Effect of Co Doping on the Superconducting Properties of Overdoped (Lu0.8Ca0.2)Ba2Cu3Oz

2006 ◽  
Vol 47 ◽  
pp. 108-112 ◽  
Author(s):  
Ho Keun Lee
Keyword(s):  
Thermoelectric Power ◽  
Room Temperature ◽  
Oxygen Depletion ◽  
Thermal Treatments ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Doping ◽  
Heat Treated ◽  
Power Measurements

The effect of Co-doping and thermal treatments on the superconducting properties of the heavily overdoped (Lu0.8Ca0.2)Ba2Cu3Oz has been investigated by X-ray diffraction, resistivity and thermoelectric power measurements. A comparative analysis of the resistivity and thermoelectric power of the (Lu0.8Ca0.2)Ba2(Cu3-xCox)Oz and the heat-treated Co-free (Lu0.8Ca0.2)Ba2Cu3Oz reveals that, in the overdoped region, the hole carriers reduced by the Co doping and by the oxygen depletion play a very similar role in the superconducting properties. As a result, a nearly common inverted parabolic correlation is observed between Tc and the planar carrier concentration determined from the room-temperature thermoelectric power measurements.

X-Ray Diffraction Analysis on Crystallite Development of Nanostructured Aluminium

2006 ◽  
Vol 118 ◽  
pp. 53-58
Author(s):  
Elisabeth Meijer ◽  
Nicholas Armstrong ◽  
Wing Yiu Yeung
Keyword(s):  
Crystallite Size ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Equal Channel Angular Extrusion ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Integral Breadth ◽  
X Ray ◽  
Heat Treated ◽  
Diffraction Peaks

This study is to investigate the crystallite development in nanostructured aluminium using x-ray line broadening analysis. Nanostructured aluminium was produced by equal channel angular extrusion at room temperature to a total deformation strain of ~17. Samples of the extruded metal were then heat treated at temperatures up to 300oC. High order diffraction peaks were obtained using Mo radiation and the integral breadth was determined. It was found that as the annealing temperature increased, the integral breadth of the peak reflections decreased. By establishing the modified Williamson-Hall plots (integral breadth vs contract factor) after instrumental correction, it was determined that the crystallite size of the metal was maintained ~80 nm at 100oC. As the annealing temperature increased to 200oC, the crystallite size increased to ~118 nm. With increasing annealing temperature, the hardness of the metal decreased from ~60 HV to ~45 HV.

scholarly journals Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth

2016 ◽  
Vol 72 (5) ◽  
pp. 702-708 ◽  
Author(s):  
Lise Pascale ◽  
Marco Truccato ◽  
Lorenza Operti ◽  
Angelo Agostino
Keyword(s):  
Superconducting Properties ◽  
X Ray Diffraction ◽  
High Quality ◽  
Superconducting Cuprates ◽  
X Ray ◽  
Co Doping ◽  
Crystalline Nature ◽  
Structure Investigations ◽  
Thz Applications ◽  
Ybco Tape

High-Tcsuperconducting cuprates (HTSC) such as YBa2Cu3O7 − x(YBCO) are promising candidates for solid-state THz applications based on stacks of intrinsic Josephson junctions (IJJs) with atomic thickness. In view of future exploitation of IJJs, high-quality superconducting YBCO tape-like single crystals (whiskers) have been synthesized from Ca–Al-doped precursors in the presence of Te. The main aim of this paper is to determine the importance of the simultaneous use of Al, Te and Ca in promoting YBCO whiskers growth with good superconducting properties (Tc= 79–84 K). Further, single-crystal X-ray diffraction (SC-XRD) refinements of tetragonal YBCO whiskers (P4/mmm) are reported to fill the literature lack of YBCO structure investigations. All the as-grown whiskers have also been investigated by means of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Our results demonstrate that the interplay of Ca, Te and Al elements is clearly necessary in order to obtain superconducting YBCO whiskers. The data obtained from SC-XRD analyses confirm the highly crystalline nature of the whiskers grown. Ca and Al enter the structure by replacing the Y and the octahedral coordinated Cu1 site, respectively, as in other similar orthorhombic compounds, while Te does not enter the structure of whiskers but its presence in the precursor is essential to the growth of the crystals.

