scholarly journals X-ray Photoelectron Studies of High-temperature Superconductors: Evidence for the Importance of Alkaline Earth Metals

1989 ◽  
Vol 42 (4) ◽  
pp. 409 ◽  
Author(s):  
JF Dobson ◽  
AE Bocquet ◽  
PC Healy ◽  
S Myhra ◽  
AM Stewart ◽  
...  
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Alkaline Earth ◽  
High Temperature Superconductors ◽  
Alkaline Earth Metals ◽  
X Ray ◽  
Binding Energy Peak ◽  
Energy Peak ◽  
Superconducting Ceramics

All high�temperature superconducting ceramics so far studied contain alkaline-earth ions, and in all cases core-level X-ray photoelectron spectroscopy shows an anomalous low-binding energy peak from these ions. We argue that this may point to electron-rich alkaline earth layers. These should be highly polarisable, allowing them to facilitate uperconductivity by screening the repulsion between electrons and/or holes in the CuD layers.

Xps Analysis of the Sapphire Surface as a Function of High Temperature Vacuum Annealing

1989 ◽  
Vol 159 ◽  
Author(s):  
E.D. Richmond
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Xps Analysis ◽  
Chemical Changes ◽  
Cleaning Procedure ◽  
Sapphire Surface ◽  
X Ray ◽  
First Time

ABSTRACTFor the first time the (1102) surface of sapphire has been investigated by X-ray photoelectron spectroscopy to ascertain chemical changes resulting from annealing in vacuum at 1300° C and 1450° C. As received substrates had a substantial surface C contaminant. For substrates that were chemically cleaned before inserting them into the MBE system no trace of carbon is detected. A residual flourine contaminant results from the cleaning procedure and is desorbed by the vacuum annealing. Spectra of annealed substrates are compared to the unannealed chemically cleaned substrates. The annealed substrates exhibit 0.4 to 0.5 eV shift to higher binding energy of the Al peak and a 0.3 eV shift to higher binding energy of the O peak. In addition, a 2% depletion of oxygen from the surface occurs.

Niobium-bearing arsenides and germanides from elemental mixtures not involving niobium: a new twist to an old problem in solid-state synthesis

2018 ◽  
Vol 74 (5) ◽  
pp. 623-627 ◽  
Author(s):  
Sviatoslav Baranets ◽  
Hua He ◽  
Svilen Bobev
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Diffraction Data ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Temperature Reactions ◽  
First Time ◽  
Synthetic Work

Three isostructural transition-metal arsenides and germanides, namely niobium nickel arsenide, Nb0.92(1)NiAs, niobium cobalt arsenide, NbCoAs, and niobium nickel germanide, NbNiGe, were obtained as inadvertent side products of high-temperature reactions in sealed niobium containers. In addition to reporting for the very first time the structures of the title compounds, refined from single-crystal X-ray diffraction data, this article also serves as a reminder that niobium containers may not be suitable for the synthesis of ternary arsenides and germanides by traditional high-temperature reactions. Synthetic work involving alkali or alkaline-earth metals, transition or early post-transition metals, and elements from groups 14 or 15 under such conditions may yield Nb-containing products, which at times could be the major products of such reactions.

X-ray photoelectron spectroscopy study of inequivalent oxygen sites in high temperature superconductors

1992 ◽  
Vol 190 (3) ◽  
pp. 249-254 ◽  
Author(s):  
R.P. Vasquez ◽  
B.D. Hunt ◽  
M.C. Foote ◽  
L.J. Bajuk ◽  
W.L. Olson
Keyword(s):  
High Temperature ◽  
Photoelectron Spectroscopy ◽  
High Temperature Superconductors ◽  
Spectroscopy Study ◽  
X Ray

scholarly journals Determination of chromium valence state in the CaO–SiO2–FeO–MgO–CrOx system by X-ray photoelectron spectroscopy

2020 ◽  
Vol 39 (1) ◽  
pp. 351-356
Author(s):  
Deman Liu ◽  
Jiang Diao ◽  
Yiyu Qiu ◽  
Guang Wang ◽  
Gang Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Oxygen Pressure ◽  
Photoelectron Spectroscopy ◽  
Valence State ◽  
Slag Basicity ◽  
X Ray ◽  
Chromium Ions ◽  
Valence States

