Size-effect Stabilization of the Low-T Ferroelectric Phase in Nanocrystalline WO3

1994 ◽  
Vol 332 ◽  
Author(s):  
Xiang-Xin Bi ◽  
W. T. Lee ◽  
Kai-An Wang ◽  
D. F. Collins ◽  
S. Bandow ◽  
...  
Keyword(s):  
Particle Size ◽  
Raman Scattering ◽  
Size Effect ◽  
Room Temperature ◽  
Ferroelectric Phase ◽  
Average Particle Size ◽  
Average Particle ◽  
Narrow Size Distribution ◽  
Experimental Conditions ◽  
Scattering Study

ABSTRACTUsing a CO2 laser to drive the pyrolysis of W(CO)6 and O2, we have synthesized nanocrystalline WO3-x particles. These nanopowders are found to exhibit a narrow size distribution with an average particle size produced in the range 5 to 10 nm, depending on the experimental conditions. Typical production rates are ∼ 2 g/h. Results from a Raman scattering study on WO3 nanopowder samples annealed in O2 indicate that a smaller particle size appears to stabilize the low-T ferroelectric phase ( < -40 °C) at room temperature.

Fe3O4 Magnetic Preparation by Bauxite Ore Washing Fine Mud

2014 ◽  
Vol 1010-1012 ◽  
pp. 961-965
Author(s):  
Jian Qiang Xiao ◽  
Guo Wei He ◽  
Yan Jin Hu
Keyword(s):  
Particle Size ◽  
Aging Time ◽  
Average Particle Size ◽  
Xrd Analysis ◽  
Test Methods ◽  
Raw Material ◽  
Molar Ratio ◽  
Average Particle ◽  
Experimental Conditions ◽  
Particle Size Analyzer

Bauxite waste sludge as a raw material, the use of reverse chemical coprecipitation synthesize Fe3O4. Researching temperature, precipitation concentration, aging time and Fe2+/Fe3+ molar ratio effect on the particle size, morphology. Optimal experimental conditions: temperature 70 °C, the precipitant NaOH mass ratio of 10%, aging time 3h, Fe2+/Fe3+ molar ratio of 2:3. Test methods using a laser particle size analyzer, XRD analysis of the products were characterized, the product is Fe3O4, the average particle size of 0.11mm.

Minimum Particle Diameter of the Vanadium/Iron Co-Doped Nano TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 989-994 ◽  
pp. 611-614
Author(s):  
Ling Li ◽  
Wen Ming Zhang ◽  
Hua Yan Zhang ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Ferric Nitrate ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Vanadium Iron ◽  
Co Doped

Vanadium/iron co-doped nanoTiO2 transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, ferric nitrate, ammonium metavanadate, etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, EDS, nanolaser particle size analyzer, and UV-Vis spectrophotometer. The photocatalytic properties of V/Fe doped TiO2 were studied through degrading acid 3R dye, and the results show that when the content of V/Fe was 0.5%, the degradation rate reached more than 96% under irridation for 60 min.

scholarly journals Monodispersed ZnO Nanoparticles and Their Use in Heterojunction Solar Cell

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Dinesh Patidar ◽  
Anusaiya Kaswan ◽  
N. S. Saxena ◽  
Kananbala Sharma
Keyword(s):  
Particle Size ◽  
Solar Cell ◽  
Ethylene Glycol ◽  
Zno Nanoparticles ◽  
Ultrasonic Treatment ◽  
Room Temperature ◽  
Power Conversion ◽  
Average Particle Size ◽  
Hexagonal Wurtzite Structure ◽  
Average Particle

Monodispersed ZnO nanoparticles have been synthesised in ethylene glycol medium using zinc acetate and sodium hydroxide at room temperature through ultrasonic treatment. The monodispersed ZnO nanoparticles were characterized by XRD, TEM, SEM, and optical spectroscopy. The results indicate that ZnO shows the hexagonal wurtzite structure having 8 nm average particle size with the band gap of 3.93 eV. ZnO nanoparticles blended with P3HT show the improvement in the interchains and intrachains ordering as compared to pure P3HT. The power conversion efficiency of P3HT/ZnO solar cell is found to be 0.88%, which is comparable with the result obtained by other researchers.

