Energetic materials: variable-temperature crystal structure of β-NTO

2003 ◽  
Vol 36 (2) ◽  
pp. 280-285 ◽  
Author(s):  
Nadezhda B. Bolotina ◽  
Elizabeth Zhurova ◽  
A. Alan Pinkerton
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Energetic Materials ◽  
Variable Temperature ◽  
Thermal Motion ◽  
X Ray Diffraction ◽  
Cell Parameters ◽  
Thermal Expansion Tensor ◽  
Principal Axes ◽  
Molecular Dynamics Calculations

The crystal structure of the metastable β form of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (β-NTO, monoclinic,P21/c) has been investigated at five temperatures in the range 100–298 K using single-crystal X-ray diffraction techniques. The second-rank thermal expansion tensor has been determined to describe thermal behavior of the crystal. The most significant thermal expansion is in a plane, which is almost perpendicular to the planes of all the NTO molecules. Perpendicular to the plane of maximal thermal expansion, a modest thermal contraction takes place. Both thermal expansion and contraction of the crystal lattice indicate anharmonicity of the atomic thermal motion. The experimental thermal variation of the unit-cell parameters is in qualitative agreement with that previously obtained from molecular dynamics calculations. Rigid-body analysis of the molecular thermal motion was performed using the libration and translation second-rank tensors. Although the translation part of the thermal motion is not strongly anisotropic, the largest displacements of the NTO molecules are oriented in the plane of maximal thermal expansion of the crystal and have significant anharmonic components. The libration motion is more anisotropic, and the largest libration as well as the largest translation principal axes are directed along the C5—N5 bond in each NTO molecule.

Structural study of monoclinic KGd(WO4)2and effects of lanthanide substitution

2001 ◽  
Vol 34 (1) ◽  
pp. 1-6 ◽  
Author(s):  
M. C. Pujol ◽  
R. Solé ◽  
J. Massons ◽  
Jna. Gavaldà ◽  
X. Solans ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Morphological Changes ◽  
Linear Thermal Expansion ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
Ionic Radii ◽  
Cell Parameters ◽  
Cooling Method ◽  
Thermal Expansion Tensor ◽  
Principal Axes

The crystal structure of monoclinic KGd(WO4)2(KGW) has been refined at room temperature by using single-crystal X-ray diffraction data. The unit-cell parameters area= 10.652 (4),b= 10.374 (6),c= 7.582 (2) Å, β = 130.80 (2)°, withZ= 4, in space groupC2/c. The linear thermal expansion tensor has been determined and the principal axes are [302], [010] and [106]. The principal axis with maximum thermal expansion (\boldalpha'_{33} = 23.44 × 10−6 K−1), {\bf X}'_{3}, was located 12° from thecaxis. Undoped crystals of KGW and crystals that were partially doped by Pr, Nd, Ho, Er, Tm and Yb were grown by the top-seeding-solution growth slow-cooling method. The effect of doping on the KGW structure was observed in the cell parameters and in morphological changes. The changes in parameters follow the changes in lanthanide ionic radii. The doped crystals show {021} and {\bar{2}21} faces in addition to the {110}, {\bar{1}11}, {010}, {130} and {310} faces which basically follow the habit of the undoped KGW crystals. The development of the faces is related to the number of the most important periodic bond chains parallel to them.

Anisotropic thermal expansion of potassium dinitramide: a variable-temperature crystallographic study

2001 ◽  
Vol 57 (2) ◽  
pp. 113-118 ◽  
Author(s):  
Michaele J. Hardie ◽  
Anthony Martin ◽  
A. Alan Pinkerton ◽  
Elizabeth A. Zhurova
Keyword(s):  
Thermal Expansion ◽  
Rigid Body ◽  
Variable Temperature ◽  
Mean Field ◽  
Field Potential ◽  
Unit Cell ◽  
Thermal Motion ◽  
X Ray Diffraction ◽  
Thermal Expansion Tensor ◽  
Rigid Body Model