AbstractThe chromium valence states in the CaO–SiO2–FeO–MgO–CrOx system were investigated by X-ray photoelectron spectroscopy (XPS). The results indicated that the XPS peaks of Cr 2p3/2 and Cr 2p1/2 locate at the binding energy of ∼577 and ∼586 eV, respectively. There are three kinds of chromium ions such as bivalent Cr(ii), trivalent Cr(iii), and hexavalent Cr(vi) in the CaO–SiO2–FeO–MgO–CrOx slag. Cr(iii) is the dominant valence state, and more than 77.99% Cr is trivalent Cr(iii). The fraction of Cr(ii)/Cr is in the range of 11.24–17.22%. The fraction of Cr(vi)/Cr is below 4.80%. The fraction of Cr(ii)/Cr decreases with increasing slag basicity, Cr2O3 content, temperature, or oxygen pressure log(PO2), while the fraction of Cr(iii)/Cr increases with increasing basicity, Cr2O3 content, temperature, or oxygen pressure. The trend of change is opposite. Low log(PO2), high Cr2O3 content, and high temperature are beneficial to reduce the toxic hexavalent Cr(vi). The slag basicity has little influence on the fraction of Cr(vi)/Cr.

Athermochemical Investigation of the La-Sr-Cu-O System

1989 ◽  
Vol 169 ◽  
Author(s):  
Joseph Bularzik ◽  
Alexandra Navrotsky ◽  
Bruce Scott ◽  
Joe Bringley ◽  
Steve Trail
Keyword(s):  
High Temperature ◽  
Alkaline Earth ◽  
High Temperature Superconductors ◽  
Solution Calorimetry ◽  
Alkaline Earth Metals ◽  
Heats Of Formation ◽  
High Temperature Solution ◽  
Calorimetric Measurements ◽  
Temperature Solution ◽  
The Stability

AbstractThe perovskite related La2‐xMxCuO4‐y oxides substituted with alkaline earth metals were one of the first classes of high temperature superconductors discovered. Determining the thermodynamic properties is important to understand the stability and superconducting mechanism of these structures. High temperature solution calorimetry, using a molten lead borate solvent, has been performed on La2CuO4 and the related Sr substituted oxides. Calorimetric measurements on CuO, La2O3 and SrCO3 yield heats of formation. A change in the trend of the heats of formation appears at Sr content 0.1, the reported orthorhombic to tetragonal transition, the onset of superconductivity and loss of oxygen.

scholarly journals Effect of Boron in a Hierarchical Nanoporous Layer Formation on Silicate Glass

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1817
Author(s):  
Takumi Ito ◽  
Erika Tabata ◽  
Yuki Ushioda ◽  
Takuya Fujima
Keyword(s):  
Silicate Glass ◽  
Photoelectron Spectroscopy ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
Layer Formation ◽  
X Ray ◽  
Formation Behavior ◽  
Nanoporous Layer ◽  
Skeleton Structure

A hierarchical nanoporous layer (HNL) can be formed on the silicate glass surface by simple alkali etching. Though it reportedly exhibits various useful functions, such as superhydrophilicity, optical anti-reflection, and material impregnation, the principle of its formation still remains unclear. In this study, HNL formation behavior was experimentally investigated while using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) to clarify the role of boron contained in glass. As a result, it was found that HNL formation was significantly promoted by boron, which was rapidly eluted prior to alkali and alkaline earth metals. This suggests that boron, which forms the skeleton structure of glass together with Si and O, elutes to partially decompose the skeleton, and extends the elution route for HNL formation.

New nanostructured manganites of LaMeIICuZnMnO6 (MeII — Mg, Ca, Sr, Ba)

2021 ◽  
Vol 103 (3) ◽  
pp. 60-66
Author(s):  
Sh.B. Kasenova ◽  
◽  
Zh.I. Sagintaeva ◽  
B.K. Kasenov ◽  
M.O. Turtubaeva ◽  
...  
Keyword(s):  
Electron Microscope ◽  
High Temperature ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
Polycrystalline Copper ◽  
X Ray ◽  
Nanostructured Particles ◽  
Copper Zinc ◽  
Temperature Interaction ◽  
Vibration Mill

The copper-zinc manganites of LaMeIICuZnMnO6 (MeII — Mg, Ca, Sr, Ba) have been synthesized with the high-temperature interaction of alkaline earth metals carbonates with oxides of lanthanum (III), copper (II), zinc (II) and manganese (III). The synthesized polycrystalline copper-zinc manganites have been grinded on the Retsch vibration mill MM301 (Germany). As a result their nanostructured particles have been obtained. Their sizes have been determined using an electron microscope Mira3 LMU, Tescan. Methods of radiography determined that all synthesized nanostructured copper-zinc manganites crystallize in the cubic syngony with the following parameters of a lattice: LaMgCuZnMnO6 — а = 13.530.02 Å, Vo = 2476.810.06 Å3, Z = 4, Voelect.cell = 619.200.02 Å3, roent = 4.52; pick = 4.500.01 g/cm3; LaCaCuZnMnO6 — а = 13.690.02 Å, Vo = 2565.730.06 Å3, Z = 4, Voelect.cell. = 641.430.02 Å3, roent = 4.43; pick = 4.410.01 g/cm3; LaSrCuZnMnO6 — а = 13.910.02 Å, Vo = 2691.420.06 Å3, Z = 4, Voelect.cell = 672.850.02 Å3, roent = 4.99; pick. = 4.960.01 g/cm3; LaBaCuZnMnO6 — а = 14.550.02 Å, Vo = 3080.270.06 Å3, Z = 4, Voelect.cell = 770.070.02 Å3, roent = 4.95; pick = 4.940.01 g/cm3. The X-ray investigations demonstrated that the values of lattice parameters of the studied copper-zinc manganites have been increased from Mg to Ba. As a result of the investigations, these compounds can be included in Pm3m spatial group.

