scholarly journals Influence of Open-Porous System on the Solid-State Phase Transition in 1-Octadecene

2019 ◽  
Vol 64 (4) ◽  
pp. 340 ◽  
Author(s):  
O. M. Alekseev ◽  
S. O. Alekseev ◽  
Yu. F. Zabashta ◽  
M. M. Lazarenko ◽  
K. I. Hnatiuk ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Silica Gel ◽  
Silica Gels ◽  
Porous System ◽  
Scanning Calorimetry ◽  
Energy Characteristics ◽  
Crystal Melting ◽  
Pore Surface Area ◽  
Thermodynamical Model

The solid-state phase transition in the silica gel–1-octadecene system has been studied at various temperatures with the help of differential scanning calorimetry and FTIR spectroscopy. Silica gels KSK-2.5, KSS-4, and Silica Gel 60 with different surface parameters are used. The temperature of the solid-state phase transition in the silica gel–1-octadecene system is shown to linearly depend on the ratio between the pore surface area and the pore volume. The energy characteristics of 1-octadecene nanocrystals in the surface layer are calculated in the framework of a thermodynamical model of crystal melting in pores.

Solid-State Transition Mechanisms of Ammonium Nitrate Phases IV, III, and II Investigated by Simultaneous Raman Spectrometry and Differential Scanning Calorimetry

1993 ◽  
Vol 47 (11) ◽  
pp. 1926-1930 ◽  
Author(s):  
Mauno E. E. Harju
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Solid State ◽  
Ammonium Nitrate ◽  
Phase Ii ◽  
State Transition ◽  
Intermediate Phase ◽  
Raman Spectrometry ◽  
Scanning Calorimetry ◽  
Solid State Transition

The solid-state transition mechanisms of ammonium nitrate IV, III, and II were studied by measuring samples simultaneously by Raman spectrometry and differential scanning calorimetry (DSC). The Raman instruments were a Fourier transform Raman spectrophotometer and triple monochromator Raman spectrophotometer with charge-coupled-device (CCD) detector. The spectral data of the transitions were collected simultaneously with the calorimetric data in the temperature-scanning mode of the calorimeter and then isothermally between transitions. The phase transition from phase IV to phase III occurred through an intermediate phase II*, whose lifetime was seven minutes maximum when the onset temperature of the reaction was close to the phase-transition IV → II onset temperature. It is concluded that there is always an intermediate phase II* between IV and III. Simultaneous Raman measurements are shown to be an effective tool for interpreting complex DSC curves.

Temperature-Dependent Solid-state Luminescence and Reversible Phase Transition of (n-Bu4N)[Au(SC6H3-3,5-Me2)2]

2003 ◽  
Vol 32 (11) ◽  
pp. 1002-1003 ◽  
Author(s):  
Seiji Watase ◽  
Takayuki Kitamura ◽  
Nobuko Kanehisa ◽  
Masami Nakamoto ◽  
Yasushi Kai ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Temperature Dependent ◽  
Reversible Phase Transition ◽  
Reversible Phase ◽  
State Luminescence

scholarly journals Phase Transition and Coefficients of Thermal Expansion in Al2−xInxW3O12 (0.2 ≤ x ≤ 1)

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4021
Author(s):  
Andrés Esteban Cerón Cerón Cortés ◽  
Anja Dosen ◽  
Victoria L. Blair ◽  
Michel B. Johnson ◽  
Mary Anne White ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Thermal Shock ◽  
Monoclinic Phase ◽  
Ceramic Materials ◽  
Precipitation Method ◽  
Scanning Calorimetry ◽  
Orthorhombic Crystal ◽  
Co Precipitation

Materials from theA2M3O12 family are known for their extensive chemical versatility while preserving the polyhedral-corner-shared orthorhombic crystal system, as well as for their consequent unusual thermal expansion, varying from negative and near-zero to slightly positive. The rarest are near-zero thermal expansion materials, which are of paramount importance in thermal shock resistance applications. Ceramic materials with chemistry Al2−xInxW3O12 (x = 0.2–1.0) were synthesized using a modified reverse-strike co-precipitation method and prepared into solid specimens using traditional ceramic sintering. The resulting materials were characterized by X-ray powder diffraction (ambient and in situ high temperatures), differential scanning calorimetry and dilatometry to delineate thermal expansion, phase transitions and crystal structures. It was found that the x = 0.2 composition had the lowest thermal expansion, 1.88 × 10−6 K−1, which was still higher than the end member Al2W3O12 for the chemical series. Furthermore, the AlInW3O12 was monoclinic phase at room temperature and transformed to the orthorhombic form at ca. 200 °C, in contrast with previous reports. Interestingly, the x = 0.2, x = 0.4 and x = 0.7 materials did not exhibit the expected orthorhombic-to-monoclinic phase transition as observed for the other compositions, and hence did not follow the expected Vegard-like relationship associated with the electronegativity rule. Overall, compositions within the Al2−xInxW3O12 family should not be considered candidates for high thermal shock applications that would require near-zero thermal expansion properties.

scholarly journals Effect of Hydrophobic Silica Nanochannel Structure on the Running Speed of a Colloidal Damper

