A Study of the Superconducting La2-xSrxCuO4 System by X-Ray Powder Diffraction

AbstractRoom temperature crystalline structures of La2-xSrxCuO4 samples with uncommonly high hole concentrations (p) up to p=0.4, annealed under 1 and 100 bars of oxygen pressure have been analyzed by X-ray diffraction. Results show that the x=0 sample with p=0.09 and superconducting below 20K is orthorhombic at room temperature. The orthorhombic distortion at 300K decreases with increasing x and becomes tetragonal when x reaches 0.08. This orthorhombic-to-tetragonal phase transformation is consistent with previous work. Samples with x≥0.28 and p≥0.31 remain tetragonal but are nonsuperconducting down to 5K. Lattice dimension anomalies have also been observed and are correlated with the sudden appearance of oxygen vacancies, as seen by the hole concentration measurements. Initially, the value of the lattice dimension a decreases and c increases monotonically with increasing x. A sudden increase in a and decrease in c begins when x reaches 0.28 for samples prepared under 1 bar of oxygen indicating a sudden loss of oxygen from the structure. This sudden reversal in lattice dimensions a and c is not present in samples annealed under 100 bars of oxygen pressure suggesting essentially no oxygen vacancies. The increase in c with x of the La2-xSrxCuO4 samples with no oxygen vacancies can be attributed mainly to the result of substituting smaller La+3 ions by larger Sr+2 ions. A study of the variation of c with the hole concentration reveals that the c lattice dimension drops sharply with no change in the hole concentration when oxygen is continuously removed from the lattice caused by an increase of the Sr content in La2-xSrxCuO4.

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Structure, Dielectric and Multiferroic Properties of Bi0.85Nd0.15Fe0.98Zr0.02O3 in Ba and Ti Co-Doping

10.21203/rs.3.rs-283706/v1 ◽

2021 ◽

Author(s):

Lizhu Zeng ◽

Yuming Lu ◽

Lujia Zhang ◽

Xin Gong ◽

Jianfeng Tang ◽

...

Keyword(s):

Room Temperature ◽

Oxygen Vacancies ◽

Solid State Reaction Method ◽

X Ray Diffraction ◽

Conventional Solid State Reaction ◽

Structure Transition ◽

X Ray ◽

Co Doping ◽

Average Grain Size ◽

Rhombohedral Perovskite Structure

Abstract Multiferroic (1- x)Bi0.85Nd0.15Fe0.98Zr0.02O3- xBaTiO3 (x = 0, 0.275, 0.3, 0.325, 0.35, 0.375, 0.4) ceramics were synthesized by the conventional solid state reaction method. X-ray diffraction studies confirm the phase transition from rhombohedral perovskite structure to pseudocubic structure with the introduction of BaTiO3. The results of the refinement indicate the BaTiO3 is successfully doped into the crystal lattice. The microstructure analysis shows that the average grain size increases with the introduction of BaTiO3. An increase in remanant polarization has been achieved at room temperature as the BaTiO3 concentration increasing. A greatly reduced leakage current density of about two orders of magnitude is observed in x = 0.375 (J = 2.4×10− 7 A/cm2) ceramic. The dielectric properties have been enhanced by the addition of BaTiO3, which is attributed to the reduction in Fe2+ ions and oxygen vacancies. Due to the grain effect and structure transition caused by the doping of BaTiO3, the magnetization reveals a slight decrease while the coercive field for x = 0.325 (Hc = 1785.8 Oe) increases to 6.4 times of the undoped ceramic.

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Pressure-Dependent Characteristics and Properties of Al2O3-SiO2 Thin Films Deposited on PET

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.368-372.1354 ◽

2008 ◽

Vol 368-372 ◽

pp. 1354-1357 ◽

Cited By ~ 2

Author(s):

Hong Hsin Huang ◽

Yuan Shing Liu ◽

Cheng Fu Yang ◽

Yen Ming Chen ◽

Cheng Yi Chen ◽

...

Keyword(s):

Thin Films ◽

Oxygen Pressure ◽

Pressure Range ◽

Room Temperature ◽

Energy Dispersive Spectrometry ◽

Sio2 Film ◽

X Ray Diffraction ◽

X Ray ◽

Uv Visible ◽

Amorphous Al2o3

Transparent and hard Al2O3-SiO2 thin films have been deposited on PET substrate by E-beam evaporation with oxygen pressure ranging from 1×10-5 to 1×10-3 Torr at room temperature. Pressuredependent characteristics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), meanwhile, apparent transmittance and hardness of thin films were evaluated by uv-visible spectroscopy (UVs) and nanoidentor, respectively. The XRD results showed that the amorphous Al2O3-SiO2 film was obtained although the intensity of the broaden peak decreased with oxygen pressure increasing. The similar morphologies and composition were obtained in pressure range. Good apparent transmittance was found, which higher than 85% in the pressure range. Apparent hardness of PET was effectively improved from 2.77 to 5.7 – 6.1 GPa depending on oxygen pressure. However, the critical load of Al2O3-SiO2 film slightly decreased with oxygen pressure increasing.

