Fe3O4: lattice parameters, thermal expansion, density, high temperature phase

2005 ◽  
pp. 1-4
Author(s):  
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
High Temperature Phase ◽  
Lattice Parameters ◽  
Temperature Phase

Anisotropic thermal expansion in yttrium silicate

2003 ◽  
Vol 18 (7) ◽  
pp. 1715-1722 ◽  
Author(s):  
Koichiro Fukuda ◽  
Hiroyuki Matsubara
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Phase Space ◽  
Linear Thermal Expansion ◽  
High Temperature Phase ◽  
Acute Angle ◽  
Temperature Phase ◽  
Space Group ◽  
Anisotropic Thermal Expansion ◽  
Increasing Temperature

In this study, crystals of Y2SiO5 were examined by high-temperature powder x-ray diffractometry to determine the changes in unit-cell dimensions with temperatures up to 1273 K for the X1 phase (the low-temperature phase, space group P121/c1) and 1473 K for the X2 phase (the high-temperature phase, space group I12/a1). The lattice deformations of both phases induced by thermal expansion were investigated by matrix algebra analysis to determine the directions and magnitudes of the principal distortions (λi, i = 1, 2, and 3). For the X1 phase, λ1 and λ2 invariably showed a positive thermal expansion. On the other hand, λ3 showed a negative thermal expansion below 1173 K; the maximum contraction of 0.10(4)% occurred at 685 K. The λ2 axis invariably coincides with the crystallographic b axis. The directions of λ1 and λ3, defined by the acute angle λ3 ^ c changed between 53(3)° (T = 394 K) and 45(1)° (T = 788 K). For the X2 phase, all of the principal distortions steadily increased with increasing temperature. The angle λ3 ^ c steadily decreased from 71(2)° to 62.1(1)° with increasing temperature. The mean linear thermal expansion coefficients were, when compared at the same temperatures, necessarily higher for the X1 phase than for the X2 phase. The lattice change of X1–RE2SiO5 (RE = Y and Yb–La), which was induced by the substitution of rare-earth (RE) ions, showed a striking resemblance with the lattice deformation of X1-Y2SiO5, which was caused by the thermal expansion. Because the lattice change of the former must be caused by the isotropic expansion of the RE sites, the anisotropic thermal expansion of the latter would be essentially attributable to the isotropic thermal expansion of the YO9 and YO7 polyhedron.

Pyramidal Slip in β Boron

1991 ◽  
Vol 49 ◽  
pp. 944-945
Author(s):  
D.M. Vanderwalker
Keyword(s):  
High Temperature ◽  
High Energy ◽  
High Temperature Phase ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Temperature Phase ◽  
Hexagonal System ◽  
System A ◽  
Pyramidal Slip ◽  
Rhombohedral Boron

Boron is a semiconductor which has applications as a high energy fuel and coating material. Thus, one can assume there is an interest in the structural andelectronic properties. Boron has been found to crystallize into several structures. The α rhombohedral boron was reported to have lattice parameters of a = 5.057 A, α = 58°4. (hexagonal coordinates a = 4.908 A, c = 12.567 A) β Rhombohedral boron, the high temperature phase, has been found to have lattice parameters a = 10.145 A, α = 65° or in the hexagonal system a = 10.944 A, c = 23.811 A with 320 atoms per unit cell.

scholarly journals Exploration of the high temperature phase evolution of electrochemically modified Sc2(WO4)3via potassium discharge

2019 ◽  
Vol 6 (10) ◽  
pp. 2718-2726
Author(s):  
Junnan Liu ◽  
Abby R. Haworth ◽  
Karen E. Johnston ◽  
Damian Goonetilleke ◽  
Neeraj Sharma
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Treatment ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Negative Thermal Expansion ◽  
Phase Evolution ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Electrochemical Discharge

Electrochemical discharge followed by thermal treatment produces K2WO4 and other phases. K2WO4 features a large negative thermal expansion coefficient between 923–1023 K.

Anisotropy of Intermolecular Interactions from the Study of the Thermal-Expansion Tensor

1998 ◽  
Vol 31 (5) ◽  
pp. 748-757 ◽  
Author(s):  
J. Salud ◽  
M. Barrio ◽  
D. O. López ◽  
J. Ll. Tamarit ◽  
X. Alcobé
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Intermolecular Interactions ◽  
Pivalic Acid ◽  
High Temperature Phase ◽  
Molecular Structures ◽  
Van Der Waals Interactions ◽  
Temperature Phase ◽  
Volume Expansivity ◽  
Thermal Expansion Tensor

The anisotropy of the intermolecular interactions in the low-temperature ordered phases of three chemically and structurally related compounds [neopentylglycol, (CH3)2C(CH2OH)2, pivalic acid, (CH3)3C(COOH), and neopentylalcohol, (CH3)3C(CH2OH)], all of which display an orientationally disordered high-temperature phase, has been shown by means of the isobaric thermal-expansion tensor. The variation of the directions of the principal components of the thermal-expansion tensor as a function of temperature, as well as the variation of its principal coefficients, is evidence of the large differences in the intermolecular interactions for each compound; or, more precisely, between the strong intermolecular hydrogen bonds and the weak van der Waals interactions. In addition, the differences in the hydrogen-bonding schemes expecteda priorifrom the molecular structures of the studied compounds have been enhanced. Finally, the volume expansivity as well as the packing coefficient have been analysed in the orientationally disordered high-temperature phase of each of the three compounds.

scholarly journals Thermal expansion effects on the one-dimensional liquid-solid phase transition in high temperature phase change materials

AIP Advances ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 025125 ◽  
Author(s):  
Rubén Darío Santiago Acosta ◽  
José Antonio Otero ◽  
Ernesto Manuel Hernández Cooper ◽  
Rolando Pérez-Álvarez
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
High Temperature ◽  
Phase Change Materials ◽  
Solid Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
One Dimensional ◽  
Solid Phase Transition ◽  
The One
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