scholarly journals The nanostructure of barium dititanate prepared by hydrothermal method

2019 ◽  
Vol 09 (02) ◽  
pp. 1950011
Author(s):  
Sarah L. Rasheed ◽  
Emad K. Al-Shakarchi
Keyword(s):  
Electron Microscopy ◽  
Reaction Time ◽  
Hydrothermal Method ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Dielectric Ceramic ◽  
Lattice Constants ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Lcr Meter

The dielectric ceramic of barium dititanate compound BaTi2O5 had been prepared through the hydrothermal process by applying different parameters, such as pH-value, reaction time, temperature and pressure. The prepared powders were examined by X-ray diffraction (XRD). The predominant phase was a monoclinic phase with lattice constants ([Formula: see text], [Formula: see text], [Formula: see text] Å), ([Formula: see text], [Formula: see text]), and the unit cell volume (527 Å3). The surface morphology was demonstrated by Scanning Electron Microscopy (SEM). It exhibited the grains in spherical and elliptical shapes with high homogeneity. The shapes of nanostructure were analyzed by Transmission Electron Microscopy (TEM). The appearance of nanostructures like the nanoparticles and nano rods were found. The size of nanoparticles was in the range of 9–31[Formula: see text]nm, and size of nanorods was 32–37[Formula: see text]nm. The dielectric measurements were done by using LCR meter at different temperature and frequencies (10, 50 and 100[Formula: see text]kHz). It was clear that the Curie temperature had a high value up to (485∘C). The relative permittivity was partially changed for two prepared samples regarding high pressure and long reaction time, which were the main preparation conditions of hydrothermal method.

Study of the preparation and properties of CeO2single/multiwall hollow microspheres

2007 ◽  
Vol 22 (6) ◽  
pp. 1472-1478 ◽  
Author(s):  
Youjin Zhang ◽  
Tao Cheng ◽  
Qixiu Hu ◽  
Zhiyong Fang ◽  
Kaidong Han
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Hollow Microspheres ◽  
X Ray ◽  
Molar Ratios ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Absorption Edges

Novel slight yellow CeO2single/multiwall hollow microspheres were synthesized by the hydrothermal method without any surfactant and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), and x-ray photoelectron spectra (XPS). The results showed that the products were CeO2single/multiwall hollow microspheres, the shells of which were composed of CeO2nanoparticles with a mean size of 70 nm. The effect of the preparation conditions, the reaction temperature, the reaction time, and the molar ratios of urea to Ce(NO3)3·6H2O on the morphology of the products, was investigated. The optimal preparation conditions are determined as follows: the reaction temperature of 230 °C, the reaction time of 6 to 10 h, and the molar ratios of urea to Ce(NO3)3·6H2O of 3:1 to 6:1. The formation mechanism of CeO2single/multiwall hollow microspheres was proposed. The ultraviolet-visible (UV-VIS) diffuse reflectance spectra of the samples were measured. The results showed that the absorption edges of the samples were red-shifted compared with that of bulk CeO2, and that the red-shift of the absorption edges and the yellow of the samples enhanced with increasing the yield of CeO2single/multiwall hollow microspheres. The catalytic activity and the recycling performance of the sample on CO oxidation were tested and theT100%(the temperature at which CO 100% conversion) was 230 °C in the first run and decreased by 270 and 205 °C compared with that of bulk CeO2and CeO2nanocrystal, respectively.

scholarly journals Hydrothermal Synthesis of Ni/Al Layered Double Hydroxide Nanorods

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Yun Zhao ◽  
Fenfei Xiao ◽  
Qingze Jiao
Keyword(s):  
Electron Microscopy ◽  
Reaction Time ◽  
Layered Double Hydroxide ◽  
Hydrothermal Reaction ◽  
Ph Value ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Double Hydroxide ◽  
Scanning Electron

Ni/Al layered double hydroxide (LDH) nanorods were successfully synthesized by the hydrothermal reaction. The crystal structure of the products was characterized by X-ray diffraction (XRD). The morphology of the products was observed using transmission electron microscopy (TEM) and field emission scanning electron microscopy (SEM). The influences of reaction time and pH value on the morphology of the Ni/Al LDHs were investigated. The result showed that the well-crystallized nanorods of Ni/Al LDHs could be obtained when the pH value was about 10.0 with a long reaction time (12–18 h) at 180°C.

Morphology Control of PbS Nanocrystals by a Novel Hydrothermal Process

2004 ◽  
Vol 99-100 ◽  
pp. 197-202 ◽  
Author(s):  
Yujie Ji ◽  
De Ren Yang ◽  
Hui Zhang ◽  
Xiang Yang Ma ◽  
Jin Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ph Value ◽  
Critical Role ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
Pbs Nanocrystals ◽  
Transmission Electron ◽  
Salt Structure ◽  
Lead Source

Star-shaped and rod-like PbS crystals have been successfully prepared by a novel thioglycolic acid (TGA) assisted hydrothermal method. X-ray diffraction (XRD) reveals that the PbS crystals are of the cubic rock-salt structure and well formed. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations show that the morphology of PbS nanocrystals is easily controlled according to sulphur source, lead source, and pH value. Furthermore, the paper gives a preliminary presntation of the mechanism and the critical role of the TGA-assisted hydrothermal synthesis of PbS nanorods

