scholarly journals Relationship between Crystal Shape, Photoluminescence, and Local Structure inSrTiO3Synthesized by Microwave-Assisted Hydrothermal Method

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Luís F. da Silva ◽  
Waldir Avansi ◽  
Mário L. Moreira ◽  
Alexandre Mesquita ◽  
Lauro J. Q. Maia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Method ◽  
Spherical Particles ◽  
Lower Amount ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Microwave Assisted ◽  
Transmission Electron ◽  
X Ray Absorption

This paper describes the effect of using different titanium precursors on the synthesis and physical properties of SrTiO3powders obtained by microwave-assisted hydrothermal method. X-ray diffraction measurements, X-ray absorption near-edge structure (XANES) spectroscopy, field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HRTEM) were carried out to investigate the structural and optical properties of the SrTiO3spherical and cubelike-shaped particles. The appropriate choice of the titanium precursor allowed the control of morphological and photoluminescence (PL) properties of SrTiO3compound. The PL emission was more intense in SrTiO3samples composed of spherelike particles. This behavior was attributed to the existence of a lower amount of defects due to the uniformity of the spherical particles.

scholarly journals Defect Persuade Paramagnetic Properties of Nickel Doped ZnS Nanocrystals and Identification of Structural, Optical, Local Atomic Structure

2021 ◽  
Author(s):  
Soumendra Ghorai ◽  
Dibyendu Bhattacharyya ◽  
Nirmalendu Patra ◽  
Shambhu Nath Jha ◽  
Anup K Ghosh
Keyword(s):  
Electron Microscopy ◽  
Atomic Structure ◽  
Defect Formation ◽  
Local Atomic Structure ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Local Structures ◽  
Transmission Electron ◽  
X Ray Absorption

Abstract We have methodically investigated the structural, spectroscopic, local atomic structure and magnetic properties of aquatic Zn1-xNixS (0≤x≤0.04) nanocrystals. The structural study of synthesized samples are observed by X-ray diffraction datas with Rietveld refinement. Proficient decrease of lattice parameters and inter-planar spacing are determined on Zn1-xNixS nanocrystals. The nanocrystalline microstructure is identified by high resolution transmission electron microscopy. The sphalerite morphology of doped samples are observed by scanning electron microscopy. Shrinkage of energy band gap is observed for doped nanocrystals. Defect formation due to doping of Ni ion is observed by photoluminescence spectroscopy with cyan color emission. X-ray absorption spectroscopy is employed for identification of local structures surrounding of Zn and Ni sites of Zn1-xNixS nanocrystals. Extended X-ray absorption fine structure investigation evidenced the existence of nanocluster within the lattice of Zn1-xNixS nanocrystals. X-ray absorption near edge structure studies confirmed incorporation of Ni2+ in ZnS lattice of Zn1-xNixS nanocrystals. The single pre-edge feature at Ni K-edge is not relying on concentration of Ni dopant in Zn1-xNixS nanocrystals. The presence of interstitial Ni is identified by significant fraction of Ni-Ni scattering paths on doped samples. Zn1-xNixS nanocrystals exhibit defect persuaded paramagnetism at room temperature.

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

Structural, morphological, and magnetic study of nanocrystalline cobalt-copper powders synthesized by the polyol process

1995 ◽  
Vol 10 (6) ◽  
pp. 1546-1554 ◽  
Author(s):  
G.M. Chow ◽  
L.K. Kurihara ◽  
K.M. Kemner ◽  
P.E. Schoen ◽  
W.T. Elam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Copper Powders ◽  
Face Centered ◽  
Increasing Temperature ◽  
X Ray Absorption

Nanocrystalline CoxCu100−x (4 ⋚ x ⋚ 49 at. %) powders were prepared by the reduction of metal acetates in a polyol. The structure of powders was characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, and vibrating sample magnetometry (VSM). As-synthesized powders were composites consisting of nanoscale crystallites of face-centered cubic (fcc) Cu and metastable face-centered cubic (fcc) Co. Complementary results of XRD, HRTEM, EXAFS, NMR, and VSM confirmed that there was no metastable alloying between Co and Cu. The NMR data also revealed that there was some hexagonal-closed-packed (hcp) Co in the samples. The powders were agglomerated, and consisted of aggregates of nanoscale crystallites of Co and Cu. Upon annealing, the powders with low Co contents showed an increase in both saturation magnetization and coercivity with increasing temperature. The results suggested that during preparation the nucleation of Cu occurred first, and the Cu crystallites served as nuclei for the formation of Co.

