MAGNETIC PROPERTIES STUDY OF SOL–GEL SYNTHESIZED COBALT-DOPED ANATASE TiO2 NANOPOWDER

2011 ◽  
Vol 10 (04n05) ◽  
pp. 581-585
Author(s):  
BISWAJIT CHOUDHURY ◽  
AMARJYOTI CHOUDHURY ◽  
RAJENDRA K SINGH
Keyword(s):  
Magnetic Measurements ◽  
Anatase Phase ◽  
Sol Gel ◽  
Weak Ferromagnetism ◽  
Annealed Sample ◽  
Blocking Temperature ◽  
Neel Temperature ◽  
Néel Temperature ◽  
Tem Analysis ◽  
Key Factor

Co doped TiO2 nanopowder has been synthesized by a simple sol–gel route. XRD and TEM analysis confirms anatase phase of TiO2 with crystallite and particle sizes of 10 and 15 nm respectively. Presence of Co is confirmed by EDX. FTIR shows a slight shift in the Ti-O bonding vibration to lower frequency suggesting dopant incorporation on Ti site. For magnetic measurements the sample with dopant amount x = 0.075 is annealed both in vacuum and air. Weak ferromagnetism and a blocking temperature of 39 K is obtained for vacuum annealed sample while ferromagnetism is lost in the air annealed sample and shows only paramagnetic behavior. Temperature dependent magnetic measurements for air annealed sample shows antiferromagnetic behavior with a Neel temperature of 36.51 K. Here we report that oxygen vacancy and cobalt aggregates is a key factor for inducing ferromagnetism–superparamagnetism in vacuum annealed sample. Appearance of Neel temperature reveals the presence of antiferromagnetic Co3O4 which is the oxidation results of metallic Co or cobalt clusters present on host TiO2 surface.

scholarly journals Size Effects on Magnetic Properties ofNi0.5Zn0.5Fe2O4Prepared by Sol-Gel Method

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Min Zhang ◽  
Zhenfa Zi ◽  
Qiangchun Liu ◽  
Peng Zhang ◽  
Xianwu Tang ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Measurements ◽  
Sol Gel ◽  
Domain Wall Motion ◽  
Blocking Temperature ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Cation Redistribution

Ni0.5Zn0.5Fe2O4particles with different particle sizes have been synthesized by sol-gel method. X-ray diffraction results show that all the samples are pure cubic spinel structure with their sizes ranging from 9 to 96 nm. The lattice constant significantly decreases with further increasing annealing temperature. The magnetic measurements show superparamagnetic nature below the particle size of 30 nm, while others show ferrimagnetic nature above the corresponding blocking temperature. The blocking temperature increases with the increase in particle size, which can be explained by Stoner-Wohlfarth theory. The saturation magnetization increases as the particle size increases, which can be explained by the cation redistribution on tetrahedral A and octahedral B sites and the domain wall motion. The variation of coercivity as a function of particle size is based on the domain structure.

scholarly journals Магнитные свойства двухфазных магнитных боросиликатных стекол, содержащих наночастицы beta-Fe-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- и Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-

2020 ◽  
Vol 46 (16) ◽  
pp. 28
Author(s):  
С.А. Борисов ◽  
А.А. Набережнов ◽  
B. Nacke ◽  
A. Nikanorov
Keyword(s):  
Magnetic Properties ◽  
Magnetic Fields ◽  
Fe3o4 Nanoparticles ◽  
Superparamagnetic Nanoparticles ◽  
Blocking Temperature ◽  
Neel Temperature ◽  
Specific Magnetization ◽  
Borosilicate Glasses ◽  
Néel Temperature ◽  
Two Phase

The magnetic properties of two-phase borosilicate glasses containing in the skeleton a mixture of β-Fe2O3 and Fe3O4 nanoparticles have been studied. The sizes of nanoparticles have been determined, the value of blocking temperature (TB ~ 330 K) for ensemble of superparamagnetic nanoparticles is obtained. It is shown that in the high applied magnetic fields the specific magnetization of these glasses increases sharply at approaching and below Neel temperature for the bulk β-Fe2O3.

