Heterogeneity in iron-doped titania flower-like nanocrystalline aggregates: detection of brookite and anatase/rutile size–strain modeling

2013 ◽  
Vol 46 (6) ◽  
pp. 1874-1876 ◽  
Author(s):  
Aleksandar Kremenovic ◽  
Mirjana Grujic Brojcin ◽  
Anna-Maria Welsch ◽  
Philippe Colomban
Keyword(s):  
Raman Spectra ◽  
Strain Analysis ◽  
Phonon Confinement ◽  
X Ray ◽  
Nanocrystallite Size ◽  
Transmission Electron ◽  
Doped Titania ◽  
Strain Modeling ◽  
Xrpd Patterns ◽  
Brookite Phase

Detailed investigations of Raman spectra and X-ray powder diffraction (XRPD) patterns of rutile-rich and anatase/brookite-poor flower-like nanocrystalline aggregates of Fe-doped TiO2shed new light with regard to its microstructure and heterogeneity. The brookite phase has been detected from the Raman spectra, and the presence of different phases in pure and doped samples is discussed. The phonon confinement model (PCM) was applied to Raman spectra, and the Warren–Averbach and simplified integral breadth methods were applied to XRPD patterns in order to obtain information about the nanocrystallite size and strain of rutile and anatase. The applied methods (i.e.XRPD size–strain analysis and the PCM fit of Raman spectra), when used in combination and together with other experimental techniques like high-resolution transmission electron microscopy, could be very useful in nanomaterial characterization.

Preparation of Graphene/MoS2 Composite for Detection of Dopamine

2022 ◽  
Vol 905 ◽  
pp. 192-197
Author(s):  
Lin Lin Cai ◽  
Xiao Qing Jiang
Keyword(s):  
Raman Spectra ◽  
Photoelectron Spectroscopy ◽  
The Other ◽  
Organic Salt ◽  
Carbon Electrode ◽  
Sodium Tartrate ◽  
X Ray ◽  
Transmission Electron ◽  
Linear Detection ◽  
Potassium Sodium Tartrate

A new composite of graphene/MoS2 is synthesized by co-exfoliation of graphite and MoS2 in isopropanol (IPA) using the organic salt potassium sodium tartrate as the assistant. The composite is characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectra. The results of TEM, XPS, and Raman spectra all illustrate that the graphene/MoS2 composite has been synthesized successfully. Furthermore, the composite is modified on glassy carbon electrode to fabricate a sensor to detect dopamine (DA). The sensor shows two linear detection ranges for DA. One is 1-45 μM and the other is 45-120 μΜ. The detection limit of the sensor (S/N=3) is 0.76 μM.

On the Study of PbTe-Based Nanocomposite Thermoelectric Materials

2012 ◽  
Vol 17 ◽  
pp. 165-174 ◽  
Author(s):  
Th. C. Hasapis ◽  
S. N. Girard ◽  
Euripides Hatzikraniotis ◽  
Konstantinos M. Paraskevopoulos ◽  
M. G. Kanatzidis
Keyword(s):  
Volume Fraction ◽  
Vibrational Properties ◽  
Effective Medium Approximation ◽  
Bilayer Thickness ◽  
Phonon Confinement ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Class ◽  
Transmission Electron ◽  
Form Features

We Report on the Structural and Vibrational Properties of the X = 0.11 and X = 0.33 Compositions of a New Class of Nanostructured Thermoelectric System (PbTe)1-X(PbSnS2)x by Means of X-Ray Diffraction, Scanning and Transmission Electron Microscopy and Infrared Reflectivity. both Compositions Are Phase Separated, where Pbsns2 Self-Segregates from Pbte to Form Features with Dimensions Ranging from Tens of Micrometers to Tens of Nanometers. Effective Medium Approximation Was Used in Order to Determine the Volume Fraction and the Dielectric Function of the Nanoscale Pbsns2 Embedded in Pbte. by Comparing the Phonon Parameters of the Nanoscale Pbsns2 and Bulk Pbsns2 Single Crystals, we Concluded that Phonon Confinement Effects and Bilayer Thickness Anisotropy within the Pbsns2 Nanostructures Embedded within Pbte Are Responsible for the Observed Variations in the Frequencies of the Shear and the Compression Modes Not Observed in Pure Crystals of Pbsns2.

