scholarly journals Rodlike YMn2O5 Powders Derived from Hydrothermal Process Using Oxygen as Oxidant

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 805
Author(s):  
Jun Shi ◽  
Jing Wang ◽  
Huifen He ◽  
Yang Lu ◽  
Zhongxiang Shi
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Process ◽  
Growth Direction ◽  
Hydrothermal Time ◽  
Hydrothermal Temperature ◽  
Remarkable Effect ◽  
Structure And Morphology ◽  
Transmission Electron ◽  
Stirring Time ◽  
Main Factors

A facile approach is proposed herein to fabricate YMn2O5 powders with the hydrothermal method with oxygen as an oxidant. The structure and morphology of the as-synthesized YMn2O5 powders were characterized by XRD, SEM, and high-resolution transmission electron microscopy (HRTEM). The results manifested that the main factors that affected the formation of the rod-like YMn2O5 structures were the stirring time, hydrothermal temperature, and hydrothermal time. The oxidation time in the air had a remarkable effect on the final product by oxidizing Mn2+ ions to Mn3+ ions and Mn4+ ions. The obtained YMn2O5 powder was single crystalline and possessed a nanorod morphology, where the growth direction was along the c axis. The possible formation mechanism involved a dissolution–crystallization mechanism. Under the 397 nm excitation, the Mn4+ ions exhibited an intense orange emission at 596 nm. The energy bandgap of YMn2O5 powders was 1.18 eV.

Shape-Controlled Synthesis of Gadolinium Oxide Nanostructure via Facile Process

2012 ◽  
Vol 182-183 ◽  
pp. 265-269
Author(s):  
Qing Zhang ◽  
Pei Wen Hao ◽  
Xin Qu ◽  
Chun Wang ◽  
Rui Xia Li
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
Hydrothermal Temperature ◽  
X Ray ◽  
Transmission Electron ◽  
Heating Treatment ◽  
Shape Controlled ◽  
Low Dimensional ◽  
Hydrolysis Of

A facile method to selectively synthesize nano-scaled Gd2O3 with different morphology such as nanosheres and nanorods has been developed in our report. The precursors GdOHCO3 can be prepared by a two-step hydrothermal process via homogeneous generation of hydroxide ions through the hydrolysis of urea, and the formation of different morphology structures were obtained under different reaction temperatures. After further heating treatment, a transformation from GdOHCO3 to cubic Gd2O3 takes place. The morphology and size of nano Gd2O3 strongly depend on that of the precursors GdOHCO3. The X-ray diffraction, transmission electron microscopy and scanning electron microscopy were employed to characterize the as-obtained low-dimensional nanostructures. And the effects of hydrothermal temperature, solvent and urea concentration on the morphologies of the products were also studied.

The Microstructure and Growth Behavior of Bi2Fe4O9 Superfine Particles Synthesized by Hydrothermal Method

2018 ◽  
Vol 281 ◽  
pp. 78-83
Author(s):  
Hai Peng Song ◽  
Qi Sun ◽  
Yuan Yu Wang
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Method ◽  
Phase Structure ◽  
Ostwald Ripening ◽  
Growth Behavior ◽  
Hydrothermal Time ◽  
Orthorhombic Structure ◽  
Hydrothermal Conditions ◽  
Hydrothermal Temperature ◽  
Transmission Electron

In this work, Bi2Fe4O9superfine particles were prepared by hydrothermal method and effects of hydrothermal conditions on the microstructure of Bi2Fe4O9, especially the concentration of OH-([OH-]) in initial solutions, were investigated. The results showed that [OH-] had obvious influences on the growth of Bi2Fe4O9under the same hydrothermal temperature and hydrothermal time. Phase structure of Bi2Fe4O9unchanged with the increase of [OH-] and maintained orthorhombic structure. Besides, the microstructure of Bi2Fe4O9was carefully studied through transmission electron microscopy (TEM). The results suggested that the mechanism of Bi2Fe4O9growth was Ostwald ripening. In conclusion, Bi2Fe4O9superfine particles with good morphology and microstructure can be successfully synthesized when the concentration of OH-is 2 mol/L and hydrothermal conditions are 240 °C for 6h.Keywords: Bi2Fe4O9, hydrothermal method, phase structure, growth mechanism Topic code numbers: C2

