Thermal expansion of cancrinite

1996 ◽  
Vol 60 (403) ◽  
pp. 949-956 ◽  
Author(s):  
Ishmael Hassan
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Mechanism ◽  
Expansion Coefficients ◽  
Cell Volumes

AbstractThermal expansion coefficients were measured for a cancrinite from Bancroft, Ontario, Canada. Measurements of cell parameters and unit-cell volumes were obtained at room temperature and at heating intervals of 50°C over the temperature range from 50 to 1400°C. The unit-cell parameters for cancrinite increase non-linearly with temperature up to 1200°C and shortly thereafter, the mineral melted. The c parameter increases more rapidly than the a parameter, and the c/a ratio increases linearly with temperature. A plausible thermal expansion mechanism for cancrinite, which is based on the framework expansion that occurs as a function of cavity content, is presented. In the thermal expansion of cancrinite, the short Na-H2O in the H2O-Na—H2O chain expands to form equal distances to the two H2O molecules in the chain. This causes the Na atoms to move towards the plane of the six-membered rings and forces the tetrahedra to rotate and the rings become more planar. The Na atoms then form bonds to all six (O1 and O2) oxygen atoms in a ring; the Na-O1 bonds become shorter and the Na-O2 bonds become longer. These effects cause an increase in both a and c, and thus an increase in the c/a ratio. A similar thermal expansion mechanism operates in the sodalite-group minerals where the six-membered rings and Na-Cl bond are involved.

Thermal expansion of anatase and rutile between 300 and 575 K using synchrotron powder X-ray diffraction

2007 ◽  
Vol 22 (4) ◽  
pp. 352-357 ◽  
Author(s):  
D. R. Hummer ◽  
P. J. Heaney ◽  
J. E. Post
Keyword(s):  
Thermal Expansion ◽  
Rietveld Analysis ◽  
Absolute Temperature ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

High-precision unit-cell parameters for the TiO2 polymorphs anatase and rutile at temperatures between 300 and 575 K have been determined using Rietveld analysis of synchrotron powder XRD data. Polynomial models were used to express the tetragonal unit-cell parameters as a function of absolute temperature, with a (anatase)=1.759 37×10−8×T2+6.418 16×10−6×T+3.779 84, c (anatase)=6.6545×10−8×T2+4.0464×10−5×T+9.4910, V (anatase)=2.237 58×10−6×T2+1.027 77×10−3×T+135.602, a (rutile)=−6.636 42×10−11×T3+1.005 01×10−7×T2−1.009 9310−5×T+4.586 34, c (rutile)=−4.115 50×10−11×T3+6.405 94×10−8×T2+4.675 61×10−7T+2.951 81, and V (rutile)=−2.7790×10−9×T3+4.2386×10−6×T2−3.3551×10−4×T+62.100. The polynomial expressions were used to calculate linear (α) and volume (β) thermal expansion coefficients of anatase and rutile between 300 and 575 K. At 298.15 K, these values were αa=4.46943×10−6 K−1, αc=8.4283×10−6 K−1, and β=17.3542×10−6 K−1 for anatase, and αa=6.99953×10−6 K−1, αc=9.36625×10−6 K−1, and β=28.680×10−6 K−1 for rutile.

Structural redetermination, thermal expansion and refractive indices of KLu(WO4)2

2006 ◽  
Vol 39 (2) ◽  
pp. 230-236 ◽  
Author(s):  
M. C. Pujol ◽  
X. Mateos ◽  
A. Aznar ◽  
X. Solans ◽  
S. Suriñach ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Near Infrared ◽  
Linear Thermal Expansion ◽  
Unit Cell ◽  
Visible Range ◽  
Unit Cell Parameters ◽  
Slow Cooling ◽  
Cell Parameters ◽  
Thermal Expansion Tensor

