Hydrothermal synthesis of micrometer doping CaWO4 phosphors assisted by polymerization

2016 ◽  
Vol 30 (19) ◽  
pp. 1650246
Author(s):  
Liyong Wang ◽  
Yuanyuan Han ◽  
Dan Wang ◽  
Shiqi Wang ◽  
Guoxin Lu ◽  
...  
Keyword(s):  
Phenol Formaldehyde ◽  
Luminescent Properties ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Lanthanide Ions ◽  
Structure Characteristic ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns

CaWO4 crystals were prepared by hydrothermal method assisting with phenol-formaldehyde polymer. The morphology can be controlled by polymer, and X-ray diffraction patterns results present a scheelite-type tetragonal structure, characteristic infrared active modes for O–W–O in the range from 500 cm[Formula: see text] to 4000 cm[Formula: see text] by Fourier transform infrared spectroscopic techniques. Raman results indicate that the crystals possess seven Raman active modes in the range from 100 cm[Formula: see text] to 1000 cm[Formula: see text]. A scanning electron microscopy study reveals that the particles exhibit uniform morphology. Luminescent properties were investigated by photoluminescence measurements, multicolor phosphors were obtained when Ca[Formula: see text] was substituted partly by lanthanide ions.

X-Ray Diffraction and Transmission Electron Microscopy Study of One-Dimensional Disorder Polytypes in SiC

1982 ◽  
Vol 40 ◽  
pp. 542-543
Author(s):  
M. Dubey ◽  
S. R. Singh ◽  
G. Singh
Keyword(s):  
Reciprocal Lattice ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
X Ray Diffraction ◽  
Lattice Imaging ◽  
One Dimensional ◽  
X Ray ◽  
Structural Modifications ◽  
Transmission Electron ◽  
Diffraction Patterns

Silicon carbide crystallizes into several structural modifications whose c-periodicities vary from 1 nm to more than 100 nm. Its high period structures are found to consist of intergrowth of smaller period structures at the unit cell level. The X-ray diffraction studies show that SiC crystals often possess one-dimensional disorder which is characterized by continuous streaks in X-ray diffraction patterns along ho.1 reciprocal lattice rows. However, it is shown that these streaks can also arise as a result of extremely high c-periodicities of the crystals as their ho.1 spots cannot be resolved easily. This contribution reports the observation of only few representative cases of so-called one-dimensional disordered crystals as observed in their X-ray and electron diffractions with lattice imaging.

An Electron Microscopy study of the BaxLa1-xFeO3-x/2 (1/2≤x≤2/3) system

1990 ◽  
Vol 48 (4) ◽  
pp. 608-609
Author(s):  
M. Parras ◽  
J.M. González-Calbet ◽  
M. Vallet-Regí ◽  
J.C. Grenier
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Chemical Analysis ◽  
Analysis Data ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Variations ◽  
Perovskite Unit Cell

In a previous paper we have shown that compositional variations in BaxLa1-xFeO3-y materials prepared in air. are accommodated in a different way than in other perovskite-related ferrites probably due to the bigger size of barium.When oxidated BaxLa1-xFe3+,4+O3-y samples in the 1/2 ≤ x ≤ 2/3 range, are reduced by annealing at 1100°C for 24h. in flowing Ar-5%H2, all iron,as deduced from chemical analysis data, is found in the III state oxidation. Powder X-ray diffraction data in this range (La1/2Ba1/2FeO2.75-La1/3Ba2/3FeO2.67) can be indexed on the basis of a single cubic perovskite unit cell (ac ≃ 3.95Å)In order to elucidate the way in which anionic vacancies are accommodated in these solids an electron diffraction (ED) and microscopy study was performed, similar results being obtained in both La1/2Ba1/2 FeO2.75 and La1/3Ba2/3FeO2.67samples.

scholarly journals Ultrasound and Microwave Coassisted Synthesis and Luminescent Properties of (Ln = La, Gd; ) Phosphors

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jing Hu ◽  
Qianming Wang
Keyword(s):  
Electron Microscopy ◽  
Processing Time ◽  
Luminescent Properties ◽  
Ultrasound Irradiation ◽  
Lanthanide Ions ◽  
X Ray Diffraction ◽  
Control Reaction ◽  
X Ray ◽  
Lanthanum Ions ◽  
Scanning Electron

In order to control reaction temperature and reduce processing time, a new method of ultrasound irradiation with microwave heating was used to synthesize (Ln = La, Gd; ) phosphors at only 80°C in 30 minutes. Their crystal structures and morphologies which have been verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM) exhibited gradual changes due to the insertion of lanthanide ions (La or Gd) in calcium molybdates. Codoping of lanthanum ions () would enhance the emission intensities that were supported by fluorescent spectrophotometry (FL).

Incommensurate modulated disorder in Ba0.85Ca2.15In6O12

1996 ◽  
Vol 52 (5) ◽  
pp. 780-789 ◽  
Author(s):  
G. Baldinozzi ◽  
F. Goutenoire ◽  
M. Hervieu ◽  
E. Suard ◽  
D. Grebille
Keyword(s):  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
X Ray ◽  
Incommensurate Structure ◽  
Resolution Electron ◽  
Complete Determination ◽  
Incommensurate Modulation ◽  
Diffraction Patterns

The tunnel structure of the oxide Ba0.85Ca2.15In6O12 has been revisited. A mono-incommensurate modulation has been evidenced by electron diffraction. The simultaneous refinement of X-ray and neutron powder diffraction patterns has allowed a complete determination of the incommensurate structure [P3({{1}\over{3}} {{1}\over{3}}γ)]. The existence of a modulated disorder, affecting Ba and Ca atoms, has been pointed out. The occupancy modulation concerning Ba and Ca atoms located on the hexagonal tunnel axis induces a modulation of the Ba—O bond lengths. The high-resolution electron microscopy study has shown the existence of twinning domains and of crystal regions possessing a defective arrangement of the modulation.

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