HYDROTHERMAL SYNTHESIS OF α-MoO3 NANORODS FOR NO2 DETECTION

2012 ◽  
Vol 11 (06) ◽  
pp. 1240044 ◽  
Author(s):  
SHOULI BAI ◽  
SONG CHEN ◽  
YUAN TIAN ◽  
RUIXIAN LUO ◽  
DIANQING LI ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Molybdenum Trioxide ◽  
Hydrothermal Process ◽  
High Sensitivity ◽  
X Ray Diffraction ◽  
Hydrothermal Temperature ◽  
X Ray ◽  
Transmission Electron ◽  
Ft Ir

Thermodynamically stable molybdenum trioxide nanorods have been successfully synthesized by a simple hydrothermal process. The product exhibits high-quality, single-crystalline layered orthorhombic structure (α- MoO3 ), and aspect ratio over 20 by characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and Fourier transform infrared (FT-IR). The growth mechanism of α- MoO3 nanorods can be understood by electroneutral and dehydration reaction, which is highly dependent on solution acidity and hydrothermal temperature. The sensing tests show that the sensor based on MoO3 nanorods exhibits high sensitivity to NO2 and is not interferred by CO and CH4 , which makes this kind sensor a competitive candidate for NO2 detection. The intrinsic sensing performance of MoO3 maybe arise from its nonstoichiometry of MoO3 owing to the presence of Mo5+ and oxygen vacancy in MoO3 lattice, which has been confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The sensing mechanism of MoO3 for NO2 is also discussed.

Control of Morphology and Growth Direction of Gallium Nitride Nanostructures

2003 ◽  
Vol 789 ◽  
Author(s):  
Seung Yong Bae ◽  
Hee Won Seo ◽  
Jeunghee Park
Keyword(s):  
Electron Microscopy ◽  
Gallium Nitride ◽  
Large Scale ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Oxide Mixture ◽  
Temperature Range ◽  
Transmission Electron

ABSTRACTVarious shaped single-crystalline gallium nitride (GaN) nanostructures were produced by chemical vapor deposition method in the temperature range of 900–1200 °C. Scanning electron microscopy, transmission electron microscopy, electron diffraction, x-ray diffraction, electron energy loss spectroscopy, Raman spectroscopy, and photoluminescence were used to investigate the structural and optical properties of the GaN nanostructures. We controlled the GaN nanostructures by the catalyst and temperature. The cylindrical and triangular shaped nanowires were synthesized using iron and gold nanoparticles as catalysts, respectively, in the temperature range of 900 – 1000 °C. We synthesized the nanobelts, nanosaws, and porous nanowires using gallium source/ boron oxide mixture. When the temperature of source was 1100 °C, the nanobelts having a triangle tip were grown. At the temperature higher up to 1200 °C the nanosaws and porous nanowires were formed with a large scale. The cylindrical nanowires have random growth direction, while the triangular nanowires have uniform growth direction [010]. The growth direction of the nanobelts is perpendicular to the [010]. Interestingly, the nanosaws and porous nanowires exhibit the same growth direction [011]. The shift of Raman, XRD, and PL bands from those of bulk was correlated with the strains of the GaN nanostructures.

scholarly journals One-step synthesis of OH-TiO 2 /TiOF 2 nanohybrids and their enhanced solar light photocatalytic performance

2018 ◽  
Vol 5 (6) ◽  
pp. 172005 ◽  
Author(s):  
Chentao Hou ◽  
Wenli Liu
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Performance ◽  
Performance Enhancement ◽  
Hydrothermal Process ◽  
Emission Spectra ◽  
Solar Light ◽  
Dominant Factor ◽  
Simulated Solar Light ◽  
Transmission Electron ◽  
Naoh Treatment

