Influence of transition metal doping on the structural, optical, and magnetic properties of TiO2 films deposited on Si substrates by a sol-gel process.
TL;DR: It is found that the magnetizations of the TM-doped TiO2 films decrease with increasing dopant content, which is related to electric disorder due to the ART.
Abstract: Transition metal (TM)-doped TiO2 films (TM = Co, Ni, and Fe) were deposited on Si(100) substrates by a sol–gel method. With the same dopant content, Co dopants catalyze the anatase-to-rutile transformation (ART) more obviously than Ni and Fe doping. This is attributed to the different strain energy induced by the different dopants. The optical properties of TM-doped TiO2 films were studied with spectroscopic ellipsometry data. With increasing dopant content, the optical band gap (EOBG) shifts to lower energy. With the same dopant content, the EOBG of Co-doped TiO2 film is the smallest and that of Fe-doped TiO2 film is the largest. The results are related to electric disorder due to the ART. Ferromagnetic behaviors were clearly observed for TM-doped TiO2 films except the undoped TiO2 film which is weakly magnetic. Additionally, it is found that the magnetizations of the TM-doped TiO2 films decrease with increasing dopant content.
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TL;DR: Among the samples, Fe-1wt% doped TiO2 nanoparticles showed the highest photocatalytic decolorization of RR198 under visible light irradiation.
136 citations
TL;DR: In this article, structural, magnetic and ferroelectric properties of Ni doped barium titanate were investigated using solid state sintering technique and it was revealed from structural studies that the phase transformation from tetragonal to hexagonal phase is strongly influenced by Ni doping concentration.
92 citations
TL;DR: In this paper, undoped and Ni-doped TiO 2 ( x Ni ǫ = 0.00, 0.50, 1.00 and 2.50 ) thin films fabricated on glass substrates by using a combination of solid-state reaction and dip coating techniques.
67 citations
11 Jan 2018
TL;DR: The enhanced rate capability and cycling stability were attributed to the enlargement of the NaO2 slab in the crystal structure because of Ti doping, which promoted Na-ion diffusion and prevented the phase transition from the P2 to the OP4/″Z″ structure.
Abstract: In this study, we developed a doping technology capable of improving the electrochemical performance, including the rate capability and cycling stability, of P2-type Na0.67Fe0.5Mn0.5O2 as a cathode material for sodium-ion batteries. Our approach involved using titanium as a doping element to partly substitute either Fe or Mn in Na0.67Fe0.5Mn0.5O2. The Ti-substituted Na0.67Fe0.5Mn0.5O2 shows superior electrochemical properties compared to the pristine sample. We investigated the changes in the crystal structure, surface chemistry, and particle morphology caused by Ti doping and correlated these changes to the improved performance. The enhanced rate capability and cycling stability were attributed to the enlargement of the NaO2 slab in the crystal structure because of Ti doping. This promoted Na-ion diffusion and prevented the phase transition from the P2 to the OP4/″Z″ structure.
62 citations
TL;DR: In this paper, the Fe-Ni co-doped and Ag deposited anatase TiO2 (Fe-Ni/Ag/TiO2) nanocomposites were successfully prepared by a simple one-pot solvothermal approach.
55 citations
References
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TL;DR: In this article, the magnetic moment was observed in undoped semiconducting or insulating oxides to become ferromagnetic at room temperature on MgO substrates, where the magnetic field was applied parallel to the film plane.
