High-Pressure Studies of the Rotor-Stator Compound C60-Cubane

2006 ◽  
Vol 987 ◽  
Author(s):  
Bertil Sundqvist ◽  
Agnieszka Iwasiewicz-Wabnig ◽  
Eva Kovats ◽  
Sandor Pekker
Keyword(s):  
Phase Transition ◽  
Atmospheric Pressure ◽  
Orthorhombic Phase ◽  
Transition Line ◽  
X Ray Diffraction ◽  
X Ray ◽  
Treatment Conditions ◽  
High Pressure Studies ◽  
Different Temperatures ◽  
Polymeric State

AbstractInsertion of cubane (C8H8) into the octahedral voids of the C60 lattice leads to the formation of an interesting rotor-stator compound which can be converted into a C60 co-polymer by heating. We have treated a number of C60·C8H8 samples for up to 3 h each in the range 380-875 K under pressures up to 2 GPa. The resulting materials were investigated by Raman spectroscopy and X-ray diffraction. Depending on treatment conditions, at least five different structural phases can be found. In addition to the four structural phases observed at atmospheric pressure and different temperatures we find that a new polymeric state is created at pressures above 1 GPa, and we tentatively identify its structure as pseudo-orthorhombic. The cubic-orthorhombic phase transition line is found to have a slope of 295 K GPa-1, much larger than the slope of the fcc-sc line in pure C60.

Study of phase transition line of PZT ceramics by X-ray diffraction

1995 ◽  
Vol 21 (6) ◽  
pp. 391-394 ◽  
Author(s):  
A. Boutarfaia ◽  
C. Boudaren ◽  
A. Mousser ◽  
S.E. Bouaoud
Keyword(s):  
Phase Transition ◽  
Transition Line ◽  
X Ray Diffraction ◽  
Pzt Ceramics ◽  
X Ray ◽  
Phase Transition Line

scholarly journals Effects of annealing parameters on phase, structure and thermochromic properties of VO2 (M) derived from nanostructured VO2(B)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hamdi Muhyuddin Barra ◽  
Soo Kien Chen ◽  
Nizam Tamchek ◽  
Zainal Abidin Talib ◽  
Oon Jew Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
X Ray ◽  
Thermogravimetric Analyzer ◽  
Different Temperatures ◽  
Thermochromic Properties ◽  
Scanning Electron

Abstract Synthesis of thermochromic VO2 (M) was successfully done by annealing hydrothermally-prepared VO2 (B) at different temperatures and times. Conversion of the metastable VO2 (B) to the thermochromic VO2 polymorph was studied using thermogravimetric analyzer (TGA) under N2 atmosphere. Moreover, the phase and morphology of the synthesized samples were studied using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), respectively. Accordingly, the XRD scans of all the annealed samples exhibited the presence of monoclinic VO2 (M), while the FE-SEM images of the samples showed the formation of nanorods and nanospheres, particularly those heated at high temperatures (650 °C and 700 °C). Meanwhile, differential scanning calorimetry (DSC) was used to measure the phase transition temperature (τc), hysteresis, and enthalpy of the prepared VO2. Based on these results, all samples displayed a τc of about 66 °C. However, the hysteresis was high for the samples annealed at lower temperatures (550 °C and 600 °C), while the enthalpy was very low for samples heated at lower annealing time (1.5 h and 1 h). These findings showed that crystallinity and nanostructure formation affected the thermochromic properties of the samples. In particular, the sample annealed at 650 °C showed better crystallinity and improved thermochromic behavior.

Structure Study of Supercritical CO2near Higher-Order Phase Transition Line by X-ray Diffraction

1997 ◽  
Vol 101 (36) ◽  
pp. 7158-7162 ◽  
Author(s):  
Takeshi Morita ◽  
Keiko Nishikawa ◽  
Masakazu Takematsu ◽  
Hanae Iida ◽  
Seiya Furutaka
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Structure Study ◽  
Higher Order ◽  
Transition Line ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Transition Line

Crystal chemistry of aegirine as an indicator of P-T conditions

2007 ◽  
Vol 71 (3) ◽  
pp. 321-326 ◽  
Author(s):  
L. Secco ◽  
A. Guastoni ◽  
F. Nestola ◽  
G. J. Redhammer ◽  
A. Dal Negro
Keyword(s):  
Cell Volume ◽  
Atmospheric Pressure ◽  
Synthesis Temperature ◽  
X Ray Diffraction ◽  
Β Cell ◽  
X Ray ◽  
Cell Parameters ◽  
Different Temperatures ◽  
The Difference ◽  
Polyhedral Volumes

AbstractOne metamorphic and four magmatic aegirines, together with two end-member aegirines synthesized at atmospheric pressure and different temperatures, were investigated by single-crystal X-ray diffraction. The limited compositional differences allow the polyhedral volumes to be almost constant in all the aegirines investigated( VM1 ≈ 11.0 Å3; VM2 ≈ 26.3 Å3; VT ≈ 2.21 Å3). However, differences in polyhedral distortions are responsible for the cell-volume variations, reflected mainly in the change of a and β cell parameters. Cell volume is only partly related to the composition of these aegirines: with increasing formation temperature, an increase in the unit-cell volume of ~1.2 Å3 is observed, while a significant contraction of the cell volume occurs during high-pressure formation. As the difference in cell volume between the two synthetic aegirines is ascribed to the different conditions of synthesis temperature, the same interpretation could be adopted for the differences observed in natural aegirines.

