scholarly journals Hydrothermal Synthesis and Optical Properties of Undoped and \(\text{Eu}^{3+}\)-doped Zinc Stannate Nanocrystals

2016 ◽  
Vol 25 (4) ◽  
pp. 327 ◽  
Author(s):  
Nguyen Duy Thien ◽  
Nguyen Ngoc Tu ◽  
Ngo Nhu Viet ◽  
Nguyen Duy Phuong ◽  
Le Van Vu ◽  
...  
Keyword(s):  
Optical Properties ◽  
Emission Spectra ◽  
Molar Ratio ◽  
Face Centered Cubic ◽  
Excitation Spectra ◽  
Cubic Crystal ◽  
Zinc Stannate ◽  
Scattering Spectra ◽  
Hydrothermal Approach ◽  
Face Centered

Abstract. In this work we report a hydrothermal approach for synthesis of zinc stannate (Zn2SnO4)nanocrystals. Our research focused on the effect of the molar ratio of initial chemicals, reaction temperature and reaction duration on the phase composition and the fluorescence properties.Structural and optical properties of the final products were investigated in detail. X-ray diffractionanalysis indicated that the Zn2SnO4 nanocrystals possess face-centered cubic crystal structure.Raman scattering spectra exhibit two characteristic vibrational modes of Zn2SnO4 crystals. Optical band gap of Eu3+-doped Zn2SnO4 nanocrystals obviously depends on Eu3+content. Theroom-temperature emission spectra of the undoped Zn2SnO4 nanocrystals show two broad bands,while the photoluminescence spectra of Eu3+-doped Zn2SnO4 nanocrystals exhibit the emissionpeaks related to the radiative intra-configurational f-f tr ansitions of Eu3+ions. The absorptiontransitions within Eu3+ions were observed both in the photoluminescence excitation spectra andin the diffuse reflection spectra.

The Influence of the Synthesis Method on the Formation of Phase Composition and Catalytic Centers Gd2Zr2O7

2020 ◽  
Vol 1009 ◽  
pp. 69-74
Author(s):  
Ekaterina Borisovna Markova ◽  
Alexander Genrihovich Cherednichenko ◽  
V.V. Kurilkin ◽  
J.M. Serov
Keyword(s):  
Crystal Structure ◽  
Synthesis Method ◽  
Nanocrystalline Powders ◽  
Face Centered Cubic ◽  
Cubic Crystal ◽  
Wide Range ◽  
Physicochemical Methods ◽  
Degradation Reaction ◽  
Cubic Structure ◽  
Face Centered

The influence of the type of crystal structure of complex gadolinium oxides on their catalytic activity was studied using a wide range of physicochemical methods. It was shown that the synthesized nanocrystalline powders Gd2Zr2O7 form highly symmetric face-centered cubic crystal structures. In the course of catalytic experiments, it was found that the formation of a cubic structure increases the degree of conversion of propane and the shift of cracking temperatures to a lower area. The formation of various defects contributes to the course of the dehydrogenation or degradation reaction due to the different number of catalytic centers.

On the Dynamical Propeties of a Strongly Anharmonic Face-Centered Cubic Crystal

1998 ◽  
Vol 12 (27n28) ◽  
pp. 2869-2879 ◽  
Author(s):  
V. I. Zubov ◽  
C. G. Rodrigues ◽  
M. F. Pascual
Keyword(s):  
Crystallographic Direction ◽  
Face Centered Cubic ◽  
Mean Square ◽  
Cubic Crystal ◽  
Cubic Lattice ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Face Centered ◽  
Anharmonic Crystals

We study the interatomic correlations and mean square relative displacements (MSRD) in anharmonic crystals on the basis of the correlative method of unsymmetrized self-consistent field (CUSF). Here we present general formulae for crystals with the anharmonicity, including the strong one, up to the fourth anharmonic terms and perform calculations of the quadratic correlation moments (QCM) in a crystal with face centered cubic lattice, namely in solid Ar. The second order of CUSF allows one to investigate correlations in this lattice between the nearest, second, third and fourth neighbors. The anharmonicity was demonstrated to have strong effect on the interatomic correlations at temperatures above 0.4 of the melting temperature causing a drastic rise near the spinodal point. The dependence of QCM on the distance between atoms and on the crystallographic direction is discussed.