Experimental Considerations and Limitations in the Application of Ultra High Temperature (2100°C) X-Ray Diffraction

1991 ◽  
Vol 35 (A) ◽  
pp. 425-429
Author(s):  
Sampath S. Iyengar
Keyword(s):  
High Temperature ◽  
Crystalline Material ◽  
Thermal Treatments ◽  
Ceramic Fibers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Controlled Atmospheres ◽  
Heat Treated ◽  
Multiple Samples

In-situ, high temperature X-ray diffraction (XRD) is an extremely useful tool for studying, monitoring or investigating crystal structure modifications as well as phase transformations in crystalline material during thermal treatments in controlled atmospheres. This technique has been used to investigate the thermal behavior of materials such as carbonate minerals, ceramic fibers, coating pigments, etc. The advantages of such a technique over the conventional practice, where samples are heat treated in a separate oven and then analyzed by XRD include: consistency of sample placement; preservation of high temperature structures to facilitate observation of metastable phases that are unstable upon exposure to outside atmosphere or during cooling; real time monitoring of reactions that occur, and products that are formed at a desired temperature or environment; and need for multiple samples or analysis.

Effect of Molybdenum and Ruthenium on the Crystallization Tendency of a New Nuclear Glass Containing High Rare-earth Concentration

2010 ◽  
Vol 1265 ◽  
Author(s):  
Daniel Caurant ◽  
Nolwenn Chouard ◽  
Odile Majerus ◽  
Jean-Luc Dussossoy ◽  
Aurelien Ledieu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Nucleating Agent ◽  
High Level Waste ◽  
Optical Absorption Spectroscopy ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Level ◽  
The Impact ◽  
Crystallization Tendency

AbstractThe impact of Nd2O3, MoO3 and RuO2 addition on the competition between the crystallization of apatite Ca2Nd8(SiO4)6O2 and powellite CaMoO4 phases which both may appear in High Level Waste nuclear glass (under certain specific conditions of cooling and glass composition) has been studied on a simplified composition belonging to the system SiO2-Na2O-CaO-Al2O3-B2O3. X-ray diffraction (at room temperature and high temperature) and scanning electron microscopy measurements have been performed on five glasses under two different thermal treatments. We show that RuO2 acts as a nucleating agent for apatite. Moreover, neodymium and molybdenum cations seem to be very close in the glassy network as Nd2O3 addition stops the phase separation of molybdates and inhibits the crystallization of CaMoO4. On the contrary, MoO3 seems to favor the crystallization of apatite. For several samples, the evolution of the distribution of Nd3+ cations after crystallization was followed by optical absorption spectroscopy.

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

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.

Solid State Reaction Study Of The System Co-Li2CO3

1996 ◽  
Vol 51 (7) ◽  
pp. 813-820
Author(s):  
A. Marini ◽  
V. Berbenni ◽  
V. Massarotti ◽  
D. Capsoni ◽  
G. Bruni
Keyword(s):  
Solid State ◽  
Thermal Treatment ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Reaction Model ◽  
Lithium Content ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reactive Processes

Abstract A detailed analysis of the reactive processes taking place in Co-Li2CO3 was performed by use of thermogravimetry and X-ray diffraction. A reaction model is proposed which accounts for the nature, stoichiometry, and amount of the phases present, at room temperature, in samples subjected to different thermal treatments. In particular it is shown that the thermal treatment influences substantially the final lithium content and the relative amount of the Li-containing phases. The results obtained for powdered samples are compared with those obtained in a previous work for plaques.

Effect of heat treatment time and temperature on the properties of YBa2Cu3O7−x

1989 ◽  
Vol 4 (5) ◽  
pp. 1093-1098 ◽  
Author(s):  
Ira Bloom ◽  
B. S. Tani ◽  
M. C. Hash ◽  
Donglu Shi ◽  
M. A. Patel ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electrical Properties ◽  
Treatment Time ◽  
The Other ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Rich Material ◽  
Scanning Electron

Two YBa2Cu3O7−x powders were investigated: one was nearly stoichiometric, and the other, CuO-rich. After being sintered at 950 °C, samples from both powders were heat-treated in oxygen at 845, 860, and 910 °C for up to 10 days. The samples were characterized by differential thermal analysis, x-ray diffraction, optical and scanning electron microscopy, iodometric titrations, and measurement of their superconducting properties (electrical resistivity, critical temperature, and critical current density). The electrical properties of the nearly stoichiometric material improved with time at all temperatures. On the other hand, the electrical properties of the CuO-rich material deteriorated with temperature, possibly owing to problems associated with grain growth at 910 °C.

