STRUCTURAL INSTABILITY AND SUPERCONDUCTIVITY OF THE (Nd, Gd, Ce)2CuO4 SYSTEM

The influence of partial substitution of Nd by Gd and Ce on the Nd 2 CuO 4n-type superconductor was studied by using X-ray diffraction measurements. For x = 0.15 Ce the maximum value of critical transition temperature Tc was obtained. The influence of Gd concentration on the lattice parameters and unit-cell volume was studied in the optimal doped sample (x = 0.15 Ce ) and in the samples with 0≤x≤0.2 Ce . The relation between structural parameters and critical transition temperature was evidenced. The transition from the structural normal phase to the distortion phase was evidenced above y = 0.75 Gd in the optimal Ce -doped sample.

Download Full-text

STRUCTURAL PHASE DIAGRAM FOR THE THERMAL CONTROLLED DISTORTION BY Gd IONS IN THE (Nd1-yGdy)1.85Ce0.15CuO4 HTS SYSTEM

International Journal of Modern Physics B ◽

10.1142/s0217979205029729 ◽

2005 ◽

Vol 19 (13) ◽

pp. 2161-2166

Author(s):

C. PELSHENKE ◽

A. V. POP ◽

O. COZAR

Keyword(s):

Phase Diagram ◽

Structural Phase ◽

Normal Phase ◽

Phase Changes ◽

Partial Substitution ◽

X Ray Diffraction ◽

X Ray ◽

Substitution Level ◽

Maximum Value ◽

Distorted Phase

The influence of partial substitution of Nd by Gd on the temperature dependence of the lattice parameters of the optimal doped Nd 1.85 Ce 0.15 CuO 4n-type superconductor (maximum value of Tc) was studied by using X-ray diffraction measurements function of temperature. The transition from the structural normal phase (I4/mmm) to the distortion phase (Acam) was evidenced above y = 0.65 Gd substitution level in ( Nd 1-y Gd y)1.85 Ce 0.15 CuO 4. The structural phase transition temperature TI-A from undistorted phase to the distorted phase changes function of Gd concentration. The structural phase diagram for thermal controlled distortion by Gd ions, TI-A = f(y) was obtained, and compared by the superconducting phase diagram Tc(y).

Download Full-text

A STUDY OF DEPOSITED YBaCuO THIN FILMS BY D.C. MAGNETRON SPUTTERING

Modern Physics Letters B ◽

10.1142/s0217984988001417 ◽

1988 ◽

Vol 01 (09n10) ◽

pp. 369-374 ◽

Cited By ~ 6

Author(s):

W. SHI ◽

J. SUN ◽

W. YAO ◽

J. JIANG ◽

L. LIU ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Transition Temperature ◽

Electron Probe ◽

Bulk Sample ◽

Critical Transition ◽

Critical Transition Temperature ◽

Sputtering Deposition ◽

X Ray ◽

Deposition Processes

The YBaCuO thin films with critical transition temperature above 77K (in our experiments, they are 83K) have been prepared successfully. The sintered oxides of Y, Ba and Cu with proper composition was used as target. To control the parameters during sputtering deposition processes is very important to obtain high Tc thin film. The composition and phase structure were investigated by means of X-fluoroscope, electron-probe and X-ray diffractometer. The second ions spectroscopies of film and bulk sample were investigated using SIMS. It is clear that thin films lost their oxygen more easily under bombardment of Ar+ with certain energy.

Download Full-text

Studies of Microstructure and Electro-Magnetic Transport Property of La0.67Ca0.33MnO3 Ceramic

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.373.205 ◽

2017 ◽

Vol 373 ◽

pp. 205-208

Author(s):

Shou Lei Xu ◽

Er Juan Xie ◽

Xiu Qing Cao ◽

Yu Yang Huang ◽

Ding Kang Xiong ◽

...

Keyword(s):

Transition Temperature ◽

Positron Lifetime ◽

Solid State Reaction Method ◽

X Ray Diffraction ◽

Metal Insulator ◽

X Ray ◽

Maximum Value ◽

The Mean ◽

Magnetic Transport ◽

Electro Magnetic

The positron annihilation techniques and X-ray diffraction have been used to study the microstructure of the La0.67Ca0.33MnO3 ceramics prepared by the solid-state reaction method at different sintered temperatures (T=1573K, 1623K, 1673K, 1723K, 1773K, 1823K). And the electro-magnetic transport behavior of the samples was measured by VSM and Resistivity modular on PPMS. According to these results, all samples show a perovskite structure, the ferromagnetic-paramagnetic and metal-insulator transitions occur at the transition temperature Tc and TMI, respectively, which is almost the same. For La0.67Ca0.33MnO3 sintered at 1673K, the mean positron lifetime is the largest, the maximum value of the magnetization is achieved on the magnetization-temperature curve at H=0.2mT, while the transition temperature occurs at about 244K.