The crystal structure of monoclinic KLu(WO4)2(KLuW) crystals was determined at room temperature by using single-crystal X-ray diffraction data. The unit-cell parameters werea= 10.576 (7),b= 10.214 (7),c= 7.487 (2) Å, β = 130.68 (4)°, withZ= 4, in space groupC2/c. The unit-cell parameters of KLu1−xYbx(WO4)2were determined in relation to Yb concentration. Vickers micro-indentations were used to study the microhardness of KLuW. The linear thermal expansion tensor was determined and the principal axis with maximum thermal expansion (\alpha_{33}' = 16.72 × 10−6 K−1), X_3', was located 13.51° from thecaxis. The room-temperature optical tensor was studied in the near-infrared (NIR) and visible range. The principal optical axis with maximum refractive index (ng= 2.113),Ng, was located 18.5° from thecaxis at 632.8 nm. Undoped and ytterbium-doped KLuW crystals were grown by the TSSG (top-seeded-solution growth) slow-cooling method. The crystals show {110}, {\bar{1}11}, {010} and {310} faces that basically constitue the habit of the KLuW crystals.

scholarly journals Lattice constants and thermal expansion of H2O and D2O Ice Ih between 10 and 265 K. Addendum

2012 ◽  
Vol 68 (1) ◽  
pp. 91-91 ◽  
Author(s):  
K. Röttger ◽  
A. Endriss ◽  
Jörg Ihringer ◽  
S. Doyle ◽  
W. F. Kuhs
Keyword(s):  
Thermal Expansion ◽  
Unit Cell ◽  
Acta Cryst ◽  
Lattice Constants ◽  
Temperature Range ◽  
Polynomial Fit ◽  
Polynomial Expression ◽  
Cell Data ◽  
Cell Volumes ◽  
Volume Cell

In a previous paper we reported the lattice constants and thermal expansion of normal and deuterated ice Ih [Röttger et al. (1994). Acta Cryst. B50, 644–648]. Synchrotron X-ray powder diffraction data were used to obtain the lattice constants and unit-cell volumes of H2O and D2O ice Ih in the temperature range 15–265 K. A polynomial expression was given for the unit-cell volumes. It turns out that the coefficients quoted have an insufficient number of digits to faithfully reproduce the volume cell data. Here we provide a table with more significant digits. Moreover, we also provide the coefficients of a polynomial fit to the previously published a and c lattice constants of normal and deuterated ice Ih for the same temperature range.

Structure and Thermal Expansion Behavior of Dy2-xGdxMo4O15 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 1665-1667
Author(s):  
M.M. Wu ◽  
X.L. Xiao ◽  
Y.Z. Cheng ◽  
J. Peng ◽  
D.F. Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Thermal Expansion ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Cell Volumes

A new series of solid solutions Dy2-xGdxMo4O15 (x = 0.0-0.9) were prepared. These compounds all crystallize in monoclinic structure with space group P21/c. The lattice parameters a, b, c and unit cell volumes V increase almost linearly with increasing gadolinium content. The intrinsic thermal expansion coefficients of Dy2-xGdxMo4O15 (x = 0.0 and 0.25) were obtained in the temperature range of 25 to 500°C with high-temperature X-ray diffraction. The correlation between thermal expansion and crystal structure was discussed.

Crystal Distortion Associated with Magnetic Ordering in Alpha Iron Oxide and Manganese Carbonate

1972 ◽  
Vol 16 ◽  
pp. 390-395 ◽  
Author(s):  
W. S. McCain ◽  
D. L. Albright
Keyword(s):  
Thermal Expansion ◽  
Lattice Constant ◽  
Room Temperature ◽  
Axial Ratio ◽  
Manganese Carbonate ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Position Parameter ◽  
Oxygen Distance

