Magnetic characterization has been performed on the members of the cuprateniobate RBa2Cu2NbO8 (R = Pr, Nd, and La) series and R1.5Ce0.5Sr2Cu2NbO10 (R = Pr, Eu, Nd, and Sm) series. The PrBCNO samples show a signature in the magnetization of a magnetic ordering at 12K.
The PrCSCNO sample is nonsuperconducting and shows two distinct orderings at 17K and 53K. No such magnetic phase transition
is observed down to 2K in the Nd and La based RBCNO materials or the Nd, Sm, and Eu based RCSCNO materials. Measurements of
the lower critical field curve, dc irreversibility line, and critical curent densities are reported for each of the superconducting
NdCSCNO, SmCSCNO, and EuCSCNO compounds. 相似文献
The samples of the series Co1+ySnyFe2- 2y- xCrxO4 ferrites with x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and y = 0.05, were prepared by the usual double sintering ceramic technique. The single- phase spinel structure of the samples was confirmed by using X- ray diffractometry technique. The lattice parameter ’a’ with an accuracy of ± 0.002 Å were determined using Bragg peaks of XRD pattern. The lattice parameter ’a’ decreases with concentration, x, which is due to the difference in the ionic radii of Cr3+ and Fe3+ ions. The X- ray intensity calculations were carried out in order to determine the possible cation distribution amongst tetrahedral (A) and octahedral [B] sites. The X- ray intensity calculations show Cr3+ ions occupying B site. The saturation magnetization, σs, and magneton number, nB (the saturation magnetization per formula unit), measured at 300 K determined from high field hysteresis loop technique decrease with increase in concentration, x, suggesting a decrease in ferrimagnetic behaviour. Thermal variation of low field a.c. susceptibility measurements from room temperature to about 800 K exhibits almost normal ferrimagnetic behaviour and the Curie temperature, TC determined from a.c. susceptibility data decreases with increase in x.
This study reports the magnetic structures of newly reported trinuclear vanadium(II)–diamine complexes. Using the isotropic
Heisenberg exchange Hamiltonian, it is suggested that there are strong intramolecular antiferromagnetic interactions among
the vanadium(II) ions. It is also suggested that these complexes are good candidates to the geometrically frustrated systems.
For part 1 see A. Bayri, J. Inorg. Organomet. Polym. Mater., (in press)
An erratum to this article can be found at 相似文献
This study reports the magnetic properties of newly reported nickel(II) complex of the antiprine Schiff base of 3-formylsalicylic
acid. Using the isotropic magnetic interaction model it is suggested that there is a strong antiferromagnetic interactions
between metal centers in dimeric units. It is also suggested that the system become demagnetized below a certain temperature.
An erratum to this article can be found at 相似文献
Microstructure and phase transformation in the Al-Cu-Fe alloys of the approximate compositional range of 20-50 at.% Cu and 2 - 10 Fe at.% have been investigated from samples quenched from their respective temperatures by means of different thermal analysis, magnetothermal analysis, scanning electron microscopy, electron probe analysis and powder X-ray diffraction. Representative phase transformations categorized as polymorphic, discontinuous precipitation,quasi-binary eutectoid, and ternary transitional U-type phase transformation are presented. These phase transformations were found to have a common feature which consumes the β phase and appears the φ phase. A schematic diagram was proposed to demonstrate the transition processes with decreasing temperature. 相似文献
“Gas Transmitting From West to East Project“ is significant.it should ensure the welding quality and safety of pipeline.The task is very arduous to guarantee the quality of the projcet in the condition of long line.complex weather and geolgy features.in this paper,the welding cold cracking susceptibility of domestic X-70 pipeline steel adopted by the project, which is one of the most interesting questions of welding quality about petrol pipeline,was studied by means of oblique Ygroove cracking test.The crack ration of surface and section was tested under the conditions of different welding materials and preheat temperature.The thickness of plate stell was 14.7mm and 10.3mm.The results reveal that X-70 pipeline steel has good crack resistance.The research has important value for the construction of large-scale pipeline engineering and the application of domestic X-70 pipeline steel. 相似文献