Investigation of Interrelation between Particle Size and Phase Transition in the Al2O3-ZrO2 System

2009 ◽  
Vol 6 ◽  
pp. 35-41
Author(s):  
Denis A. Ivanov-Pavlov ◽  
Vladimir G. Konakov ◽  
Elena N. Solovieva ◽  
Viktor M. Ushakov ◽  
Natalia V. Borisova
Keyword(s):  
Phase Transition ◽  
Particle Size ◽  
Sol Gel ◽  
Scanning Calorimetry ◽  
Gel Method ◽  
Sol Gel Method ◽  
Drying Conditions ◽  
Phase Symmetry ◽  
Adsorption Desorption ◽  
Zro2 System

Powder precursors of the Al2O3-ZrO2 system were synthesized by the sol-gel method. Dispersity of the powders depended on synthesis and drying conditions. Differential Scanning Calorimetry, X-Ray diffraction, and method of adsorption–desorption isotherms were used to characterize the interrelations between particle size and phase transition in the Al2O3-ZrO2 system. It was revealed that azeotropic drying under overpressure is quite effective for obtaining well-dispersed powder precursors synthesized by the sol-gel method. In contrast to bulk materials, tetragonal, cubic, and monoclinic phases were found to exist in a wider temperature-composition range. It was shown that the existing phase symmetry in the well-dispersed powders correlates with the crystallite size.

Preparation of Tungsten-Doped VO2 (M) Nanoparticles through Sol-Gel Method and Hydrothermal Synthesis

2014 ◽  
Vol 881-883 ◽  
pp. 960-963 ◽  
Author(s):  
Ji Qi ◽  
Bin Zhao ◽  
Naisen Yu ◽  
Chen Niu ◽  
Guan Gran Sun
Keyword(s):  
Phase Transition ◽  
Vanadium Dioxide ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
New Process ◽  
Scanning Electron

A new process was developed for synthesizing tungsten-doped vanadium dioxide VO2(M) from ammonium metavanadate. The process includes obtaining V2O5by pyrolysing NH4VO3, doping tungsten in V2O5by sol-gel method, and reducing V2O5to VO2(M) with hydrazine by hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were applied to characterizing the product. The experimental results indicated that tungsten doped VO2(M) nanoparticles were successfully synthesized. The product VO2(M) presents mainly rod-like and block-like morphology. The phase transition temperature decreases with tungsten doped amount increasing, the phase transition takes place over the range from 36.23°C to 62.16°C and the largest enthalpy of the phase transition is 16.24J/g.

Synthesis of LiV3O8 Crystallites via an Improved Citric Acid Assisted Sol-Gel Method

2012 ◽  
Vol 512-515 ◽  
pp. 227-230 ◽  
Author(s):  
Dun Qiang Wang ◽  
Li Yun Cao ◽  
Jian Feng Huang ◽  
Jian Peng Wu
Keyword(s):  
Particle Size ◽  
Citric Acid ◽  
Metal Ion ◽  
Sol Gel ◽  
Structure Stability ◽  
Ir Absorption ◽  
Scanning Calorimetry ◽  
Gel Method ◽  
Sol Gel Method ◽  
Average Size

Lithium trivanadate (LiV3O8) powders have many attractive characteristics such as high specific energy density, good rate capacity and long cycle life due to their unique crystal structure and outstanding structure stability as cathode material for rechargeable lithium batteries. LiV3O8 crystallites were synthesized under different conditions via a combined ultrasonic irradiation and sol-gel method. The as-prepared LiV3O8 powders were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) absorption spectra. The thermal decomposition process was investigated using thermogravimetric (TG) and differential scanning calorimetry (DSC). The effects of molar ratios of metal ion/citric acid and calcinations temperature on phases and microstructure of the powders were investigated. Results indicate that calcinations temperatures have significant influence on the particle morphology, particle size and particle size distribution of the powders. The pure and rod-like LiV3O8 powders with an average size of 0.2-1 μm are obtained at 350 and 400 °C. With the increase of calcinations temperature, the powders exhibit preferred growth orientation along (100) planes. The crystallites obtained at 550 and 600 °C are composed by LiV3O8 with a small amount of Li0.3V2O5 phase, both of which exhibit tabular morphologies with an average size of 2-10 μm.

