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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

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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

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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

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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