scholarly journals Intrinsic Defect Engineering in Eu3+ Doped ZnWO4 for Annealing Temperature Tunable Photoluminescence

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 99 ◽  
Author(s):  
Bao-gai Zhai ◽  
Long Yang ◽  
Yuan Huang
Keyword(s):  
Optical Absorption ◽  
Thermal Annealing ◽  
Density Functional ◽  
Annealing Temperature ◽  
Intrinsic Defect ◽  
Defect Engineering ◽  
Intrinsic Defects ◽  
X Ray ◽  
Color Tunable ◽  
Co Precipitation

Eu3+ doped ZnWO4 phosphors were synthesized via the co-precipitation technique followed by subsequent thermal annealing in the range of 400–1000 °C. The phase, morphology, elemental composition, chemical states, optical absorption, and photoluminescence (PL) of the phosphors were characterized by X-ray diffraction, scanning electron microscopy, dispersive X-ray spectroscopy, X-ray photoelectron spectrometry, diffuse UV–vis reflectance spectroscopy, PL spectrophotometry, and PL lifetime spectroscopy, respectively. It is found that the PL from Eu3+ doped ZnWO4 is tunable through the control of the annealing temperature. Density functional calculations and optical absorption confirm that thermal annealing created intrinsic defects in ZnWO4 lattices play a pivotal role in the color tunable emissions of the Eu3+ doped ZnWO4 phosphors. These data have demonstrated that intrinsic defect engineering in ZnWO4 lattice is an alternative and effective strategy for tuning the emission color of Eu3+ doped ZnWO4. This work shows how to harness the intrinsic defects in ZnWO4 for the preparation of color tunable light-emitting phosphors.

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]

Doped ZnO Nanowires Obtained by Thermal Annealing

2007 ◽  
Vol 7 (2) ◽  
pp. 700-703 ◽  
Author(s):  
C. X. Shan ◽  
Z. Liu ◽  
C. C. Wong ◽  
S. K. Hark
Keyword(s):  
Thermal Annealing ◽  
Doping Concentration ◽  
Annealing Temperature ◽  
Zno Nanowires ◽  
X Ray Diffraction ◽  
X Ray ◽  
Doped Zno ◽  
Znse Nanowires ◽  
Annealing Method ◽  
Scanning Electron

Doped ZnO nanowires were prepared in a very simple and inexpensive thermal annealing method using ZnSe nanowires as a precursor. As doped, P doped, and As/P codoped ZnO nanowires were obtained in this method. X-ray diffraction shows that the zincblende ZnSe nanowires were converted to doped wurtzite ZnO nanowires. The incorporation of the dopants was confirmed by energy dispersive X-ray spectroscopy. The doping concentration could be adjusted by changing the annealing temperature and duration. Scanning electron microscopy indicated that the morphology of the ZnSe nanowires was essentially retained after the annealing and doping process. Photoluminescence spectroscopy also verified the incorporation of the dopants into the nanowires.

scholarly journals Near-IR Emitting Si Nanocrystals Fabricated by Thermal Annealing of SiNx/Si3N4 Multilayers

2019 ◽  
Vol 9 (22) ◽  
pp. 4725
Author(s):  
D. M. Zhigunov ◽  
A. A. Popov ◽  
Yu. M. Chesnokov ◽  
A. L. Vasiliev ◽  
A. M. Lebedev ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Photoelectron Spectroscopy ◽  
Annealing Temperature ◽  
X Ray ◽  
Near Ir ◽  
Transmission Electron ◽  
Si Nanocrystals ◽  
Mean Size ◽  
The One ◽  
Multilayered Thin Films