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Magnetoelectric Effect in Multiferroic Perovskite-Oxide Composites

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.45.2514 ◽

2006 ◽

Vol 45 ◽

pp. 2514-2519 ◽

Cited By ~ 1

Author(s):

Manabu Gomi ◽

K. Ban ◽

Naoya Nishimura ◽

Takeshi Yokota

Keyword(s):

Room Temperature ◽

Magnetoelectric Effect ◽

Spontaneous Magnetization ◽

Hole Concentration ◽

Perovskite Oxide ◽

X Ray Diffraction ◽

X Ray ◽

Oxide Composites ◽

Curie Temperatures ◽

Magnetic Dielectric

Magnetic, dielectric properties and magnetoelectric effect of ceramics with a composition of 0.9 BaTiO3-0.1 LaMnO3 have been investigated. X-ray diffraction measurements showed that the sintered ceramics are composites containing a small amount of (La, Ba)MnO3 phase in the BaTiO3 matrix. These composites were multiferroic, having ferromagnetic and ferroelectric Curie temperatures of 330 K and 392 K respectively. We found that the composite sintered at 1150 °C exhibits a reduction of spontaneous magnetization as large as 55 % at room temperature when an electric field of 1.4 KV/mm is applied. This reduction is probably ascribed to a change of hole concentration distribution in the precipitated ferromagnetic (La, Ba)MnO3 and the resultant decrease of ferromagnetic Curie temperature.

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FABRICATION OF BaFe12O19 NANOWIRES BY A HYDROTHERMAL PROCESS AND THEIR MAGNETIC PROPERTIES

Modern Physics Letters B ◽

10.1142/s021798490601055x ◽

2006 ◽

Vol 20 (07) ◽

pp. 359-364 ◽

Cited By ~ 1

Author(s):

JUN WANG ◽

YUEJIN ZHU

Keyword(s):

Electron Microscopy ◽

Saturation Magnetization ◽

Room Temperature ◽

Oxygen Vacancies ◽

Hydrothermal Process ◽

Annealing Treatment ◽

Magnetization Measurement ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron

Magnetic BaFe 12 O 19 nanowires have been prepared by a hydrothermal process. The nanowires with diameters ~ 15 nm and lengths ~ 2 μ m are clearly visible in Transmission Electron Microscopy (TEM) image. The physical properties of the BaFe 12 O 19 nanowires were further characterized by X-ray diffraction (XRD) and magnetization measurement. The results of the magnetization measurement show that the sample displays ferromagnetic properties at room temperature and its saturation magnetization (Ms) reaches 13.36 emu/g. Annealing treatment of the sample in air at 800°C leads to the increasing of the saturation magnetization (Ms: 65.7 emu/g). It is suggested that the oxygen vacancies should be responsible for the low saturation magnetization, which is also supported by the magnetic property (Ms: 21.6 emu/g) of the sample annealed at 800°C in argon shield.

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ROOM-TEMPERATURE FERROMAGNETISM IN SnO2 NANOFIBERS AND NANOTUBES PREPARED BY ELECTROSPINNING

NANO ◽

10.1142/s179329201450026x ◽

2014 ◽

Vol 09 (02) ◽

pp. 1450026 ◽

Cited By ~ 2

Author(s):

JIAN-GUO ZHAO ◽

WEI-YING ZHANG ◽

ER-QING XIE ◽

XIU-YUN AN ◽

JIE-CAI FU ◽

...

Keyword(s):

Room Temperature ◽

Oxygen Vacancies ◽

Room Temperature Ferromagnetism ◽

Magnetization Measurement ◽

Zero Field ◽

X Ray Diffraction ◽

Rutile Structure ◽

X Ray ◽

Selected Area Electron Diffraction ◽

Electrospinning Method

SnO 2 nanofibers and nanotubes were synthesized by electrospinning method. Magnetization measurement indicates that the SnO 2 nanofibers and nanotubes annealed in air at 500°C exhibit the room-temperature ferromagnetism and the ferromagnetism of nanotubes is stronger than the nanofibers. Selected area electron diffraction, X-ray diffraction and Raman measurements show that all the samples possess a typical rutile structure and no other impurity phases are observed. The results of the Raman spectra also indicate that there are lots of defects existing in the fabricated samples. The observed room-temperature ferromagnetism in SnO 2 nanofibers and nanotubes possibly originates from oxygen vacancies. The field cooled (FC) and zero-field-cooled (ZFC) magnetization curves indicate that the Curie temperature TC is above 300 K.

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Effect of the incorporation of BiFeO3 on the structural, electrical and magnetic properties of the lead-free Bi0.5Na0.5TiO3

AIMS Materials Science ◽

10.3934/matersci.2021048 ◽

2021 ◽

Vol 8 (5) ◽

pp. 792-808

Author(s):

Wolfgang Zúñiga-Mera ◽

◽

Sonia Gaona Jurado ◽

Alejandra Isabel Guerrero Duymovic ◽

Claudia Fernanda Villaquirán Raigoza ◽

...