High-Pressure X-Ray Diffraction Studies of Elastic Anomalies in Superlattice

1991 ◽  
Vol 231 ◽  
Author(s):  
Y. Fujii ◽  
Y. Ohishi ◽  
H. Konishi ◽  
N. Nakayama ◽  
T. Shinjo
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
Orthorhombic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Stacking ◽  
Diamond Anvil ◽  
Elastic Anomalies ◽  
Structural Aspects

AbstractThis paper has made an overview on elastic and structural aspects of three distinct superlattices under hydrostatic pressure up to about 8GPa, which were studied by our unique x-ray diffraction technique incorporated with a diamond-anvil cell. They are metallic fcc/fcc Au/Ni, bcc/fcc Mo/Ni, and semiconductive epitaxially-grown PbSe/SnSe superlattices. In their layer-stacking direction, both metallic superlattices show the supermodulus behavior while the semiconductive one doesn't. However, its pressure-driven cubic-to-orthorhombic phase transition, successively taking place in the SnSe and PbSe layers, has been found to significantly shift by stress due to its epitaxial growth.

scholarly journals Large electromechanical strain and unconventional domain switching near phase convergence in a Pb-free ferroelectric

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Sarangi Venkateshwarlu ◽  
Lalitha K. Venkataraman ◽  
Valentin Segouin ◽  
Frederick P. Marlton ◽  
Ho Chin Hin ◽  
...  
Keyword(s):  
Phase Transition ◽  
Room Temperature ◽  
Domain Switching ◽  
Polarization Vector ◽  
Orthorhombic Phase ◽  
Image Correlation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reversible Phase Transition ◽  
Domain Reorientation

Abstract In many ferroelectrics, large electromechanical strains are observed near regions of composition- or temperature- driven phase coexistence. Phenomenologically, this is attributed to easy re-orientation of the polarization vector and/or phase transition, although their effects are highly convoluted and difficult to distinguish experimentally. Here, we used synchrotron X-ray scattering and digital image correlation to differentiate between the microscopic mechanisms leading to large electrostrains in an exemplary Pb-free piezoceramic Sn-doped barium calcium zirconate titanate. Large electrostrains of ~0.2% measured at room-temperature are attributed to an unconventional effect, wherein polarization switching is aided by a reversible phase transition near the tetragonal-orthorhombic phase boundary. Additionally, electrostrains of ~0.1% or more could be maintained from room temperature to 140 °C due to a succession of different microscopic mechanisms. In situ X-ray diffraction elucidates that while 90° domain reorientation is pertinent below the Curie temperature (TC), isotropic distortion of polar clusters is the dominant mechanism above TC.

High Pressure Synchrotron Diffraction of KCa2Nb3O10, a Layered Perovskite Compound

1998 ◽  
Vol 524 ◽  
Author(s):  
K. A. Steiner ◽  
W. T. Petuskey
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
Orthorhombic Phase ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Synchrotron Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Diamond Anvil

ABSTRACTHigh pressure synchrotron x-ray diffraction experiments were conducted on KCa2Nb3O10, to determine lattice constants as a function of pressure. A diamond anvil cell was used to produce pressures up to 66 GPa. A phase transition occurred at 13.5 GPa. From the lattice constants, linear compressibilities of 8.55 × 10-4 GPa-1 in the a direction, -9.40 × 10-4 GPa-1 in the b direction, and 142 × 10-4 GPa-1 in the c direction, and a bulk modulus of 68.5 GPa were found for the lower pressure orthorhombic phase.

scholarly journals Annealing effects on the optical and electrochemical properties of tantalum pentoxide films

2021 ◽  
Author(s):  
Wei Ren ◽  
Guang-Dao Yang ◽  
Ai-Ling Feng ◽  
Rui-Xia Miao ◽  
Jun-Bo Xia ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electron Beam Evaporation ◽  
Electrochemical Stability ◽  
The Other ◽  
Tantalum Pentoxide ◽  
Film Electrode ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Annealing Effects

AbstractTantalum pentoxide (Ta2O5) has attracted intensive attention due to their excellent physicochemical properties. Ta2O5 films were synthesized via electron beam evaporation (EBE) and subsequently annealed at different temperatures ranging from 300 to 900 °C. X-ray diffraction (XRD) results show that amorphous Ta2O5 thin films form from 300 to 700 °C and then a phase transition to polycrystalline β-Ta2O5 films occurs since 900 °C. The surface morphology of the Ta2O5 films is uniform and smooth. The resulted Ta2O5 films exhibit excellent transmittance properties for wavelengths ranging from 300 to 1100 nm. The bandgap of the Ta2O5 films is broadened from 4.32 to 4.46 eV by annealing. The 900 °C polycrystalline film electrode has improved electrochemical stability, compared to the other amorphous counterparts.

X-Ray Diffraction and μ-Raman Investigation of the Monoclinic-Orthorhombic Phase Transition in Th1−xUx(C2O4)2·2H2O Solid Solutions

2010 ◽  
Vol 49 (4) ◽  
pp. 1921-1931 ◽  
Author(s):  
Nicolas Clavier ◽  
Nina Hingant ◽  
Murielle Rivenet ◽  
Saïd Obbade ◽  
Nicolas Dacheux ◽  
...  
Keyword(s):  
Phase Transition ◽  
Solid Solutions ◽  
Orthorhombic Phase ◽  
X Ray Diffraction ◽  
X Ray
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