Silicon nanocrystals in silicon nitride matrix are fabricated by thermal annealing of SiNx/Si3N4 multilayered thin films, and characterized by transmission electron microscopy, X-ray reflectivity and diffraction analysis, photoluminescence and X-ray photoelectron spectroscopy techniques. Si nanocrystals with a mean size of about 4 nm are obtained, and their properties are studied as a function of SiNx layer thickness (1.6–2 nm) and annealing temperature (900–1250 °C). The effect of coalescence of adjacent nanocrystals throughout the Si3N4 barrier layers is observed, which results in formation of distinct ellipsoidal-shaped nanocrystals. Complete intermixing of multilayered film accompanied by an increase of nanocrystal mean size for annealing temperature as high as 1250 °C is shown. Near-IR photoluminescence with the peak at around 1.3–1.4 eV is detected and associated with quantum confined excitons in Si nanocrystals: Photoluminescence maximum is red shifted upon an increase of nanocrystal mean size, while the measured decay time is of order of microsecond. The position of photoluminescence peak as compared to the one for Si nanocrystals in SiO2 matrix is discussed.

Effects of thermal annealing on the distribution of boron and phosphorus in p-i-n structured silicon nanocrystals embedded in silicon dioxide

2021 ◽  
Author(s):  
Keita Nomoto ◽  
Xiang-Yuan Cui ◽  
Andrew Breen ◽  
Anna Ceguerra ◽  
Ivan Perez-Wurfl ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Thermal Annealing ◽  
Silicon Nanocrystals ◽  
Density Functional ◽  
Oxygen Vacancies ◽  
Annealing Temperature ◽  
Atom Probe ◽  
Functional Theory ◽  
Dopant Atoms ◽  
P Type

Abstract Thermal annealing temperature and time dictate the microstructure of semiconductor materials such as silicon nanocrystals (Si NCs). Herein, atom probe tomography (APT) and density functional theory (DFT) calculations are used to understand the thermal annealing temperature effects on Si NCs grown in a SiO2 matrix and the distribution behaviour of boron (B) and phosphorus (P) dopant atoms. The APT results demonstrate that raising the annealing temperature promotes growth and increased P concentration of the Si NCs. The data also shows that the thermal annealing does not promote the incorporation of B atoms into Si NCs. Instead, B atoms tend to locate at the interface between the Si NCs and SiO2 matrix. The DFT calculations support the APT data and reveal that oxygen vacancies regulate Si NC growth and dopant distribution. This study provides the detailed microstructure of p-type, intrinsic, and n-type Si NCs with changing annealing temperature and highlights how B and P dopants preferentially locate with respect to the Si NCs embedded in the SiO2 matrix with the aid of oxygen vacancies. These findings will guide us towards future optoelectronic applications.

Reduction of the Optical Absorption of Zinc Germanium Phosphide Via Post-Growth Thermal Anneal

1999 ◽  
Vol 607 ◽  
Author(s):  
How-Ghee Ang ◽  
Leng-Leng Chng ◽  
Yiew-Wang Lee ◽  
Colin J. Flynn ◽  
Phil C. Smith ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Coefficient ◽  
Thermal Annealing ◽  
Annealing Time ◽  
Near Infrared ◽  
Annealing Temperature ◽  
Near Band Edge ◽  
Percentage Decrease ◽  
Optimal Annealing Temperature ◽  
Zinc Germanium Phosphide

AbstractThis paper describes the reduction of the near-band-edge absorption of zinc germanium phosphide (ZGP) through thermal annealing. The effects of the annealing time, temperature and vapour atmosphere on the reduction of the optical absorption in the near infrared (NIR) region are reported. Results have shown that the optical absorption at 2µm is reduced by at least 50% upon thermal anneal of ZGP. The optimal annealing temperature was 600'C and the optimal annealing time ranged from 200 - 400 h. Annealing in vacuum yielded a larger reduction in the 2-µm optical absorption compared to annealing in the presence of additional zinc and phosphorus vapours. Re-annealing ZGP further reduced the absorption coefficient at 2-µm. However, the percentage decrease in the 2-µm absorption coefficient was much smaller compared to the first thermal anneal.

