Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.