Development of Heterostructured Ferroelectric SrZrO3/CdS Photocatalysts with Enhanced Surface Area and Photocatalytic Activity

2020 ◽  
Vol 20 (6) ◽  
pp. 3770-3779 ◽  
Author(s):  
Umar Farooq ◽  
Farheen Naz ◽  
Ruby Phul ◽  
Nayeem Ahmad Pandit ◽  
Sapan Kumar Jain ◽  
...  
Keyword(s):  
Particle Size ◽  
Dielectric Constant ◽  
Photocatalytic Activity ◽  
Surface Area ◽  
Room Temperature ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Bet Surface Area ◽  
Cds Nanoparticles ◽  
Average Particle

This paper reports the attempt to develop an efficient heterostructure photocatalyst by employing SrZrO3 as ferroelectric substrate with deposited nanostructured CdS semiconductor on the surface. Primarily bare SrZrO3 and CdS nanoparticles were synthesized by using polymeric citrate precursor and co-precipitation routes, respectively. The chemical deposition technique was used to develop the CdS over the surface of the pre-synthesized SrZrO3 nanoparticles. The synthesized bare nanoparticles and their heterostructure were characterized by XRD which shows the formation of orthorhombic and face centred cubic (FCC) phases of SrZrO3 and CdS, respectively. TEM was used to estimate the morphology and particle size of as-synthesized nanoparticles, which shows the average particle size of 14, 24 and 25 nm for SrZrO3, CdS and SrZrO3/CdS, respectively. The BET surface area of SrZrO3, CdS and SrZrO3/CdS samples was found to be 299, 304 and 312 m2/g respectively. Methylene blue was used as model pollutant to determine the photocatalytic activity of the synthesized nanomaterials. The heterostructure shows an enhanced activity as compared to bare nanoparticles. Dielectric constant and dielectric loss of the nanoparticles was investigated as a function of frequency at room temperature and as a function of temperature at 500 kHz. The room temperature dielectric constant for SrZrO3, CdS and SrZrO3/CdS was found to be 13.2, 17.8 and 25.5 respectively at 100 kHz.

scholarly journals Improving the CO and CH4 Gas Sensor Response at Room Temperature of α-Fe2O3(0001) Epitaxial Thin Films Grown on SrTiO3(111) Incorporating Au(111) Islands

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 848
Author(s):  
Aída Serrano ◽  
Jesús López-Sánchez ◽  
Iciar Arnay ◽  
Rosalía Cid ◽  
María Vila ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Gas Sensing ◽  
Structural Characteristics ◽  
Average Particle Size ◽  
Average Particle ◽  
Epitaxial Thin Films ◽  
Before And After ◽  
Crystallographic Axes ◽  
Gas Exposure

In this work, the functional character of complex α-Fe2O3(0001)/SrTiO3(111) and Au(111) islands/α-Fe2O3(0001)/SrTiO3(111) heterostructures has been proven as gas sensors at room temperature. Epitaxial Au islands and α-Fe2O3 thin film are grown by pulsed laser deposition on SrTiO3(111) substrates. Intrinsic parameters such as the composition, particle size and epitaxial character are investigated for their influence on the gas sensing response. Both Au and α-Fe2O3 layer show an island-type growth with an average particle size of 40 and 62 nm, respectively. The epitaxial and incommensurate growth is evidenced, confirming a rotation of 30° between the in-plane crystallographic axes of α-Fe2O3(0001) structure and those of SrTiO3(111) substrate and between the in-plane crystallographic axes of Au(111) and those of α-Fe2O3(0001) structure. α-Fe2O3 is the only phase of iron oxide identified before and after its functionalization with Au nanoparticles. In addition, its structural characteristics are also preserved after Au deposition, with minor changes at short-range order. Conductance measurements of Au(111)/α-Fe2O3(0001)/SrTiO3(111) system show that the incorporation of epitaxial Au islands on top of the α-Fe2O3(0001) layer induces an enhancement of the gas-sensing activity of around 25% under CO and 35% under CH4 gas exposure, in comparison to a bare α-Fe2O3(0001) layer grown on SrTiO3(111) substrates. In addition, the response of the heterostructures to CO gas exposure is around 5–10% higher than to CH4 gas in each case.

PREPARATION AND CHARACTERIZATION OF SiO2 NANOPARTICLE AND MESOPOROUS SILICATE MOLECULAR SIEVE MCM-48

2002 ◽  
Vol 01 (05n06) ◽  
pp. 539-543
Author(s):  
KYUNG WON SEO ◽  
SUNG DU MOON ◽  
YOUNG SOO KANG ◽  
YONG JOO KIM
Keyword(s):  
Particle Size ◽  
Molecular Sieve ◽  
Pore Diameter ◽  
Average Particle Size ◽  
Mesoporous Molecular Sieve ◽  
Average Particle ◽  
Narrow Size Distribution ◽  
Sem Image ◽  
Mesoporous Silicate

Nanosize SiO 2 particles with narrow size distribution were produced by modified Stober–Fink–Bohn method. Average particle size was determined as 170 nm by SEM image. Organosilica mesoporous molecular sieve (MCM-48) was synthesized. The calcined MCM-48 has pore diameter of 26.8 Å and a surface area of 1024 m 2 g -1 by BET (Brunauer–Emmet–Teller) measurement.