TiO 2 /TiOF 2 nanohybrids were quickly synthesized through a hydrothermal process using titanium n-butoxide (TBOT), ethanol (C 2 H 5 OH) and hydrofluoric acid as precursors. The prepared nanohybrids underwent additional NaOH treatment (OH-TiO 2 /TiOF 2 ) to enhance their photocatalytic performance. In this paper, the mechanism of NaOH affecting the pathway of transformation from TBOT (Ti precursor) to TiO 2 nanosheets was discussed. The synthesized TiO 2 /TiOF 2 and OH-TiO 2 /TiOF 2 were characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction pattern (XRD), Fourier infrared spectroscopic analysis (FT-IR), Photoluminescence (PL) emission spectra and UV–visible diffuse reflection spectra (UV–vis DRS). The photocatalytic activity and stability of synthesized samples were evaluated by degradation of methylene blue (MB) under the simulated solar light. The results showed that a larger ratio of TiO 2 to TiOF 2 in TiO 2 /TiOF 2 and OH-TiO 2 /TiOF 2 nanohybrids could allow for even higher MB conversion compared with only TiO 2 nanosheets. NaOH treatment can wash off the F ions from TiOF 2 and induce this larger ratio. The highest efficiency of MB removal was just above 90% in 1 h. Lower electron–hole pairs recombination rate is the dominant factor that induces the photocatalytic performance enhancement of TiO 2 /TiOF 2 nanohybrids. The synthesized OH-TiO 2 /TiOF 2 nanohybrids exhibit great potential in the abatement of organic pollutants.

Preparation of Titanium Oxide Nanotube by Hydrothermal Process

2007 ◽  
Vol 124-126 ◽  
pp. 1165-1168 ◽  
Author(s):  
M. Qamar ◽  
Cho Rong Yoon ◽  
Hyo Jin Oh ◽  
Anna Czoska ◽  
K. Park ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Titanium Oxide ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Hollow Fibers ◽  
Systematic Analysis ◽  
Transmission Electron ◽  
Tio2 Sol ◽  
Naoh Solution

The TiO2 sol was prepared hydrothermally in an autoclave from aqueous TiOCl2 solutions as starting precursor. Hollow fibers were obtained when sol-gel derived TiO2 sol was treated chemically with NaOH solution and subsequently heated in autoclave under various conditions. A systematic analysis of the influence of different NaOH concentrations on the formation of nanotubes has been carried out using XRD and SEM. The phase structure of the synthesized material was determined by transmission electron microscopy and found that these materials are, infact, hollow fibers widely known as nanotubes. From the TEM images, the outer and inner diameters of the tubes were measured ca. 8 and about 4 nm, respectively, with several hundred nanometers in length.

scholarly journals A comparative study on the VOCs sensing behaviors of various ZnO nanostructures

2020 ◽  
Vol 9 (4) ◽  
pp. 117-122
Author(s):  
Vuong Nguyen Minh ◽  
Dung Dinh Tien ◽  
Hieu Hoang Nhat ◽  
Nghia Nguyen Van ◽  
Truong Nguyen Ngoc Khoa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hierarchical Structure ◽  
Hydrothermal Process ◽  
Zno Nanostructures ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
Electrospinning Technique ◽  
Transmission Electron ◽  
Volatile Organic ◽  
Wet Chemical

The volatile organic compounds (VOCs) sensing layers were studied using ZnO nanomaterials with different morphologies including hierarchical nanostructure (ZnO-H), nanorods (ZnO-NRs), commercial nanoparticles (ZnO-CNPs) and wet chemical synthesized nanoparticles (ZnO-HNPs). ZnO hierarchical structure was fabricated by an electrospinning technique followed by hydrothermal process. ZnO vertical nanorods structure was fabricated by hydrothermal method, while ZnO nanoparticles based sensors were prepared from commercial powder and wet chemical method. The morphology and properties of the fabricated samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). VOCs sensing responses toward acetone, ethanol and methanol with respect to altered ZnO nanostructureswas systematically compared at different working temperatures. The enhanced response at low working temperatures induced by theopen space hierarchical structure was observed. The VOCs sensing mechanisms of the ZnO nanostructures based sensing layer were also explained and discussed in detail. 

