Two kinds of Nd 1+ x Ba 2- x Cu 3O 7- δ , the sintered samples and zone melted samples, were treated in pure Ar at 950 ℃. The substitution of Nd ions for Ba ions in the Nd 1+ x Ba 2- ...Two kinds of Nd 1+ x Ba 2- x Cu 3O 7- δ , the sintered samples and zone melted samples, were treated in pure Ar at 950 ℃. The substitution of Nd ions for Ba ions in the Nd 1+ x Ba 2- x Cu 3O 7- δ before and after the heat treatment was investigated by XRD. In order to know the effects of heat treatment, the T c and J c of samples with and without the heat treatment in Ar were comparatively studied. The results show that the substitution of Nd for Ba decreases, whereas T c and J c increase after the treatment. The Nd 1+ x Ba 2- x Cu 3O 7- δ samples were oxygenated in pure oxygen at 300 ℃ . Based on the XRD spectra it was found that the samples with x <0.4 can transform from tetragonal phase into orthorhombic phase after the oxygenation, whereas in the sample with x >0.4 no phase transition occurs even after a long time oxygenation.展开更多
Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on...Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on the structure and oxygen content for x = 0.0 - 0.5 in the compound Gd1-xLaxBa2Cu3O7-δ (GLBCO-123 phase) have been investigated. Samples were synthesized by using a wet-mixing method from powders of Gd2O2, La2O2, BaO, CuO, and solution of HNO3. Based on the analysis of XRD data and SEM-EDXA, it confirms that the sample has formed the GLBCO-123 phase, as expected. It has been obtained that the lattice parameters a and c are increased while the parameter b is slightly decreased with increasing content of Lanthanum. The oxygen content slightly decreased and structure of the Gd1-xLaxBa2Cu3O7-δ phase changed from orthorhombic to tetragonal with increasing the content of Lanthanum.展开更多
The Raman and infrared spectra, resistivity as well as thermoelectric power of Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ ( x =0, 0.1, 0.2, 0.5, 0.8 and 1.0) are studied carefully. It was found that the structure character...The Raman and infrared spectra, resistivity as well as thermoelectric power of Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ ( x =0, 0.1, 0.2, 0.5, 0.8 and 1.0) are studied carefully. It was found that the structure characteristics of RSr 2Cu 2.7 Mo 0.3 O 7- δ cuprates are different from those of RBa 2Cu 3O 7- δ . The variations of the microstructure in Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ with Nd doping affect the carrier distribution, so as a result the superconductivity changes. Furthermore, it is pointed out that the microstructure variations with the large rare earth ionic substitution cause the widely existing rare earth ionic size effect in HTSC.展开更多
Since the discovery of high-T<sub>c</sub> superconductors, additions of proper elements to YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> system have been proved to be qu...Since the discovery of high-T<sub>c</sub> superconductors, additions of proper elements to YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> system have been proved to be quite effective in both mechanism researches and improvements of sample preparation technique. Recently, an interesting phenomenon in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> was reported by Feng Yong et al., i.e. when being doped with appropriate amounts of V<sub>2</sub>O<sub>5</sub>, samples which have been quenched in air from 900℃ to展开更多
One of the basic ingredients in conventional preparation of cuprates-based superconducting materials such as the Nd-Ba-Cu-O superconducting system, especially the Nd1Ba2Cu3O7-δ phase is Barium Carbonate (BaCO3). It h...One of the basic ingredients in conventional preparation of cuprates-based superconducting materials such as the Nd-Ba-Cu-O superconducting system, especially the Nd1Ba2Cu3O7-δ phase is Barium Carbonate (BaCO3). It has the potential to produce the carbon dioxide (CO2) air pollutant. Therefore it is necessary to look for other materials as the source of Ba atom which does not produce CO2 gas. In this research has been successfully made the Nd1Ba2Cu3O7-δ phase with the Barium Hydroxide Octahydrate (Ba(OH)2·8H2O) as a source of Ba atom. The results of the characterization XRD has been shown the main peaks of the Nd1Ba2Cu3O7-δ phase. Refinement of the XRD data by using Rietica software, obtained the value of GofF (Goodness of Fit) = 1.7023 and lattice parameter a ≈ b < c/3 with a value of c/3 = 3.9275 A.展开更多