Minimum Particle Diameter of the Sulfur-Doped Nano-TiO2 Transparent Hydrosol at Room Temperature

2014 ◽  
Vol 587-589 ◽  
pp. 788-791
Author(s):  
Ling Li ◽  
Hua Yan Zhang ◽  
Xiao Wei Li ◽  
Zi Hao Xu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Photocatalytic Performance ◽  
Raw Materials ◽  
Average Particle Size ◽  
Particle Diameter ◽  
Synthesis Process ◽  
Average Particle ◽  
Hydrolysis Method ◽  
Particle Size Analyzer

Sulfur-doped nanoTiO2transparent hydrosol with an average particle size of 3.8 nm was synthesized by a novel complexation-controlled hydrolysis method at room temperature and atmospheric pressure by using TiCl4, thiourea, organic carboxylic acid, NH3H2O, D-sorbitol etc. as raw materials. The composition, phase structure, particle size, absorbance spectrum, and photocatalytic performance of samples were characterized by XRD, nanolaser particle size analyzer, ultraviolet-visible spectrophotometer. In addition, the influence of reaction conditions in the synthesis process was also studied. The results indicate that when nanoparticle doped with 0.5% S, and the reflux time was 15 min, the photocatalytic performance of sulfur-doped TiO2hydrosol was best.

Ultrafine TiO2 Powders Prepared from Aqueous TiCl4 Solutions at Room Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 2135-2138
Author(s):  
Hong Liang Yi ◽  
Jie Zhang ◽  
Ming Tu Ma ◽  
Hao Zhang ◽  
Bong Ho Lee ◽  
...  
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Ph Value ◽  
Anatase Phase ◽  
Average Particle Size ◽  
Rutile Phase ◽  
Average Particle ◽  
Spectral Peaks ◽  
Scherrer Formula ◽  
Stock Solutions

Ultrafine TiO2 powders as rutile and anatase phase were simply precipitated at room temperature for only tens of hours by simply controlling the pH value and Ti4+ concentration via aqueous TiCl4 solution. Under the optimal pH value and Ti4+ concentration, the average particle size of powders with rutile phase was 3.7nm, while that of powders with anatase phase was 3.0nm. The average particle size was calculated from the broadening of corresponding X-ray spectral peaks by Scherrer formula. In addition, 3.0 mol.l-1 are suggested to be used as concentration of stock solutions instead of the current concentration 2.0 mol.l-1.

Solid Oil Particles Formation of Ginger Rhizome Using Rapid Expansion Supercritical Carbon Dioxide Solution (RESS) as an Environmentally Friendly Method

2015 ◽  
Vol 1113 ◽  
pp. 428-433
Author(s):  
N.A. Zainuddin ◽  
I. Norhuda ◽  
I.S. Adeib ◽  
Siti Halimah Sarijo
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Rapid Expansion ◽  
Average Particle ◽  
Extraction Temperature ◽  
Experimental Conditions ◽  
Ginger Rhizome ◽  
The One ◽  
Environmentally Friendly Method ◽  
Oil Particles

Particles formations of ginger rhizome were successfully produced by using Rapid expansion supercritical solution (RESS). In this study, effect of extraction temperature (40,45,55 and 65 °C) and constant extraction pressure 4000 Psi were investigated on the particle size of the produced particles. Based on the different experimental conditions, the smallest particle size of ginger after processing via the RESS process was obtained at extraction temperature of 40 °C and extraction pressure, 4000 Psi. Temperature is the one factor that can affect the average particle size of the solid oil particle. The size of the ginger particles were monitored by scanning electron microscopy (SEM).

Correlation Between Quantum Nanocrystal Particle Size and Photoluminescence Using Raman Scattering

1994 ◽  
Vol 358 ◽  
Author(s):  
E. W. Forsvthe ◽  
E. A. Whittaker ◽  
F.H. Pollak ◽  
B. S. Sywe ◽  
G. S. Tompa ◽  
...  
Keyword(s):  
Particle Size ◽  
Porous Silicon ◽  
Raman Scattering ◽  
Average Particle Size ◽  
Visible Spectral Range ◽  
Luminescence Spectra ◽  
Average Particle ◽  
Particle Size Range ◽  
Quantum Size ◽  
Transmission Electron

ABSTRACTThe PL (photoluminescence) and EL (electroluminescence) demonstrated for porous silicon and silicon rich SiO2 films have provided exciting opportunities for the integration of optoelectronics and Si digital electronics. Recent work has suggested that the porous silicon luminescence results from either quantum size or surface state effects. In this report, we review PL demonstrated in the visible spectral range from quantum nanocrystals (QNC) formed from Si embedded in an SiO2 matrix. We used Raman scattering to estimate the QNC particle size and correlated the shift in the luminescence spectra to the observed change in the Raman spectra. The PL spectrum peak shifted from 7000 to 8000 Å as the average particle size increased from ∼50 to 70 Å, measured from Raman scattering. Further, High Resolution Transmission Electron Microscopy, HRTEM, and X-ray Diffraction, XRD, measurements confirmed the particle size range. PL lifetime measurements and excitation intensity studies are also presented. The stable nature of the QNC embedded in an insulating or semiconducting matrix offers further advances towards the integration of optoelectronics with Si devices.

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