scholarly journals Defect engineering on V2O3 cathode for long-cycling aqueous zinc metal batteries

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kefu Zhu ◽  
Shiqiang Wei ◽  
Hongwei Shou ◽  
Feiran Shen ◽  
Shuangming Chen ◽  
...  
Keyword(s):  
Density Functional ◽  
Active Material ◽  
Density Functional Theory Calculations ◽  
Defect Engineering ◽  
Functional Theory ◽  
X Ray ◽  
Positron Annihilation Lifetime ◽  
Multivalent Ions ◽  
Ion Storage ◽  
Zn Ions

AbstractDefect engineering is a strategy that is attracting widespread attention for the possibility of modifying battery active materials in order to improve the cycling stability of the electrodes. However, accurate investigation and quantification of the effect of the defects on the electrochemical energy storage performance of the cell are not trivial tasks. Herein, we report the quantification of vanadium-defective clusters (i.e., up to 5.7%) in the V2O3 lattice via neutron and X-ray powder diffraction measurements, positron annihilation lifetime spectroscopy, and synchrotron-based X-ray analysis. When the vanadium-defective V2O3 is employed as cathode active material in an aqueous Zn coin cell configuration, capacity retention of about 81% after 30,000 cycles at 5 A g−1 is achieved. Density functional theory calculations indicate that the vanadium-defective clusters can provide favorable sites for reversible Zn-ion storage. Moreover, the vanadium-defective clusters allow the storage of Zn ions in V2O3, which reduces the electrostatic interaction between the host material and the multivalent ions.

Synthesis of α-Fe2O3 nanoparticles and analyzing the effect of annealing temperature on its properties

2020 ◽  
Vol 38 (1) ◽  
pp. 116-121
Author(s):  
Bhargavi Ram Thimmiah ◽  
Gobi Nallathambi
Keyword(s):  
Size Distribution ◽  
Potassium Hydroxide ◽  
Annealing Temperature ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
X Ray ◽  
The Mean ◽  
Co Precipitation ◽  
Tga Analysis ◽  
Uniform Size Distribution

Abstractα-Fe2O3 nanoparticles were synthesized via co-precipitation technique using ferric and ferrous salts and potassium hydroxide as precipitation agents. The samples were calcined at 350 °C, 550 °C and 750 °C for 3 hours. The obtained iron oxide was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dynamic light scattering (DLS). Crystallinity of the sample was studied by X-ray diffraction. SEM micrographs showed nonuniform size distribution of the particles forming agglomerates. TGA analysis revealed trace amount of weight loss and material stability for the samples calcined at temperatures above 500 °C. DLS results indicated that increasing of annealing temperature resulted in reduction of the particle size and more uniform size distribution. At the maximum annealing temperature of 750 °C, the mean diameter of the particles of 100 nm was observed.

Thermal Annealing-Activated Crystallinity Metastasis of Al:ZnO Thin Films

2015 ◽  
Vol 1109 ◽  
pp. 181-185 ◽  
Author(s):  
Mohd Firdaus Malek ◽  
Mohamad Hafiz Mamat ◽  
M.Z. Musa ◽  
M. Rusop
Keyword(s):  
Thin Films ◽  
Thermal Annealing ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Dip Coating ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dip Coating Technique ◽  
Multilayered Thin Films

Multilayered thin films of aluminum-doped ZnO (Al:ZnO) have been deposited by the sol-gel dip coating technique. Experimental results indicated that the thermal annealing temperature affected the crystallinity of the Al:ZnO films. X-ray diffraction (XRD) analysis showed that thin films were preferentially orientated along the c-axis plane. The preferred orientation along (0 0 2) plane becomes more pronounced as the thermal annealing being increased. The film thickness ranges between 180 and 690 nm. In our experiments, the most optimum condition of Al:ZnO annealing temperature was both 500 oC.

Sign in / Sign up

Export Citation Format

Share Document