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Thermal Polymorphis...
Thermal Polymorphism and Decomposition of Y(BH4)(3)
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Ravnsbaek, Dorthe B. (author)
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Filinchuk, Yaroslav (author)
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Cerny, Radovan (author)
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Ley, Morlen B. (author)
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- Haase, Dörthe (author)
- Lund University,Lunds universitet,MAX IV-laboratoriet,MAX IV Laboratory
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Jakobsen, Hans J. (author)
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Skibsted, Jorgen (author)
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Jensen, Torben R. (author)
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(creator_code:org_t)
- 2010-03-16
- 2010
- English.
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 1520-510X .- 0020-1669. ; 49:8, s. 3801-3809
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http://dx.doi.org/10...
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https://pure.au.dk/w...
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https://doi.org/10.1...
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Abstract
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- The structure and thermal decomposition of Y(BH4)(3) is studied by in situ synchrotron radiation powder X-ray diffraction (SR-PXD), B-11 MAS NMR spectroscopy, and thermal analysis (thermogravimetric analysis/differential scanning calorimetry). The samples were prepared via a metathesis reaction between LiBH4 and YCl3 in different molar ratios mediated by ball milling. A new high temperature polymorph of Y(BH4)(3), denoted beta-Y(BH4)(3), is discovered besides the Y(BH4)(3) polymorph previously reported, denoted alpha-Y(BH4)(3). beta-Y(BH4)(3) has a cubic crystal structure and crystallizes with the space group symmetry Pm (3) over barm and a bisected a-axis, a = 5.4547(8) angstrom, as compared to alpha-Y(BH4)(3), a = 10.7445(4) angstrom (Pa (3) over bar). beta-Y(BH4)(3) crystallizes with a regular ReO3-type structure, hence the Y3+ cations form cubes with BH4 anions located on the edges. This arrangement is a regular variant of (he distorted Y3+ cube observed in alpha-Y(BH4)(3), which is similar to the high pressure phase of ReO3. The new phase, beta-Y(BH4)(3) is formed in small amounts during ball milling; however, larger amounts are formed under moderate hydrogen pressure via a phase transition from alpha- to beta-Y(BH4)(3), at similar to 180 degrees C. Upon further heating, beta-Y(BH4)(3) decomposes at similar to 190 degrees C to YH3, which transforms to YH2 at 270 degrees C. An unidentified compound is observed in the temperature range 215-280 degrees C, which may be a new Y B H containing decomposition product. The final decomposition product is YB4. These results show that boron remains in the solid phase when Y(BH4)(3) decomposes in a hydrogen atmosphere and that Y(BH4)(3) may store hydrogen reversibly.
Subject headings
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
Publication and Content Type
- art (subject category)
- ref (subject category)
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