The Doped YBCO Superconductor Crystal Structure Simulation

Pinning process plays an important role in improving utility properties of $YBa_2Cu_3O_{7-δ}$ (YBCO) superconductors. As a consequence of the low coherent length, the most effective pinning centers in such type of materials should have nanometer size dimensions. An efficient way of introducing such centers can be a chemical substitution in the YBCO lattice. Computer simulation of locally distorted YBCO crystal structure due to the substitutions has been performed

The Doped YBCO Superconductor Crystal Structure Simulation

Pinning process plays an important role in improving utility properties of $YBa_2Cu_3O_{7-δ}$ (YBCO) superconductors. As a consequence of the low coherent length, the most effective pinning centers in such type of materials should have nanometer size dimensions. An efficient way of introducing such centers can be a chemical substitution in the YBCO lattice. Computer simulation of locally distorted YBCO crystal structure due to the substitutions has been performed

Synthesis of Nanocrystalline BaCeO₃ by Oxalate Coprecipitation for YBa₂Cu₃O₇ Bulk Superconductors

Barium cerate (BaCeO₃) is one of the preferred additions to bulk YBa₂Cu₃O₇ single-grain superconductors to inhibit the growth of Y₂BaCuO₅ particles. The present paper investigates synthesis of very fine barium cerate powder and its use in YBa₂Cu₃O₇ bulk superconductor growth. The crystalline barium cerate was synthesized by oxalate co-precipitation from barium and cerium nitrates. X-ray diffraction in air and vacuum was performed to understand the formation of barium cerate as well as to determinate its crystal structure. Size and shape of BaCeO₃ particles were studied by scanning electron microscopy. The BaCeO₃ was used to grow YBa₂Cu₃O₇ bulk superconductor. Microstructure of prepared YBa₂Cu₃O₇ crystal shows that the barium cerate in the final product is very fine and uniformly distributed throughout the whole YBa₂Cu₃O₇ crystal

Magnetic Study of the Fe Coated by Au Nanoparticles

Nanosized iron-gold magnetic nanoparticles with an average particle size 10 nm were prepared by a reverse micelle method. The magnetic properties measurements of DC and AC magnetization confirm behaviour typical of a superparamagnetic system, such as the irreversibility of the zero-field-cooled and field-cooled curves, the frequency dependence of a blocking temperature $T_B$, and revealing of coercivity H_C below blocking temperature. The quantitative analysis of AC susceptibility due to value of parameter $C_1$ = Δ$T_B$/($T_B$ Δ log f)=0.0242 confirming the existence of inter-particle interaction in our system

Electrical Resistance Anomalies in Holmium Thin Films below 20 K in Magnetic Field

Electrical resistance (R) of Ho thin films evaporated in vacuum ≈ $10^{-7}$ Pa was studied in a temperature range from 2 K up to 300 K and in magnetic field up to 9 T. Measurements showed resistance anomalies below 20 K - minima of R value in 36 nm and 215 nm thin films and resistivity maximum at 3.58 K in 215 nm Ho film. Increasing value of the magnetic field, applied perpendicular to film surface up to 5 T, caused increasing suppression of the R minima in these films with subsequent disappearance of them in fields above 5 T. Maximum of R value in 215 nm thin film at 3.58 K decreased with increasing flux density up to 5 T and it was suppressed at fields above 5 T. X-ray diffraction of these films revealed two phases composition consisting of the hexagonal Ho and of cubic $HoH_2$. The preferential crystal orientation of both phases was detected

Electrical Resistance Anomalies in Holmium Thin Films below 20 K in Magnetic Field

Electrical resistance (R) of Ho thin films evaporated in vacuum ≈ $10^{-7}$ Pa was studied in a temperature range from 2 K up to 300 K and in magnetic field up to 9 T. Measurements showed resistance anomalies below 20 K - minima of R value in 36 nm and 215 nm thin films and resistivity maximum at 3.58 K in 215 nm Ho film. Increasing value of the magnetic field, applied perpendicular to film surface up to 5 T, caused increasing suppression of the R minima in these films with subsequent disappearance of them in fields above 5 T. Maximum of R value in 215 nm thin film at 3.58 K decreased with increasing flux density up to 5 T and it was suppressed at fields above 5 T. X-ray diffraction of these films revealed two phases composition consisting of the hexagonal Ho and of cubic $HoH_2$. The preferential crystal orientation of both phases was detected

Magnetic Properties of Thorium Ferricyanide

The magnetic properties of Th$\text{}_{3}$[Fe(CN)$\text{}_{6}$]·10H$\text{}_{2}$O were investigated. It was shown that this compound is antiferromagnetically ordered in the low temperature region. The observed antiferromagnetic ordering is stable only in the low field

[Ni(bpy)(ox)]: a candidate in the class of Haldane gap systems (bpy = 2,2′-bipyridine, ox = oxalate)

[Ni(bpy)(ox)] (bpy = 2,2ʹ-bipyridine; ox = oxalate) was solvothermally prepared in the microcrystalline form and identified by chemical analyses and IR spectroscopy. X-ray powder diffractometry indicates its isostructural character with analogous complexes [M(bpy)(ox)], and thus, its chain-like crystal structure formed of {Ni(bpy)} building units linked by bridging oxalate anions coordinated in a bis(chelate) fashion. The temperature dependence of the magnetic susceptibility and the field dependence of the magnetization reveal that the studied compound belongs to the class of systems with a Haldane gap. The estimated magnitude of the gap Eg ≈ 13.4 cm−1 is comparable with those found in archetypal Haldane gap systems.This work was supported by the Slovak grant agencies VEGA [grant number 1/0075/13]; APVV [grant number APVV-0132-11]; VVGS [grant number VVGS-2014-164]; Ministry of Science and Innovation (Spain) [grant number MAT2011–27233-C02–01]- European Union Regional Development Fund; Diputación General de Aragón [grant number E-16]; the European Union Regional Development Fund (Slovakia) [ITMS: 26220120047]. NF thanks National Scholarship Programme of the Slovak Republic for financial support of her research stay at the University of Zaragoza (Spain).Peer Reviewe

Structure of Melt-Spun Co 2 MnAl Heusler Alloy

The growth-related microstructure and texture of the Co2MnAl-type Heusler alloy in the form of a melt-spun ribbon was studied by electron microscopy, electron backscattered diffraction and X-ray diffraction. It is shown that melt spinning produces a single-phase disordered Heusler alloy. The fine grain structure at the wheel side of the ribbon exhibits no texture, while dominant columnar grain structure formed on the free surface side exhibits the 111 fibre texture with a declination by about 10 degrees in the spinning direction. The dendritic growth of columnar crystals causes inhomogeneity of the chemical composition on a micrometre scale with a higher Co and Al concentration in the centre of dendritic arms and a higher concentration of Mn at the dendrite arm boundaries

Structure of Melt-Spun Co₂MnAl Heusler Alloy

The growth-related microstructure and texture of the Co₂MnAl-type Heusler alloy in the form of a melt-spun ribbon was studied by electron microscopy, electron backscattered diffraction and X-ray diffraction. It is shown that melt spinning produces a single-phase disordered Heusler alloy. The fine grain structure at the wheel side of the ribbon exhibits no texture, while dominant columnar grain structure formed on the free surface side exhibits the ⟨111⟩ fibre texture with a declination by about 10 degrees in the spinning direction. The dendritic growth of columnar crystals causes inhomogeneity of the chemical composition on a micrometre scale with a higher Co and Al concentration in the centre of dendritic arms and a higher concentration of Mn at the dendrite arm boundaries