Crystal growth and physical properties of an antiferromagnetic molecule: trans-dibromidotetrakis(acetonitrile)chromium(III) tribromide, [CrBr2(NCCH3)4](Br3)

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Ranuri S. Dissanayaka Mudiyanselage ◽  
Tai Kong ◽  
Weiwei Xie
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
Interaction Analysis ◽  
Theoretical Calculations ◽  
Magnetic Feature ◽  
Maximum Temperature ◽  
Neel Temperature ◽  
X Ray Diffraction ◽  
Néel Temperature ◽  
X Ray

The synthesis, crystal structure determination, magnetic properties and bonding interaction analysis of a novel 3d transition-metal complex, [CrBr2(NCCH3)4](Br3), are reported. Single-crystal X-ray diffraction results show that [CrBr2(NCCH3)4](Br3) crystallizes in space group C2/m (No. 12) with a symmetric tribromide anion and the powder X-ray diffraction results show the high purity of the material specimen. X-ray photoelectron studies with a combination of magnetic measurements demonstrate that Cr adopts the 3+ oxidation state. Based on the Curie–Weiss analysis of magnetic susceptibility data, the Néel temperature is found to be around 2.2 K and the effective moment (μeff) of Cr3+ in [CrBr2(NCCH3)4](Br3) is ∼3.8 µB, which agrees with the theoretical value for Cr3+. The direct current magnetic susceptibility of the molecule shows a broad maximum at ∼2.3 K, which is consistent with the theoretical Néel temperature. The maximum temperature, however, shows no clear frequency dependence. Combined with the observed upturn in heat capacity below 2.3 K and the corresponding field dependence, it is speculated that the low-temperature magnetic feature of a broad transition in [CrBr2(NCCH3)4](Br3) could originate from a crossover from high spin to low spin for the split d orbital level low-lying states rather than a short-range ordering solely; this is also supported by the molecular orbital diagram obtained from theoretical calculations.

Exchange bias of CoO1−δ/(NiFe,Fe) system with blocking temperature beyond Néel temperature of bulk CoO

2015 ◽  
Vol 107 (17) ◽  
pp. 172404 ◽  
Author(s):  
S. L. Ding ◽  
R. Wu ◽  
J. B. Fu ◽  
X. Wen ◽  
H. L. Du ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Blocking Temperature ◽  
Neel Temperature ◽  
Néel Temperature

scholarly journals The Magnetic Susceptibility Bifurcation in the Ni-Doped Sb2Te3 Topological Insulator with Antiferromagnetic Order Accompanied by Weak Ferromagnetic Alignment

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Shiu-Ming Huang ◽  
Pin-Cing Wang ◽  
Hao-Lun Jian ◽  
Mitch M. C. Chou
Keyword(s):  
Magnetic Susceptibility ◽  
Field Cool ◽  
Zero Field Cool ◽  
Weak Ferromagnetism ◽  
Antiferromagnetic Order ◽  
Zero Field ◽  
Neel Temperature ◽  
Néel Temperature ◽  
Magnetic Anisotropy Energy ◽  
Weak Ferromagnetic

AbstractThe magnetic susceptibility reveals a discontinuity at Néel temperature and a hysteresis loop with low coercive field was observed below Néel temperature. The magnetic susceptibility of zero field cool and field cool processes coincide at a temperature above the discontinuity, and they split at temperature blow the discontinuity. The magnetic susceptibility splitting is larger at lower external magnetic fields. No more magnetic susceptibility splitting was observed at a magnetic field above 7000 Oe which is consistent with the magnetic anisotropy energy. Our study supports that these magnetic susceptibility characteristics originate from an antiferromagnetic order accompanied by weak ferromagnetism.

Preparation, Characterization and Photocatalytic Properties of Cu, P-codoped TiO2 Nanoparticles

2011 ◽  
Vol 239-242 ◽  
pp. 2562-2565 ◽  
Author(s):  
Mei Ru Xu ◽  
Gang Ni ◽  
Fang Zhao
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Calcination Temperature ◽  
Crystalline Phase ◽  
Anatase Phase ◽  
Sol Gel ◽  
Tetrabutyl Titanate ◽  
Tem Analysis ◽  
Gel Method ◽  
Phase Transform

A novel copper and phosphorus codoped TiO2 photocatalyst was synthesized by modified sol–gel method using tetrabutyl titanate, Cu(NO3)2 and H3PO4 as precursors. The samples were characterized by XRD, TEM, TGA, EDX. The TGA indicated the calcination temperature is 450°C. The XRD results showed undoped and Cu, P-codoped TiO2 nanoparticles only include anatase phase, and the temperture of crystalline phase transform for Cu, P codeped TiO2 had changed compared with undoped. The TEM analysis revealed the doping of Cu and P suppressed the growth of TiO2 grains. The photocatalytic activity of samples was tested for degradation of 20 mg·L−1 methyl orange (MO) solutions. The results showed photocatalytic activity of the catalysts with 0.5% Cu, 0.375% P-codoped TiO2 was higher than pure TiO2 under ultraviolet (UV).

