The Magnetic and Photo-Catalytic Properties of Fe Doped TiO2 Nanocrystalline Powder Synthesized by Mechanical Alloying

2007 ◽  
Vol 534-536 ◽  
pp. 229-232 ◽  
Author(s):  
Young Rang Uhm ◽  
S.H. Woo ◽  
Min Ku Lee ◽  
Chang Kyu Rhee
Keyword(s):  
Mechanical Alloying ◽  
Paramagnetic Phase ◽  
Uv Absorption ◽  
Spherical Particles ◽  
Nanocrystalline Powders ◽  
Ferromagnetic Phase ◽  
Nanocrystalline Powder ◽  
Mechanically Alloyed ◽  
Doped Tio2 ◽  
Average Grain Size

Fe-doped TiO2 nanocrystalline powders were prepared by mechanical alloying (MA) by varying Fe contents up to 8.0 wt.%. The TEM analyses were carried out to clarify morphologies and position of Fe within the mechanically alloyed powders. The Fe-doped powder consisted of spherical particles, and the average grain size was less than 10 nm. For the Fe-doped TiO2, the color of the powders changed from white to bright yellow with increasing concentration of Fe. The UVvis absorption showed that the UV absorption for the Fe-doped powder shifted to a longer wavelength (red shift) and the photo-efficiency was enhanced. The absorption threshold depends on the concentration of nano-sized Fe dopant. Mössbauer spectrum for 4 wt.% Fe showed the ferromagnetic phase (sextet) and paramagnetic phase (doublet). However, the only paramagnetic phase (doublet) was seen for 8 wt.% Fe. As the Fe concentration increased up to 4 wt.%, the UV-vis absorption and the magnetization were increased. The beneficial effect of Fe doping for photocatalysis and ferromagnetism was observed at the critical dopant concentration of 4 wt.%. Based on the UV absorption and magnetization, the dopant level was localized to the valence band of TiO2.

Microstructure and Spectroscopy of Lu2O3:Eu Prepared Using Various Synthesis Techniques

2004 ◽  
Vol 99-100 ◽  
pp. 25-30 ◽  
Author(s):  
E. Zych ◽  
J. Trojan-Piegza ◽  
L. Kępiński ◽  
P. Dorenbos
Keyword(s):  
Uniform Distribution ◽  
Spherical Particles ◽  
Nanocrystalline Powders ◽  
Nanocrystalline Powder ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
X Ray ◽  
Methods Of Synthesis ◽  
Excited Luminescence ◽  
Subsequent Decomposition

Nanocrystalline powders of Lu2O3:Eu with activator content varying between 0.2%-10% were prepared using four different methods of synthesis. The products differed in their microstructure and crystallites sizes. Combustion of Lu(NO3)3 with urea produced strongly agglomerated material, most probably with significantly non-uniform distribution of the Eu3+ dopant. Replacing urea with glycine for the combustion produced only slightly agglomerated, voluminous, fluffy powder. Applying the Pechini technique resulted in significantly agglomerated powder while the homogeneous precipitation of Lu(OH)3 with urea at 90 °C and its subsequent decomposition to Lu2O3 at 650 °C resulted in a powder of perfectly spherical particles with a uniform size of about 130 nm with very low agglomeration. The efficiency of X-ray excited luminescence of our nanocrystalline Lu2O3:5%Eu was compared to that of the commercial microcrystalline Gd2O2S:Eu. It was found that the commercial phosphor performed four times more efficiently than our nanocrystalline powder. We consider this to be rather encouraging as the fabrication of our powder is not optimized yet. It seems that Lu2O3:Eu, even in nanocrystalline form, can perform much more efficiently which would make it a promising X-ray phosphor.

Characterization and Photocatalytic Properties of Transition Metal Doped TiO2 and Nanocomposite TiO2 Powders Synthesized by Mechanical Alloying

2007 ◽  
Vol 119 ◽  
pp. 195-198
Author(s):  
Dong Hyun Kim ◽  
Ha Sung Park ◽  
Jae Han Jho ◽  
Wheung Whoe Kim ◽  
Sun Jae Kim ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Transition Metal ◽  
Mechanical Alloying ◽  
Rutile Phase ◽  
Alloyed Powder ◽  
Doped Tio2 ◽  
Average Grain Size ◽  
Xrd Patterns ◽  
Metal Doped

Transition metal doped TiO2 (Ni, Fe, Cu) and nanocomposite TiO2 powders with rutile phase were synthesized by mechanical alloying and heat treatment, and were characterized by XRD, TEM, UV-DRS, and PL (Photoluminescence). Photocatalytic activity was also investigated with the degradation rate of 4-chlorophenol and measured by total organic carbon analyzer. TEMEDP and XRD patterns showed that the transition metal doped powders (only alloyed powder) were in the form of rutile phase with the particle size of 20-30 nm. The average grain size of transition metal doped powders was in the range of less than 10 nm. However, after heat treatment, the alloyed powder formed composite of the titanate and rutile phase. The UV-DRS and PL investigation showed that Ni doped 8 wt% nanocomposite TiO2 had the higher wavelength range (600-660 nm) (2.0-1.9 eV) than that of the commercial P-25 powder(380-400 nm) by Degussa Co. indicating that the Ni 8 wt% doped nanocomposite TiO2 shifted the absorption into the visible light region and thus, enhanced the photocatalytic activity. Further, these results agreed well with TOC investigation. Formation of titanate in transition metal doped TiO2 due to heat treatment was found to control the grain growth of nano-sized TiO2 and to enhance its thermal stability at high temperature.