Download Full-text

Preparation of MgB2 Films by Directly Electrophoretic Depositing MgB2 Powder on Ti Substrates

Materials Science Forum ◽

10.4028/www.scientific.net/msf.861.270 ◽

2016 ◽

Vol 861 ◽

pp. 270-276

Author(s):

Feng Hua Li ◽

Han Gao ◽

Bo Wen Zhang ◽

Qing Lian Zhu

Keyword(s):

Electron Microscopy ◽

Gas Flow ◽

Xrd Analysis ◽

Atomic Ratio ◽

Deposition Method ◽

Critical Transition ◽

X Ray Diffraction ◽

Critical Transition Temperature ◽

X Ray ◽

Scanning Electron

MgB2 powder was fabricated by sintering the mixture of pure Mg and B powder with atomic ratio of Mg : B=1:2. The magnetic property of the powder indicated that it was superconducting and its critical transition temperature was 39K. Titanium based MgB2 films were obtained by electrophoretic deposition method using Ni sheet as anode and titanium tapes as cathode. The films were annealed at 500°C for 2 hours, subjected to argon-hydrogen (95%Ar+5%H2) gas flow. The results of X-ray diffraction (XRD) analysis showed that the composition of the film was mainly MgB2. The observation under scanning electron microscopy (SEM) showed that the film of MgB2 was uniform and dense. The electrical resistivity of double-side MgB2 film was about 5.280×10-8Ω/m.

Download Full-text

Fabrication and study the effect of the laser on the properties of the compound Tl2-xHgxBa2-ySryCa2Cu3O10+δ superconductor

Ibn AL- Haitham Journal For Pure and Applied Science ◽

10.30526/2017.ihsciconf.1789 ◽

2018 ◽

pp. 168

Author(s):

A. Kareem Dahash Ali ◽

Nihad Ali Shafeek

Keyword(s):

Transition Temperature ◽

Solid State ◽

Hydrostatic Pressure ◽

Electrical Properties ◽

Co2 Laser ◽

Temperature Shift ◽

Unit Cell ◽

X Ray Diffraction ◽

X Ray ◽

Structural And Electrical Properties

This study included the fabrication of compound (Tl2-xHgxBa2-ySryCa2Cu3O10+δ) in a manner solid state and under hydrostatic pressure ( 8 ton/cm2) and temperature annealing(850°C), and determine the effect of the laser on the structural and electrical properties elements in the compound, and various concentrations of x where (x= 0.1,0.2,0.3 ). Observed by testing the XRD The best ratio of compensation for x is 0.2 as the value of a = b = 5.3899 (A °), c = 36.21 (A °) show that the installation of four-wheel-based type and that the best temperature shift is TC= 142 K .When you shine a CO2 laser on the models in order to recognize the effect of the laser on these models showed the study of X-ray diffraction of these samples when preparing models with different concentrations of the values of x, the best ratio of compensation is 0.2 which showed an increase in the values of the dimensions of the unit cell a=b = 5.3929 (A °), c = 36.238 (A°). And the best transition temperature after shedding laser is TC=144 K.

Download Full-text

Mining Wastes of an Albite Deposit as Raw Materials for Vitrified Mullite Ceramics

Minerals ◽

10.3390/min11030232 ◽

2021 ◽

Vol 11 (3) ◽

pp. 232

Author(s):

Pedro J. Sánchez-Soto ◽

Eduardo Garzón ◽

Luis Pérez-Villarejo ◽

George N. Angelopoulos ◽

Dolores Eliche-Quesada

Keyword(s):

Particle Size ◽

Raw Materials ◽

Phase Evolution ◽

Particle Size Analysis ◽

Size Analysis ◽

Mining Wastes ◽

X Ray Diffraction ◽

X Ray ◽

Maximum Value

In this work, an examination of mining wastes of an albite deposit in south Spain was carried out using X-ray Fluorescence (XRF), X-ray diffraction (XRD), particle size analysis, thermo-dilatometry and Differential Thermal Analysis (DTA) and Thermogravimetric (TG) analysis, followed by the determination of the main ceramic properties. The albite content in two selected samples was high (65–40 wt. %), accompanied by quartz (25–40 wt. %) and other minor minerals identified by XRD, mainly kaolinite, in agreement with the high content of silica and alumina determined by XRF. The content of Na2O was in the range 5.44–3.09 wt. %, being associated with albite. The iron content was very low (<0.75 wt. %). The kaolinite content in the waste was estimated from ~8 to 32 wt. %. The particle size analysis indicated values of 11–31 wt. % of particles <63 µm. The ceramic properties of fired samples (1000–1350 °C) showed progressive shrinkage by the thermal effect, with water absorption and open porosity almost at zero at 1200–1250 °C. At 1200 °C, the bulk density reached a maximum value of 2.38 g/cm3. An abrupt change in the phase evolution by XRD was found from 1150 to 1200 °C, with the disappearance of albite by melting in accordance with the predictions of the phase diagram SiO2-Al2O3-Na2O and the system albite-quartz. These fired materials contained as main crystalline phases quartz and mullite. Quartz was present in the raw samples and mullite was formed by decomposition of kaolinite. The observation of mullite forming needle-shape crystals was revealed by Scanning Electron Microscopy (SEM). The formation of fully densified and vitrified mullite materials by firing treatments was demonstrated.