文摘Two kinds of Nd 1+ x Ba 2- x Cu 3O 7- δ , the sintered samples and zone melted samples, were treated in pure Ar at 950 ℃. The substitution of Nd ions for Ba ions in the Nd 1+ x Ba 2- x Cu 3O 7- δ before and after the heat treatment was investigated by XRD. In order to know the effects of heat treatment, the T c and J c of samples with and without the heat treatment in Ar were comparatively studied. The results show that the substitution of Nd for Ba decreases, whereas T c and J c increase after the treatment. The Nd 1+ x Ba 2- x Cu 3O 7- δ samples were oxygenated in pure oxygen at 300 ℃ . Based on the XRD spectra it was found that the samples with x <0.4 can transform from tetragonal phase into orthorhombic phase after the oxygenation, whereas in the sample with x >0.4 no phase transition occurs even after a long time oxygenation.
文摘Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on the structure and oxygen content for x = 0.0 - 0.5 in the compound Gd1-xLaxBa2Cu3O7-δ (GLBCO-123 phase) have been investigated. Samples were synthesized by using a wet-mixing method from powders of Gd2O2, La2O2, BaO, CuO, and solution of HNO3. Based on the analysis of XRD data and SEM-EDXA, it confirms that the sample has formed the GLBCO-123 phase, as expected. It has been obtained that the lattice parameters a and c are increased while the parameter b is slightly decreased with increasing content of Lanthanum. The oxygen content slightly decreased and structure of the Gd1-xLaxBa2Cu3O7-δ phase changed from orthorhombic to tetragonal with increasing the content of Lanthanum.
文摘The Raman and infrared spectra, resistivity as well as thermoelectric power of Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ ( x =0, 0.1, 0.2, 0.5, 0.8 and 1.0) are studied carefully. It was found that the structure characteristics of RSr 2Cu 2.7 Mo 0.3 O 7- δ cuprates are different from those of RBa 2Cu 3O 7- δ . The variations of the microstructure in Y 1- x Nd x Sr 2Cu 2.7 Mo 0.3 O 7- δ with Nd doping affect the carrier distribution, so as a result the superconductivity changes. Furthermore, it is pointed out that the microstructure variations with the large rare earth ionic substitution cause the widely existing rare earth ionic size effect in HTSC.
文摘Since the discovery of high-T<sub>c</sub> superconductors, additions of proper elements to YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> system have been proved to be quite effective in both mechanism researches and improvements of sample preparation technique. Recently, an interesting phenomenon in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> was reported by Feng Yong et al., i.e. when being doped with appropriate amounts of V<sub>2</sub>O<sub>5</sub>, samples which have been quenched in air from 900℃ to
文摘One of the basic ingredients in conventional preparation of cuprates-based superconducting materials such as the Nd-Ba-Cu-O superconducting system, especially the Nd1Ba2Cu3O7-δ phase is Barium Carbonate (BaCO3). It has the potential to produce the carbon dioxide (CO2) air pollutant. Therefore it is necessary to look for other materials as the source of Ba atom which does not produce CO2 gas. In this research has been successfully made the Nd1Ba2Cu3O7-δ phase with the Barium Hydroxide Octahydrate (Ba(OH)2·8H2O) as a source of Ba atom. The results of the characterization XRD has been shown the main peaks of the Nd1Ba2Cu3O7-δ phase. Refinement of the XRD data by using Rietica software, obtained the value of GofF (Goodness of Fit) = 1.7023 and lattice parameter a ≈ b < c/3 with a value of c/3 = 3.9275 A.