Luminescence and Optical Properties of Li2O3:Gd2O3:B2O3:Sm2O3 Glasses System

2014 ◽  
Vol 979 ◽  
pp. 479-482 ◽  
Author(s):  
Warawut Sa-Ardsin ◽  
Patarawagee Yasaka ◽  
J. Kaewkhao ◽  
K. Boonin
Keyword(s):  
Optical Properties ◽  
Absorption Spectra ◽  
Excited States ◽  
Emission Spectra ◽  
Concentration Quenching ◽  
Excitation Spectra ◽  
Quenching Effect ◽  
Air Atmosphere ◽  
Glass Matrices ◽  
Concentration Quenching Effect

The samarium-doped lithium-gadolinium borate [60Li2O:10Gd2O3:(30-x) B2O3:xSm2O3] (LGBO:Sm3+) glasses have been melted and quenched in stainless plate under an air atmosphere. Some physical and optical properties within wavelength concerned and photoluminescence of the LGBO:Sm3+glasses were measured and discussed. The density of glasses dropped until 0.10 mol% and tends to increase after that point, while molar volume of the glasses tends to increase with concentration of Sm2O3.. In absorption spectra, there are 2 obvious peaks in UV-VIS range and 6 peaks in NIR range indicating the Sm3+in glass matrices. The sharpness of a peak, in the absorption spectra, also increases with concentration of the dopant. The 7 obvious peaks in excitation spectra represent the transitions from the ground state6H5/2to various excited states. Furthermore, The emission spectra were observed under 404 nm light from the Xenon compact arc lamps, and showed the concentration quenching effect (CQE) at 1.00 mol% of Sm3+. Additional, The lifetimes showed decreasing trend with concentration of Sm2O3.. As the result, The LGBO:Sm3+glass doped with 1.00 mol% of Sm3+gives the highest result for luminescence properties.

Upconversion Luminescence Properties of Er3+ Doped Yb2Ti2O7 Nanophosphor by Gd3+ Codoping

2016 ◽  
Vol 16 (4) ◽  
pp. 3690-3694 ◽  
Author(s):  
B. S Cao ◽  
J. L Wu ◽  
X. H Wang ◽  
Z. Q Feng ◽  
B Dong
Keyword(s):  
Cell Parameter ◽  
Upconversion Luminescence ◽  
Sol Gel ◽  
Nominal Composition ◽  
Face Centered Cubic ◽  
Cubic Crystal ◽  
Crystal Field Symmetry ◽  
Field Symmetry ◽  
Face Centered ◽  
Upconversion Emissions

Er3+ doped Yb2Ti2O7 nanophosphors by Gd3+ codoping with nominal composition of (Er0.05Yb0.95−xGdx)2Ti2O7 (x = 0, 0.2, 0.4, 0.6, 0.8, and 0.95) have been prepared by sol–gel method. −Er3+–Gd3+ codoped Yb2Ti2O7 was characteristic of a typical face-centered cubic crystal phase, and the unit cell parameter increased linearly with the increase of Gd3+ concentration. Under a 976 nm laser diode excitation, both green and red upconversion emissions were observed and the upconversion emissions were enhanced significantly by Gd3+ codoping, showing the strongest green and red emissions at 80 mol% Gd3+ codoping. The intensity ratio of green to red emissions (Igreen/Ired) increased monotonously with the increase of Gd3+ concentration. The energy transfer between Yb3+ and Er3+ and the variation of local crystal field symmetry of Er3+ by the substitution of Yb3+ by Gd3+ ions led to the improvement of upconversion properties of Er3+–Gd3+ codoped Yb2Ti2O7 nanophosphors.

Optical properties and carrier dynamics of ensembles of InP nanowires grown on non-single-crystal platforms

2009 ◽  
Vol 1178 ◽  
Author(s):  
Takehiro Onishi ◽  
Andrew J. Lohn ◽  
Nobuhiko P. Kobayashi
Keyword(s):  
Optical Properties ◽  
Single Crystal ◽  
Quartz Substrate ◽  
Chemical Vapor ◽  
Blue Shift ◽  
Growth Direction ◽  
Longitudinal Optical ◽  
Face Centered Cubic ◽  
Single Crystal Surfaces ◽  
Face Centered

AbstractOptically active InP nanowires were grown on a quartz substrate covered with a layer (100 nm) of hydrogenated amorphous silicon (a-Si:H) by metalorganic chemical vapor deposition (MOCVD), demonstrating that single-crystal semiconductor nanowires can be formed on non-single-crystal surfaces. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, cathodoluminescence (CL), and photoluminescence (PL) were used to characterize the structural and optical properties of the nanowires. The nanowires on a-Si:H grew in random directions with high density. The XRD suggests that nanowires having either hexagonal-close-packed or face-centered cubic lattices co-exist. The Raman spectrum shows peaks associated with transverse optical (TO) and longitudinal optical (LO) branches of InP. The CL intensity does not vary signi?cantly along the growth direction and appears to be originated from the entire structure of the nanowire when probed at various positions. The CL data suggests that recombination is slow enough to allow the carriers to diffuse the complete length of the nanowires (˜2 m in length) before recombining. The PL spectrum suggested the nanowire had a part that contributes to the observed blue shift while the other part had nearly bulk feature in their structure.

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