Hydrothermal growth of ferromagnetic Fe-doped TiO2 films

Chan, Kelvin Y. S.; Goh, Gregory K. L.

doi:10.1016/j.tsf.2007.07.068

Cited by 13 publications

(8 citation statements)

References 27 publications

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“…Also it should be mentioned that the M-H and M-T dependence of our Fe-doped TiO 2 nanotubes are similar to those in many other reports on Fe-doped TiO 2 lms, nanoparticles, and bulk crystals. 34,35,48 These all together strongly suggest that the ferromagnetic signal from our Fedoped TiO 2 nanotube samples is intrinsic resulting from Fe atoms substituting Ti atoms. The mechanism of ferromagnetism in doped transition-metal oxides is still under debate.…”

Section: Magnetic Propertiesmentioning

confidence: 54%

“…[29][30][31][32] Fe is a good dopant for fabricating magnetic semiconductors. [33][34][35] Cu and Nb co-doped TiO 2 thin lms with N have been shown to increase the photocatalytic activity of TiO 2 . 36 The morphology of grown TiO 2 nanotubes was examined using a eld-emission scanning electron microscope (FE-SEM) JEOL 7401F.…”

Section: Methodsmentioning

confidence: 99%

“…Magnetic properties of Fe-doped TiO 2 nanotube samples were studied as Fe is frequently chosen as the magnetic dopant when pursuing magnetic semiconductors. 34,35,48 Fig. 8 presents the magnetization vs. magnetic eld dependence (M-H) measured at 300 K aer subtracting the diamagnetic background.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

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Doping of wide-bandgap titanium-dioxide nanotubes: optical, electronic and magnetic properties

et al. 2014

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Doping semiconductors is an important step for their technological application. While doping bulk semiconductors can be easily achieved, incorporating dopants in semiconductor nanostructures has proven difficult. Here, we report a facile synthesis method for doping titanium-dioxide (TiO₂) nanotubes that was enabled by a new electrochemical cell design. A variety of optical, electronic and magnetic dopants were incorporated into the hollow nanotubes, and from detailed studies it is shown that the doping level can be easily tuned from low to heavily-doped semiconductors. Using desired dopants - electronic (p- or n-doped), optical (ultraviolet bandgap to infrared absorption in co-doped nanotubes), and magnetic (from paramagnetic to ferromagnetic) properties can be tailored, and these technologically important nanotubes can be useful for a variety of applications in photovoltaics, display technologies, photocatalysis, and spintronic applications.

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Section: Magnetic Propertiesmentioning

confidence: 54%

Section: Methodsmentioning

confidence: 99%

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Doping of wide-bandgap titanium-dioxide nanotubes: optical, electronic and magnetic properties

et al. 2014

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“…It is well-known that hydrothermal synthesis can be used to produce bulk single crystals and epitaxial films of various materials and hopefully this work will show that the subset of materials that can be formed in a single crystalline nanostructured form can be expanded significantly. Although hydrothermal synthesis is generally performed in a pressurized aqueous solution at high temperatures, there are examples of growth of epitaxial films, for example ZnO, − TiO 2 , and BaTiO 3 , at ambient pressure and low temperatures (<95 °C). Here, we selected ZnO as the material to be grown given the already extensive literature on the low-temperature hydrothermal synthesis of ZnO crystals and the demonstrations of selective-area epitaxy and lateral epitaxial overgrowth of ZnO on two-dimensional patterned substrates from an aqueous solution at ∼90 °C. , While the hydrothermal bottom-up growth of polycrystalline ZnO in 3D colloidal crystal templates has also been reported, prior to our work here, epitaxy in a 3D structured template had not been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Low-Temperature Hydrothermal Synthesis of Colloidal Crystal Templated Nanostructured Single-Crystalline ZnO

et al. 2017

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Single crystal semiconductors almost always exhibit better optoelectrical properties than their polycrystalline or amorphous counterparts. While three-dimensionally (3D) nanostructured semiconductor devices have been proposed for numerous applications, in the vast majority of reports, the semiconductor is polycrystalline or amorphous, greatly reducing the potential for advanced properties. While technologies for 3D structuring of semiconductors via use of a 3D template have advanced significantly, approaches for epitaxially growing nanostructured single crystal semiconductors within a template remain limited. Here, we demonstrate the epitaxial growth of 3D-structured ZnO through colloidal templates formed from 225 and 600 nm diameter colloidal particles via a low-temperature (∼80 °C) hydrothermal process using a flow reactor. The effects of the pH of the reaction solution as well as the additive used on the 3D epitaxy process are investigated. The optical and electrical properties of the epitaxially grown nanostructured ZnO are probed by reflectance, photoluminescence, and Hall effect measurements. It is found that the epitaxially grown nanostructured ZnO generally exhibits properties superior to those of polycrystalline ZnO. The demonstrated hydrothermal epitaxy process should be applicable to other chemical solution-based deposition techniques and help extend the range of materials that can be grown into a 3D nanostructured single-crystalline form.

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“…One of the most commonly used methods to enhance visible light absorption is to dope the material with cations and anions, including vanadium,6 chromium,7 iron,8 cobalt,9 copper,10 zinc,11 nitrogen12 and boron 13. Of the preceding, Fe is of interest owing to its octahedral trivalent radius of 0·079 nm, which is similar to that of octahedral tetravalent Ti (0·075 nm) 14.…”

Section: Introductionmentioning

confidence: 99%

Iron doped titania thin films prepared by spin coating

Nakaruk

Lin

Koshy

et al. 2012

Advances in Applied Ceramics

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Thin films of titania (TiO 2 ) doped with 1-5 wt-%Fe were spin coated on glass slides and then annealed at 500uC for 2 h. Results revealed that all of the films were y500 nm in thickness and consisted of anatase. Increasing the dopant levels revealed the following trends: the major (101) anatase peak shifted to larger lattice spacing [the peaks were normalised using the principal (210) chromium coating peak as an in situ standard]; the microstructures showed increasing shrinkage cracking, a phenomenon that has not been reported previously; the optical transmittance generally decreased; the amplitude of the transmittance curves generally decreased; and the optical indirect band gap decreased from 3?40 to 3?18 eV, possibly due to silicon contamination, residual thermal stress and/or the formation of midgap states from Fe doping.

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Hydrothermal growth of ferromagnetic Fe-doped TiO2 films

Cited by 13 publications

References 27 publications

Doping of wide-bandgap titanium-dioxide nanotubes: optical, electronic and magnetic properties

Doping of wide-bandgap titanium-dioxide nanotubes: optical, electronic and magnetic properties

Low-Temperature Hydrothermal Synthesis of Colloidal Crystal Templated Nanostructured Single-Crystalline ZnO

Iron doped titania thin films prepared by spin coating

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