scholarly journals Magnetic, structural and Mössbauer study of soils from an ancient mining area in Huancavelica-Peru

2021 ◽  
Vol 243 (1) ◽  
Author(s):  
M. A. Castillo Corzo ◽  
L. E. Borja-Castro ◽  
L. De Los Santos Valladares ◽  
J. C. González ◽  
J. Medina Medina ◽  
...  
Keyword(s):  
High Spin ◽  
Room Temperature ◽  
Mining Area ◽  
Magnetic Component ◽  
Tetrahedral Coordination ◽  
Mössbauer Study ◽  
Spin Configuration ◽  
Magnetization Measurements ◽  
Iron Bearing

AbstractWe present the magnetic, structural and 57Fe Mossbauer characterization of soils collected from an ancient mercury contaminated city named Huancavelica in Peru. The characterization results indicate that silicates and carbonates are the main mineralogical constituents in the samples. In addition, 57Fe Mössbauer spectra at room temperature reveal, the presence of two components: a magnetic component related to magnetic Fe-oxides (magnetite, hematite, goethite) and a high non-magnetic component related to Fe+3 in high spin configuration and tetrahedral coordination in silicates. The magnetization measurements present screening of paramagnetic, ferromagnetic and antiferromagnetic signals, typical from soils containing different silicates and iron minerals. Remarkably the Verwey and Morin transitions corresponding to magnetite and hematite, respectively, are screened by the paramagnetic signal corresponding to the major silicate components in the samples. Overall, the soils are mainly composed of crystalline and amorphous silicates, calcites and iron bearing which are typical from Andean soils.

Chalkogenides of the transition elements. VI. X-Ray, neutron, and magnetic investigation of the spinels Co3O4, NiCo2O4, Co3S4, and NiCo2S4

1968 ◽  
Vol 46 (22) ◽  
pp. 3463-3476 ◽  
Author(s):  
Osvald Knop ◽  
K. I. G. Reid ◽  
Sutarno ◽  
Yasuaki Nakagawa
Keyword(s):  
Neutron Diffraction ◽  
High Spin ◽  
Room Temperature ◽  
Spin States ◽  
Transition Elements ◽  
Thermal Stabilities ◽  
Magnetization Measurements ◽  
X Ray ◽  
Magnetic Investigation ◽  
Diffraction Patterns

The crystal structures of the spinels Co3O4, NiCo2O4, Co3S4, and NiCo2S4 were refined from X-ray and neutron powder data. Their lattice parameters at room temperature and the positional parameters of the oxygen and sulfur atoms were: Co3O4, 8.0835 ± 6 Å, 0.2640 ± 8; NiCo2O4, 8.114 ± 14 Å, 0.2583 ± 34; Co3S4, 9.4055 ± 12 Å, 0.2591 ± 5; NiCo2S4, 9.3872 ± 7 Å, 0.2591 ± 3. The thermal stabilities of the two oxides in air and in oxygen at 1 atm were investigated by thermogravimetric analysis and differential thermal analysis, and the magnetization of NiCo2O4 was measured down to 4.2 °K in fields up to 11.70 kOe. From neutron diffraction NiCo2O4. was found to be inverse, while NiCo2S4 was shown to be normal. The results of the magnetization measurements and the neutron-diffraction patterns at 111 and 393 °K were found to be equally consistent with the magnetic structure proposed for NiCo2O4 by Blasse, Co2+[Ni3+Co3+]O4 (Co2+ in a high-spin and Ni3+ andCo3+ in low-spin states), and with Co3+[Ni2+Co3+]O4 (Co3+ in 8(a) in a high-spin and Co3+ in 16(d) in a low-spin state). The sublattice magnetizations were not completely aligned even at 4.2 °K; the net magnetic moment derived from the magnetization measurements was only 1.25 μB, which is lower than the value of 2 μB expected from either model. At 111 °K the moments of the ions in the tetrahedral and octahedral sites were estimated to be 1.9 ± 0.2 and −0.5 ± 0.1 bohr magnetons respectively.

Synthesis and Characterization of Three New Emissive Mononuclear CuI Heteroleptic Complexes with Functionalized 6-Cyano-2,2′-bipyridine Chelating Ligands

2020 ◽  
Vol 73 (7) ◽  
pp. 640
Author(s):  
Wan-Man Wang ◽  
Peng Ju ◽  
Man-Hong Jing ◽  
Ping Yu ◽  
Qin Huang
Keyword(s):  
Room Temperature ◽  
Photophysical Properties ◽  
Coordination Geometry ◽  
Chelating Ligands ◽  
Tetrahedral Coordination ◽  
Solid States ◽  
Single Crystal Structures ◽  
Heteroleptic Complexes ◽  
Distorted Tetrahedral Coordination

A new series of luminescent mononuclear CuI complexes with functionalized 6-cyano-2,2′-bipyridine chelating ligands, [Cu(xantphos)(cbpy)]ClO4 (1), [Cu(xantphos)(4,4’-Me2cbpy)]ClO4·CH2Cl2·H2O (2), and [Cu(POP)(cbpy)]ClO4·CH2Cl2 (3) (xantphos=4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; POP=bis(2-diphenylphosphinophenyl)ether; 4,4’-Me2cbpy=4,4’-dimethyl-6-cyano-2,2′-bipyridine; cbpy=6-cyano-2,2′-bipyridine) have been successfully prepared, and their structures and photophysical properties are investigated. Single crystal structures of the three complexes reveal a distorted tetrahedral coordination geometry around the CuI centres with the P atoms of diphosphane ligands and N donors of 2,2′-bipyridine ring. Luminescence measurements indicate that these CuI complexes display good emission properties both in the solution and solid states at room temperature, which can be well modulated through modifying the structure of 6-cyano-2,2′-bipyridine. It is shown that the introduction of two electron-donating methyl groups at the 4,4’-positions of the 6-cyano-2,2′-bipyridine is favourable to enhance the luminescence properties of the CuI complexes.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

scholarly journals Synthesis and characterization of a new ZIF-67@MgAl2O4 nanocomposite and its adsorption behaviour