SYNTHESIS OF AN IONIC LIQUID-BASED MAGNETORHEOLOGICAL FLUID DISPERSING Fe84Nb3V4B9 NANOCRYSTALLINE POWDERS

2010 ◽  
Vol 24 (10) ◽  
pp. 1227-1234 ◽  
Author(s):  
LINGFEI CAO ◽  
HYUNSEO PARK ◽  
GJERGJ DODBIBA ◽  
TOYOHISA FUJITA
Keyword(s):  
Ionic Liquid ◽  
Mechanical Alloying ◽  
Nanocrystalline Powders ◽  
Magnetic Flux Density ◽  
Magnetic Clusters ◽  
Mr Fluid ◽  
Structure Morphology ◽  
Average Grain Size ◽  
Digital Microscope ◽  
20 Nm

A new magnetorheological (MR) fluid was synthesized by dispersing Fe 84 Nb 3 V 4 B 9 nanocrystalline powders in a nonvolatile ionic liquid (N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate), which is stable from 282K to 573K. The structure, morphology, and magnetization of Fe 84 Nb 3 V 4 B 9 nanocrystalline powders prepared by mechanical alloying were analyzed by using an X-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscopy (SEM), respectively. The magnetic clusters of the synthesized MR fluid were observed by using a digital microscope, and its MR properties were measured by using a cone-plate type viscometer. The experimental results showed that Fe 84 Nb 3 V 4 B 9 nanocrystalline powders with an average grain size of 10–20 nm can be prepared by mechanical alloying. The MR fluid is magnetic-field-responsive, behaves like non-Newtonian fluids, and its magnetorheological properties are influenced by the applied magnetic flux density and the width of magnetic clusters.

Nanocrystalline and Ultrafine Grained Materials by Mechanical Alloying

2007 ◽  
Vol 534-536 ◽  
pp. 209-212 ◽  
Author(s):  
Erde Wang ◽  
Lian Xi Hu
Keyword(s):  
Mechanical Alloying ◽  
Nanocrystalline Powder ◽  
Powder Materials ◽  
Hydrogen Storage Material ◽  
Mechanically Alloyed ◽  
Al Composite ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials ◽  
Institute Of Technology ◽  
Synthesized Materials

Recent research at Harbin Institute of Technology on the synthesis of nanocrystalline and untrafine grained materials by mechanical alloying is reviewed. Examples of the materials include aluminum alloy, copper alloy, Ti/Al composite, magnesium-based hydrogen storage material, and Nd2Fe14B/α-Fe magnetic nanocomposite. Details of the processes of mechanical alloying and consolidation of the mechanically alloyed nanocrystalline powder materials are presented. The microstructure characteristics and properties of the synthesized materials are addressed.

scholarly journals SYNTHESIS AND CHARACTERIZATION OF TiB2 NANOCRYSTALLINE POWDER BY MECHANICAL ALLOYING

2012 ◽  
Vol 05 ◽  
pp. 204-211 ◽  
Author(s):  
MAHBOOBEH MOALLEM ◽  
MOHAMMAD HASAN ABBASI ◽  
FATHOLLAH KARIM ZADEH
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Lattice Strain ◽  
Structural Evolution ◽  
Nanocrystalline Powder ◽  
Combustion Mechanism ◽  
Mechanically Alloyed ◽  
Xrd Patterns

In this investigation, TiB 2 nanocrystalline powder was synthesized by mechanical alloying of the elemental mixture of Ti and B powders in argon atmosphere. In order to study the structural evolution of the powder during ball milling, X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used. Adiabatic temperature calculations were performed for characterization of TiB 2 powder. Also, the effects of heat treatment on the structural evolution and thermal stability of mechanically alloyed powders were investigated. It was found from the XRD patterns that TiB 2 was formed via combustion mechanism. By increasing milling time, the grain size decreased while the lattice strain increased. SEM micrographs showed that TiB 2 particles were spherical. The grain size and lattice strain reached 24 nm and 1.8% respectively, after 60 hours ball milling.