The structure of potassium dinitramide (KDN), KN3O4, has been refined in the temperature range 85–298 K from single-crystal X-ray diffraction data. The unit-cell axial lengths and the cell volume decrease linearly on cooling with the b axis being the most sensitive to the change of temperature. The β cell angle increases with decreasing temperature. The thermal expansion of KDN is significantly anisotropic, expanding along the b axis [010] more than three times the amount parallel to any other crystallographic direction. Other eigenvectors of the thermal expansion tensor lie approximately parallel to the diagonals of the ac plane. A rigid-body analysis of the dinitramide ion using the TLS formalism was performed and shows that the thermal motion of the anion is well represented by the rigid-body model. The eigenvalues of the libration tensor show significant anisotropy, whereas the translation tensor is close to isotropic. The variation of all descriptions of the thermal motion with respect to temperature indicates an anharmonic contribution to the mean field potential. The direction of greatest unit-cell expansion coincides with the largest components of the displacement tensor of the potassium ions and the direction of the largest atomic amplitudes due to the libration of the dinitramide anions.

A high temperature structural phase transition in crocoite (PbCrO4) at 1068 K: crystal structure refinement at 1073 K and thermal expansion tensor determination at 1000 K

2000 ◽  
Vol 64 (2) ◽  
pp. 291-300 ◽  
Author(s):  
K. S. Knight
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Thermal Expansion ◽  
High Temperature ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Structure Type ◽  
Temperature Phase ◽  
Thermal Expansion Tensor ◽  
Principal Axes

AbstractHigh-resolution, neutron time-of-flight, powder diffraction data have been collected on natural crocoite between 873 and 1073 K. Thermal analysis carried out in the 1920s had suggested that chemically pure PbCrO4 exhibited two structural phase transitions, at 964 K, to the β phase, and at 1056 K, to the γ phase. In this study, no evidence was found for the α-β structural phase transition, however a high-temperature phase transition was found at ∼1068 K from the ambient-temperature monazite structure type to the baryte structure type. The phase transition, close to the temperatures reported for the β to γ phase modifications, is first order and is accompanied by a change in volume of −1.6%. The crystal structure of this phase has been refined using the Rietveld method to agreement factors of Rp = 0.018, Rwp = 0.019, Rp = 0.011. No evidence for premonitory behaviour was found in the temperature dependence of the monoclinic lattice constants rom 873 K to 1063 K and these have been used to determine the thermal expansion tensor of crocoite just below the phase transition. At 1000 K the magnitudes of the tensor coefficients are α11, 2.66(1) × 10−5 K−1; α22, 2.04(1) × 10−5 K−1; α33, 4.67(4) × 10−5 K−1; and α13, −1.80(2) × 10−5 K−1 using the IRE convention for the orientation of the tensor basis. The orientation of the principal axes of the thermal expansion tensor are very close to those reported previously for the temperature range 50–300 K.

Crystal structure, electrical, and thermal properties of Ca0.5Th0.5VO4

2009 ◽  
Vol 24 (12) ◽  
pp. 3551-3558 ◽  
Author(s):  
S.J. Patwe ◽  
S. Nagabhusan Achary ◽  
Avesh K. Tyagi
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Rietveld Refinements ◽  
Cell Parameters ◽  
Expansion Behavior ◽  
High Temperature Xrd ◽  
Zircon Type

Ca0.5Th0.5VO4 was prepared by a solid-state reaction of component oxides and characterized by powder x-ray diffraction (XRD) at ambient and higher temperatures and impedance spectroscopy. Crystal structure was refined by Rietveld refinements from powder XRD data. At room temperature, Ca0.5Th0.5VO4 has a zircon-type tetragonal (I41/amd) lattice with unit cell parameters: a = 7.2650(1) and c = 6.4460(1) Å. Despite the large charge difference, Ca2+ and Th4+ are statistically distributed over a single site. The crystal structure of Ca0.5Th0.5VO4 is built from the (Ca/Th)O8 (bisdisphenoid) and VO4 tetrahedra. The in situ high-temperature XRD studies on Ca0.5Th0.5VO4 revealed anisotropic thermal expansion behavior with coefficients of thermal expansion αc = 10.96 × 10−6/°C and αa = 5.32 × 10−6/°C. The impedance measurements carried out in the temperature range from ambient to 800 °C indicate semiconducting behavior with appreciable ionic conductivity above 400 °C. The activation energy obtained from the temperature-dependent AC conductivity data is ∼1.37 eV. In wider range of frequencies and temperatures, the relative permittivity of approximately 50 to 60 is observed for Ca0.5Th0.5VO4.