Annealing Effects on the Physical and Magnetic Properties of Tb1.5Y1.5Fe5O12 Films Nanoparticles Prepared by Sol-Gel Method

2013 ◽  
Vol 756 ◽  
pp. 91-98 ◽  
Author(s):  
Ftema W. Aldbea ◽  
Noor Bahyah Ibrahim ◽  
Mustafa Hj. Abdullah
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Annealing Temperature ◽  
Quartz Substrate ◽  
Sol Gel ◽  
Lattice Parameter ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Iron Garnet

Terbium –substituted yttrium iron garnet (Tb1.5Y1.5Fe5O12) films nanoparticles were successfully prepared by a sol-gel method. The films were deposited on the quartz substrate using spin coating technique. To study effect of annealing temperature, the annealing process was executed at 700, 800 and 900 °C in air for 2 hours. The X-ray diffraction (XRD) proved that the pure phase of garnet structure was detected for the film annealed at 900 °C. The lattice parameter increased with the increment of annealing temperature and the highest value of 12.35 Å was obtained at 900 °C. Field Emission Scanning Electron Microscope (FE-SEM) results showed that the particle size increased from 43nm to 56nm as annealing temperature increased from 700 to 900°C. The film’s thickness also affected by increasing of annealing temperature and become thin at 900 °C due to densification process occurred at high annealing temperature. The elemental compositions of the Tb1.5Y1.5Fe5O12 film were detected using an Energy Dispersive X-raySpectroscopy (EDX). Magnetic properties at room temperature were measured using a Vibrating Sample Magnetometer (VSM).The saturation magnetization Ms increased with the annealingtemperature and showed a high value of 104emu/cm3, but the coercivity Hc of the film was decreased due to the increment of the particle size. Normal 0 21 false false false MS X-NONE X-NONE MicrosoftInternetExplorer4 Terbium –substituted yttrium iron garnet (Tb1.5Y1.5Fe5O12) films nanoparticles were successfully prepared by a sol-gel method. The films were deposited on the quartz substrate using spin coating technique. To study effect of annealing temperature, the annealing process was executed at 700, 800 and 900°C in air for 2 hours. The X-ray diffraction (XRD) proved that the pure phase of garnet structure was detected for the film annealed at 900 °C. The lattice parameter increased with the increment of annealing temperature and the highest value of 12.35 Å was obtained at 900 °C. Field Emission Scanning Electron Microscope (FE-SEM) results showed that the particle size increased from 43nm to 56nm as annealing temperature increased from 700 to 900 °C. The film’s thickness also affected by increasing of annealing temperature and become thin at 900 °C due to densification process occurred at high annealing temperature. The elemental compositions of the Tb1.5Y1.5Fe5O12 film were detected using an Energy Dispersive X-ray Spectroscopy (EDX). Magnetic properties at room temperature were measured using a Vibrating Sample Magnetometer (VSM).The saturation magnetization Ms increased with the annealing temperature and showed a high value of 104emu/cm3, but the coercivity Hc of the film was decreased due to the increment of the particle size. st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

scholarly journals Synthesis of Spherical Silica by Sol-Gel Method and Its Application as Catalyst Support

2011 ◽  
Vol 10 (2) ◽  
pp. 25
Author(s):  
Anirut Leksomboon ◽  
Bunjerd Jongsomjit
Keyword(s):  
Particle Size ◽  
Ethylene Glycol ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Weight Ratio ◽  
Gel Method ◽  
Sol Gel Method ◽  
Spherical Silica

In this present study, the spherical silica support was synthesized from tetraethyloxysilane (TEOS), water, sodium hydroxide, ethylene glycol and n-dodecyltrimethyl ammonium bromide (C12TMABr). The particle size was controlled by variation of the ethylene glycol co-solvent weight ratio of a sol-gel method preparation in the range of 0.10 to 0.50. In addition, the particle size apparently increases with high weight ratio of co-solvent, but the particle size distribution was broader. The standard deviation of particle diameter is large when the co-solvent weight ratio is more than 0.35 and less than 0.15. However, the specific surface area was similar for all weight ratios ranging from 1000 to 1300 m2/g. The synthesized silica was spherical and has high specific surface area. The cobalt was impregnated onto the obtained silica to produce the cobalt catalyst used for CO2 hydrogenation.</

Preparation of La0.75Sr0.25Cr0.5Mn0.5O3-δ Nanometer Powders by Sol-Gel Method and Research about its Electrochemical Performance

2013 ◽  
Vol 712-715 ◽  
pp. 257-261
Author(s):  
Yin Lin Wu ◽  
Qing Hui Wang ◽  
Ling Wang ◽  
Hai Yan Zhao
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Electrochemical Performance ◽  
Heat Treatment Temperature ◽  
Sol Gel ◽  
Treatment Temperature ◽  
Preparation Process ◽  
Gel Method ◽  
Sol Gel Method ◽  
Ft Ir

The La0.75Sr0.25Cr0.5Mn0.5O3-δnanometer powders were prepared by citric acid sol-gel method.The samples were characterized by DTA, FT-IR, XRD, TEM techniques. The preparation process, morphology of synthesized powders, the best heat-treatment temperature and the electrochemical performance had been studied. The results show that the spherical nanometer powders can be obtained and the best heat-treatment temperature is 800°C. The particle size is about 30nm and Ea is 0.071 eV.

