scholarly journals Effect of Thermal Annealing on Conformation of MEH-PPV Chains in Polymer Matrix: Coexistence of H- and J-Aggregates

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1771
Author(s):  
Shu Hu ◽  
Yang Liao ◽  
Yang Zhang ◽  
Xiaoliang Yan ◽  
Zhenlu Zhao ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Annealing Temperature ◽  
Photophysical Properties ◽  
Weight Ratio ◽  
Pmma Film ◽  
Host Matrix ◽  
Extended Conformation ◽  
J Aggregates ◽  
Pmma Blends ◽  
Conformation Transition

In diluted solid solution using poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and polymethyl methacrylate (PMMA) or polystyrene (PS), both aggregated and extended conformations could be formed according to the weight ratio. Aggregated conformation in as-cast MEH-PPV/PMMA film presented a J-aggregate-like photoluminescence (PL) emission. After annealing at 160 °C, its PL showed characteristics of both J- and H-aggregates at the same time; however, extended conformation showed an oligomer-like emission, which was not sensitive to either measurement temperature or annealing temperature. Thus, the conformation transition between aggregated and extended is unlikely to happen in MEH-PPV/PMMA blends during thermal annealing. On the contrary, in MEH-PPV/PS blends, extended conformation dominated in as-cast film with oligomer-like emissions; after annealing at 160 °C, both J- and H- aggregate-like PL emissions were observed, indicating the conformation transitioned from extended to aggregated. Therefore, our work may suggest a new method to manipulate photophysical properties of conjugated polymers by combining appropriate host matrix and thermal annealing processes.

Nickel Oxide Coated on Pretreated MWCNTs as an Electrode for Supercapacitor

2013 ◽  
Vol 829 ◽  
pp. 654-658
Author(s):  
Lida Mahmoudi ◽  
Farzad Mahboubi ◽  
Moreteza Saghafi Yazdi
Keyword(s):  
Nickel Oxide ◽  
Thermal Annealing ◽  
Nickel Hydroxide ◽  
Annealing Temperature ◽  
Electrochemical Characteristics ◽  
Sem Images ◽  
Electroactive Materials ◽  
Nanotubular Structure ◽  
Individual Cnts ◽  
The Individual

Nickel oxide/carbon nanotubes (NiO/CNTs) composite materials for supercapacitor are prepared by chemically depositing of nickel hydroxide onto CNTs pretreated by ultrasonication and followed by thermal annealing at 200-300°C. A series of NiO/CNTs composites with different weight ratios of CNTs and different annealing temperature are synthesized via the same route. The scanning electron microscope (SEM) images show that the nucleation of the nickel hydroxide formed on the outer walls of CNTs due to ultrasonic cavitations, and then nickel oxide coated uniformly on the outer surface of the individual CNTs after thermal annealing. The NiO/CNTs electrode presents a maximum specific capacitance of 254 F/g as well as a good cycle life in 2 M KOH electrolyte. The good electrochemical characteristics of NiO/CNTs composite can be attributed to the three-dimensionally interconnected nanotubular structure with a thin film of electroactive materials.

scholarly journals Correlation between thermal annealing temperature and Joule-heating based insulator-metal transition in VO2 nanobeams

2013 ◽  
Vol 103 (20) ◽  
pp. 203114 ◽  
Author(s):  
Servin Rathi ◽  
Jin-Hyung Park ◽  
In-yeal Lee ◽  
Min Jin Kim ◽  
Jeong Min Baik ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Joule Heating ◽  
Annealing Temperature ◽  
Insulator Metal Transition

Investigation of the influence of the mode of heat treatment of the initial powder on the efficiency of sintering zirconium ceramics by dilatometry

2021 ◽  
Vol 103 (3) ◽  
pp. 17-24
Author(s):  
S. Shevelev ◽  
◽  
E. Sheveleva ◽  
O. Stary ◽  
Keyword(s):  
Thermal Annealing ◽  
Zirconium Dioxide ◽  
Annealing Temperature ◽  
Average Particle Size ◽  
Average Particle ◽  
Sintered Ceramic ◽  
Tetragonal Modification ◽  
Thermal Sintering ◽  
Powder Compacts ◽  
High Degree

Using methods of synchronous thermal and X-ray structural analyzes applied to zirconium dioxide powders partially stabilized with yttrium obtained by chemical coprecipitation the processes of dehydration of these powders during annealing in air have been investigated. Using the dilatometry method, the regularities of compaction of powder compacts have been investigated with thermal sintering. It was found that the resulting powders mainly consist of the tetragonal modification zirconium dioxide and are nano-sized. The average particle size was 25 nm. The resulting powders are characterized by a high degree of agglomeration. It is shown that an increase in the thermal annealing temperature from 500 to 700ºС leads to partial baking of individual particles inside the agglomerate, and causes the formation of hard agglomerates, the presence of which complicates the processes of compaction and subsequent sintering. The presence of such agglomerates prevents the production of ceramics with high mechanical characteristics: density and porosity. Thermal annealing temperature increase leads to a decrease in the density of the sintered ceramic and a decrease in its hardness.

