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
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
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.
