Structural and thermogravimetric studies of group I and II borohydrides
This thesis investigates the structure and thermal behaviour of LiBH4, NaBH4, KBH4, LiK(BH4)2, Ca(BH4)2 and Sr(BH4)2. LiK(BH4)2 is the first mixed alkali metal borohydride and was synthesised and characterised during this work. The crystal structures of these borohydrides were studied using variabl...
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| Materiálatiipa: | Oahppočájánas |
| Giella: | English |
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2010
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| _version_ | 1826304412015919104 |
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| author | Nickels, E |
| author2 | Edwards, P |
| author_facet | Edwards, P Nickels, E |
| author_sort | Nickels, E |
| collection | OXFORD |
| description | This thesis investigates the structure and thermal behaviour of LiBH4, NaBH4, KBH4, LiK(BH4)2, Ca(BH4)2 and Sr(BH4)2. LiK(BH4)2 is the first mixed alkali metal borohydride and was synthesised and characterised during this work. The crystal structures of these borohydrides were studied using variable temperature neutron and synchrotron X-ray diffraction. The synthesis of isotopically enriched samples of 7Li11BD4, Li11BD4, Na11BD4 and K11BD4 allowed high quality neutron diffraction data to be collected. Particular attention was paid to the exact geometry of the borohydride ions which were generally found to be perfect tetrahedra but with orientational disorder. New structures of Ca(BH4)2 were identified and the first crystal structure of Sr(BH4)2 was determined from synchrotron X-ray diffraction data. Solid state 11B NMR and Raman spectroscopy provided further information about the structure of these borohydrides. The thermal behaviour of the borohydrides was investigated using thermogravimetric analysis with mass spectrometry of the decomposition gas products. Hydrogen is the main decomposition gas product from all of these compounds but small amounts of B2H6 and BH3 were also detected during decomposition. Thermogravimetic analyses of Na11BD4 and K11BD4 were completed whilst collecting in-situ neutron diffraction data allowing information about structural changes and mass losses to be combined in order to better understand the decomposition process. |
| first_indexed | 2024-03-07T06:17:24Z |
| format | Thesis |
| id | oxford-uuid:f18f8f7c-1837-4b96-b4bb-5f964e93899c |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T06:17:24Z |
| publishDate | 2010 |
| record_format | dspace |
| spelling | oxford-uuid:f18f8f7c-1837-4b96-b4bb-5f964e93899c2022-03-27T11:56:53ZStructural and thermogravimetric studies of group I and II borohydridesThesishttp://purl.org/coar/resource_type/c_db06uuid:f18f8f7c-1837-4b96-b4bb-5f964e93899cInorganic chemistryCrystallographySolid state chemistryHydrogen StorageChemical crystallographyNMR spectroscopyEnglishOxford University Research Archive - Valet2010Nickels, EEdwards, PDavid, WThis thesis investigates the structure and thermal behaviour of LiBH4, NaBH4, KBH4, LiK(BH4)2, Ca(BH4)2 and Sr(BH4)2. LiK(BH4)2 is the first mixed alkali metal borohydride and was synthesised and characterised during this work. The crystal structures of these borohydrides were studied using variable temperature neutron and synchrotron X-ray diffraction. The synthesis of isotopically enriched samples of 7Li11BD4, Li11BD4, Na11BD4 and K11BD4 allowed high quality neutron diffraction data to be collected. Particular attention was paid to the exact geometry of the borohydride ions which were generally found to be perfect tetrahedra but with orientational disorder. New structures of Ca(BH4)2 were identified and the first crystal structure of Sr(BH4)2 was determined from synchrotron X-ray diffraction data. Solid state 11B NMR and Raman spectroscopy provided further information about the structure of these borohydrides. The thermal behaviour of the borohydrides was investigated using thermogravimetric analysis with mass spectrometry of the decomposition gas products. Hydrogen is the main decomposition gas product from all of these compounds but small amounts of B2H6 and BH3 were also detected during decomposition. Thermogravimetic analyses of Na11BD4 and K11BD4 were completed whilst collecting in-situ neutron diffraction data allowing information about structural changes and mass losses to be combined in order to better understand the decomposition process. |
| spellingShingle | Inorganic chemistry Crystallography Solid state chemistry Hydrogen Storage Chemical crystallography NMR spectroscopy Nickels, E Structural and thermogravimetric studies of group I and II borohydrides |
| title | Structural and thermogravimetric studies of group I and II borohydrides |
| title_full | Structural and thermogravimetric studies of group I and II borohydrides |
| title_fullStr | Structural and thermogravimetric studies of group I and II borohydrides |
| title_full_unstemmed | Structural and thermogravimetric studies of group I and II borohydrides |
| title_short | Structural and thermogravimetric studies of group I and II borohydrides |
| title_sort | structural and thermogravimetric studies of group i and ii borohydrides |
| topic | Inorganic chemistry Crystallography Solid state chemistry Hydrogen Storage Chemical crystallography NMR spectroscopy |
| work_keys_str_mv | AT nickelse structuralandthermogravimetricstudiesofgroupiandiiborohydrides |