Electric and Magnetic Properties of Epitaxial Fe2−xTixO3+σ Films

2000 ◽  
Vol 623 ◽  
Author(s):  
T. Fujii ◽  
K. Ayama ◽  
M. Nakanishi ◽  
M. Sohma ◽  
K. Kawaguchi ◽  
...  
Keyword(s):  
Spontaneous Magnetization ◽  
Mixed Valence ◽  
Room Temperature Resistivity ◽  
Half Metallic ◽  
Metallic Oxides ◽  
Corundum Structure ◽  
Valence States ◽  
Ilmenite Structure ◽  
Ti Content ◽  
Temperature Resistivity

AbstractSolid solution films of the σ-Fe2O3-FeTiO3 series are one of the candidates for noble half-metallic oxides. They were epitaxially formed on σ-Al2O3(001) single crystalline substrates by O2 -reactive evaporation method. The Fe2−x TixO3+σ films prepared at higher Ts=973 K and with larger Ti content x≤0.4 had the ilmenite structure with R3 symmetry. Other films at lower Ts or with smaller x possessed the corundum structure with R3c. Only the films with R3 symmetry had large ferrimagnetic moments, though the observed spontaneous magnetization was less than half of the ideal value expected from the fully ordered structure. Room temperature resistivity of intermediate composites dropped to 10−lΔcm due to the formation of the mixed valence states between Fe2+ and Fe3+. However the Fe2+ content of the films was rather small as compared with stoichiometric Fe2−xTixO3. The Ti-rich films had large oxygen nonstoichio netry of about σ=0.3.

Cerium oxide nanomaterial with dual antioxidative scavenging potential: Synthesis and characterization

2021 ◽  
pp. 088532822110134
Author(s):  
Sushant Singh ◽  
Udit Kumar ◽  
David Gittess ◽  
Tamil S Sakthivel ◽  
Balaashwin Babu ◽  
...  
Keyword(s):  
Cerium Oxide ◽  
Biological Systems ◽  
Mixed Valence ◽  
Stable Solution ◽  
Ability To Act ◽  
Valence States ◽  
Transmission Electron ◽  
Efficient Reduction ◽  
Rich Media

Many studies have linked reactive oxygen species (ROS) to various diseases. Biomedical research has therefore sought a way to control and regulate ROS produced in biological systems. In recent years, cerium oxide nanoparticles (nanoceria, CNPs) have been pursued due to their ability to act as regenerative ROS scavengers. In particular, they are shown to have either superoxide dismutase (SOD) or catalase mimetic (CAT) potential depending on the ratio of Ce3+/Ce4+ valence states. Moreover, it has been demonstrated that SOD mimetic activity can be diminished by the presence of phosphate, which can be a problem given that many biological systems operate in a phosphate-rich environment. Herein, we report a CNP formulation with both SOD and catalase mimetic activity that is preserved in a phosphate-rich media. Characterization demonstrated a highly dispersed, stable solution of uniform-sized, spherical-elliptical shaped CNP of 12 ± 2 nm, as determined through dynamic light scattering, zeta potential, and transmission electron microscopy. Mixed valence states of Ce ions were observed via UV/Visible spectroscopy and XPS (Ce3+/Ce4+ > 1) (Ce3+∼ 62%). X-ray diffraction and XPS confirmed the presence of oxygen-deficient cerium oxide (CeO2-x) particles. Finally, the CNP demonstrated very good biocompatibility and efficient reduction of hydrogen peroxide under in-vitro conditions.

scholarly journals Rare-earth (RE) nanolaminates Mo4RE4Al7C3 featuring ferromagnetism and mixed-valence states

2018 ◽  
Vol 2 (11) ◽  
Author(s):  
Q. Tao ◽  
T. Ouisse ◽  
D. Pinek ◽  
O. Chaix-Pluchery ◽  
F. Wilhelm ◽  
...  
Keyword(s):  
Rare Earth ◽  
Mixed Valence ◽  
Valence States

scholarly journals A novel and potentially scalable CVD-based route towards SnO2:Mo thin films as transparent conducting oxides

2021 ◽  
Author(s):  
Tianlei Ma ◽  
Marek Nikiel ◽  
Andrew G. Thomas ◽  
Mohamed Missous ◽  
David J. Lewis
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Mixed Valence ◽  
Chemical Vapour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conducting Oxides ◽  
Valence States ◽  
3 Omega ◽  
First Time

AbstractIn this report, we prepared transparent and conducting undoped and molybdenum-doped tin oxide (Mo–SnO2) thin films by aerosol-assisted chemical vapour deposition (AACVD). The relationship between the precursor concentration in the feed and in the resulting films was studied by energy-dispersive X-ray spectroscopy, suggesting that the efficiency of doping is quantitative and that this method could potentially impart exquisite control over dopant levels. All SnO2 films were in tetragonal structure as confirmed by powder X-ray diffraction measurements. X-ray photoelectron spectroscopy characterisation indicated for the first time that Mo ions were in mixed valence states of Mo(VI) and Mo(V) on the surface. Incorporation of Mo6+ resulted in the lowest resistivity of $$7.3 \times 10^{{ - 3}} \Omega \,{\text{cm}}$$ 7.3 × 10 - 3 Ω cm , compared to pure SnO2 films with resistivities of $$4.3\left( 0 \right) \times 10^{{ - 2}} \Omega \,{\text{cm}}$$ 4.3 0 × 10 - 2 Ω cm . Meanwhile, a high transmittance of 83% in the visible light range was also acquired. This work presents a comprehensive investigation into impact of Mo doping on SnO2 films synthesised by AACVD for the first time and establishes the potential for scalable deposition of SnO2:Mo thin films in TCO manufacturing. Graphical abstract

scholarly journals Correction: Effects of mixed-valence states of Eu-doped FAPbI3 perovskite crystals studied by first-principles calculation

