scholarly journals Фазовый переход первого рода в нанотубулярном диоксиде титана

2021 ◽  
Vol 63 (12) ◽  
pp. 2016
Author(s):  
А.А. Сушникова ◽  
А.А. Валеева ◽  
И.Б. Дорошева ◽  
А.А. Ремпель
Keyword(s):  
Phase Transition ◽  
Amorphous State ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Titanium Foil ◽  
Outer Diameter ◽  
Functional Material ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Synthesis Conditions

Titanium dioxide (TiO2) nanotubes array with the length of 16 μm and the outer diameter of 100 nm were synthesized by anodic oxidation of titanium foil in an electrolyte solution containing a fluorine-containing solution of ethylene glycol. The selected synthesis conditions make it possible to separate the nanotubular array from the titanium foil and study it as a homogeneous functional material. The performed scanning electron microscopy study and Brunauer–Emmett–Teller analysis allowed to get data on the morphology of the samples. X-ray diffraction, thermogravimetric, and differential scanning calorimetry analysis made it possible to determine the temperature of the phase transition of the amorphous state into crystalline anatase (sp.gr. I4/amd). Observed phase transition of first order takes place at temperature about 350 °С.

A Simple Method for Synthesis of PbS Nanoparticles Using 2-Mercaptoethanol as the Capping Agent

2012 ◽  
Vol 31 (6) ◽  
pp. 723-725 ◽  
Author(s):  
Gholamreza Nabiyouni ◽  
Parviz Boroojerdian ◽  
Kambiz Hedayati ◽  
Davood Ghanbari
Keyword(s):  
Electron Microscopy ◽  
Electronic Absorption Spectra ◽  
Blue Shift ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Sulfur Source ◽  
Capping Agent ◽  
X Ray Diffraction ◽  
Simple Method ◽  
Vis Spectroscopy

AbstractLead sulfide nanoparticles were synthesized at room temperature via a simple chemical reaction. In this synthesis, 2-mercaptoethanolwas used as the capping agent and sodium sulfide was used as a sulfur source. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy Electron microscopy study showed that without using a capping agent the bulk PbS is obtained, while adding the mercaptoethanol leads to production of nanoparticles. We found that the electronic absorption spectra as well as the particle sizes depend on the used capping agents. Two exitonic peaks with a large blue shift were observed when mercaptoethanol was used.

scholarly journals Crystallization Features of Amorphous Rapidly Quenched High Cu Content TiNiCu Alloys upon Severe Plastic Deformation

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2670
Author(s):  
Alexander Glezer ◽  
Nikolay Sitnikov ◽  
Roman Sundeev ◽  
Alexander Shelyakov ◽  
Irina Khabibullina
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Copper Content ◽  
Melt Spinning ◽  
High Pressure Torsion ◽  
Amorphous State ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cu Content ◽  
Rapid Melt Quenching

In recent years, the methods of severe plastic deformation and rapid melt quenching have proven to be an effective tool for the formation of the unique properties of materials. The effect of high-pressure torsion (HPT) on the structure of the amorphous alloys of the quasi-binary TiNi–TiCu system with a copper content of more than 30 at.% produced by melt spinning technique has been analyzed using the methods of scanning electron microscopy, X-ray diffraction analysis, and differential scanning calorimetry (DSC). The structure examinations have shown that the HPT of the alloys with a Cu content ranging from 30 to 40 at.% leads to nanocrystallization from the amorphous state. An increase in the degree of deformation leads to a substantial change in the character of the crystallization reflected by the DSC curves of the alloys under study. The alloys containing less than 34 at.% Cu exhibit crystallization peak splitting, whereas the alloys containing more than 34 at.% Cu exhibit a third peak at lower temperatures. The latter effect suggests the formation of regions of possible low-temperature crystallization. It has been established that the HPT causes a significant decrease in the thermal effect of crystallization upon heating of the alloys with a high copper content relative to that of the initial amorphous melt quenched state.

Phase transitions of (1−x) PbZrO3 + x (Na1/2Bi1/2)TiO3 (0.01 ≤ x ≤ 0.15) solid solutions

1999 ◽  
Vol 14 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Jung-Kun Lee ◽  
Hyuk-Joon Youn ◽  
Kug Sun Hong
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Solid Solutions ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Two Phase ◽  
Phase Transition Temperatures ◽  
Temperature Phase Transition ◽  
Increasing Temperature

Morphotropic phase boundaries and temperature dependent phase transitions of (1 – x) PbZrO3 + x (Na1/2Bi1/2)TiO3 (0.01 ≤ x ≤ 0.15) solid solutions were investigated by x-ray diffraction, differential scanning calorimetry (DSC), and dielectric property analysis. Two morphotropic phase transitions at room temperature were found at x = 0.1 and 0.13, which were from antiferroelectric orthorhombic (with 4 × 4 × 2 superlattice [orthorhombic (I)]) to antiferroelectric orthorhombic (with 2 × 2 × 2 superlattice [orthorhombic (II)]) and from orthorhombic (II) to ferroelectric rhombohedral, respectively. With increasing temperature, the samples with 0.01 ≤ x < 0.1 showed two phase transitions, i.e., from orthorhombic (I) to orthorhombic (II) and from orthorhombic (II) to cubic. The other samples had only one phase transition with increasing temperature. Phase transition temperatures of all the samples were measured using DSC, and a phase diagram for the solid solutions was constructed. A model illustrating the antiparallel shift of Pb ions in the orthorhombic (II) phase was also proposed.

