Enthalpy of phase transition of isonicotinic acid

2017 ◽  
Vol 25 (7) ◽  
pp. 971-975 ◽  
Author(s):  
Dongfang Zhao ◽  
Guanghui Liu ◽  
Jian Sun ◽  
Lisheng Wang
Keyword(s):  
Phase Transition ◽  
Isonicotinic Acid ◽  
Enthalpy Of Phase Transition

Preparation of RHA-Paraffin Phase Change Materials

2011 ◽  
Vol 399-401 ◽  
pp. 1156-1159
Author(s):  
Jun Wang ◽  
Bao Guo Ma ◽  
Jian Liang Zhang ◽  
Wen Yang
Keyword(s):  
Phase Transition ◽  
Phase Change ◽  
Phase Change Material ◽  
Rice Husk ◽  
Absorption Rate ◽  
Phase Change Materials ◽  
Rice Husk Ash ◽  
Dsc Analysis ◽  
Change Material ◽  
Enthalpy Of Phase Transition

In this paper, a kind of RHA-paraffin phase change material was prepared, and the SEM was used for observing its internal morphologies, DSC analysis was carried out for detecting its temperature and enthalpy of phase transition. The results showed that rice husk ash have a greater absorption rate for paraffin; a large number of pores of the RHA were filled by paraffin in the RHA-paraffin phase change material, and the absorption rate can reach 53.5%.

scholarly journals Enthalpy of Phase Transition and Prediction of Phase Equilibria in Systems of Glycols and Glycol Ethers

10.12737/4142 ◽  
2014 ◽  
Vol 2 (1) ◽  
pp. 86-90
Author(s):  
Zoya Esina ◽  
Aleksandr- Miroshnikov- ◽  
Margarita-Rashidovna Korchuganova-
Keyword(s):  
Phase Transition ◽  
Phase Equilibria ◽  
Glycol Ethers ◽  
Enthalpy Of Phase Transition

Comparison between Vanadium Dioxides Produced by Ammonium Metavanadate and Vanadium Pentoxide

2011 ◽  
Vol 306-307 ◽  
pp. 234-237 ◽  
Author(s):  
Ji Qi ◽  
Chen Niu ◽  
Ying Mei Xu ◽  
Hua Hai ◽  
Lei Zou
Keyword(s):  
Phase Transition ◽  
Vanadium Pentoxide ◽  
Thermal Reduction ◽  
Ammonium Metavanadate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Ammonia Gas ◽  
X Ray ◽  
Pentagonal Prism ◽  
Enthalpy Of Phase Transition

The facile processes were developed for synthesizing vanadium dioxide (VO2) by pyrolyzing ammonium metavanadate (NH4VO3) in nitrogen (N2) flow and by thermal reduction of vanadium pentoxide (V2O5) in ammonia gas. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were applied to analyzing the product VO2. The experimental results indicated that VO2microcrystal particles were successfully synthesized from both NH4VO3and V2O5. From NH4VO3the product VO2presents two kinds of micro morphologies, torispherical and pentagonal prism. The phase transition mainly takes place at 337.8K and 341.8K. The average enthalpy of phase transition is 28.82 J/g. From V2O5the product VO2presents rhombohedral. The phase transition temperature is approximately 342.6K and the enthalpy of phase transition is 44.90 J/g.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

Dynamic low-dose electron diffraction and imaging of phase transitions in polymers

1993 ◽  
Vol 51 ◽  
pp. 890-891
Author(s):  
David C. Martin ◽  
Jun Liao
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Electron Diffraction ◽  
Low Dose ◽  
Dark Field ◽  
Continuous Change ◽  
Selected Area Electron Diffraction ◽  
Resolution Electron ◽  
Chain Axis ◽  
High Resolution Electron Micrographs

By careful control of the electron beam it is possible to simultaneously induce and observe the phase transformation from monomer to polymer in certain solid-state polymcrizable diacetylenes. The continuous change in the crystal structure from DCHD diacetylene monomer (a=1.76 nm, b=1.36 nm, c=0.455 nm, γ=94 degrees, P2l/c) to polymer (a=1.74 nm, b=1.29 nm, c=0.49 nm, γ=108 degrees, P2l/c) occurs at a characteristic dose (10−4C/cm2) which is five orders of magnitude smaller than the critical end point dose (20 C/cm2). Previously we discussed the progress of this phase transition primarily as observed down the [001] zone (the chain axis direction). Here we report on the associated changes of the dark field (DF) images and selected area electron diffraction (SAED) patterns of the crystals as observed from the side (i.e., in the [hk0] zones).High resolution electron micrographs (HREM), DF images, and SAED patterns were obtained on a JEOL 4000 EX HREM operating at 400 kV.

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