scholarly journals Synthesis of Ge1−xSnx Alloy Thin Films by Rapid Thermal Annealing of Sputtered Ge/Sn/Ge Layers on Si Substrates

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2248 ◽  
Author(s):  
Hadi Mahmodi ◽  
Md Hashim ◽  
Tetsuo Soga ◽  
Salman Alrokayan ◽  
Haseeb Khan ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Near Infrared ◽  
Annealing Temperature ◽  
Solid Phase ◽  
Infrared Region ◽  
Alloy Formation ◽  
Phase Mixing ◽  
Si Substrates ◽  
Msm Photodetector

In this work, nanocrystalline Ge1−xSnx alloy formation from a rapid thermal annealed Ge/Sn/Ge multilayer has been presented. The multilayer was magnetron sputtered onto the Silicon substrate. This was followed by annealing the layers by rapid thermal annealing, at temperatures of 300 °C, 350 °C, 400 °C, and 450 °C, for 10 s. Then, the effect of thermal annealing on the morphological, structural, and optical characteristics of the synthesized Ge1−xSnx alloys were investigated. The nanocrystalline Ge1−xSnx formation was revealed by high-resolution X-ray diffraction (HR-XRD) measurements, which showed the orientation of (111). Raman results showed that phonon intensities of the Ge-Ge vibrations were improved with an increase in the annealing temperature. The results evidently showed that raising the annealing temperature led to improvements in the crystalline quality of the layers. It was demonstrated that Ge-Sn solid-phase mixing had occurred at a low temperature of 400 °C, which led to the creation of a Ge1−xSnx alloy. In addition, spectral photo-responsivity of a fabricated Ge1−xSnx metal-semiconductor-metal (MSM) photodetector exhibited its extending wavelength into the near-infrared region (820 nm).

Effects of thermal annealing temperature and duration on hydrothermally grown ZnO nanorod arrays

2009 ◽  
Vol 255 (11) ◽  
pp. 5861-5865 ◽  
Author(s):  
X.Q. Zhao ◽  
C.R. Kim ◽  
J.Y. Lee ◽  
C.M. Shin ◽  
J.H. Heo ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Annealing Temperature ◽  
Zno Nanorod ◽  
Nanorod Arrays ◽  
Zno Nanorod Arrays

scholarly journals Effect of cation size on electrochemical properties of polymer electrolyte

2019 ◽  
Vol 17 (42) ◽  
pp. 76-84
Author(s):  
Mohammed Kadhim Jawad
Keyword(s):  
Polymer Electrolytes ◽  
Ionic Conduction ◽  
Weight Ratio ◽  
Dielectric Behavior ◽  
Gel Polymer Electrolytes ◽  
Host Matrix ◽  
Ether Oxygen ◽  
Solution Cast ◽  
Increasing Temperature ◽  
Cation Size

This study investigates the ionic conduction dependence on the size of alkaline cations in gel polymer electrolytes based on double iodide can enhance by incorporating a salt having a bulky cation. Group of gel polymer electrolytes with polyethylene oxide (PEO) as a host matrix based on double salts potassium iodide (KI) and rubidium iodide (RbI) with different weight ratio prepared by using solution cast technique.  The maximum value of conductivity reaches (6.03 10⁻3 at 293 K) S/cm for an electrolyte which content (KI 45%, RbI 5%) from binary salt. The ionic conductivity of for gel polymer electrolytes gradually increases by increasing temperature. The real dielectric constant results confirm that the dielectric behavior of the PEO material is a thermally activated process. FTIR results confirm that the shifting of peaks is another way to prove the interactions between PEO and binary salt ascribed to the formation of a transient cross-linking complex between the cations of the ionic liquids and the ether oxygen of the PEO.

Ajustement par recuits rapides RTA (rapid thermal annealing) des contraintes dans des couches minces de tungstène utilisées comme absorbant pour des masques à rayons X

1991 ◽  
Vol 69 (3-4) ◽  
pp. 451-455 ◽  
Author(s):  
H. Lafontaine ◽  
J. F. Currie ◽  
S. Boily ◽  
M. Chaker ◽  
H. Pépin
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Annealing Temperature ◽  
Rf Power ◽  
X Ray ◽  
Stress Changes ◽  
Different Temperatures ◽  
Absorbing Layer ◽  
Good Agreement ◽  
Sputtering System

Tungsten thin films are deposited with a triode sputtering system in order to obtain an absorbing layer for X-ray masks. The mechanical stress is studied as a function of different pressure and RF power conditions during deposition. Rapid thermal annealing at different temperatures and durations is performed in order to produce films under low compressive stress. We observe that the stress changes occur over the time scale of seconds at the annealing temperature and that the corresponding activation energies are low (60 meV). Grain growth in a preferred orientation explains the observed changes in stress. The magnitude in the change of stress is in good agreement with a model proposed by Hoffman et al. relating the stress to grain size and grain boundary dimensions. [Journal translation]

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