Promoted phase transition of titania nanoparticles prepared by a photo-assisted sol-gel method

2002 ◽  
Vol 26 (8) ◽  
pp. 975-977 ◽  
Author(s):  
Haimei Liu ◽  
Wensheng Yang ◽  
Ying Ma ◽  
Yaan Cao ◽  
Jiannian Yao
Keyword(s):  
Phase Transition ◽  
Sol Gel ◽  
Titania Nanoparticles ◽  
Gel Method ◽  
Sol Gel Method

Structural, Ferroelectric, Pyroelectric, and Dielectric Study of Bi0.5Na0.5TiO3 Ceramics synthesized with Precursors Obtained by Sol-Gel Method doped with Lanthanum

2021 ◽  
Author(s):  
José de Jesus Serralta-Macías1 ◽  
Francisco de Paula Calderón-Piñar ◽  
Osmany García Zaldivar ◽  
Daniel Olguin ◽  
jose martin yañez limon
Keyword(s):  
Ferroelectric Properties ◽  
Sol Gel ◽  
Rhombohedral Phase ◽  
Sodium Titanate ◽  
Dielectric Study ◽  
Scanning Calorimetry ◽  
Gel Method ◽  
Sol Gel Method ◽  
Diffraction Patterns ◽  
Ferroelectric Hysteresis

Abstract In this work, the ferroelectric, pyroelectric and dielectric properties of La-doped bismuth sodium titanate ceramics (BNLT) using amounts from 0 to 6.7 at.% La were studied. The precursor powders used to make dense BNLT ceramics were obtained by the sol-gel method using the acetic acid route. All samples were calcined at 700°C for 1hr and sintered at 1150°C for 30 min in an encapsulated crucible to avoid Na and Bi volatilization, obtaining relative densities equal or higher than 94%. The obtained X-ray diffraction patterns typical of the perovskite structure, confirm the incorporation of lanthanum into the lattice, evolving from rhombohedral phase to a mixture of rhombohedral and cubic structure for higher concentrations. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) results indicate that the crystallization of precursors powders of BNT takes place between 500 and 700°C. Additionally, the Scanning Electron Microscopy (SEM) micrographs reveal a decrement of grain size from 4.5 to 0.5 μm with increasing La content. The ferroelectric hysteresis curves show that the best ferroelectric properties were obtained for BNT 1.3% La, where the obtained values of remnant polarization and coercive field were Pr=29 μC/cm2 and Ec=39 kV/cm respectively. Also, at this concentration, the pyroelectric response shows the higher value, 4 times the pyroelectric signal of the pure BNT.

Controlled synthesis and enhanced photoelectro-catalytic activity of a 3D TiO2 nanotube array/TiO2 nanoparticle heterojunction using a combined dielectrophoresis/sol–gel method

2019 ◽  
Vol 7 (17) ◽  
pp. 4981-4987 ◽  
Author(s):  
Ruiyu Bao ◽  
Chen Chen ◽  
Jianxin Xia ◽  
Huiying Chen ◽  
Hua Li
Keyword(s):  
Particle Size ◽  
Catalytic Activity ◽  
Surface Morphology ◽  
Sol Gel ◽  
Tio2 Nanoparticle ◽  
Controlled Synthesis ◽  
Tio2 Nanotube Array ◽  
Nanotube Array ◽  
Gel Method ◽  
Sol Gel Method

The surface morphology and particle size of materials can be controlled using DEP technology.

The Rutile Phase of TiO2/Graphene Films: Sol–Gel Method, Phase Transition, Photocatalytic Properties

2020 ◽  
Vol 207 (1) ◽  
pp. 108-117
Author(s):  
Jin Liu ◽  
Yuanyuan Lv ◽  
Weihu Zhang ◽  
Zhiyong Zhang ◽  
Anyi Wang
Keyword(s):  
Phase Transition ◽  
Sol Gel ◽  
Rutile Phase ◽  
Photocatalytic Properties ◽  
Gel Method ◽  
Sol Gel Method ◽  
Graphene Films

Study on the Synthesis of Batches of the System Y-Ba-Cu-O Using Sol-Gel Method

2014 ◽  
Vol 91 ◽  
pp. 19-23
Author(s):  
Plamen Pashev ◽  
Rositsa Raykova ◽  
Yancho Hristov ◽  
Bogdan Bogdanov
Keyword(s):  
Particle Size ◽  
Citric Acid ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Blue Solution ◽  
Transformation Processes ◽  
Nitrate Solutions ◽  
Thermally Treated

The study presented deal with preparation of batches of the system Y-Ba-Cu-O using sol-gel method and citric acid as precursor. Batches with particle size of 100 nm containing each of the phases Y123 and Y211 were prepared. The stoichiometric amounts of Y, Ba and Cu oxides were dissolved in 65% HNO3 until clear blue solution was observed under heating to 80 ̊С. The nitrate solutions obtained were neutralized to pH = 6 with 25% solution of NH3 (p.a.), then С6Н8О7 was added as the gels obtained were thermally treated. The transformation processes taking place under change of temperature were studied by IR, XRD, DTA and SEM.

Sign in / Sign up

Export Citation Format

Share Document