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Structural Studies of Structural Studies of Metal-Hydrogen InteractionsMetal-Hydrogen Interactions
in Solid-State Metal Hydridesin Solid-State Metal Hydrides
SINQ Users’ MeetingPSI, 27 Jan 2005
Yaroslav Filinchuk
on behalf of theLaboratory of Crystallography
University of Geneva
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LaD2+x
Refined average D-atom displacements ()in octahedral interstices as a function
of refined composition LaD2+x
Calculated atom relaxations (Å) aroundtetrahedral hydrogen vacancy in La32H95
Renaudin et al., 2004 HRPTHRPT
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
3Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
ErNi3 : HRPTHRPT, , λλ ~ 1.15 Å~ 1.15 Å
RR-3-3mmcentrocentro
Single-crysal-like refinement from powder data ! Filinchuk et al., 2004
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Deuteration on site, or in-situ
RR33mmnon-centronon-centro
β1-ErNi3D1.23(1) : HRPTHRPT, , λλ ~ 1.49 Å~ 1.49 Å
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Filinchuk et al., 2004
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Alloy ErNi3
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Filinchuk et al., 2004
HRPTHRPT
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β-deuteride ErNi3D1.23
β-deuteride ErNi3D1.23
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Anisotropic cell expansion along cAB2 block is filled with deuterium
Filinchuk et al., 2004
Symmetry loss
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β-deuteride ErNi3D1.97
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Isotropic cell expansionAB5 block is partially filled with D
Filinchuk et al., 2004
Trigonal prism [NiD3]
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-deuteride ErNi3D3.75
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Anisotropic cell expansion along aAB5 block is filled with deuterium
Filinchuk et al., 2004
Tetrahedral [NiD4] :similar to LaMg2NiD7 & Mg2NiD4
different from ErCo3Dx & YCo3Dx
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D 2
LaNiLaNi33BB
c
a
LaNi3B → LaNi3BD2.5-3
Imma, oI20 → Cmcm, oC80
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Filinchuk et al., 2004
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The unit cell is doubled along a and b
b
a
LaNiLaNi33BHBH2.72.7
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
HRPTHRPT
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Two dimentionalframework Ni-D
D-Ni bond-valence sums are equal to 1 for each of 4 D-atom sitesLa3+B0[Ni3D3]
3–
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Filinchuk et al., 2004
HRPTHRPT
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Temperature dependence of the cubic cell parameter and of deuterium occupancies in ZrTi2D4.3 (from DMCDMC data)
3 00 5 00 7 00 1 00 00 .0
0 .1
0 .2
0 .3
0 .4
0 .5
0 .6
0 .7
0 .8
0 .9
1 .0
Tem pera ture (K )O
ccup
ancy
3 2e
9 6g
3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 8 0 0 9 0 0 1 0 00
8 .1 5
8 .1 6
8 .1 7
8 .1 8
8 .1 9
8 .2 0
a (Å )
Tem perature (K )
decom position
Tokaychuk et al., 2004
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
ZrTi3
Zr2Ti2
Fd-3m
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Energy difference between the two deuterium sites in ZrTi2Dx
0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 00
1 2 0
1 0 0
8 0
6 0
4 0
2 00
S k r ip o v e t a l. , 2 0 0 0D M C , To k a y c h u k e t a l ., 2 0 0 4E
(m
Ev)
Te m p e ra tu re (K )
1 4 0
Dynamicalhydrogendisorder
127 meV
Metal to hydrogen interactions are important (!)Metal to hydrogen interactions are important (!)
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
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Phase transitions in alkali borohydrides Renaudin et al., 2004 DMCDMC
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Ordering of BD4- anion:
Fm-3m to P42
/nmc
Badger’s rule
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ErCo3-D2 : in-situ NPD, 60°C, 0-16 bar
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
Filinchuk et al., 2004 DMCDMCConditions
vacuum 4.978(2) 24.227(18) 520.0(5)
Little portionsof D2
let in
4.979(4) 24.25(3) 520.8(9) 4.9837(16) 25.463(17) 547.7(4) 1.07(4)
4.9859(9) 25.626(10) 551.7(2) 1.14(3)
4.9871(8) 25.690(9) 553.3(2) 1.20(3)
4.9894(9) 25.834(9) 557.0(2) 1.27(3)
4.9910(9) 25.963(8) 560.1(2) 1.36(3)
4.9910(9) 26.018(8) 561.3(2) 1.38(4)
4.9914(10) 26.032(9) 561.7(2) 1.38(3) 5.217(9) 26.21(9) 617(3)
2.5 bar D2 4.9920(10) 26.017(9) 561.5(3) 1.37(3) 5.213(5) 26.16(4) 616(1)
2.5 bar D2 4.9924(13) 25.997(11) 561.2(3) 1.35(4) 5.210(3) 26.14(3) 614.5(8)
3.0 bar D2 4.996(4) 25.94(3) 560.7(10) 1.35 5.211(2) 26.07(2) 613.2(5) 3.75
4.0 bar D2 5.2189(8) 26.044(7) 614.3(2) 3.84(6)
6 bar D2 5.2250(8) 26.071(7) 616.4(2) 3.91(6)
9 bar D2 5.2277(8) 26.098(7) 617.7(2) 4.13(5)
12 bar D2 5.2298(7) 26.115(6) 618.6(2) 4.17(5)
16 bar D2 5.2318(8) 26.134(7) 619.5(2) 4.20(6)
16 bar, 25°C 5.2356(7) 26.202(6) 622.0(2) 4.30(5)
• phase diagram• cell expansion• deuterium content
ErCo3 ErCo3D1.6 ErCo3D4.0
Accurate structures
from HRPTHRPT data
Magnetic structures: DMCDMC (1.5-210K)Co-Co exchange interactions are correlated with Co-D bonding
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Techniques used to study Metal-Hydrogen Interactions
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005
HRPTHRPT• detailed investigation of complex structures• in-situ NPD (tiny structural changes)
DMCDMC• structure dynamics (hydrogen motion)• in-situ NPD (complex phase diagrams)• magnetic structures (M-M interactions)• high-resolution NPD (phase transitions)
Diffraction at SINQ
Complementary
• Synchrotron powder & single crystal diffraction • INS & Raman spectrosc.• magnetic & el. properties• ab-initio calculations
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This work has been partially performed at the Swiss Spallation Neutron Source SINQ,
Paul Scherrer Institute, Villigen, Switzerland
We acknowledge the help of Denis Sheptyakov, Aziz Daoud-Aladine and Lukas Keller
Y. Filinchuk SINQ Users’ Meeting, 27 Jan 2005