Nanostructured CaWO4, CaWO4:Eu3+ and CaWO4:Tb3+ Particles: Sonochemical Synthesis and Luminescent Properties

2008 ◽  
Vol 8 (3) ◽  
pp. 1183-1190 ◽  
Author(s):  
Chunxia Li ◽  
Cuikun Lin ◽  
Xiaoming Liu ◽  
Jun Lin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Field Emission ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Nanostructured CaWO4, CaWO4:Eu3+, and CaWO4:Tb3+ phosphor particles were synthesized via a facile sonochemical route. X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, low voltage cathodoluminescence spectra, and photoluminescence lifetimes were used to characterize the as-obtained samples. The X-ray diffraction results indicate that the samples are well crystallized with the scheelite structure of CaWO4. The transmission electron microscopy and field emission scanning electron microscopy images illustrate that the powders consist of spherical particles with sizes from 120 to 160 nm, which are the aggregates of even smaller nanoparticles ranging from 10 to 20 nm. Under UV light or electron beam excitation, the CaWO4 powder exhibited a blue emission band with a maximum at 430 nm originating from the WO2−4 groups, while the CaWO4:Eu3+ powder showed red emission dominated by 613 nm ascribed to the 5D0 → 7F2 of Eu3+, and the CaWO4:Tb3+ powders showed emission at 544 nm, ascribed to the 5D4 → 7F5 transition of Tb3+. The PL excitation and emission spectra suggest that the energy is transferred from WO2−4 to Eu3+CaWO4:Eu3+ and to Tb3+ in CaWO4:Tb3+. Moreover, the energy transfer from WO2−4 to Tb3+ in CaWO4:Tb3+ is more efficient than that from WO2−4 to Eu3+ in CaWO4:Eu3+. This novel and efficient pathway could open new opportunities for further investigating the novel properties of tungstate materials.

Rapid Synthesis of Uniform CdSe Nanorods by a Microwave-Assisted Solvothermal Method in Ethylenediamine

2020 ◽  
Vol 20 (10) ◽  
pp. 6495-6499
Author(s):  
Maokun Han ◽  
Ruijuan Qi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solvothermal Method ◽  
X Ray Diffraction ◽  
Rapid Synthesis ◽  
X Ray ◽  
Microwave Assisted ◽  
Aspect Ratios ◽  
Transmission Electron ◽  
Cdse Nanorods

A rapid microwave-assisted solvothermal method is reported for the synthesis of uniform CdSe nanorods in ethylenediamine (EDA) using CdCl2 and elemental Se as reactants. The resultant nanorods have a diameter of approximately 10 nm and a length of approximately 300 nm. Our experiments show that the concentrations of EDA and CdCl2 play important roles in product morphology. The well-dispersed CdSe nanorods with high aspect ratios were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), UV-vis absorption and photoluminescence (PL).

Preparation and Characterizations of a-Fe2O3 Nanorods and their Properties

2016 ◽  
Vol 852 ◽  
pp. 346-348
Author(s):  
Hong Cai ◽  
Qing Bo Du ◽  
Ji Gui Xu ◽  
Hong Wei Shi ◽  
Jun Zhu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hydrothermal Method ◽  
Magnetic Measurement ◽  
Remnant Magnetization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Fundamental Research ◽  
Scanning Electron

a-Fe2O3 nanorods over large areas were successfully synthesized by hydrothermal method, using FeCl3 as iron source and PVP as surfactant. The as-synthesized a-Fe2O3 nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and magnetic measurement system (SQUID-VSM) . The results show that the nanorods prepared by hydrothermal method with the diameter of about 70 nm and the length of about 300 nm. The magnetic properties of the synthesized nanorods were studied, and the remnant magnetization and coercivity of the α-Fe2O3 nanorods at 300K are found to be 0.07emu/g and 2300Oe, respectively. The a-Fe2O3 nanorods reported here may have opportunities for both fundamental research and technological applications.

scholarly journals New Insight on the Hydrogen Absorption Evolution of the Mg–Fe–H System under Equilibrium Conditions