Structure of Oxides Grown on Zr-20Nb Alloy

1994 ◽  
Vol 357 ◽  
Author(s):  
O.T. Woo ◽  
D.J. Lockwood ◽  
Y.P. Lin ◽  
V.F. Urbanic
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
High Symmetry ◽  
X Ray Diffraction ◽  
Short Term ◽  
X Ray ◽  
Transmission Electron

AbstractOxides grown on Zr-20Nb were characterized by Raman Spectroscopy (RS), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). These oxides were steamformed at 400°C, water-formed at 360 °C and at 300 °C, and air-grown at 400°C. For the oxides grown after relatively short exposures at 360°C and at 400°C, Raman spectra revealed broad peaks at 260 and 660 cm− indicating a crystal structure with high symmetry. Comparison with reference Raman spectra of cubic (c), tetragonal (t), and monoclinic (m) ZrO2 suggested that the oxide was predominantly nearly-cubic (tetragonal with c/a ratio ≈ 1), with minor amounts of moxide. The tetragonality is found to be consistent with TEM analyses and XRD results which showed the presence of a doublet near 2θ ° 74°. The crystal structure in the short-term exposed oxides is interpreted in terms of a tetragonal distortion arising from the displacement of oxygen atoms within the cubic ZrO2 crystal structure. For oxides grown after longer periods of exposure at 300°C and at 400°C, RS and XRD indicate increased amounts of m-oxide.

scholarly journals Structural, Optical, and Photocatalytic Properties of ZnSe Nanoparticles Influenced by the Milling Time

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1125
Author(s):  
Bui Thi Thu Hien ◽  
Vu Thanh Mai ◽  
Pham Thi Thuy ◽  
Vu Xuan Hoa ◽  
Tran Thi Kim Chi
Keyword(s):  
Raman Spectra ◽  
Milling Time ◽  
Blue Emission ◽  
Near Band Edge ◽  
X Ray Diffraction ◽  
Znse Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Average Size

ZnSe nanoparticles (NPs) were prepared by combining both hydrothermal and mechanical milling methods. Transmission electron microscopy images show that fabricated ZnSe NPs with a sphere-like shape have an average size (d) in the range of 20–100 nm, affected by changing the milling time from 10 to 60 min. All the samples crystalize in zincblende-type structure without impurities, as confirmed by analyzing X-ray diffraction patterns, Raman spectra, and energy-dispersive X-ray spectroscopy. Carefully checking Raman spectra, we have observed the broadening and redshift of vibration modes as decreasing NP size, which are ascribed to extra appearance of disorder and defects. The photoluminescence study has found a blue emission at 462 nm attributed to the excitonic near-band edge and a broad defect-related emission around 520–555 nm. Increasing milling time leads to the decrease in the exciton-emission intensity, while the defect-related emissions increase gradually. Interestingly, as decreasing d, we have observed an improved photodegradation of Rhodamine B under UV irradiation, proving application potentials of ZnSe NPs in photocatalytic activity.

Effects of nitrogen flow rates on reactively sputtered nanocrystal-(Ti,Al)xN1-x/amorphous-SiyN1-y nanolaminate films

2004 ◽  
Vol 19 (8) ◽  
pp. 2322-2329 ◽  
Author(s):  
Bao-Shun Yau ◽  
Jow-Lay Huang ◽  
Ding-Fwu Lii
Keyword(s):  
Flow Rate ◽  
Target Surface ◽  
Nitrogen Flow ◽  
Nitrogen Flow Rate ◽  
Flow Rates ◽  
X Ray ◽  
Nanocrystallite Size ◽  
Compositional Modulation ◽  
Atomic Force ◽  
Transmission Electron

Nanocrystal-(Ti,Al)xN1-x/amorphous-SiyN1-y nanolaminate films were deposited periodically under different nitrogen flow rates. The composition, microstructure and mechanical properties of nanolaminate films were investigated by x-ray photoelectron spectroscope, x-ray diffractometer, scanning and transmission electron microscopy, atomic force microscope, and nanoindentation apparatus. Results indicated that the formation of the compound on the target surface was substantially influenced by the deposition rate, composition and crystallite size of the nanolaminate films. Nanolaminate structure with periodic compositional modulation and sharp interfaces were deposited at different nitrogen flow rate. Smaller nanocrystallite size, round-shaped grain features, smoother surface morphology, higher hardness, and reduced elastic modulus were obtained for nanolaminate films with increasing the nitrogen flow rate.

scholarly journals Pengaruh Ethanolamina (MEA) dalam Pembentukan TiO2 dari Bahan Awal Ti Butoksida

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Rika Rahayu ◽  
◽  
Posman Manurung ◽  
Yanti Yulianti ◽  
◽  
...  
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tem Characterization ◽  
Transmission Electron ◽  
Imagej Software ◽  
Uv Lamps ◽  
Brookite Phase

