Details
| Original language | English |
|---|---|
| Pages (from-to) | 332-344 |
| Number of pages | 13 |
| Journal | Zeitschrift fur Kristallographie |
| Volume | 218 |
| Issue number | 5 |
| Publication status | Published - 1 May 2003 |
Abstract
X-ray single crystal, X-ray powder and specific heat investigations were carried out on alumosilicate NaNO3-sodalite between 290 K and 1100 K. Single crystal structure determinations at 295 K, 505 K and 720 K reveal the sodalite structure in its partially collapsed form in space group P4̄3n whereas at 935 K the z coordinate of the framework oxygen is shifted to z = 0.5 according to an untilted sodalite framework in Pm̄n. The sodium ions are located on 8e (x, x, x) position in P4̄3n and become statistically distributed on 16i (x, x, x) in Pm3̄n. The displacements of the nitrate atoms are extraordinarily enlarged at 935 K compared to the values at the lower temperatures. Analysis of the X-ray powder data show a discontinuity in the thermal expansion behaviour at Tc = 930 K with the temperature dependence of the lattice parameter described by acalc = a1 - A(Tc - T)0.5, a1 = BT + a0 (A = 0.57 pm K-0.5, B = 5.84·103 pm K-0.5, a0 = 909.9 pm, T in K) which is related to a square root decrease of the volume strain. The anomalous thermal expansion compromises a gradual contraction of TO4 units and the disappearence of structural tilt with increasing temperature. The refined data reveal a change of z coordinate of O1 proportional to (Tc-T)1/4 in P4̄3n which is considered as an effective order parameter in a Landau tricritical description of the phase transition triggered by the displacement of the cage filling ions.
ASJC Scopus subject areas
- Materials Science(all)
- General Materials Science
- Physics and Astronomy(all)
- Condensed Matter Physics
- Chemistry(all)
- Inorganic Chemistry
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In: Zeitschrift fur Kristallographie, Vol. 218, No. 5, 01.05.2003, p. 332-344.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Anomalous thermal expansion behaviour of Na8[AlSiO4]6(No3)2 -sodalite
T2 - P4̄3n to Pm3̄n phase transition by untilting and contraction of TO4 units
AU - Rüscher, C. H.
AU - Gesing, Th M.
AU - Buhl, J. Chr
N1 - Funding Information: M. Wickleder (Dep. of Inorganic Chemistry, University of Cologne) for single crystal data collection, Dr. Hiltmann (DLR Cologne) for DSC-measurements and Dipl. Chem. C. Kühn (ZFM, Dep. of Inorganic Chemistry, University of Hannover) for X-ray powder data collection and the DFG (Ru764/3) for financial support.
PY - 2003/5/1
Y1 - 2003/5/1
N2 - X-ray single crystal, X-ray powder and specific heat investigations were carried out on alumosilicate NaNO3-sodalite between 290 K and 1100 K. Single crystal structure determinations at 295 K, 505 K and 720 K reveal the sodalite structure in its partially collapsed form in space group P4̄3n whereas at 935 K the z coordinate of the framework oxygen is shifted to z = 0.5 according to an untilted sodalite framework in Pm̄n. The sodium ions are located on 8e (x, x, x) position in P4̄3n and become statistically distributed on 16i (x, x, x) in Pm3̄n. The displacements of the nitrate atoms are extraordinarily enlarged at 935 K compared to the values at the lower temperatures. Analysis of the X-ray powder data show a discontinuity in the thermal expansion behaviour at Tc = 930 K with the temperature dependence of the lattice parameter described by acalc = a1 - A(Tc - T)0.5, a1 = BT + a0 (A = 0.57 pm K-0.5, B = 5.84·103 pm K-0.5, a0 = 909.9 pm, T in K) which is related to a square root decrease of the volume strain. The anomalous thermal expansion compromises a gradual contraction of TO4 units and the disappearence of structural tilt with increasing temperature. The refined data reveal a change of z coordinate of O1 proportional to (Tc-T)1/4 in P4̄3n which is considered as an effective order parameter in a Landau tricritical description of the phase transition triggered by the displacement of the cage filling ions.
AB - X-ray single crystal, X-ray powder and specific heat investigations were carried out on alumosilicate NaNO3-sodalite between 290 K and 1100 K. Single crystal structure determinations at 295 K, 505 K and 720 K reveal the sodalite structure in its partially collapsed form in space group P4̄3n whereas at 935 K the z coordinate of the framework oxygen is shifted to z = 0.5 according to an untilted sodalite framework in Pm̄n. The sodium ions are located on 8e (x, x, x) position in P4̄3n and become statistically distributed on 16i (x, x, x) in Pm3̄n. The displacements of the nitrate atoms are extraordinarily enlarged at 935 K compared to the values at the lower temperatures. Analysis of the X-ray powder data show a discontinuity in the thermal expansion behaviour at Tc = 930 K with the temperature dependence of the lattice parameter described by acalc = a1 - A(Tc - T)0.5, a1 = BT + a0 (A = 0.57 pm K-0.5, B = 5.84·103 pm K-0.5, a0 = 909.9 pm, T in K) which is related to a square root decrease of the volume strain. The anomalous thermal expansion compromises a gradual contraction of TO4 units and the disappearence of structural tilt with increasing temperature. The refined data reveal a change of z coordinate of O1 proportional to (Tc-T)1/4 in P4̄3n which is considered as an effective order parameter in a Landau tricritical description of the phase transition triggered by the displacement of the cage filling ions.
UR - http://www.scopus.com/inward/record.url?scp=0041804095&partnerID=8YFLogxK
U2 - 10.1524/zkri.218.5.332.20731
DO - 10.1524/zkri.218.5.332.20731
M3 - Article
AN - SCOPUS:0041804095
VL - 218
SP - 332
EP - 344
JO - Zeitschrift fur Kristallographie
JF - Zeitschrift fur Kristallographie
SN - 0044-2968
IS - 5
ER -