Molecular Reorientation in the Plastic Crystalline Phase of Tris

1979 ◽  
Vol 32 (4) ◽  
pp. 905 ◽  
Author(s):  
RE Wasylishen ◽  
PF Barron ◽  
DM Doddrell
Keyword(s):  
Phase Transition ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Molecular Reorientation ◽  
Liquid Phase Transition ◽  
X Ray ◽  
Spin Lattice

Carbon-13 N.M.R. spectra of tris(hydroxymethyl)aminomethane (Tris) have been measured between 407 and 461 K. Proton-decoupled 13C N.M.R. spectra of solid Tris between 407 K and its melting point are relatively sharp (v� < 30 Hz) indicating rapid overall molecular reorientation in this temperature range. It was not possible to detect a 13C N.M.R, signal for Tris below 407 K. The observed 13C N.M.R. spin-lattice relaxation times appear continuous across the solid ↔ liquid phase transition. From the temperature dependence of T1, a rotational activation energy of 51.6 � 6 kJ mol-1 is calculated, which indicates that the molecules must expend considerable energy in reorienting. The N.M.R. results are discussed in relation to previous differential scanning calorimetry and X-ray diffraction data which indicate that Tris undergoes a solid ↔ solid transition at 407 K.

Crystallization of Amorphous Cu49.7Ti31.8Zr11.3Ni7.2 Alloy

2016 ◽  
Vol 869 ◽  
pp. 464-469 ◽  
Author(s):  
Carlos Triveño Rios ◽  
R. Contieri
Keyword(s):  
Low Cost ◽  
Centrifugal Casting ◽  
Amorphous State ◽  
Bulk Sample ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
High Fracture ◽  
Crystalline Materials ◽  
Thermal Crystallization ◽  
Arc Melting

Bulk metallic glasses are attractive materials for structural and functional applications when compared to crystalline materials. The Cu-based glasses exhibit particular interest due primarily to their relatively low cost and high fracture resistance. In this work the Cu49.7Ti31.8Zr11.3Ni7.2 alloy was prepared from the mixture of pure metals by arc melting and following the ingot was re-melted by centrifugal casting in wedge-section copper mould. The structure of wedge bulk sample was evaluated by a combination of X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The results show that the amorphous state is formed in the thinner region and it is maintained up to thickness of 3.5 mm in the wedge bulk-sample. The crystallization temperature was observed above 400 °C coinciding with the studies of thermal crystallization by XRD and DSC. Dynamical heating of the amorphous phase from room temperature up to 750°C showed the formation of CuTi, Cu10Zr7 e Cu2TiZr crystalline phases.

scholarly journals Preparation and Characterisation of Nobiletin-Loaded Nanostructured Lipid Carriers

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Wei Huang ◽  
Huating Dou ◽  
Houjiu Wu ◽  
Zhigao Sun ◽  
Hua Wang ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Chemical Interaction ◽  
Amorphous State ◽  
Spherical Shape ◽  
Entrapment Efficiency ◽  
Nanostructured Lipid Carriers ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Lipid Mixture ◽  
Food Response

The objective of this manuscript was to investigate and optimise the potential of nanostructured lipid carriers (NLCs) as a carrier system for nobiletin (NOB), which was prepared by high-pressure homogenisation method. Additionally, this study was focused on the application of NOB-loaded NLC (NOB-NLC) in functional food. Response surface method with a three-level Box–Behnken design was validated through analysis of variance, and the robustness of the design was confirmed through the correspondence between the values measured in the experiments and the predicted ones. Properties of the prepared NOB-NLC, such as Z-average, polydispersity, entrapment efficiency, zeta potential, morphology, and crystallinity, were investigated. NOB-NLC exhibited a spherical shape with a diameter of 112.27 ± 5.33 nm, zeta potential of −35.1 ± 2.94 mV, a polydispersity index of 0.251 ± 0.058, and an EE of 81.06%  ±  6.02%. Results from X-ray diffraction and differential scanning calorimetry of NOB-NLC reviewed that the NOB crystal might be converted to an amorphous state. Fourier transform infrared spectroscopic analysis demonstrated that chemical interaction was absent between the compound and lipid mixture in NOB-NLC.

Preparation of Tungsten-Doped VO2 (M) Nanoparticles through Sol-Gel Method and Hydrothermal Synthesis

2014 ◽  
Vol 881-883 ◽  
pp. 960-963 ◽  
Author(s):  
Ji Qi ◽  
Bin Zhao ◽  
Naisen Yu ◽  
Chen Niu ◽  
Guan Gran Sun
Keyword(s):  
Phase Transition ◽  
Vanadium Dioxide ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
New Process ◽  
Scanning Electron

A new process was developed for synthesizing tungsten-doped vanadium dioxide VO2(M) from ammonium metavanadate. The process includes obtaining V2O5by pyrolysing NH4VO3, doping tungsten in V2O5by sol-gel method, and reducing V2O5to VO2(M) with hydrazine by hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were applied to characterizing the product. The experimental results indicated that tungsten doped VO2(M) nanoparticles were successfully synthesized. The product VO2(M) presents mainly rod-like and block-like morphology. The phase transition temperature decreases with tungsten doped amount increasing, the phase transition takes place over the range from 36.23°C to 62.16°C and the largest enthalpy of the phase transition is 16.24J/g.

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