Spontaneous ferromagnetism at room temperature in oxygen-rich dicalcium cuprate Ca2CuO3+δ

1996 ◽  
Vol 11 (7) ◽  
pp. 1804-1809 ◽  
Author(s):  
Mahjoub A. Abdelgadir ◽  
Richard S. Burrows ◽  
Darl H. McDaniel
Keyword(s):  
Saturation Magnetization ◽  
Elemental Analysis ◽  
Applied Field ◽  
Room Temperature ◽  
Magnetic Impurity ◽  
Oxygen Depletion ◽  
Excess Oxygen ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar

Stoichiometric Ca2CuO3, having square-planar Cu-chains [C. L. Teske and H. Müller-Buschbaum, Z. Anorg. Allg. Chem. 379, 234 (1970); M. Hjorth and J. Hyldtoft, Acta Chem. Scand. 44, 516 (1990)], is expectedly antiferromagnetic due to 1D intrachain superexchange [K. Okuda, S. Noguchi, K. Konishi, H. Deguchi, and K. Takeda, J. Magn. Magn. Mater. 104–107, 817 (1992)]. Nonetheless, we report remarkable spontaneous ferromagnetism at 293 K after sintering, prominently in oxygen. This apparently introduced excess oxygen at vacant quasioctahedral sites, promoting spin-flip and ferromagnetic interchain coupling. Thermogravimetry (TGA) revealed excess oxygen, ≈0.17 O/Cu. X-ray diffraction (XRD) yielded a comparatively smaller unit cell. Ferromagnetism disappeared by oxygen depletion, mimicking reported nonmagnetism of Ca2CuO3−δ [Okuda et al. (1992)]. Elemental analysis showed insignificant magnetic impurity traces. Tc ranged between 680 K and 723 K, depending on freshness and purity. Saturation magnetization varied with processing, optimally 0.30 A · m2/kg at 1.0 T applied field. Coercivity and remanence varied with purity.

scholarly journals X-Ray Diffraction and Raman Spectroscopic Studies of Glasses and Glass-Ceramics Inside the A2O-MoO3-Nb2O5-P2O5 (A= Li, Na) Systems

2010 ◽  
Vol 12 (3,4) ◽  
pp. 207
Author(s):  
H. Bih ◽  
L. Bih ◽  
M.P.F. Graça ◽  
M.A. Valente ◽  
B. Elouadi
Keyword(s):  
Glass Ceramics ◽  
Spectroscopic Studies ◽  
Phosphate Glasses ◽  
Molar Ratio ◽  
Thermal Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Heat Treated ◽  
Quenching Method

<p>Phosphate glasses in the system (50-x)A<sub>2</sub>O-xMoO<sub>3</sub>-10Nb<sub>2</sub>O<sub>5</sub>-40P<sub>2</sub>O<sub>5</sub> (AMo-40), with x=0; 30 and A=Li or Na were prepared by the melt quenching method. The effect in the crystallization behaviour of the glass due to the introduction of MoO<sub>3</sub> in the glass composition and varying the molar ratio between network modifiers and network formers (M/F) was studied. The prepared glasses were heat-treated in air, at 550, 600 and 650 ºC for 4 hours. The structure, of the obtained samples, was studied by differential thermal analysis (DTA), X-ray powder diffraction (XRD), Raman spectroscopy and the morphology by scanning electron microscopy (SEM). It was found that the replacement of Li<sub>2</sub>O or Na<sub>2</sub>O by MoO<sub>3</sub> reduces the number of the crystallised phases. In the lithium-niobiophosphate glasses the presence of MoO<sub>3</sub> promotes the formation of NbOPO<sub>4</sub> and reduces the formation of ortho- and pyro-phosphate phases. The thermal treatments affect the arrangements of the network structure of the AMo-40-glasses.</p>

Sintering, Microstructure and Electrical Properties of MnO2 and CuO-Doped [Na0.515K0.485]0.94Li0.06(Nb0.99Ta0.01)O3 Ceramics

2013 ◽  
Vol 770 ◽  
pp. 258-261
Author(s):  
Pornsuda Bomlai
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Room Temperature ◽  
Secondary Recrystallization ◽  
Lead Free ◽  
Reaction Sintering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Doping ◽  
Sintering Method

Ceramics with formula (1-x-y)[Na0.515K0.485]0.94Li0.06(Nb0.99Ta0.01)O3 (NKLNT) xMnO2yCuO (when x, y = 0, 0.005 and 0.01) were prepared by a reaction sintering method. The effects of doping level on sinterability and properties of NKLNT ceramics were studied. The results indicated that the co-doping of MnO2 and CuO was effective in promoting the densification of ceramics. Grain growth during secondary recrystallization was also affected, leading to larger grain size with x, y = 0.01 sample. X-ray diffraction data showed that the orthorhombic tetragonal morphotropic phase boundary existed in all the samples. At room temperature, the dielectric properties of NKLNT ceramics were improved by doping of appropriate MnO2 and CuO content. The temperature dependence of dielectric constant showed a decrease slightly in Curie temperature (TC) with increasing MnO2 and CuO content. The composition with x = 0.005, y = 0 exhibited favorable properties for the promising lead-free piezoelectric candidate material.

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