scholarly journals Synthesis of Thermochromic W-Doped VO2(M/R) Nanopowders by a Simple Solution-Based Process

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Lihua Chen ◽  
Chunming Huang ◽  
Gang Xu ◽  
Lei Miao ◽  
Jifu Shi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Structural Properties ◽  
Valence State ◽  
Simple Solution ◽  
Tungsten Content ◽  
Scanning Calorimetry ◽  
First Time ◽  
W Doping

Thermochromic W-doped VO2nanopowders were prepared by a novel and simple solution-based method and characterized by a variety of techniques. We mainly investigated the effect of tungsten dopant on the structural properties and phase transition ofV1-xWxO2. The as-obtained nanopowders with tungsten content of ≤2.5 at% can be readily indexed as monoclinic VO2(M) while that of 3 at% assigned into the rutile VO2(R). The valence state of tungsten in the nanopowders is +6. TEM and XRD results show that the substitution of W atom for V in VO2results in a decrease of thedspace of the (011) plane. The phase transition temperature is determined by differential scanning calorimetry (DSC). It is found, for the first time, that the reduction of transition temperature reaches to 17 K per 1 at% of W doping with the tungsten extents of ≤1 at%, but only 9.5 K per 1 at% with the tungsten extents of >1 at%. The reason of this arises from the difficulty of the formation ofV3+-W4+andV3+-W6+pairs by the increasing of W ions doping in theV1-xWxO2system.

scholarly journals Interaction of plant alkaloid, berberine, with zwitterionic and negatively charged phospholipid bilayers

2011 ◽  
Vol 34 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Justyna Gąsiorowska ◽  
Olga Wesołowska ◽  
Krystyna Michalak
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Fluorescence Quenching ◽  
Electrostatic Interactions ◽  
Phospholipid Bilayers ◽  
Scanning Calorimetry ◽  
Double Peak ◽  
Pharmacological Activities ◽  
First Time ◽  
Thermotropic Properties

Interaction of plant alkaloid, berberine, with zwitterionic and negatively charged phospholipid bilayers Berberine exhibits many pharmacological activities e.g. antibacterial, anti-inflammatory, antiproliferative and apoptosis-inducing. Interaction of berberine with model membranes was studied for the first time using differential scanning calorimetry, fluorescence spectroscopy and turbidity measurements. Influence of berberine on thermotropic properties of bilayers formed from zwitterionic DMPC was insignificant, whereas in bilayers formed from negatively charged DMPG berberine reduced the temperature and cooperativity of main phospholipid phase transition. In higher concentrations berberine induced complex double-peak transition, with the new peak appearing in temperature higher than the original one. It suggested the interaction of the alkaloid with lipid headgroup region of the bilayer. Additionally, berberine quenched fluorescence of Prodan to a higher extent than Laurdan that pointed to stronger interaction with membrane segments close to its surface. Berberine-induced fluorescence quenching of both probes was more pronounced in DPPG than in DPPC bilayers. It was concluded that electrostatic interactions governed berberine association with model membrane.

Rheological Properties of Sodium Dodecyl Sulphate-Based Supramolecules Hydrogel Induced by Aluminum Ion

2011 ◽  
Vol 233-235 ◽  
pp. 1966-1971
Author(s):  
Ying Xue Zhou ◽  
Xiao Dong Fan
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Salt Concentration ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Electron Micrograph ◽  
Scanning Calorimetry ◽  
Nonlinear Rheology ◽  
Cylindrical Micelles

Surfactant hydrogels were prepared composed of sodium dodecyl sulphate(SDS) /Al(NO3)3 /H2O systmes. Steady and oscillatory shear experiments were carried out to evaluate the inner structure of the gel with variable Al(NO3)3 concentration at a fixed SDS 20wt% composition in gel region. The results indicated that hydrogels showed shear-induced thinning nonlinear rheology behaviors. Phase transition was measured by differential scanning calorimetry and the transition temperature(Tgel) increased with aluminum salt concentration increasing. It is in conformity with electron micrograph of microstructures from spherical, short rod-like to larger cylindrical micelles. Littler salt change resulted in larger micelles transition derived from supramolecule structure of SDS and Al3+.

Liquid–solid transition of water confined in nanoporous titanium dioxide

2016 ◽  
Vol 30 (19) ◽  
pp. 1650250
Author(s):  
Xin Gao ◽  
Qiang Wang ◽  
Gang Sun ◽  
Chenxi Li ◽  
Lin Hu
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Titanium Dioxide ◽  
Transition Temperature ◽  
Pore Size ◽  
Phase Transition Temperature ◽  
Porous Titanium ◽  
Molar Enthalpy ◽  
Scanning Calorimetry ◽  
Filling Fraction

In this work, we performed differential scanning calorimetry (DSC) experiments to investigate the phase transition temperature and the molar enthalpy of the absorbed water confined in porous titanium dioxide. The porous titanium dioxide with three different pore size distribution and different filling fraction of the absorbed water were examined. We found that both the pore size of the examined samples and the filling fraction of the absorbed water affected the water’s phase transition temperature and its molar enthalpy.