Microstructures and Growth Characteristics of Self-Assembled InAs/GaAs Quantum Dots Investigated by Transmission Electron Microscopy

2007 ◽  
Vol 26-28 ◽  
pp. 1207-1210
Author(s):  
Hyung Seok Kim ◽  
Ju Hyung Suh ◽  
Chan Gyung Park ◽  
Sang Jun Lee ◽  
Sam Kyu Noh ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Chemical Potential ◽  
Early Stage ◽  
Compressive Strain ◽  
Potential Gradient ◽  
Growth Direction ◽  
Transmission Electron ◽  
Self Assembled

The microstructure and strain characteristics of self-assembled InAs/GaAs quantum dots (QDs) were studied by using transmission electron microscopy. Compressive strain was induced to uncapped QDs from GaAs substrate and the misfit strain largely increased after the deposition of GaAs cap layer. Tensile strain outside QD was extended along the vertical growth direction; up to 15 nm above the wetting layer. Vertically nonaligned and aligned stacked QDs were grown by adjusting the thickness of GaAs spacer layers. The QDs with a lens-shaped morphology were formed in the early stage of growth, and their apex was flattened by the out-diffusion of In atoms upon GaAs capping. However, aligned QDs maintained their lens-shaped structure with round apex after capping. It is believed that their apex did not flatten because the chemical potential gradient of In was relatively low due to the adjacent InAs QD layers.

Growth of epitaxial ZnO films on Si(111)

2002 ◽  
Vol 722 ◽  
Author(s):  
Chunming Jin ◽  
Ashutosh Tiwari ◽  
A. Kvit ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Transparent Conducting Oxide ◽  
Deposition Process ◽  
Growth Direction ◽  
Zno Films ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
X Ray ◽  
Transmission Electron ◽  
Aln Buffer

AbstractEpitaxial ZnO films have been grown on Si(111) substrates by employing a AlN buffer layer during a pulsed laser-deposition process. The epitaxial structure of AlN on Si(111) substrate provides a template for ZnO growth. The resultant films are evaluated by transmission electron microscopy, x-ray diffraction, and electrical measurements. The results of x-ray diffraction and electron microscopy on these films clearly show the epitaxial growth of ZnO films with an orientational relationship of ZnO[0001]||Aln[0001]||Si[111] along the growth direction and ZnO[2 11 0]||AlN[2 11 0]||Si[0 11] along the in-plane direction. High electrical conductivity (103 S/m at 300 K) and a linear I-V characteristics make these epitaxial films ideal for microelectronic, optoelectronic, and transparent conducting oxide applications.

SYNTHESIS OF TUBULAR Ge NANOSTRUCTURES

2010 ◽  
Vol 09 (01n02) ◽  
pp. 75-81
Author(s):  
L. Z. PEI ◽  
H. S. ZHAO ◽  
H. Y. YU ◽  
J. L. HU
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Pore Size ◽  
Formation Process ◽  
Room Temperature ◽  
Hydrothermal Process ◽  
Rolling Mechanism ◽  
Transmission Electron ◽  
Inner Pore

Hollow germanium tubular nanostructures have been obtained by a hydrothermal process at a temperature of 400°C and pressure of 7 MPa with quick cooling to room temperature. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) show that the germanium tubular nanostructures are polycrystalline and have open-end structures at the tips. The diameter of germanium tubular nanostructures is about 40–70 nm and the inner pore size is about 10 nm in average. We propose the rolling mechanism for the formation of tubular nanostructures from lamellar nanostructures to explain the possible formation process of germanium tubular nanostructures.

Sign in / Sign up

Export Citation Format

Share Document