Abstract: Remarkable room-temperature ferromagnetism was observed in undoped $\mathrm{Ti}{\mathrm{O}}_{2}$, $\mathrm{Hf}{\mathrm{O}}_{2}$, and ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ thin films. The magnetic moment is rather modest in the case of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ films on MgO substrates (while on ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ substrates, it is negative showing diamagnetism) when the magnetic field was applied parallel to the film plane. In contrast, it is very large in the other two cases (about 20 and $30\phantom{\rule{0.3em}{0ex}}\mathrm{emu}∕{\mathrm{cm}}^{3}$ for $200\text{\ensuremath{-}}\mathrm{nm}$-thick $\mathrm{Ti}{\mathrm{O}}_{2}$ and $\mathrm{Hf}{\mathrm{O}}_{2}$ films, respectively). Since bulk $\mathrm{Ti}{\mathrm{O}}_{2}$, $\mathrm{Hf}{\mathrm{O}}_{2}$, and ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ are clearly diamagnetic, and moreover, there are no contaminations in any substrate, we must assume that the thin film form, which might create necessary defects or oxygen vacancies, would be the reason for undoped semiconducting or insulating oxides to become ferromagnetic at room temperature.
772 citations
"Influence of transition metal dopin..." refers background in this paper
...These magnetic phenomena are extraordinary and different from the magnetic results of the literature [7-11,21], which suggest that there are complex magnetisms in these samples....
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...Recently, roomtemperature FM [9] and reversible FM [10] in undoped...
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TL;DR: The experimental status of O-DMS including the recent results on ZnO-and TiO2-based systems is described in this paper, where the authors present a review of the experimental status and experimental results on O-diluted magnetic semiconductors.
Abstract: Oxide-diluted magnetic semiconductors (O-DMS) have attracted a great deal of interest in recent years due to the possibility of inducing room temperature ferromagnetism These materials are of particular interest for spintronic devices such as spin valves This review describes the experimental status of the O-DMS including the recent results on ZnO- and TiO2-based systems
381 citations
"Influence of transition metal dopin..." refers background in this paper
...It has been widely studied due to its potential applications in spintronics [1-3]....
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TL;DR: In this review an attempt is made to capture the scope and spirit of this effort aimed at inducing spin functionality (magnetism, spin polarization) and thereby novel magneto-transport and Magneto-optic effects in such oxides.
Abstract: Over the past decade intensive research efforts have been carried out by researchers around the globe on exploring the effects of dilute doping of magnetic impurities on the physical properties of functional non-magnetic metal oxides such as TiO2 and ZnO. This effort is aimed at inducing spin functionality (magnetism, spin polarization) and thereby novel magneto-transport and magneto-optic effects in such oxides. After an early excitement and in spite of some very promising results reported in the literature, this field of diluted magnetic semiconducting oxides (DMSO) has continued to be dogged by concerns regarding uniformity of dopant incorporation, the possibilities of secondary ferromagnetic phases, and contamination issues. The rather sensitive dependence of magnetism of the DMSO systems on growth methods and conditions has led to interesting questions regarding the specific role played by defects in the attendant phenomena. Indeed, it has also led to the rapid re-emergence of the field of defect ferromagnetism. Many theoretical studies have contributed to the analysis of diverse experimental observations in this field and in some cases to the predictions of new systems and scenarios. In this review an attempt is made to capture the scope and spirit of this effort highlighting the successes, concerns, and questions.
357 citations
"Influence of transition metal dopin..." refers background in this paper
...It has been widely studied due to its potential applications in spintronics [1-3]....
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Book•
15 Jun 2000
TL;DR: In this paper, the authors present a more complex Kroeger-Vink diagram for MX with Schottky disorder, which they use to represent the effect of impurities on the concentration of defect complexes.
