Matches in SemOpenAlex for { <https://semopenalex.org/work/W2014206957> ?p ?o ?g. }
Showing items 1 to 93 of
93
with 100 items per page.
- W2014206957 endingPage "2583" @default.
- W2014206957 startingPage "2577" @default.
- W2014206957 abstract "Proton and fluorine NMR data in NH4BF4 and its totally deuterated analog reflect the presence of isotropic and rapid BF4− tumbling as well as onset of isotropic NH4+ ion motion in the orthorhombic phase. A linewidth transition in the 19F spin system from 19±1 G2 at 133°K to 2.5±0.5 G2 at 198°K and 19F thermal relaxation times measured in ND4BF4 from 210° to 478°K yield a span of 19F correlation times from 3×10−4 sec (168°K) to 6.4×10−11 sec (472°K). The transition to the cubic modification at 472°K decreases the 19F correlation time to 2.6×10−12 sec (478°K). Above 318°K, fluorine relaxation in NH4BF4 is dominated by intraionic dipolar interactions, while below this temperature cross relaxation with protons located on neighboring ammonium ions becomes evident. Deuteration removes this contributor to the 19F relaxation. The apparent activation energy for BF4− motion is slightly dependent upon temperature, and increases somewhat with increasing temperature. The pre-exponential factor associated with 19F correlation times above 318°K is abnormally small, possibly reflecting a decrease in the effective moment of inertia by mechanical coupling between BF4− motion and NH4+ motion. Crystallographic measurement of the orthorhombic unit cell parameters from 190° to 296°K shows rapid linear expansion of a and c axes in the range 190° to 260°K, with a marked decrease in the rate of variation of these axis lengths with temperature above 260°K. In the same temperature region a shallow proton T1 minimum is observed, which may be associated with the modification of NH4+ ion motion by lattice expansion or simply due to cross relaxation with the 19F spin system. Proton T1 data also show a shallow plateau at higher temperatures due to interionic dipolar coupling and the BF4− motion. The x-ray data suggest the possibility of a subtle crystallographic change at low temperatures. A small linewidth transition is observed for the proton spin system in the range 173°K (4.0±0.1 G2) to 223°K (2.9±0.1 G2) apparently associated with interionic dipolar coupling." @default.
- W2014206957 created "2016-06-24" @default.
- W2014206957 creator A5004936043 @default.
- W2014206957 creator A5036664072 @default.
- W2014206957 creator A5041105303 @default.
- W2014206957 creator A5044998534 @default.
- W2014206957 creator A5063210589 @default.
- W2014206957 date "1967-10-15" @default.
- W2014206957 modified "2023-10-17" @default.
- W2014206957 title "Ion Motion in Tetrafluoroborate Salts. I. NH4BF4and ND4BF4" @default.
- W2014206957 cites W1974326092 @default.
- W2014206957 cites W2028981806 @default.
- W2014206957 cites W2031206824 @default.
- W2014206957 cites W2040319162 @default.
- W2014206957 cites W2040859729 @default.
- W2014206957 cites W2044560822 @default.
- W2014206957 cites W2050600792 @default.
- W2014206957 cites W2071795721 @default.
- W2014206957 cites W2082384446 @default.
- W2014206957 cites W2112418586 @default.
- W2014206957 cites W2318881289 @default.
- W2014206957 doi "https://doi.org/10.1063/1.1712272" @default.
- W2014206957 hasPublicationYear "1967" @default.
- W2014206957 type Work @default.
- W2014206957 sameAs 2014206957 @default.
- W2014206957 citedByCount "36" @default.
- W2014206957 crossrefType "journal-article" @default.
- W2014206957 hasAuthorship W2014206957A5004936043 @default.
- W2014206957 hasAuthorship W2014206957A5036664072 @default.
- W2014206957 hasAuthorship W2014206957A5041105303 @default.
- W2014206957 hasAuthorship W2014206957A5044998534 @default.
- W2014206957 hasAuthorship W2014206957A5063210589 @default.
- W2014206957 hasConcept C115624301 @default.
- W2014206957 hasConcept C121332964 @default.
- W2014206957 hasConcept C145148216 @default.
- W2014206957 hasConcept C154881586 @default.
- W2014206957 hasConcept C15744967 @default.
- W2014206957 hasConcept C161790260 @default.
- W2014206957 hasConcept C173523689 @default.
- W2014206957 hasConcept C178790620 @default.
- W2014206957 hasConcept C184779094 @default.
- W2014206957 hasConcept C185592680 @default.
- W2014206957 hasConcept C2776029896 @default.
- W2014206957 hasConcept C2780872544 @default.
- W2014206957 hasConcept C37243968 @default.
- W2014206957 hasConcept C46141821 @default.
- W2014206957 hasConcept C54516573 @default.
- W2014206957 hasConcept C55493867 @default.
- W2014206957 hasConcept C58364064 @default.
- W2014206957 hasConcept C62520636 @default.
- W2014206957 hasConcept C77805123 @default.
- W2014206957 hasConcept C8010536 @default.
- W2014206957 hasConceptScore W2014206957C115624301 @default.
- W2014206957 hasConceptScore W2014206957C121332964 @default.
- W2014206957 hasConceptScore W2014206957C145148216 @default.
- W2014206957 hasConceptScore W2014206957C154881586 @default.
- W2014206957 hasConceptScore W2014206957C15744967 @default.
- W2014206957 hasConceptScore W2014206957C161790260 @default.
- W2014206957 hasConceptScore W2014206957C173523689 @default.
- W2014206957 hasConceptScore W2014206957C178790620 @default.
- W2014206957 hasConceptScore W2014206957C184779094 @default.
- W2014206957 hasConceptScore W2014206957C185592680 @default.
- W2014206957 hasConceptScore W2014206957C2776029896 @default.
- W2014206957 hasConceptScore W2014206957C2780872544 @default.
- W2014206957 hasConceptScore W2014206957C37243968 @default.
- W2014206957 hasConceptScore W2014206957C46141821 @default.
- W2014206957 hasConceptScore W2014206957C54516573 @default.
- W2014206957 hasConceptScore W2014206957C55493867 @default.
- W2014206957 hasConceptScore W2014206957C58364064 @default.
- W2014206957 hasConceptScore W2014206957C62520636 @default.
- W2014206957 hasConceptScore W2014206957C77805123 @default.
- W2014206957 hasConceptScore W2014206957C8010536 @default.
- W2014206957 hasIssue "8" @default.
- W2014206957 hasLocation W20142069571 @default.
- W2014206957 hasOpenAccess W2014206957 @default.
- W2014206957 hasPrimaryLocation W20142069571 @default.
- W2014206957 hasRelatedWork W1973103945 @default.
- W2014206957 hasRelatedWork W1974845456 @default.
- W2014206957 hasRelatedWork W1976738135 @default.
- W2014206957 hasRelatedWork W2008404815 @default.
- W2014206957 hasRelatedWork W2033102087 @default.
- W2014206957 hasRelatedWork W2058351167 @default.
- W2014206957 hasRelatedWork W2081948068 @default.
- W2014206957 hasRelatedWork W2094461135 @default.
- W2014206957 hasRelatedWork W2517882679 @default.
- W2014206957 hasRelatedWork W4323659084 @default.
- W2014206957 hasVolume "47" @default.
- W2014206957 isParatext "false" @default.
- W2014206957 isRetracted "false" @default.
- W2014206957 magId "2014206957" @default.
- W2014206957 workType "article" @default.