scholarly journals Photocatalytic antibacterial performance of TiO2and Ag-doped TiO2againstS. aureus.P. aeruginosaandE. coli

2013 ◽  
Vol 4 ◽  
pp. 345-351 ◽  
Author(s):  
Kiran Gupta ◽  
R P Singh ◽  
Ashutosh Pandey ◽  
Anjana Pandey
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Annealed Sample ◽  
Bacterial Strains ◽  
X Ray Diffraction ◽  
Photoexcited Electron ◽  
Antibacterial Performance ◽  
Transmission Electron ◽  
Vis Spectroscopy

This paper reports the structural and optical properties and comparative photocatalytic activity of TiO2and Ag-doped TiO2nanoparticles against different bacterial strains under visible-light irradiation. The TiO2and Ag-doped TiO2photocatalysts were synthesized by acid catalyzed sol–gel technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL). The XRD pattern revealed that the annealed sample of TiO2has both anatase and rutile phases while only an anatase phase was found in Ag-doped TiO2nanoparticles. The decreased band-gap energy of Ag-doped TiO2nanoparticles in comparison to TiO2nanoparticles was investigated by UV–vis spectroscopy. The rate of recombination and transfer behaviour of the photoexcited electron–hole pairs in the semiconductors was recorded by photoluminescence. The antimicrobial activity of TiO2and Ag-doped TiO2nanoparticles (3% and 7%) was investigated against both gram positive (Staphylococcus aureus) and gram negative (Pseudomonas aeruginosa,Escherichia coli) bacteria. As a result, the viability of all three microorganisms was reduced to zero at 60 mg/30 mL culture in the case of both (3% and 7% doping) concentrations of Ag-doped TiO2nanoparticles. Annealed TiO2showed zero viability at 80 mg/30 mL whereas doped Ag-TiO27% showed zero viability at 40 mg/30 mL culture in the case ofP. aeruginosaonly.

scholarly journals Investigation of Photocatalytic Activity of TiO2 Nanoparticles Synthesized By Sol-Gel Technique

2021 ◽  
Author(s):  
R. S. Gedam ◽  
G. K. Sukhadeve ◽  
S.Y. Janbandhu ◽  
S. Upadhyay
Keyword(s):  
Photocatalytic Activity ◽  
Anatase Phase ◽  
Sol Gel ◽  
Optical Absorption Spectra ◽  
Energy Band Gap ◽  
Tem Analysis ◽  
Xrd Study ◽  
Heat Treated ◽  
Gel Technique ◽  
Scanning Electron

Abstract Anatase phase TiO2 nanoparticles were synthesized by sol-gel method using titanium(IV) butoxide as a starting material. The pH of solution was maintained by adding HNO3 and NaOH. The obtained powder was heat treated at 350̊ C for 2 hours. The XRD study shows that the crystalline size and crystalinity of samples increases with pH of solution. Raman spectra confirm the dominance of anatase phase of TiO2. Morphology study of samples was done by scanning electron microscope (SEM). The size of prepared samples was calculated by XRD and confirmed by TEM analysis. The energy band gap was calculated by optical absorption spectra and it was found to decrease by increasing pH of the solution. The photodegration activity of IC dye under visible light irradiation was carried out by synthesized TiO2 Nanoparticles.

Size-dependence of Magnetic Properties of Bismuth Ferrite Nanopowders

2001 ◽  
Vol 676 ◽  
Author(s):  
J. Li ◽  
H. He ◽  
F. Lü ◽  
Y. Duan ◽  
D. Song
Keyword(s):  
Particle Size ◽  
Magnetic Measurements ◽  
Bismuth Ferrite ◽  
Sol Gel ◽  
Weak Ferromagnetism ◽  
Edge Length ◽  
X Ray Diffraction ◽  
Sol Gel Process ◽  
Spin Arrangement ◽  
Rhombohedral Crystal

ABSTRACTA series of BiFeO3 nanopowders were prepared by the sol-gel process. X-ray diffraction analysis shows that their rhombohedral crystal symmetry remains unchanged. However, as the particle size decreases, the edge length of the unit cell increases markedly and the angle between the edges deviates increasingly from 60°. Magnetic measurements show obvious weak ferromagnetism. The magnetization and magnetic susceptibility increase with decreasing particle size. Mössbauer studies reveal that the spin canting angles in the smaller particles are bigger and have a wider distribution. The magnetic structure in these particles is a complicated uncompensated antiferromagnetic spin arrangement.

Sign in / Sign up

Export Citation Format

Share Document