Deposition of Cobalt Doped Zinc Oxide Thin Film Nano-Composites Via Pulsed Electron Beam Ablation

MRS Advances ◽  
2016 ◽  
Vol 1 (6) ◽  
pp. 433-439 ◽  
Author(s):  
Asghar Ali ◽  
Patrick Morrow ◽  
Redhouane Henda ◽  
Ragnar Fagerberg
Keyword(s):  
Zinc Oxide ◽  
Electron Beam ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Oxide Thin Film ◽  
X Ray ◽  
Pulsed Electron Beam ◽  
Deposited Films

AbstractThis study reports on the preparation of cobalt doped zinc oxide (Co:ZnO) films via pulsed electron beam ablation (PEBA) from a single target containing 20 w% Co on sapphire (0001) and silicon (100) substrates. The films have been deposited at various temperatures (350оC, 400оC, 450оC) and pulse frequencies (2 Hz, 4 Hz), under a background argon (Ar) pressure of about 3 mtorr, and an accelerating voltage of 14 kV. The surface morphology has been examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). According to SEM analysis, the films consist of nano-globules whose size is in the range of 80-178 nm. Energy dispersive x-ray spectroscopy (EDX) reveals that deposition is congruent and the prepared films contain ∼20±5 w% cobalt. It has been found that the nano-globules in the deposited films are cobalt-rich zones containing ∼70 w% Co. From x-ray photoelectron spectroscopy (XPS) analysis, Co 2p3/2 peaks indicate that the deposited films contain CoO (binding energy = 780.5 eV) as well as metallic Co (binding energy = 778.1-778.5 eV). X-ray diffraction (XRD) analysis supports the presence of metallic Co hcp phase (2ϴ = 44.47° and 47.43°) in the films.

TEMPERATURE DEPENDENCE OF THE HALL EFFECT IN La2−xSrxCuO4 AND ABa2Cu3O7 (A=Y, Gd) HIGH TEMPERATURE SUPERCONDUCTORS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 1067-1070 ◽  
Author(s):  
M. Petravić ◽  
A. Hamzić ◽  
B. Leontić ◽  
L. Forró
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Hall Effect ◽  
Normal State ◽  
High Temperature Superconductors ◽  
The Other ◽  
Hall Constant ◽  
High Temperature Superconducting ◽  
Superconducting Ceramics ◽  
Hall Effect Measurements

We present Hall effect measurements in the normal state of the high temperature superconducting ceramics La2−xSrxCuO4 (x=0, 0.1, 0.15, 0.2, 0.25, 0.3), YBa2Cu3o7 and GdBa2Cu3O7 . The first family has temperature independent Hall constant for x>0, while in the other two systems RH is proportional to 1/T. From the Hall effect it follows that the transport in these compounds is hole-like.

scholarly journals Functional Nanoscale Phase Separation and Intertwined Order in Quantum Complex Materials

2021 ◽  
Vol 6 (4) ◽  
pp. 40
Author(s):  
Gaetano Campi ◽  
Antonio Bianconi
Keyword(s):  
Phase Separation ◽  
High Temperature ◽  
Physical Properties ◽  
High Precision ◽  
High Temperature Superconductors ◽  
Complex Materials ◽  
Structural Units ◽  
X Ray ◽  
Nanoscale Phase Separation ◽  
Complex Matter

Nanoscale phase separation (NPS), characterized by particular types of correlated disorders, plays an important role in the functionality of high-temperature superconductors (HTS). Our results show that multiscale heterogeneity is an essential ingredient of quantum functionality in complex materials. Here, the interactions developing between different structural units cause dynamical spatiotemporal conformations with correlated disorder; thus, visualizing conformational landscapes is fundamental for understanding the physical properties of complex matter and requires advanced methodologies based on high-precision X-ray measurements. We discuss the connections between the dynamical correlated disorder at nanoscale and the functionality in oxygen-doped perovskite superconducting materials.

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