Microstructure of mechanically alloyed and hot-pressed Al5CuZr2

1990 ◽  
Vol 48 (4) ◽  
pp. 970-971
Author(s):  
T. E. Mitchell ◽  
P. B. Desch ◽  
R. B. Schwarz
Keyword(s):  
Mechanical Alloying ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Rapid Quenching ◽  
Hardened Steel ◽  
Alloyed Powder ◽  
Ion Milling ◽  
Mechanical Grinding ◽  
Mechanically Alloyed ◽  
Steel Container

Al3Zr has the highest melting temperature (1580°C) among the tri-aluminide intermetal1ics. When prepared by casting, Al3Zr forms in the tetragonal DO23 structure but by rapid quenching or by mechanical alloying (MA) it can also be prepared in the metastable cubic L12 structure. The L12 structure can be stabilized to at least 1300°C by the addition of copper and other elements. We report a TEM study of the microstructure of bulk Al5CuZr2 prepared by hot pressing mechanically alloyed powder.MA was performed in a Spex 800 mixer using a hardened steel container and balls and adding hexane as a surfactant. Between 1.4 and 2.4 wt.% of the hexane decomposed during MA and was incorporated into the alloy. The mechanically alloyed powders were degassed in vacuum at 900°C. They were compacted in a ram press at 900°C into fully dense samples having Vickers hardness of 1025. TEM specimens were prepared by mechanical grinding followed by ion milling at 120 K. TEM was performed on a Philips CM30 at 300kV.

Microstructure, Magnetic and Mössbauer Studies of Mechanically Alloyed FeCoNi Nanocrystalline Powders

2021 ◽  
Author(s):  
Rakia Daly ◽  
Nawel Khitouni ◽  
Maria Luisa Escoda ◽  
Núria LIorca Isern ◽  
Sunol Martinez Juan Jose ◽  
...  
Keyword(s):  
Nanocrystalline Powders ◽  
Mechanically Alloyed ◽  
Mössbauer Studies

New Fe-Ni Based Metal-Metalloid Glassy Alloys Prepared by Mechanical Alloying and Rapid Solidification

1996 ◽  
Vol 455 ◽  
Author(s):  
J. J. Suñol ◽  
M. T. Clavaguera-Mora ◽  
N. Clavaguera ◽  
T. Pradell
Keyword(s):  
Mechanical Alloying ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Magnetic Interaction ◽  
Processing Route ◽  
Mechanically Alloyed ◽  
Scanning Calorimetry ◽  
Glassy Alloys ◽  
Rapidly Solidified ◽  
Thermal Stability Of

ABSTRACTMechanical alloying and rapid solidification are two important routes to obtain glassy alloys. New Fe-Ni based metal-metalloid (P-Si) alloys prepared by these two different processing routes were studied by differential scanning calorimetry and transmission Mössbauer spectroscopy. Mechanical alloyed samples were prepared with elemental precursors, and different nominal compositions. Rapidly solidified alloys were obtained by melt-spinning. The structural analyses show that, independent of the composition, the materials obtained by mechanical alloying are not completely disordered whereas fully amorphous alloys were obtained by rapid solidification. Consequently, the thermal stability of mechanically alloyed samples is lower than that of the analogous material prepared by rapid solidification. The P/Si ratio controls the magnetic interaction of the glassy ribbons obtained by rapid solidification. The experimental results are discussed in terms of the degree of amorphization and crystallization versus processing route and P/Si ratio content.

scholarly journals Effect of Milling Parameters on the Development of a Nanostructured FCC–TiNb15Mn Alloy via High-Energy Ball Milling

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1225
Author(s):  
Cristina García-Garrido ◽  
Ranier Sepúlveda Sepúlveda Ferrer ◽  
Christopher Salvo ◽  
Lucía García-Domínguez ◽  
Luis Pérez-Pozo ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Ball Mill ◽  
Milling Time ◽  
High Energy ◽  
Planetary Mill ◽  
Nominal Composition ◽  
Mechanically Alloyed ◽  
Milling Parameters ◽  
Energy Ball ◽  
Full Conversion

In this work, a blend of Ti, Nb, and Mn powders, with a nominal composition of 15 wt.% of Mn, and balanced Ti and Nb wt.%, was selected to be mechanically alloyed by the following two alternative high-energy milling devices: a vibratory 8000D mixer/mill® and a PM400 Retsch® planetary ball mill. Two ball-to-powder ratio (BPR) conditions (10:1 and 20:1) were applied, to study the evolution of the synthesized phases under each of the two mechanical alloying conditions. The main findings observed include the following: (1) the sequence conversion evolved from raw elements to a transitory bcc-TiNbMn alloy, and subsequently to an fcc-TiNb15Mn alloy, independent of the milling conditions; (2) the total full conversion to the fcc-TiNb15Mn alloy was only reached by the planetary mill at a minimum of 12 h of milling time, for either of the BPR employed; (3) the planetary mill produced a non-negligible Fe contamination from the milling media, when the highest BPR and milling time were applied; and (4) the final fcc-TiNb15Mn alloy synthesized presents a nanocrystalline nature and a partial degree of amorphization.

Preparation of Al-Fe-V-Si Nanocrystalline Powders by Double Mechanical Alloying

2000 ◽  
Vol 331-337 ◽  
pp. 1225-1230 ◽  
Author(s):  
L.J. Zheng ◽  
J.X. Lin ◽  
B.S. Li ◽  
B.J. Zhang ◽  
M.K. Tseng
Keyword(s):  
Mechanical Alloying ◽  
Nanocrystalline Powders
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