Abstract: 1. Introduction Reference 2. A Few Useful Crystal Structures Introduction Close-Packed Structures Structures for Eight-Coordinate Cations Structures for Ternary Compounds Conclusion References Problems 3. Lattice Defects and the Law of Mass Action Introduction Lattice Defects as Part of the Equilibrium State The Law of Mass Action Another View of Mass Action Lattice Disorder in Elemental Solids Summary References 4. Intrinsic Ionic Disorder Lattice Defects and Reference States Conservation Rules Defect Notation Major Types of Intrinsic Ionic Disorder General Comments on Intrinsic Ionic Disorder References Problems 5. Extrinsic Ionic Disorder Introduction The AgCl-CdCl[2 System The CaF[2-CaO System The TiO[2-Nb[2O[5 System Summary of Important Points Schematic Representation of Defect Concetrations Summary of Extrinsic Ionic Disorder References Problems 6. Defect Complexes and Associates Introduction Complexes Containing an Impurity Center and an Ionic Defect Intrinsic Ionic Defect Associates The Effect of Impurities on the Concentrations of Defect Complexes and Associates References 7. Ionic Transport Introduction Basic Concepts of Diffusion Ionic Conduction in Crystalline Solids Intrinsic and Extrinsic Ionic Conduction Fast Ion Conductors References 8. Intrinsic Electronic Disorder Introduction The Development of Energy Bonds The Mass-Action Approach The Fermi Function Holes, Waves, and Effective Masses Electronic Conductivity Hopping Mechanisms The Band Structure of Compounds Chemistry and the Band Gap Summary References 9. Extrinsic Electronic Disorder Introduction Interactions with the Gaseous Ambient The Choice of Compensating Defect The Chemical Consequences of Electronic Compensation The Interactions of Impurity Centers with Electrons and Holes The Situation for Compounds Summary References 10. Intrinsic Nonstoichiometry Introduction Nonstoichiometry in Pure Crystalline Compounds Nonstoichiometry and Equilibrium Defect Concentrations The Hypothetical Compund MX with Schottky Disorder Summary of the Kroeger-Vink Diagram for MX Conclusion of the Discussion of MX A More Complex Kroeger-Vink Diagram Summary of the Kroeger-Vink Diagrams for Intrinsic Nonstoichiometry Enthalpy Relationships Conclusion Reference Problems 11. Extrinsic Nonstoichiometry Introduction A Simple Example: Donor-Doped MX Enthalpy Relationships A More Complex Example: Acceptor-Doped M[2O[3 General Considerations Nonstoichiometric Reactions in the Impurity-Controlled Region Problems 12. Titanium Dioxide Introduction The Amount of Nonstoichiometry The Equilibrium Electrical Conductivity of Undoped TiO[2 The Seebeck Coefficient of Undoped TiO[2 Ionic Conduction in TiO[2 The Effect of Dopants on TiO[2 General Comments on the Defect Chemistry of TiO[2 References Problems 13. Cobalt Oxide and Nickel Oxide Introduction Cobaltous Oxide, CoO Nickelous Oxide, NiO Summary References 14. Barium Titanate Introduction General Expectations The Equilibrium Conductivity of Undoped BaTiO[3 Insulating Properties of BaTiO[3 Acceptor-Doped BaTiO[3 Ionic Conduction in BaTiO[3 Donor-Doped BaTiO[3 Trivalent Dopants in BaTiO[3 Summary References 15. Order versus Disorder Block Structures Summary References Index
351 citations
TL;DR: In this paper, the authors investigated numerically the properties of metallo-dielectric, one-dimensional, photonic band-gap structures and showed that interference effects give rise to a new transparent metallic structure that permits the transmission of light over a tunable range of frequencies, for example, the ultraviolet, the visible or the infrared wavelength range.
Abstract: We investigate numerically the properties of metallo-dielectric, one-dimensional, photonic band-gap structures. Our theory predicts that interference effects give rise to a new transparent metallic structure that permits the transmission of light over a tunable range of frequencies, for example, the ultraviolet, the visible, or the infrared wavelength range. The structure can be designed to block ultraviolet light, transmit in the visible range, and reflect all other electromagnetic waves of lower frequencies, from infrared to microwaves and beyond. The transparent metallic structure is composed of a stack of alternating layers of a metal and a dielectric material, such that the complex index of refraction alternates between a high and a low value. The structure remains transparent even if the total amount of metal is increased to hundreds of skin depths in net thickness.
342 citations