2021 ◽  
Vol 11 (15) ◽  
pp. 6808
Author(s):  
Gengbiao Chen ◽  
Zhiwen Liu
Keyword(s):  
Fractal Dimension ◽  
Silica Gel ◽  
Fractal Theory ◽  
Percolation Model ◽  
Silica Gels ◽  
Practical Significance ◽  
Running Speed ◽  
Fractal Percolation ◽  
Micropore Structure ◽  
Hydrophobic Silica

A colloidal damper (CD) can dissipate a significant amount of vibrations and impact energy owing to the interface power that is generated when it is used. It is of great practical significance to study the influence of the nanochannel structure of hydrophobic silica gel in the CD damping medium on the running speed of the CD. The fractal theory was applied to observe the characteristics of the micropore structure of the hydrophobic silica gel by scanning electron microscopy (SEM), the primary particles were selected to carry out fractal analysis, and the two-dimensional fractal dimension of the pore area and the tortuous fractal dimension of the hydrophobic silica gel pore structure were calculated. The fractal percolation model of water in hydrophobic silica nanochannels based on the slip theory could thus be obtained. This model revealed the relationship between the micropore structure parameters of the silica gel and the running speed of the CD. The CD running speed increases with the addition of grafted molecules and the reduction in pore size of the silica gel particles. Continuous loading velocity testing of the CD loaded with hydrophobic silica gels with different pore structures was conducted. By comparing the experimental results with the calculation results of the fractal percolation model, it was determined that the fractal percolation model can better characterize the change trend of the CD running velocity for the first loading, but the fractal dimension was changed from the second loading, caused by the small amount of water retained in the nanochannel, leading to the failure of fractal characterization.

scholarly journals Unusual piezochromic fluorescence of a distyrylpyrazine derivative crystals: phase transition through [2 + 2] photocycloaddition under UV irradiation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Young-Jae Jin ◽  
Hyosang Park ◽  
Byung-Chun Moon ◽  
Jae Hong Kim ◽  
Wang-Eun Lee ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Uv Irradiation ◽  
Mechanical Grinding ◽  
Green Color ◽  
H Nmr ◽  
Uv Visible ◽  
Stacking Structure ◽  
Orange Color ◽  
Molecular Stacking

AbstractThe piezochromic fluorescence (FL) of a distyrylpyrazine derivative, 2,3-diisocyano-5,6-distyrylpyrazine (DSP), was investigated in this study. Depending on the recrystallization method, DSP afforded two different crystals with green and orange FL emission. The orange color FL emission crystal (O-form) was easily converted to the green color FL emission one (G-form) by manual grinding. The G-form was also converted to a slightly different orange color FL emission crystal (RO-form) by a weak UV irradiation. When the RO-form was ground again, the G-form was regenerated. The FL colors changed between the G- and RO-forms over several ten times by repeated mechanical grinding and UV irradiation. The FL, UV–visible, 1H-NMR and XRD results showed that the O (or RO)-to-G transformation induced by mechanical stress results from the change of degree of molecular stacking from dense molecular stacking structure to relatively loose molecular stacking structure, whereas the G-to-RO reconversion by UV irradiation results from return to dense molecular stacking structure again due to lattice movement (lattice slipping) allowed by photocycloaddition in solid-state.

Characterization of some mesogenic alkyl 1-thioglycosides

2002 ◽  
Vol 80 (8) ◽  
pp. 1162-1165 ◽  
Author(s):  
B Henrissat ◽  
G K Hamer ◽  
M G Taylor ◽  
R H Marchessault
Keyword(s):  
Phase Transition ◽  
Liquid Crystal ◽  
Solid State ◽  
Solid State Nmr ◽  
Liquid Crystalline ◽  
Liquid Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Crystalline Phases

A series of dodecyl 1-thio-β-D-glycosides has been synthesized and characterized (DSC, NMR, CP MAS, X-ray diffraction) as possible new marking materials with liquid-crystalline properties. These compounds undergo solid to liquid crystal phase transitions at various temperatures, which depend on the nature of the carbohydrate part of the structure. Their liquid-crystalline phases show extreme shear thinning behaviour.Key words: liquid crystal, powder X-ray diffraction, phase transition, thioglycoside, solid-state NMR, marking material

Solid-State Reactions in Multilayer Ni/Ti Thin Film Composites

1990 ◽  
Vol 205 ◽  
Author(s):  
Gillian E. Winters ◽  
K.M. Unruh ◽  
C.P. Swann ◽  
M.E. Patt ◽  
B.E. White ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Reactions ◽  
Metastable Solid Solution ◽  
State Transformation ◽  
Solid State Transformation ◽  
Scanning Calorimetry ◽  
The Individual ◽  
Thin Film Composites ◽  
Film Composites ◽  
Rf Sputter Deposition

AbstractMultilayer films, consisting of alternating layers of crystalline Ni and Ti, have been prepared by RF sputter deposition over a range of modulation wavelengths corresponding to an overall composition of Ni50Ti50. These films have been characterized by xray diffraction and Rutherford backscattering measurements. The solid-state transformation by interdiffusional mixing of the individual layers has been directly studied by differential scanning calorimetry and correlated with structural measurements. These measurements indicate that the solid-state reaction of Ni and Ti multilayers proceeds through the formation of a metastable solid solution of Ti in Ni followed by the formation of intermetallic equilibrium compounds. No direct calorimetric or structural evidence for the formation of an amorphous Ni-Ti phase has been found in these samples.

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