Energetic materials: variable-temperature crystal structures of two biguanidinium dinitramides

2003 ◽  
Vol 36 (6) ◽  
pp. 1334-1341 ◽  
Author(s):  
Nadezhda B. Bolotina ◽  
Michaele J. Hardie ◽  
A. Alan Pinkerton
Keyword(s):  
Thermal Expansion ◽  
Crystal Structures ◽  
Energetic Materials ◽  
Variable Temperature ◽  
Atomic Displacement ◽  
Thermal Motion ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
Thermal Displacements ◽  
Atomic Displacement Parameters

The crystal structures of the energetic materials biguanidinium mono-dinitramide C2H8N{}_{5}^{\,+}.N3O{}_{4}^{\,-}, (BIGH)(DN), and biguanidinium bis-dinitramide C2H9N{}_{5}^{\,2+}.2N3O{}_{4}^{\,-}, (BIGH2)(DN)2, have been determined at several temperatures in the range 85–298 K using single-crystal X-ray diffraction techniques. The thermal expansion second-rank tensors have been determined to describe the thermal behavior of the crystals studied. Strongly anisotropic thermal expansion is most important in the direction perpendicular to the least-squares planes of the dinitramide ions in both cases, suggesting that the atomic thermal motion is significantly anharmonic in these crystals. Anharmonicity of thermal motion is also evident from the non-linear temperature dependence of the atomic displacement parameters. Rigid-body analysis of thermal motion both of dinitramide anions and of biguanidinium cations was performed using the libration and translation second-rank tensors. For both compounds, the libration thermal motion is strongly anisotropic with the dominating libration axes oriented in a similar manner in both anions and cations. Although the translation motion of the ions is not strongly anisotropic, the axes of largest thermal displacements are close to the directions of greatest thermal expansion of the crystals.

Synthesis and structural characterization of BaV4O9

2007 ◽  
Vol 63 (2) ◽  
pp. 270-276 ◽  
Author(s):  
Thomas Reeswinkel ◽  
Sebastian Prinz ◽  
Karine M. Sparta ◽  
Georg Roth
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Structural Characterization ◽  
Room Temperature ◽  
Monoclinic Space Group ◽  
Temperature Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Tensor

The new spin ½ V4+ barium oxovanadate BaV4O9 was synthesized and studied by means of single-crystal X-ray diffraction. Its room-temperature structure is monoclinic, space group P2/c. We discuss the temperature evolution of the crystal structure and thermal expansion tensor of the material between 293 and 100 K.

Structure, crystal growth and physical anisotropy of KYb(WO4)2, a new laser matrix

2002 ◽  
Vol 35 (1) ◽  
pp. 108-112 ◽  
Author(s):  
M. C. Pujol ◽  
X. Mateos ◽  
R. Solé ◽  
J. Massons ◽  
Jna. Gavaldà ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Principal Axis ◽  
Linear Thermal Expansion ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
Thermal Expansion Tensor ◽  
Principal Axes ◽  
Top Seeded Solution Growth ◽  
Prime 2

The crystal structure of monoclinic KYb(WO4)2(KYbW) crystals has been refined (in space groupC2/c) at room temperature by using single-crystal X-ray diffraction data. KYbW undoped crystals were grown by the TSSG (top-seeded-solution growth) slow-cooling method. The crystals show {110}, {\bar{1}11}, {010} and {310} faces, which basically define their habit. The linear thermal expansion tensor has been determined and the principal axis with maximum thermal expansion (\alpha ^{\,\prime}_{33} = 16.68 × 10−6 K−1), {\bf X}^{\,\prime}_{3}, was located 12° from thecaxis. Its principal {\bf X}^{\,\prime}_{1}, {\bf X}^{\,\prime}_{2} and {\bf X}^{\,\prime}_{3} axes are [302], [010] and [106] directions, respectively, in the crystallographic system. The optical tensor has been studied at λ = 632.8 nm at room temperature; two principal axes,NgandNm, are located in theacplane, while the other,Np, is parallel to [010]. The principal axis with maximum refractive index (ng= 2.45),Ng, was located 19° from thecaxis.