AbstractThe magnetic crystal disrortion of weakly ferromagnetic α-Fe2O3 was investigated by x-ray diffraction techniques. Here crystal distortion is taken as the temperature dependent changes of lattice constants and thermal expansion coefficients. Moreover, the oxygen position parameter and the carbon-oxygen distance of MnCO3 were determined.The lattice constants and thermal expansion coefficients of α-Fe2O3 were measured from room temperature down to 243°K. The crystal distortion, as measured by the changes in lattice constants, thermal expansion coefficients and axial ratio, was found to be highly anisotropic. The co hexagonal lattice constant was influenced very slightly by magnetic distortion; it changed only by 0.01 percent between room temperature and the Morin temperature of 254°K. On the other hand, the ao lattice constant changes by 0.11 percent between room temperature and the Morin temperature. The thermal expansion coefficients of the lattice constants showed a similar contrast. The co coefficient was found to be independent of temperature from room temperature down to the Morin temperature. However, in the same temperature range, the ao coefficient showed an anomalous increase with decreasing temperature. In addition, the ao coefficient showed an infinite discontinuity at the Morin temperature.The change in the axial ratio with temperature suggests that the net weak ferromagnetic moment of α-Fe2O3 reaches a maximum at 275°K.The oxygen position parameter, x, in MnCO3 as determined from two reflections has a value of 0.2702 ± 0.001. The carbon-oxygen distance as calculated from the lattice constants and the oxygen position parameter is 1.29 ±0.002 Å. This value is another confirmation of the Pauling theory of the resonating carbonate structure.

Thermal Expansion of SrZr4-xTix(PO4)6 Ceramics

2018 ◽  
Vol 281 ◽  
pp. 169-174
Author(s):  
Yang Wang ◽  
Yuan Yuan Song ◽  
Yuan Yuan Zhou ◽  
Lu Ping Yang ◽  
Fu Tian Liu
Keyword(s):  
Thermal Expansion ◽  
Relative Density ◽  
Thermophysical Properties ◽  
Sintering Temperature ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
High Relative Density ◽  
Low Thermal Expansion ◽  
Expansion Coefficients

Low thermal expansion ceramics have been widely applied in multiple fields. In this paper, a series of low thermal expansion ceramics SrZr4-xTix(PO4)6 was prepared and characterized. The SrZr4-xTix(PO4)6 ceramics could be well sintered in the temperature range of 1400~1500 °C. The effect of the addition of Ti substituting Zr and the sintering temperature was studied. The Ceramic with x =0.1 sintered at 1450 °C, the SrZr4-xTix(PO4)6 had a high relative density. The thermal expansion coefficients were about 3.301×10-6 °C-1. It was demonstrated that the microstructure of the SrZr4-xTix(PO4)6 could be altered by adding varying amount of Ti to tailor the thermophysical properties of the material.

Tetra-n-butylammonium iodide: a space-group revision

2007 ◽  
Vol 63 (3) ◽  
pp. o1464-o1466 ◽  
Author(s):  
Wiesław Prukała ◽  
Bogdan Marciniec ◽  
Maciej Kubicki
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Space Group ◽  
Cell Parameters ◽  
Temperature Determination

The crystal structure of tetra-n-butylammonium iodide, C16H36N+·I−, has been redetermined at room temperature and at 100 (1) K. In the low-quality (R = 0.142) room-temperature determination by Wang, Habenschuss, Xenopoulos & Wunderlich [Mol. Cryst. Liq. Cryst. Sci. Technol. Sect. A (1995), 264, 115–129], this structure was described as crystallizing in the space group C2 with Z′ = 2. Our results prove that the correct space group is C2/c (with the same unit-cell parameters as in the original determination) at both temperatures. In the crystal structure, the iodide anions fill the voids in the grid-like cationic structure. Weak C—H...I interactions (eight per anion) strengthen this packing.

X-ray powder diffraction data of anilinium trimolybdate tetrahydrate and anilinium trimolybdate dihydrate

1999 ◽  
Vol 14 (4) ◽  
pp. 280-283 ◽  
Author(s):  
A. Rafalska-Łasocha ◽  
W. Łasocha ◽  
M. Michalec
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns

The X-ray powder diffraction patterns of anilinium trimolybdate tetrahydrate, (C6H5NH3)2Mo3O10·4H2O, and anilinium trimolybdate dihyhydrate, (C6H5NH3)2Mo3O10·2H2O, have been measured in room temperature. The unit cell parameters were refined to a=11.0670(7) Å, b=7.6116(8) Å, c=25.554(3) Å, space group Pnma(62) and a=17.560(2) Å, b=7.5621(6) Å, c=16.284(2) Å, β=108.54(1)°, space group P21(4) or P21/m(11) for orthorhombic anilinium trimolybdate tetrahydrate and monoclinic anilinium trimolybdate dihydrate, respectively.

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