RSC Advances ◽  
2021 ◽  
Vol 11 (22) ◽  
pp. 13245-13255
Author(s):  
Mehdi Davoodi ◽  
Fatemeh Davar ◽  
Mohammad R. Rezayat ◽  
Mohammad T. Jafari ◽  
Mehdi Bazarganipour ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnesium Aluminate ◽  
Synthesis And Characterization ◽  
Magnesium Aluminate Spinel ◽  
Adsorption Behaviour ◽  
Zeolitic Imidazolate Framework ◽  
Simple Method

New nanocomposite of zeolitic imidazolate framework-67@magnesium aluminate spinel (ZIF-67@MgAl2O4) has been fabricated by a simple method at room temperature with different weight ratios.

The Flexibility of Long Chain Substituents Influences Spin-Crossover in Isomorphous Lipid Bilayer Crystals

2021 ◽  
Author(s):  
Iurii Galadzhun ◽  
Rafal Kulmaczewski ◽  
Namrah Shahid ◽  
Oscar Cespedes ◽  
Mark J Howard ◽  
...  
Keyword(s):  
Lipid Bilayer ◽  
High Spin ◽  
Room Temperature ◽  
Spin Crossover ◽  
Pyridine Derivatives ◽  
Long Chain

[Fe(bpp)2][BF4]2 (bpp = 2,6-di{pyrazol-1-yl}pyridine) derivatives bearing a bent geometry of hexadec-1-ynyl or hexadecyl substituents pyrazole are isomorphous, and high-spin at room temperature. However, only the latter compound undergoes an abrupt,...

scholarly journals Synthesis and characterization of [7]triangulene

Nanoscale ◽  
2021 ◽  
Author(s):  
Shantanu Mishra ◽  
Kun Xu ◽  
Kristjan Eimre ◽  
Hartmut Komber ◽  
Ji Ma ◽  
...  
Keyword(s):  
High Spin ◽  
Ground States ◽  
Synthesis And Characterization ◽  
Spintronic Devices

Triangulene and its π-extended homologues constitute non-Kekulé polyradical frameworks with high-spin ground states, and are anticipated to be key components of organic spintronic devices. We report a combined in-solution and...

Processing by Pulsed Laser Deposition and Structural, Morphological and Chemical Characterization of Bi-Pb-Sr-Ca-Cu-O and Bi-Pb-Sb-Sr-Ca-Cu-O Thin Films

2010 ◽  
Vol 75 ◽  
pp. 202-207
Author(s):  
Victor Ríos ◽  
Elvia Díaz-Valdés ◽  
Jorge Ricardo Aguilar ◽  
T.G. Kryshtab ◽  
Ciro Falcony
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Chemical Characterization ◽  
Laser Deposition ◽  
Nominal Composition ◽  
Deposition Parameters ◽  
The Relationship

Bi-Pb-Sr-Ca-Cu-O (BPSCCO) and Bi-Pb-Sb-Sr-Ca-Cu-O (BPSSCCO) thin films were grown on MgO single crystal substrates by pulsed laser deposition. The deposition was carried out at room temperature during 90 minutes. A Nd:YAG excimer laser ( = 355 nm) with a 2 J/pulse energy density operated at 30 Hz was used. The distance between the target and substrate was kept constant at 4,5 cm. Nominal composition of the targets was Bi1,6Pb0,4Sr2Ca2Cu3O and Bi1,6Pb0,4Sb0,1Sr2Ca2Cu3OSuperconducting targets were prepared following a state solid reaction. As-grown films were annealed at different conditions. As-grown and annealed films were characterized by XRD, FTIR, and SEM. The films were prepared applying an experimental design. The relationship among deposition parameters and their effect on the formation of superconducting Bi-system crystalline phases was studied.

scholarly journals Synthesis and Characterization of Lithium-Ion Conductive LATP-LaPO4 Composites Using La2O3 Nano-Powder

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3502
Author(s):  
Fangzhou Song ◽  
Masayoshi Uematsu ◽  
Takeshi Yabutsuka ◽  
Takeshi Yao ◽  
Shigeomi Takai
Keyword(s):  
Room Temperature ◽  
Conduction Mechanism ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Nano Powder ◽  
Powder Addition

LATP-based composite electrolytes were prepared by sintering the mixtures of LATP precursor and La2O3 nano-powder. Powder X-ray diffraction and scanning electron microscopy suggest that La2O3 can react with LATP during sintering to form fine LaPO4 particles that are dispersed in the LATP matrix. The room temperature conductivity initially increases with La2O3 nano-powder addition showing the maximum of 0.69 mS∙cm−1 at 6 wt.%, above which, conductivity decreases with the introduction of La2O3. The activation energy of conductivity is not largely varied with the La2O3 content, suggesting that the conduction mechanism is essentially preserved despite LaPO4 dispersion. In comparison with the previously reported LATP-LLTO system, although some unidentified impurity slightly reduces the conductivity maximum, the fine dispersion of LaPO4 particles can be achieved in the LATP–La2O3 system.

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