Structural and thermal properties of the monoclinic Lu2SiO5single crystal: evaluation as a new laser matrix

2009 ◽  
Vol 42 (2) ◽  
pp. 284-294 ◽  
Author(s):  
Hengjiang Cong ◽  
Huaijin Zhang ◽  
Jiyang Wang ◽  
Wentao Yu ◽  
Jiandong Fan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Specific Heat ◽  
Linear Thermal Expansion ◽  
Cell Parameters ◽  
Thermal Expansion Tensor ◽  
Anisotropic Thermal Conductivity

The crystal structure of monoclinic Lu2SiO5(LSO) crystals, grown by the Czochralski method, was determined at room temperature by X-ray diffraction. The unit-cell parameters area= 10.2550 (2),b= 6.6465 (2),c= 12.3626 (4) Å, β = 102.422 (1)° in space groupI2/a. The linear thermal expansion tensor was determined along thea,b,candc* directions over the temperature range from 303.15 to 768.15 K, and the principal coefficients of the thermal expansion tensor are found to be αI= −1.0235 × 10−6 K, αII= 4.9119 × 10−6 K and αIII= 10.1105 × 10−6 K. The temperature dependence of the cell volume and monoclinic angle were also evaluated. In addition, the specific heat and the thermal diffusivity were measured over the temperature ranges from 293.15 to 673.15 K and from 303.15 to 572.45 K, respectively. As a result, the anisotropic thermal conductivity could be calculated and is reported for the first time, to the best of the authors' knowledge. The specific heat capacity of LSO is 139.54 J mol−1 K−1, and the principal components of the thermal conductivity arekI= 2.26 W m−1 K−1,kII= 3.14 W m−1 K−1andkII= 3.67 W m−1 K−1at 303.15 K. A new structure model was proposed to better understand the relationships between the crystal structure and anisotropic thermal properties. In comparison with other laser matrix crystals, it is found that LSO possesses relatively large anisotropic thermal properties, and owing to its small heat capacity it has a moderate thermal conductivity, which is similar to those of the tungstates but lower than those of the vanadates.

Temperature dependence of thermal expansion tensors of energetic materials

2015 ◽  
Vol 48 (5) ◽  
pp. 1364-1380 ◽  
Author(s):  
Nadezhda B. Bolotina ◽  
A. Alan Pinkerton
Keyword(s):  
Thermal Expansion ◽  
Temperature Dependence ◽  
Diffraction Data ◽  
Energetic Materials ◽  
Variable Temperature ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray

Unit-cell values as well as thermal expansion tensors for 13 energetic materials are calculated from variable-temperature X-ray diffraction data. The thermal expansion tensors and their temperature dependence are reported numerically, algebraically and graphically.

Variable-temperature crystal structure studies of m-nitroaniline

2001 ◽  
Vol 57 (3) ◽  
pp. 346-352 ◽  
Author(s):  
Grażyna Wójcik ◽  
Jolanta Holband
Keyword(s):  
Crystal Structure ◽  
Cross Sections ◽  
Thermal Evolution ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Lattice Contraction ◽  
Thermal Expansion Coefficients ◽  
Principal Axes ◽  
Expansion Coefficients ◽  
Intermolecular Distances

The crystal structure of m-nitroaniline has been examined at several temperatures over the 90–350 K range. Thermal evolution of the lattice parameters reveals a weak anomaly at 110 K and an important one at 300 K. The thermal expansion coefficients have been calculated at several temperatures and the principal axes cross-sections of the tensor were drawn. The lattice contraction along the b axis direction has been observed. The rigid-body analysis including an attached rigid group has provided the values of the translation and libration tensors at temperatures studied. The results indicate that m-nitroaniline undergoes a glass transition around 130 K arising from freezing molecular librations and translations. From above 340 K the growing plasticity of the m-nitroaniline crystal results in the loss of X-ray diffraction reflections. This is probably a second-order phase transition. It is coupled with a considerable increase in the nitro group torsion amplitude, but the NH...O hydrogen bonds are preserved. Analysis of the temperature evolution of short intermolecular distances enabled us to consider the occurrence of reorienting aggregates of hydrogen-bonded molecules in the high-temperature plastic phase.

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