Characterization of nanophase titania particles synthesized using in situ steric stabilization

1997 ◽  
Vol 12 (7) ◽  
pp. 1755-1765 ◽  
Author(s):  
A. G. Gaynor ◽  
R. J. Gonzalez ◽  
R. M. Davis ◽  
R. Zallen
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Phase Transformation ◽  
High Water ◽  
Molar Ratio ◽  
Transformation Behavior ◽  
X Ray ◽  
Infrared Techniques

Ultrafine titania particles were synthesized from titanium tetraethoxide (TEOT) dissolved in ethanol. The concentration of water and of the soluble polymer hydroxypropylcellulose (HPC) were varied to control particle size. The HPC adsorbed onto the titania particles during growth, providing a steric barrier to aggregation. Electron microscopy showed that particles smaller than 70 nm were formed at high water concentrations (R > 120 where R is the molar ratio [H2O]/[TEOT]) and in the presence of HPC. The annealing-induced, phase-transformation behavior of these particles (amorphous → anatase → rutile) from 100 to 1000 °C was characterized by x-ray, Raman, and infrared techniques. The conversion of anatase to rutile occurred more readily for particles made at high water concentrations and with HPC. For particles formed by premixing TEOT with HPC prior to hydrolysis at R = 155, an 800 °C anneal yielded a rutile fraction exceeding 95%; particles made at R = 5.5 with no HPC showed negligible conversion at this temperature.

scholarly journals In-situ characterization of highly reversible phase transformation by synchrotron X-ray Laue microdiffraction

2016 ◽  
Vol 108 (21) ◽  
pp. 211902 ◽  
Author(s):  
Xian Chen ◽  
Nobumichi Tamura ◽  
Alastair MacDowell ◽  
Richard D. James
Keyword(s):  
Phase Transformation ◽  
In Situ Characterization ◽  
X Ray ◽  
Reversible Phase ◽  
Laue Microdiffraction

Phase Transformation Behavior and Stability of LiNiO 2 Cathode Material for Li‐Ion Batteries Obtained from In Situ Gas Analysis and Operando X‐Ray Diffraction

ChemSusChem ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2240-2250 ◽  
Author(s):  
Lea de Biasi ◽  
Alexander Schiele ◽  
Maria Roca‐Ayats ◽  
Grecia Garcia ◽  
Torsten Brezesinski ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Cathode Material ◽  
Gas Analysis ◽  
Li Ion Batteries ◽  
X Ray Diffraction ◽  
Transformation Behavior ◽  
X Ray ◽  
Phase Transformation Behavior ◽  
Li Ion

Preparation and Characterization of Monodisperse Ceria Microspheres

2010 ◽  
Vol 434-435 ◽  
pp. 850-852
Author(s):  
Qi Wang ◽  
Bo Yin ◽  
Zhen Wang ◽  
Gen Li Shen ◽  
Yun Fa Chen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Electron Microscope ◽  
Crystalline Form ◽  
X Ray ◽  
Transmission Electron ◽  
Particle Size Analyzer ◽  
Scanning Electron

In present work, ceria microspheres were synthesized by template hydrothermal method. Crystalline form of the as-synthesized ceria microspheres was defined by X-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Dispersibility of ceria microspheres was comprehensively characterized using scanning electron microscope (SEM) observation and laser particle size analyzer. Furthermore, the ultraviolet light absorption performances of ceria microspheres with several different sizes were compared by ultraviolet visible spectrophotometer. The results showed that ceria microspheres presented excellent UV absorbent property and the size influence was remarkable.

Structural Characterization of Microwave-Assisted Solution-Synthesized Strontium-Substituted Hydroxyapatite

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650115
Author(s):  
Jianguo Liao ◽  
Yanqun Li ◽  
Xiali Guan ◽  
Jingxian Liu ◽  
Yongxiang Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Hexagonal Structure ◽  
Hydroxyapatite Nanoparticles ◽  
Solution Synthesis ◽  
X Ray ◽  
Molar Ratios ◽  
Microwave Assisted ◽  
Transmission Electron