Effect of hydrothermal dwell time on the diameter-controlled synthesis and magnetic property of MnO2 nanorods

2014 ◽  
Vol 28 (06) ◽  
pp. 1450045 ◽  
Author(s):  
Arbab Mohammad Toufiq ◽  
Fengping Wang ◽  
Qurat-ul-Ain Javed ◽  
Yan Li
Keyword(s):  
Electron Microscopy ◽  
Reaction Time ◽  
Dwell Time ◽  
Hydrothermal Reaction ◽  
Ferromagnetic Behavior ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
Transmission Electron ◽  
Facile Hydrothermal Route ◽  
Hydrothermal Reaction Time

In this paper, single crystalline 1D tetragonal MnO 2 pen-type nanorods were synthesized by varying the dwell time through a facile hydrothermal route at a reaction temperature of 250°C. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies showed that the diameter of MnO 2 nanorods decreases from 460 nm to 250 nm with the increase in hydrothermal reaction time from 5 h to 15 h. Field-emission scanning electron microscopy (FESEM) and TEM studies revealed the evolution of improved surface morphology of MnO 2 nanorods that are prepared with longer hydrothermal reaction time. The magnetic properties of the products were evaluated using vibrating sample magnetometer (VSM) at room temperature, which showed that the as-prepared samples exhibit weak ferromagnetic behavior. The effect of diameter on the magnetization values was observed and discussed in detail.

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. 

Synthesis of PZT Disks by a Hydrothermal Method

2012 ◽  
Vol 174-177 ◽  
pp. 592-595
Author(s):  
Lin Lin Yang ◽  
Yong Gang Wang ◽  
Yu Jiang Wang ◽  
Xiao Feng Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hydrothermal Method ◽  
Formation Mechanism ◽  
Powder Diffraction ◽  
Self Assembly ◽  
Hydrothermal Process ◽  
X Ray ◽  
Extended Length ◽  
Scanning Electron

The organization of nanostructures across extended length scales is a key challenge in the design of integrated materials with advanced functions. PbZr0.52Ti0.48O3multilayer disks which were constructed by oriented rectangle nanoparticles were easily prepared by a simple surfactant-free hydrothermal process. The as-prepared powders were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the as-prepared PZT disks were constructed by self-assembly of rectangle nanoparticles by a perfect manner. The formation mechanism of the products was discussed.

Understanding the Growth Mechanisms of Tin Oxide Nanowires by Chemical Vapor Deposition

2021 ◽  
Vol 21 (4) ◽  
pp. 2538-2544
Author(s):  
Nguyen Minh Hieu ◽  
Nguyen Hoang Hai ◽  
Mai Anh Tuan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Chemical Mapping ◽  
X Ray Diffraction ◽  
Lattice Constants ◽  
Transmission Electron ◽  
Scanning Transmission

Tin oxides nanowires were prepared by chemical vapor deposition using shadow mask. X-ray diffraction indicated that the products were tetragonal having crystalline structure with lattice constants a = 0.474 nm and c = 0.318 nm. The high-resolution transmission electron microscopy revealed that inter planar spacing is 0.25 nm. The results chemical mapping in scanning transmission electron microscopy so that the two elements of Oxygen and Tin are distributed very homogeneously in nanowires and exhibit no apparent elements separation. A bottom-up mechanism for SnO2 growth process has been proposed to explain the morphology of SnO2 nanowires.

scholarly journals A Novel Process for the Synthesis of NaV2O5 Mesocrystals from Alkaline-Stripped Vanadium Solution via the Hydrothermal Hydrogen Reduction Method

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 271
Author(s):  
Guobin Zhang ◽  
Yimin Zhang ◽  
Shenxu Bao ◽  
Liuhong Zhang
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Reduction ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Reduction Process ◽  
Oriented Attachment ◽  
Synthesis Process ◽  
Synthesis Mechanism ◽  
Time Saving ◽  
Synthesis Time

NaV2O5 mesocrystals were successfully synthesized from an alkaline-stripped pentavalent vanadium solution through a novel hydrothermal hydrogen reduction process. The optimal conditions for the hydrogen partial pressure, reaction temperature, initial solution pH value, and reaction time for the pure-phase NaV2O5 synthesis were ascertained to be 4 MPa, 200 °C, 4.0, and 2 h, respectively. The synthesis time (only 2 h) was greatly shortened, by nine times, compared with the most time-saving (18 h) hydrothermal process at present. X-ray diffraction (XRD) analysis revealed that the as-prepared powders demonstrated a typical layered orthorhombic structure of NaV2O5. The purity of the as-prepared NaV2O5 reached up to 99.98%. An electrochemical test showed that the as-prepared NaV2O5 has a potential application in sodium ion batteries. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the as-prepared NaV2O5 powders were identified to have rod-like mesocrystals consisting of small rods which preferentially grow along the (010) direction. Furthermore, the phase transformation mechanism and crystal growth mechanism in NaV2O5 preparation were discussed systematically, based on which the synthesis mechanism of NaV2O5 was proposed as pentavalent vanadates pre-sedimentation, hydrogen reduction with dehydration, sodium ions insertion, and finally self-assembly oriented attachment. The synthesis process is characterized as time-saving and low-cost, and thus it may have great application prospects.

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