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 967 ◽  
Author(s):  
Julián Puszkiel ◽  
M. Castro Riglos ◽  
José Ramallo-López ◽  
Martin Mizrahi ◽  
Thomas Gemming ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Formation Mechanism ◽  
X Ray Diffraction ◽  
Equilibrium Conditions ◽  
Edge Structure ◽  
X Ray ◽  
Solid Diffusion ◽  
Transmission Electron ◽  
Scanning Transmission

Mg2FeH6 is regarded as potential hydrogen and thermochemical storage medium due to its high volumetric hydrogen (150 kg/m3) and energy (0.49 kWh/L) densities. In this work, the mechanism of formation of Mg2FeH6 under equilibrium conditions is thoroughly investigated applying volumetric measurements, X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and the combination of scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HR-TEM). Starting from a 2Mg:Fe stoichiometric powder ratio, thorough characterizations of samples taken at different states upon hydrogenation under equilibrium conditions confirm that the formation mechanism of Mg2FeH6 occurs from elemental Mg and Fe by columnar nucleation of the complex hydride at boundaries of the Fe seeds. The formation of MgH2 is enhanced by the presence of Fe. However, MgH2 does not take part as intermediate for the formation of Mg2FeH6 and acts as solid-solid diffusion barrier which hinders the complete formation of Mg2FeH6. This work provides novel insight about the formation mechanism of Mg2FeH6.

Research on Phases and Morphology of Fe-Se Powders Synthesized by Hydrothermal Method

2012 ◽  
Vol 184-185 ◽  
pp. 1171-1174
Author(s):  
Ke Gao Liu ◽  
Zhong Quan Ma ◽  
Jian Hua Wang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Method ◽  
Impurity Phase ◽  
Experimental Results ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
The Poor ◽  
Transmission Electron

The Fe-Se powders have been prepared by hydrothermal method at temperatures of 160, 180 and 200 °C from FeCl3•6H2O and SeO2. The phases and morphology of the products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) respectively. Experimental results show that, the major phases of these product powders are all FeSe2, the impurity phase Se can be identified in spite of poor crystallinity of all samples. The poor crystallinity becomes seriously at lower synthesizing temperature under the experimental conditions. These product powders consist of grains, rods or flakes with sizes of 20~300nm, among which the product obtained at 180 °C has the smallest size of 20~40 nm.

Graphene-like nanostructures obtained from Biomass

2013 ◽  
Vol 1505 ◽  
Author(s):  
Gabriela Borin Barin ◽  
Yane Honorato Santos ◽  
Jennyfer Alves Rocha ◽  
Luiz Pereira da Costa ◽  
Antônio Gomes Souza Filho ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Hydrothermal Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Coir Dust ◽  
Coconut Coir ◽  
Scanning Electron

ABSTRACTTwo dimensional (2D) carbon nanomaterials such as few graphite layers or graphene are extensively studied due to their unique properties suitable to be exploiting in a wide range of technological applications. Recently, the growth of high quality graphene monolayers using insects and waste as carbon precursors was reported in the literature. This methodology opened a new way to convert the waste carbon into a high-value-added product. In the present work coconut coir dust, an agroindustrial biomass, was used as biotemplate for preparing carbonaceous materials. Carbon structures were synthesized through pyrolysis under nitrogen atmosphere (100mL/min) at 500, 1000, and 1500°C during 2 hours. Starting materials were coconut coir dust in natura and coconut coir dust hydrothermally treated. The samples were characterized by X-ray diffraction, Raman Spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Raman spectra showed the D band for all samples, related to the presence of defects in sp2 carbon structure and G band, indicative of graphite crystallites. It was also observed that the sample carbonized at 1500°C from coconut coir dust treated by hydrothermal method showed G’ band at 2685cm-1 associated with the stacking order along the c-axis. X-ray diffraction analysis showed a broad peak around 2θ= 22° related to the presence of amorphous carbon. By increasing the pyrolysis temperature changes in XRD diffractograms were observed and the sample which was pyrolysed at 1500°C from coconut coir dust hydrothermally treated showed peaks at 2θ= 26.5°, 43° e 45° assigned to (002), (100) (101) graphite plans, respectively. Scanning electron microscopy images showed the presence of overlapping sheets and plates. Transmission Electron Microscopy (TEM) images of coconut coir dust in natura unveiled the formation of amorphous sheet. Coconut coir dust in natura and treated by the hydrothermal method pyrolysed at 1500°C, lead to the formation of some graphitic domains and few graphene layers.

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