Abstract
H2C4O4 (Squaric acid, henceforth abbreviated by SQA) is one of the most studied hydrogen-bonded anti-ferroelectrics in the KH2PO4 (KDP) family. Here, we report the static hydrogen lineshape which shows a mixed state behavior of order-disorder and a displacive feature in the anti-ferroelctric (AFE)/paraelectric (PE) phase transition of SQA. We obtained the dipolar splitting data from the nonlinear fitting curve of the static hydrogen lineshape. The calculated proton-proton distance showed an increase at temperatures above the transition temperature Tc. As temperature increases through Tc, the inter-atomic distance shows a peculiar S-shape variation. This S-shape variation around Tc is also observed in other NMR reports for SQA, where the chemical shift variation is used to characterize the deformation of the C4O4 squarate group. Here, we used the dipolar interaction, instead of the chemical shift information, to detect the geometrical change of the hydrogen. Below the transition temperature Tc, the proton interactions showed long-range order whereas it showed short range order at temperatures above Tc. The peculiar S-shape variation from the hydrogen lineshape analysis can be understood as another piece of experimental evidence for a mixed state for the phase transition in SQA.
| Original language | English |
|---|---|
| Pages (from-to) | 1253-1256 |
| Number of pages | 4 |
| Journal | Journal of the Korean Physical Society |
| Volume | 57 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 2010 Nov 15 |
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Keywords
- Dipolar interaction
- Ferroelectrics
- Nuclear magnetic resonance (NMR)
- Phase transition
ASJC Scopus subject areas
- Physics and Astronomy(all)
Cite this
Experimental observation of hydrogen in a mixed state of order-disorder and displacive behavior in squaric acid. / Kim, Se Hun; Lee, Cheol Eui; Dalal, N. S.; Han, Doug Young.
In: Journal of the Korean Physical Society, Vol. 57, No. 5, 15.11.2010, p. 1253-1256.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Experimental observation of hydrogen in a mixed state of order-disorder and displacive behavior in squaric acid
AU - Kim, Se Hun
AU - Lee, Cheol Eui
AU - Dalal, N. S.
AU - Han, Doug Young
PY - 2010/11/15
Y1 - 2010/11/15
N2 - H2C4O4 (Squaric acid, henceforth abbreviated by SQA) is one of the most studied hydrogen-bonded anti-ferroelectrics in the KH2PO4 (KDP) family. Here, we report the static hydrogen lineshape which shows a mixed state behavior of order-disorder and a displacive feature in the anti-ferroelctric (AFE)/paraelectric (PE) phase transition of SQA. We obtained the dipolar splitting data from the nonlinear fitting curve of the static hydrogen lineshape. The calculated proton-proton distance showed an increase at temperatures above the transition temperature Tc. As temperature increases through Tc, the inter-atomic distance shows a peculiar S-shape variation. This S-shape variation around Tc is also observed in other NMR reports for SQA, where the chemical shift variation is used to characterize the deformation of the C4O4 squarate group. Here, we used the dipolar interaction, instead of the chemical shift information, to detect the geometrical change of the hydrogen. Below the transition temperature Tc, the proton interactions showed long-range order whereas it showed short range order at temperatures above Tc. The peculiar S-shape variation from the hydrogen lineshape analysis can be understood as another piece of experimental evidence for a mixed state for the phase transition in SQA.
AB - H2C4O4 (Squaric acid, henceforth abbreviated by SQA) is one of the most studied hydrogen-bonded anti-ferroelectrics in the KH2PO4 (KDP) family. Here, we report the static hydrogen lineshape which shows a mixed state behavior of order-disorder and a displacive feature in the anti-ferroelctric (AFE)/paraelectric (PE) phase transition of SQA. We obtained the dipolar splitting data from the nonlinear fitting curve of the static hydrogen lineshape. The calculated proton-proton distance showed an increase at temperatures above the transition temperature Tc. As temperature increases through Tc, the inter-atomic distance shows a peculiar S-shape variation. This S-shape variation around Tc is also observed in other NMR reports for SQA, where the chemical shift variation is used to characterize the deformation of the C4O4 squarate group. Here, we used the dipolar interaction, instead of the chemical shift information, to detect the geometrical change of the hydrogen. Below the transition temperature Tc, the proton interactions showed long-range order whereas it showed short range order at temperatures above Tc. The peculiar S-shape variation from the hydrogen lineshape analysis can be understood as another piece of experimental evidence for a mixed state for the phase transition in SQA.
KW - Dipolar interaction
KW - Ferroelectrics
KW - Nuclear magnetic resonance (NMR)
KW - Phase transition
UR - http://www.scopus.com/inward/record.url?scp=78549245870&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78549245870&partnerID=8YFLogxK
U2 - 10.3938/jkps.57.1253
DO - 10.3938/jkps.57.1253
M3 - Article
AN - SCOPUS:78549245870
VL - 57
SP - 1253
EP - 1256
JO - Journal of the Korean Physical Society
JF - Journal of the Korean Physical Society
SN - 0374-4884
IS - 5
ER -