Influence of thermal treatments on phase formation and magnetic behaviour in metal transition doped TiO2

Cabrera, Alejandro; Errico, L. A.; Torres, C.E. Rodrı́guez; Sánchez, F.

doi:10.1016/j.physb.2006.07.032

Cited by 18 publications

(5 citation statements)

References 6 publications

(9 reference statements)

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“…In this context, transition-metal-doped titanium dioxide (TiO 2 ) single crystals, thin films, and nanoparticles have been extensively studied in recent years [1,[5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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One-pot fabrication and magnetic studies of Mn-doped TiO₂nanocrystals with an encapsulating carbon layer

Bhattacharyya¹,

Pucci²,

Zitoun³

et al. 2008

Nanotechnology

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Mn-doped TiO(2) nanocrystals encapsulated in a carbon layer (Ti(1-x)Mn(x)O(2)@C) were synthesized by the one-pot RAPET (reaction under autogenic pressure at elevated temperature) technique. Manganese was doped into the body-centered tetragonal TiO(2) anatase phase to give a Mn:Ti atomic ratio of 1%, 5% and 10%. The surface modification by carbon was achieved in order to make the cubic/tetragonal nanocrystals non-toxic and biocompatible. Electron paramagnetic resonance (EPR) studies revealed a broad resonance (centered at g = 1.9977 due to the interacting spins in the oxide matrix) with increased dopant concentration and the resonance due to carbon. Manganese is mainly present as +II or +III oxidation states. The magnetic behavior was found to be very dependent on the manganese concentration with a ferromagnetic behavior of the 1% doped sample due to the coupling between carriers and manganese spins. A predominant paramagnetic behavior was observed for the higher Mn-doped samples. This study opens up a new dimension for the carbon encapsulation of room-temperature ferromagnetic diluted magnetic semiconductor (DMS) nanomaterials.

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“…In this context, transition-metal-doped titanium dioxide (TiO 2 ) single crystals, thin films, and nanoparticles have been extensively studied in recent years [1,[5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…The nature of magnetism is observed to vary in the reports on Mn-doped TiO 2 samples, in regard to roomtemperature ferromagnetism [7][8][9], superparamagnetism [5], paramagnetism [6], and antiferromagnetism with a Néel temperature T N = 41-65 K [10].…”

Section: Introductionmentioning

confidence: 99%

One-pot fabrication and magnetic studies of Mn-doped TiO₂nanocrystals with an encapsulating carbon layer

Bhattacharyya¹,

Pucci²,

Zitoun³

et al. 2008

Nanotechnology

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“…It may be noted that the anatase→rutile phase transformation occurred at the annealing temperature of 500 • C. In contrast, anatase generally is considered to transform to rutile at temperatures above > 600 • C [21] in bulk materials and at ∼ 700-800 • C in thin films [6,7]. However, Mn is known to promote the transformation to rutile [21,[23][24][25], which explains the present results.…”

Section: Resultsmentioning

confidence: 51%

Surface Modification of Titanium Dioxide Thin Films via Manganese Doping

Nakaruk

Chen

Waibel

et al. 2012

e-J. Surf. Sci. Nanotechnol.

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Mn-doped TiO2 thin films were produced by spin coating on FTO glass substrates to investigate the effects of Mn concentration on the structural, morphological, and optical properties of the films. Titanium isopropoxide and manganese chloride tetrahydrate were used as titanium and manganese sources respectively, in the precursor solution with isopropanol. The solution was added drop-wise on the substrate which was spun at 2000 rpm; annealing was done in air at 500 • C for 5 h. Films with very low dopant concentrations (≤ 1 wt%) were composed of anatase; those with moderate concentrations (3−5 wt%) showed the presence of anatase and rutile; while those with high Mn concentrations (≤ 7 wt% Mn) showed rutile formation. Increasing the dopant concentrations resulted in a slight increase in the surface roughness, except for the sample with 15 wt% Mn, that showed surface dimple formation. The films containing ≤ 10 wt% Mn showed similarity in grain sizes (∼ 10 nm) and thickness (∼ 300 nm). All the films showed relatively high transparencies, with the absorption edges shifting to longer wavelengths with increasing Mn levels. The optical indirect band gaps of the films decreased from 3.32 eV to 2.86 eV, and this data suggests that the formation of shallow trapping sites and reduced rate of electron-hole recombination are the result of the variable valence of Mn.