Keyword(s):

Room Temperature ◽

Oxygen Vacancies ◽

Structural Phase ◽

Magnetic Hysteresis ◽

X Ray Diffraction ◽

Electrical Measurements ◽

X Ray ◽

Electrical And Magnetic Properties ◽

System 1 ◽

Rhombohedral Symmetry

<abstract> Powders of the system (1–<italic>x</italic>)Bi0.5Na0.5TiO3–<italic>x</italic>BiFeO3 (<italic>x</italic> = 0, 0.02, 0.08, 0.10) are synthesized by the combustion reaction method. The crystal structure and the particle size of Bi0.5Na0.5TiO3 are modified by the incorporation of BiFeO3, as can be seen from the infrared spectroscopy and X-ray diffraction results. The inclusion of iron and the increase in the molar percentage of bismuth in the BNT matrix generate new bonds with a different force constant. The structural analysis showed that the addition of BFO to the BNT does not induce any structural phase transition, preserving the rhombohedral symmetry of the Bi0.5Na0.5TiO3 system. The electrical measurements show that the incorporation of iron increases the conductivity of the system generated by an increase in the concentration of oxygen vacancies; alternatively, the addition of 10% of BiFeO3 generates ferrimagnetic behavior reflected in the magnetic hysteresis curves obtained at room temperature. </abstract>

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Electron Microscopy of Human Gallstones

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100065523 ◽

1971 ◽

Vol 29 ◽

pp. 296-297

Author(s):

C. Wolpers ◽

R. Blaschke

Keyword(s):

Electron Microscopy ◽

Room Temperature ◽

Bile Pigment ◽

X Ray Diffraction ◽

Triclinic Crystal System ◽

X Ray ◽

Follow Up Study ◽

Infra Red ◽

Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

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Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173996 ◽

1990 ◽

Vol 48 (4) ◽

pp. 172-173

Author(s):

Naoki Yamamoto ◽

Makoto Kikuchi ◽

Tooru Atake ◽

Akihiro Hamano ◽

Yasutoshi Saito

Keyword(s):

Phase Transition ◽

Electron Microscope Study ◽

Room Temperature ◽

Hexagonal Lattice ◽

Ferroelectric Materials ◽

Temperature Phase ◽

X Ray Diffraction ◽

X Ray ◽

Periodic Arrays ◽

Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

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Xenon Trioxide Adducts of O-Donor Ligands; [(CH3)2CO]3XeO3, [(CH3)2SO]3(XeO3)2, (C5H5NO)3(XeO3)2, and [(C6H5)3PO]2XeO3

10.26434/chemrxiv.7092263.v1 ◽

2018 ◽

Author(s):

Katherine Marczenko ◽

James Goettel ◽

Gary Schrobilgen

Keyword(s):

Room Temperature ◽

Triphenylphosphine Oxide ◽

Donor Ligands ◽

Mechanical Shock ◽

X Ray Diffraction ◽

X Ray ◽

Oxygen Coordination ◽

Xenon Trioxide ◽

Distorted Octahedra ◽

Coordination Spheres

Oxygen coordination to the Xe(VI) atom of XeO3 was observed in its adducts with triphenylphosphine oxide, dimethylsulfoxide, pyridine-N-oxide, and acetone. The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO3, which detonates when mechanically or thermally shocked, the solid [(C6H5)3PO]2XeO3, [(CH3)2SO]3(XeO3)2, and (C5H5NO)3(XeO3)2 adducts are insensitive to mechanical shock, but undergo rapid deflagration when ignited by a flame. Both [(C6H5)3PO]2XeO3 and (C5H5NO)3(XeO3)2 are air-stable whereas [(CH3)2SO]3(XeO3)2 slowly decomposes over several days and [(CH3)2CO]3XeO3 undergoes adduct dissociation at room temperature. The xenon coordination sphere of [(C6H5)3PO]2XeO3 is a distorted square pyramid which provides the first example of a five-coordinate XeO3 adduct. The xenon coordination spheres of the remaining adducts are distorted octahedra comprised of three Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO3. Quantum-chemical calculations were used to assess the Xe---O adduct bonds, which are predominantly electrostatic σ-hole bonds between the nucleophilic oxygen atoms of the bases and the σ-holes of the xenon atoms.

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Effect of trytophan as dopant on potassium acid phthalate single crystals

10.31221/osf.io/cn28k ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Single Crystals ◽

Room Temperature ◽

Visible Region ◽

X Ray Diffraction ◽

X Ray ◽

Slow Evaporation Technique ◽

Absorption Studies ◽

Evaporation Technique ◽

Potassium Acid Phthalate ◽

Acid Phthalate

Optically transparent single crystals of potassium acid phthalate (KAP, 0.5 g) 0.05 g and 0.1 g (1 and 2 mol %) trytophan were grown in aqueous solution by slow evaporation technique at room temperature. Single crystal X- ray diffraction analysis confirmed the changes in the lattice parameters of the doped crystals. The presence of functional groups in the crystal lattice has been determined qualitatively by FTIR analysis. Optical absorption studies revealed that the doped crystals possess very low absorption in the entire visible region. The dielectric constant has been studied as a function of frequency for the doped crystals. The thermal stability was evaluated by TG-DSC analysis.

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