2021 ◽  
Vol 2 (8) ◽  
pp. 2759-2759
Author(s):  
Atsushi Suzuki ◽  
Takeo Oku
Keyword(s):  
First Principles ◽  
Mixed Valence ◽  
First Principles Calculation ◽  
Valence States

Correction for ‘Effects of mixed-valence states of Eu-doped FAPbI3 perovskite crystals studied by first-principles calculation’ by Atsushi Suzuki et al., Mater. Adv., 2021, DOI: 10.1039/D0MA00994F.

Influence of Modulation Wavelength Induced Order on the Physical Properties of Nb/Rare Earth Superlattices

1984 ◽  
Vol 37 ◽  
Author(s):  
L. H. Greene ◽  
W. L. Feldmann ◽  
J. M. Rowell ◽  
B. Batlogg ◽  
R. Hull ◽  
...  
Keyword(s):  
Rare Earth ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Residual Resistance ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Sputter Deposited ◽  
Residual Resistance Ratio ◽  
Temperature Resistivity ◽  
Modulation Wavelength

AbstractWe report the observation of a higher degree of preferred crystalline orientation in Nb/rare earth superlattices for modulation wavelengths in the range of 200 Å to 500 Å than that exhibited by single component films. All films and multilayers are sputter deposited onto room temperature sapphire substrates. Electronic transport measurements also show that the residual resistance ratio is higher and the room temperature resistivity is lower than for multilayers of either greater or lower periodicities. Transmission electron micrographs (TEM) showing excellent layering, grain size comparable to the layer thickness, and evidence of some degree of epitaxy are presented.

scholarly journals Computational Intelligence Approach for Estimating Superconducting Transition Temperature of Disordered MgB2Superconductors Using Room Temperature Resistivity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Taoreed O. Owolabi ◽  
Kabiru O. Akande ◽  
Sunday O. Olatunji
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Room Temperature ◽  
Optimization Technique ◽  
Support Vector ◽  
Measuring Instruments ◽  
Room Temperature Resistivity ◽  
Superconducting Transition ◽  
Experimental Values ◽  
Temperature Resistivity

Doping and fabrication conditions bring about disorder in MgB2superconductor and further influence its room temperature resistivity as well as its superconducting transition temperature (TC). Existence of a model that directly estimatesTCof any doped MgB2superconductor from the room temperature resistivity would have immense significance since room temperature resistivity is easily measured using conventional resistivity measuring instrument and the experimental measurement ofTCwastes valuable resources and is confined to low temperature regime. This work develops a model, superconducting transition temperature estimator (STTE), that directly estimatesTCof disordered MgB2superconductors using room temperature resistivity as input to the model. STTE was developed through training and testing support vector regression (SVR) with ten experimental values of room temperature resistivity and their correspondingTCusing the best performance parameters obtained through test-set cross validation optimization technique. The developed STTE was used to estimateTCof different disordered MgB2superconductors and the obtained results show excellent agreement with the reported experimental data. STTE can therefore be incorporated into resistivity measuring instruments for quick and direct estimation ofTCof disordered MgB2superconductors with high degree of accuracy.

Mixed-Valence States in MMX-Chains Complex, Pt2(dta)4I

1996 ◽  
Vol 285 (1) ◽  
pp. 311-316 ◽  
Author(s):  
Hiroshi Kitagawa ◽  
Noriaki Onodera ◽  
Jeung-Sun Ahn ◽  
Tadaoki Mitani ◽  
Misa Kim ◽  
...  
Keyword(s):  
Mixed Valence ◽  
Valence States

Rapid microwave-assisted hydrothermal synthesis of CeO2 octahedra with mixed valence states and their catalytic activity for thermal decomposition of ammonium perchlorate

2019 ◽  
Vol 6 (7) ◽  
pp. 1735-1743 ◽  
Author(s):  
Jing Shi ◽  
Huixiang Wang ◽  
Yequn Liu ◽  
Xiaobo Ren ◽  
Haizhen Sun ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Hydrothermal Synthesis ◽  
Ammonium Perchlorate ◽  
Oxygen Vacancies ◽  
Mixed Valence ◽  
High Concentration ◽  
Microwave Assisted ◽  
Valence States

CeO2 octahedra are prepared rapidly and they exhibit improved catalytic activity due to high concentration of oxygen vacancies and exposed (111) facets.

Structure and mixed-valence states of the trinuclear iron(II,III,III) pivalate complex-pivalic acid adduct, [Fe3O(O2CCMe3)6(Me3CCO2H)3] (Me = −CH3)

1995 ◽  
Vol 236 (1-2) ◽  
pp. 155-161 ◽  
Author(s):  
Kohko Asamaki ◽  
Tadahiro Nakamoto ◽  
Satoshi Kawata ◽  
Hirotoshi Sano ◽  
Motomi Katada ◽  
...  
Keyword(s):  
Mixed Valence ◽  
Pivalic Acid ◽  
Valence States ◽  
Acid Adduct
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