Hydroxyapatite and strontium-substituted hydroxyapatite nanoparticles (n-HA and Sr-HA) were prepared by microwave-assisted solution synthesis with aqueous solutions of various Sr/(Sr[Formula: see text]Ca) molar ratios ranging from 0% to 15%. The structural properties of the hydroxyapatite powders were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy and Raman spectra, field emission scanning electron microscopy coupled with energy dispersive X-ray spectrometry and transmission electron microscopy. The results confirmed that strontium ions had been incorporated into the hydroxyapatite lattice. The synthetic n-HA and Sr-HA nanocrystalline consisted of hydroxyapatite crystalline phase with hexagonal structure, and the particle size was 30–40 × 60–70[Formula: see text]nm and 40–50 × 70–80[Formula: see text]nm, respectively. The calcined HA particle size ranged from about 120[Formula: see text]nm to 150[Formula: see text]nm, the calcined Sr-HA products were composed of spherical aggregates with a size of about 70–100[Formula: see text]nm. The incorporation of Sr ions lead to the formation of vacancies in the crystal structure of the HA. The results indicated that the strontium substitution did not change the crystal structures. More Sr resulted in less calcined crystallites and formed agglomerates owing to the size effect.

scholarly journals In Situ Growth Behavior of SiC Whiskers with High Aspect Ratio in the Synthesis of ZrB2-SiC Composite Powders

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3502 ◽  
Author(s):  
Xiaoqing Lian ◽  
Xiaohu Hua ◽  
Xiaogang Wang ◽  
Lirong Deng
Keyword(s):  
Electron Microscopy ◽  
Aspect Ratio ◽  
Molten Salt ◽  
Heating Temperature ◽  
Growth Behavior ◽  
Molar Ratio ◽  
Composite Powders ◽  
X Ray ◽  
Sic Whiskers

Aiming to provide key materials in order to improve the fracture toughness of ZrB2 ceramics, ZrB2-SiC composite powders with in situ grown SiC whiskers were successfully synthesized via a simple molten-salt-assisted ferrous-catalyzed carbothermal reduction method. Thermodynamic calculations on the ZrO2-SiO2-B2O3-C-Fe system were carried out. The effects of heating temperature and ferrous catalyst amount on the growth behavior of SiC whiskers in ZrB2-SiC composite powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The results showed that the aspect ratio of SiC whiskers and the relative content of ZrB2 particles increased with increasing heating temperature (1523–1723 K) and a molar ratio of Fe to ZrSiO4 from 0:1 to 0.2:1. Phase-pure ZrB2-SiC composite powders were obtained at 1723 K when the molar ratio of raw materials was 0.2:0.5:1:1.5:8.4 (Fe:NaCl:ZrSiO4:B2O3:C). Single crystalline β-SiC whiskers with a mean diameter of 0.15 μm and an aspect ratio of 70–120 were homogeneously distributed in the final composite powders. A molten-salt-assisted iron-catalyzed vapor–solid mechanism was promoted for the growth mechanism of in situ grown SiC whiskers.

Synthesis and Characterization of Flower-Sphere MoS2

2011 ◽  
Vol 695 ◽  
pp. 429-432 ◽  
Author(s):  
Jun Zhou ◽  
Xin Zhe Lan ◽  
Ping Ren ◽  
Qiu Li Zhang ◽  
Yong Hui Song ◽  
...  
Keyword(s):  
Particle Size ◽  
Hydrothermal Systems ◽  
Molar Ratio ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Xrd Patterns ◽  
Scanning Electron

The flower-sphere molybdenum disulfide has been synthesized by reaction of Na2MoO4 and CS(NH2)2 with NH2OH·HCl or H2C2O4 as reductant. The microstructure and chemical composition of the product were characterized by means of X-ray diffraction and scanning electron microscope. XRD patterns showed that the molar ratio of Mo to S had a great effect on the purity of the product. When the molar ratio of Mo to S was 1:5, the product was nearly pure MoS2. SEM images showed that the particle size increased as the molar ratio of Mo to S reduced. The MoS2 microspheres had rough surfaces and were constructed with sheet-like structures in the two systems. But the product from the system of NH2OH·HCl as reductant has the bigger particle size, clearer petal-sheets, coarser surface and weaker agglomeration than that from the system H2C2O4 as reductant. The possible chemical reactions in hydrothermal systems were preliminarily discussed.

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