Structural Phase Transition of Tungsten-Doped Vanadium Dioxide Nanopowders Prepared by Thermolysis

2008 ◽  
Vol 8 (3) ◽  
pp. 1417-1421 ◽  
Author(s):  
Zifei Peng ◽  
Wei Jiang ◽  
Heng Liu
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Vanadium Dioxide ◽  
Structural Phase ◽  
Hysteresis Loops ◽  
Tungstic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Transmission Electron

Tungsten-doped vanadium dioxide (VO2) nanopowders were prepared by thermolysis of (NH4)5[(VO)6(CO3)4(OH)9] · 10H2O at low temperature, with active white powdery tungstic acid used as a substitutional dopant. The composition and microstructure of the powders were examined by X-ray diffraction, transmission electron microscope, and differential scanning calorimetry. The change in electrical resistance due to the S–M transition was measured from 0 to 150 °C by the four-probe method. Hysteresis loops and differential scanning calorimetry analysis of the samples indicated that the phase-transition temperature of VO2 nanopowders was 67.15 °C. For tungstendoped VO2 nanopowders, the temperature was reduced to 26.46 °C. After sintering the nanopowders, Tc rose from 26.46 °C to 34.85 °C with the sizes increasing to the bulk. A significant direct correlation between particle size and Tc was confirmed. The results indicated that white powdery tungstic acid is exceptionally effective as a dopant for reducing transition temperature.

Sintered compacts of nano and micron-sized BaTiO3: Dramatic influence on the microstructure and dielectric properties

2006 ◽  
Vol 21 (4) ◽  
pp. 816-822 ◽  
Author(s):  
Vishnu Shanker ◽  
Tokeer Ahmad ◽  
Henry Ip ◽  
Ashok K. Ganguli
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
High Dielectric Constant ◽  
Scanning Calorimetry ◽  
Ferroelectric Transition ◽  
Maximum Dielectric Constant ◽  
High Dielectric ◽  
First Time

Sintered compacts of nano-sized and micron-sized BaTiO3 show sharp ferroelectric transition and high dielectric constant at specific compositions. The sintered compacts with 1 wt% nano-BaTiO3 show a maximum dielectric constant of 1680. At the transition temperature (Tc) there are two maxima at 0.5 and 2 wt%. The variation in the dielectric constant at Tc is also reflected in the behavior of the ferroelectric transition as studied by differential scanning calorimetry. This interesting oscillatory variation of the dielectric constant and dielectric loss with increase in the amount of nanoparticles in the sintered compacts is observed for the first time. The variation of the dielectric properties and the ferroelectric transition of the sintered compacts could be related to subtle changes in the microstructure.

Phase Transitions by Dilatometry, Part I: Synthesis, Characterisation and Isotropic to Smectic-A and Smectic-A to Smectic-B Transitions in Two Liquid Crystalline Higher Homologues of N-(p-n-nonyloxybenzylidene) p-n-alkylanilines

2004 ◽  
Vol 59 (9) ◽  
pp. 537-542 ◽  
Author(s):  
C. Rama Chandra Prabhu ◽  
S. Lakshminarayana ◽  
V. G. K. M. Pisipatia
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Liquid Crystalline ◽  
Scanning Calorimetry ◽  
First Order ◽  
Smectic A ◽  
M 12 ◽  
Phase Variants ◽  
Enthalpy Data

Two higher homologues of N(p-n-nonyloxybenzylidene)p-n-alkylanilines, viz. the 9O.m series with m = 12 and 16, are synthesised and characterised by thermal microscopy, differential scanning calorimetry and density studies. The compounds exhibit the phase variants smectic-A, smectic-B and smectic-G. Density studies reveal the first order nature of the isotropic to smectic-A and smectic-A to smectic-B transitions. An estimate of the pressure dependence of the phase transition temperature, using volume and enthalpy data, is presented. A comparison of these results with those reported on nO.m and other liquid crystalline compounds is presented.

Synthesis of VO2(A) Nanostructures by a Hydrothermal Method and their Transition to VO2(M)

2011 ◽  
Vol 295-297 ◽  
pp. 368-372 ◽  
Author(s):  
Ya Lan Zhong ◽  
Yi Fu Zhang ◽  
Xin Liu ◽  
Xing Hai Liu ◽  
Chi Huang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Hydrothermal Method ◽  
Scanning Calorimetry ◽  
Facile Hydrothermal Method ◽  
X Ray ◽  
Transmission Electron ◽  
First Time

VO2(A) nanobelts have been synthesized using V2O5, H2O2, ethanol, H2O as the starting materials through a facile hydrothermal method. The as-obtained products were characterized by X-ray powder diffraction (XRD), X-ray photoelecton spectroscopy (XPS), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Some parameters, such as, the reaction time, reaction temperature and the ratio of EtOH/H2O, have greatly influenced on the phases and morphologies of the final products. It was found that VO2(A) can be converted to VO2(M) at 700 °C for 2 h for the first time. Furthermore, the phase transition properties of VO2(A) and VO2(M) phases were respectively studied.

scholarly journals Thermal analysis: basic concept of differential scanning calorimetry and thermogravimetry for beginners

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Nurul Fatahah Asyqin Zainal ◽  
Jean Marc Saiter ◽  
Suhaila Idayu Abdul Halim ◽  
Romain Lucas ◽  
Chin Han Chan
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Commercial Application ◽  
Scanning Calorimetry ◽  
Teaching Activities ◽  
Sample Decomposition ◽  
Calibration Baseline

AbstractWe present an overview for the basic fundamental of thermal analysis, which is applicable for educational purposes, especially for lecturers at the universities, who may refer to the articles as the references to “teach” or to “lecture” to final year project students or young researchers who are working on their postgraduate projects. Description of basic instrumentation [i.e. differential scanning calorimetry (DSC) and thermogravimetry (TGA)] covers from what we should know about the instrument, calibration, baseline and samples’ signal. We also provide the step-by-step guides for the estimation of the glass transition temperature after DSC as well as examples and exercises are included, which are applicable for teaching activities. Glass transition temperature is an important property for commercial application of a polymeric material, e.g. packaging, automotive, etc. TGA is also highlighted where the analysis gives important thermal degradation information of a material to avoid sample decomposition during the DSC measurement. The step-by-step guides of the estimation of the activation energy after TGA based on Hoffman’s Arrhenius-like relationship are also provided.

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