Titanium dioxide has been prepared through the sol gel method using the addition of ethanolamine. The research was conducted to study the effect of MEA on the formation of TiO2. The amount of MEA was varied to 0; 0.5; 1; 1.5; and 2 ml respectively. The samples were calcined at a temperature of 500 ºC. TiO2was characterized using X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and photocatalyst tests using UV lamps. The XRD characterization results showed that in the A sample an anatase phase was formed whereas in the Csample an anatase phase and a brookite phase were formed. The resultof TEM characterization using ImageJ software show that the particle size of TiO2 is26,1 nm, respectively. The results of the characterization of the fastest photocatalyst catalyst test occurred in sample C which the variation of MEA is 1 ml.

scholarly journals Analysis of Polymorphic Nanocrystals ofTiO2by X-Ray Rietveld Refinement and High-Resolution Transmission Electron Microscopy: Acetaldehyde Decomposition

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
R. Carrera ◽  
N. Castillo ◽  
E. Arce ◽  
A. L. Vázquez ◽  
M. Moran-Pineda ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rietveld Refinement ◽  
Sol Gel ◽  
Photocatalytic Decomposition ◽  
X Ray ◽  
Transmission Electron ◽  
Treated Sample ◽  
Crystallite Sizes ◽  
Brookite Phase ◽  
Small Crystallite

In this work,TiO2nanocrystals were synthesized by the sol-gel method. These materials were annealed at 200 and500∘C; and characterized by the XRD-Rietveld refinement; and by BET and TEM. As for the low-temperature-treated sample (200∘C), nanocrystals with small crystallite sizes (7 nm) and high abundance of anatase, coexisting with the brookite phase, were obtained. Meanwhile, the sample annealed at500∘C showed an increased crystallite size (22 nm) and an important polymorphic increment. The sample annealed at200∘C showed a high activity in the photocatalytic decomposition of acetaldehyde.

Phonon Confinement in SiC Nanocrystals: Comparison of the Size Determination Using Transmission Electron Microscopy and Raman Spectroscopy

2007 ◽  
Vol 61 (8) ◽  
pp. 855-859 ◽  
Author(s):  
M. Havel ◽  
D. Baron ◽  
L. Mazerolles ◽  
Ph. Colomban
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Phonon Confinement ◽  
Silicon Carbide Fibers ◽  
Transmission Electron ◽  
Crystallite Dimension ◽  
Average Size ◽  
Actual Size

Silicon carbide fibers of different generation/processing routes (NLM-Nicalon and Tyranno SA3) were thermally treated to trigger the growth of nanocrystals, which were analyzed using Raman spectroscopy and transmission electron microscopy (TEM). The nanocrystals were also aged in molten sodium nitrate to investigate their reactivity. The spatial correlation model has been used to model the Raman spectra and extract accurate and statistical information on the nanocrystallites' structure and dimension. For the NLM fibers, an average size of 2.5 to 7.0 nm was calculated, which was in good agreement with TEM observations. For the Tyranno SA3 fiber, despite the heavily faulted stacking sequence, the Raman peaks remained sharp, indicating that the crystallite dimension calculated from the Raman spectra is only dependent on the actual size of the nanocrystals and is not affected by the sequence of the stacking faults.

Micro-Raman Scattering Properties of Highly Oriented AlN Films

1998 ◽  
Vol 12 (19) ◽  
pp. 1963-1974 ◽  
Author(s):  
Ming S. Liu ◽  
K. W. Nugent ◽  
S. Prawer ◽  
L. A. Bursill ◽  
J. L. Peng ◽  
...  
Keyword(s):  
Aluminum Nitride ◽  
Raman Scattering ◽  
Film Plane ◽  
Phonon Confinement ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
X Ray ◽  
Transmission Electron ◽  
Scattering Geometry ◽  
Confinement Model

Micro-Raman scattering by highly oriented crystalline aluminum nitride has been measured. Phonon modes in AlN were identified in different scattering geometry configurations and scattering polarizations. The phonon modes revealed that aluminum nitride films are highly oriented with the wurtzite c-axis direction normal to the film plane. The Raman scattering modes are broadened and shifted due to grain boundaries and other defects in the films. The defect scattering was analysed using the phonon confinement model. These results were compared with results obtained from X-ray diffraction powder patterns and high-resolution transmission electron microscopy.

Effects of Calcination Temperature on Photoreduction Activity of Cu/TiO2 Nanoparticles

2011 ◽  
Vol 55-57 ◽  
pp. 1648-1652
Author(s):  
Jing Wei ◽  
Xin Tan ◽  
Tao Yu ◽  
Lin Zhao
Keyword(s):  
Calcination Temperature ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Chemical Properties ◽  
Titania Nanoparticles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
One Step ◽  
Doped Titania

A one step sol-gel method was used for preparation of Cu doped titania nanoparticles (NPs). The crystal structures, morphologies and chemical properties were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). We discussed the calcination temperature effection on the photoreduction activity of Cu/TiO2. When the calcination temperature was 500°C, the synthesized Cu/TiO2 performed the highest photocatalytic activity.

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