The Crystal Structure of Sodium Nitrate in the High-Temperature Phase.

Strømme, K. O.; Jacobsen, G. G.; Seip, H. M.; Holme, Tord; Lindberg, Alf A.; Jansen, Gert; Lamm, Bo; Samuelsson, Benny

doi:10.3891/acta.chem.scand.23-1616

Cited by 41 publications

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“…In each case, at least, the high temperature phase has a structure best described as a statistical mixture of calcitelike and aragonitelike structures. 28 No rotational freedom of the nitrate ion is involved in the NaNOa transition, although the increasing anharmonicity of the in-phase librational mode of motion is evident in the continuous decrease in frequency of the associated Raman band from 183 to ~160 cm-1 through the transition,29 and the considerable broadening of the band which accompanies the shift. A further decrease in the frequency of this band occurs on melting without significant further change in bandwidth.30 Thus as Ubbelohde and coworkers,31 have suggested, the nitrate ion in these melts is evidently by no means freely rotating, even in two dimensions, in the liquid state near the melting point, but may be participating in structural interchanges between sites which offer different librational barriers.…”

Section: Discussionmentioning

confidence: 99%

Corresponding states and the glass transition for alkali metal nitrates

Angell¹,

Helphrey²

1971

J. Phys. Chem.

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Section: Discussionmentioning

confidence: 99%

Corresponding states and the glass transition for alkali metal nitrates

Angell¹,

Helphrey²

1971

J. Phys. Chem.

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“…The free rotational model and twoposition disordered models have been identified essentially with the XY and Ising models, respectively [14]. Also, the disordering due to the reorientation of the NO 3 ions has been modeled for the disordered aragonite structure [15], disordered calcite structure [4] and the mixture of those two models [16], as pointed out in a previous study [6]. Additionally, the orientational disordering in NaNO 3 and CaCO 3 has been studied by molecular dy-namics simulation using semiempirical potential models [17,18].…”

Section: No mentioning

confidence: 99%

Temperature Dependence of the Raman Intensity and the Bandwidth Close to the Order-Disorder Phase Transition in NaNO3

Yurtseven¹,

Aslan²

2012

OPJ

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We analyze the temperature dependence of the Raman intensity using the experimental data according to a power-law formula close to the order-disorder transition (Tc = 549 K) in NaNO 3. From this analysis, we extract the value of β = 0.26 as the critical exponent for the order parameter, which indicates a tricritical phase transition in this crystalline system. Using the temperature dependence of the order parameter, the Raman bandwidth is calculated at various temperatures in NaNO3. Our calculated bandwidths describe adequately the observed behaviour of the order-disorder transition in this crystal

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“…[43][44][45] Theoretical treatments of the vibrations have also been carried out. 46,47 a disordered calcite structure), 27,28 until it melts at about 307 °C. At low temperatures, below ~260 K, NaNO 3 adopts another phase.…”

Section: Ramanmentioning

confidence: 99%

The NaNO3/KNO3 system: the position of the solidus and sub-solidus

Berg

Kerridge²

2004

Dalton Trans.

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The existing evidence for the nature of the phase diagram for the binary system sodium nitrate-potassium nitrate is reviewed and in particular whether the system is of the continuous solid solution type, as has often been stated in the last 80 years, or whether this system is of the eutectic type as was earlier believed and has again been asserted recently. Additional evidence from Raman spectroscopy and Raman mapping on the 50 : 50 mol%(minimum melting point) composition is now presented, supporting the eutectic classification. Abrupt changes in wavenumber, or in the wavenumber-temperature gradient of five Raman bands indicate a solid-state transition at about 115 degrees C and are attributed to a phase transition in KNO(3)-rich areas. On a fast cooled sample, Raman bands attributed to sodium nitrate-rich and potassium nitrate-rich areas were found to persist up to and slightly beyond the melting point, and although their wavenumber-positions converged, the apparent single band could still be resolved into the two bands which could be attributed to the Na-rich and K-rich areas. On cooling, the reverse change took place quickly. Measurements with the initially slow cooled sample, where these areas were bigger, showed that the spectral bands reverted to the room-temperature wavenumber values, after holding at 22 degrees C for only 60-90 min.

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The Crystal Structure of Sodium Nitrate in the High-Temperature Phase.

Cited by 41 publications

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Corresponding states and the glass transition for alkali metal nitrates

Corresponding states and the glass transition for alkali metal nitrates

Temperature Dependence of the Raman Intensity and the Bandwidth Close to the Order-Disorder Phase Transition in NaNO<sub>3</sub>

The NaNO3/KNO3 system: the position of the solidus and sub-solidus

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The Crystal Structure of Sodium Nitrate in the High-Temperature Phase.

Cited by 41 publications

References 0 publications

Corresponding states and the glass transition for alkali metal nitrates

Corresponding states and the glass transition for alkali metal nitrates

Temperature Dependence of the Raman Intensity and the Bandwidth Close to the Order-Disorder Phase Transition in NaNO&lt;sub&gt;3&lt;/sub&gt;

The NaNO3/KNO3 system: the position of the solidus and sub-solidus

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Temperature Dependence of the Raman Intensity and the Bandwidth Close to the Order-Disorder Phase Transition in NaNO<sub>3</sub>