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“…In the FexTi 1 _x0 2 thin film of x=O.l26, small Ms of 0.051 j.lBIFe was deyected [11]. In the bulk FexTi 1 _x0 2 system, the Ms of 0.4-0.7 f.lBIFe were observed [12,13].…”

Section: 4-------------mentioning

confidence: 97%

“…They correspond to 0.024 ,u 8 /Fe-ion for x=O.OS and 0.035 ,u 8 /Fe-ion for =0.1. Room temperature ferromagnetism were reported for FexTi 1 _x0 2 thin film [10,11] and bulk [12,13]. However room temperature ferromagnetism by secondary phase such as Fe 3 0 4 [14], a -Fe 2 0 3 [15] or absence of ferromagnetism [ 16] were also reported for thin film and bulk system.…”

Section: Magnetic Property Of Fe Doped Rutile Ti0mentioning

confidence: 99%

Ferromagnetism of V and Fe Doped TiO<sub>2</sub> by Mechanical Milling

Kimishima¹,

Ishihara²,

Uehara³

et al. 2008

Trans. Mat. Res. Soc. Japan

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Vanadium and iron doped rutile-type Ti0 2 were prepared by mechanical milling(MM) at 500 rpm for 15 minutes from the powder mixtures of (x/2)V 2 0 5 (V 2 0 3) + (1-x)Ti0 2 and (x/2) y-Fe 2 0 3 +(1-x)Ti0 2 • XRD results showed the particle diameter d was about 1 Onm for host Ti02 powder by MM, and MM for the mixtures of V205/Ti02 and y-Fe203/Ti02 realizes the V and Fe doped Ti02 nano powders. Magnetization measurement showed that M at 300K and 5 kOe was 0.002(x=0.1)-0.004(x=0.05) /.1 BN-ion for Vx Ti1-x02, 0.024(x=0.05)-0.035(x=0.1) /.1 BIFe-ion for FexTiJ-x02.Thus the diluted ferro-magnetic semiconductor powder of (V,Fe)xTi1-x02 with Tc higher than room temperature were successfully prepared by MM. But all of them were insulators, and not half metallic.

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Influence of thermal treatments on phase formation and magnetic behaviour in metal transition doped TiO2

Cited by 18 publications

References 6 publications

One-pot fabrication and magnetic studies of Mn-doped TiO₂nanocrystals with an encapsulating carbon layer

One-pot fabrication and magnetic studies of Mn-doped TiO₂nanocrystals with an encapsulating carbon layer

Surface Modification of Titanium Dioxide Thin Films via Manganese Doping

Ferromagnetism of V and Fe Doped TiO<sub>2</sub> by Mechanical Milling

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Influence of thermal treatments on phase formation and magnetic behaviour in metal transition doped TiO2

Cited by 18 publications

References 6 publications

One-pot fabrication and magnetic studies of Mn-doped TiO2nanocrystals with an encapsulating carbon layer

One-pot fabrication and magnetic studies of Mn-doped TiO2nanocrystals with an encapsulating carbon layer

Surface Modification of Titanium Dioxide Thin Films via Manganese Doping

Ferromagnetism of V and Fe Doped TiO<sub>2</sub> by Mechanical Milling

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Product

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One-pot fabrication and magnetic studies of Mn-doped TiO₂nanocrystals with an encapsulating carbon layer

One-pot fabrication and magnetic studies of Mn-doped TiO₂nanocrystals with an encapsulating carbon layer