Download Full-text

Effect of the BSCCO superconducting properties by tiny Y2O3 addition

Modern Physics Letters B ◽

10.1142/s0217984916503280 ◽

2016 ◽

Vol 30 (26) ◽

pp. 1650328

Author(s):

Yan Dong ◽

Aimin Sun ◽

Bin Xu ◽

Hongtao Zhang ◽

Meng Zhang

Keyword(s):

Volume Fraction ◽

Superconducting Properties ◽

X Ray Diffraction ◽

Critical Transition Temperature ◽

Solid State Reaction Technique ◽

X Ray ◽

Oxide Addition ◽

One Step ◽

Step Transition ◽

Y2o3 Addition

In this paper, the effect of tiny Y2O3 addition in (Bi,[Formula: see text]Pb)-2223 superconductor prepared by solid state reaction technique was studied. The properties of samples have been investigated via X-ray diffraction (XRD), resistance–temperature ([Formula: see text]–[Formula: see text]) curve, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). XRD data indicated that all samples are multiphase and the major phases are high-temperature phases and low-temperature phases. The volume fraction of (Bi,[Formula: see text]Pb)-2223 is not great change with tiny Y2O3 addition. All samples exhibit superconducting phase with the critical transition temperature and one-step transition, however, the transition width was decreased with the Y2O3 addition up to 0.04 wt.% and sharp increased with the excessive oxide addition. SEM pictures show that the Y2O3 appeared on the flake-type grains surface obviously, but the number and size of the hole between grains are decreased in the 0.04 wt.% addition.

Download Full-text

Study on Phases and Thermoelectric Properties of Bulk Fe4Sb12 and Fe3CoSb12 Prepared by Milling and Sintering

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.1526 ◽

2011 ◽

Vol 121-126 ◽

pp. 1526-1529

Author(s):

Ke Gao Liu ◽

Jing Li

Keyword(s):

Thermoelectric Properties ◽

Impurity Phase ◽

Semiconductor Materials ◽

Thermal Constant ◽

X Ray Diffraction ◽

X Ray ◽

Seebeck Coefficients ◽

Maximum Value ◽

Type Semiconductor ◽

P Type

Bulk Fe4Sb12 and Fe3CoSb12 were prepared by sintering at 600 °C. The phases of samples were analyzed by X-ray diffraction and their thermoelectric properties were tested by electric constant instrument and laser thermal constant instrument. Experimental results show that, the major phases of bulk samples are skutterudite with impurity phase FeSb2. The electric resistivities of the samples increase with temperature rising at 100~500 °C. The bulk samples are P-type semiconductor materials. The Seebeck coefficients of the bulk Fe4Sb12 are higher than those of bulk Fe3CoSb12 samples at 100~200 °C but lower at 300~500 °C. The power factor of the bulk Fe4Sb12 samples decreases with temperature rising while that of bulk Fe3CoSb12 samples increases with temperature rising at 100~500 °C. The thermal conductivities of the bulk Fe4Sb12 samples are relatively higher than those of and Fe3CoSb12, which maximum value is up to 0.0974 Wm-1K-1. The ZT value of bulk Fe3CoSb12 increases with temperature rising at 100~500 °C, the maximum value is up to 0.031.The ZT values of the bulk Fe4Sb12 samples are higher than those of bulk Fe3CoSb12 at 100~300 °C while lower at 400~500 °C.

Download Full-text

COMPOSITION DEPENDENCE OF SUPERCONDUCTIVITY AND CRYSTAL STRUCTURE IN La(Ba1−xCax)2Cu3O7−y SYSTEM

Modern Physics Letters B ◽

10.1142/s0217984989000492 ◽

1989 ◽

Vol 03 (04) ◽

pp. 307-311 ◽

Cited By ~ 4

Author(s):

N. CAO ◽

J.Q. ZHENG ◽

X.Y. SHAO ◽

X.S. CHEN ◽

W.Y. GUAN

Keyword(s):

Crystal Structure ◽

Transition Temperature ◽

Superconducting Transition Temperature ◽

Composition Dependence ◽

Superconducting Transition ◽

Orthorhombic Structure ◽

X Ray Diffraction ◽

X Ray ◽

Resistivity Measurements ◽

Zero Resistance

The composition dependence of superconductivity and crystal structure in La ( Ba 1−x Ca x)2 Cu 3 O 7−y system was determined by the resistivity measurements and X-ray diffraction analysis. The superconducting transition temperature is raised with the increase of Ca content till x=0.6, at which the zero resistance temperature of the sample is 81.5 K. In the meanwhile, the crystal structure of the sample changed from tetragonal (x=0) to orthorhombic structure (x=0.2, 0.4, 0.6). With further increase of Ca content, the superconductivity decrease for the sample of x=0.8 with mixed phases including the orthorhombic oxygen-deficient perovskite-like (ODP) structure and no superconducting transition is found at 4.2 K for the sample of x=1 without the ODP structure. A possible explanation of these experimental results is given.

Download Full-text