Electron-doped superconducting cuprate of Eu 2– x Ce x CuO 4+α–δ has been studied in the whole doping regime from x = 0.10–0.20 with reducing oxygen content to investigate the relation between the crystal structure and the hopping conduction in the normal state. Parameter of the crystal structure has been extracted from the X-ray diffraction (XRD) measurement while hopping conduction parameters have been obtained from resistivity measurements. The Eu–O bond length decreases with the increasing doping concentration, indicating the successful doping by the partial replacing of Eu 3+ with Ce 4+ . The resistivity increases with decreasing temperature in all measured samples. This is an indication of bad metal-like behavior in the whole regime in the normal state of electron-doped superconducting cuprate of Eu 2– x Ce x CuO 4+α–δ . The temperature dependence of resistivity was analyzed by the Arrhenius law and the variable range hopping model. It is found that the hopping conduction mechanism more likely follows the variable range hopping rather than the Arrhenius law, indicating that the hopping mechanism occurs in three dimensions. The Cu–O bond length probably plays an important role in decreasing the activation energy. The decreasing value of the activation energy correlates with the increase in the localization radius.
The effect of nonmagnetic Zn impurities on the structural parameters and effective magnetic moment of electron-doped superconducting cuprates Eu2−xCexCu1−yZnyO4+α−δ (ECCZO) with x = 0.10 and 0.15 and y = 0 and 0.01 has been investigated using XRD and SQUID measurements. From XRD measurements, it is found that the lattice parameter of c and the Cu-O bond length increase with increasing y. The crystallite size of ECCZO samples was relatively smaller than the sample without impurities determined by the Debye–Scherrer equation and the W-H Plot method. Changes in the lattice parameters of c and Cu-O bond length can affect the appearance of superconductivity (Tc). The smaller the value of the lattice parameter of c and the Cu-O bond length causes the distance between the conducting layer and the charge reservoir to be close enough so that the charge transfer process becomes easier. From the magnetic susceptibility measurement, paramagnetic characteristics were observed for samples with x = 0.10. Meanwhile, for samples with x = 0.15, diamagnetic characteristics can be identified in sample with y = 0. The onset of Tc was observed around 11 K, as indicated by a change from paramagnetic to diamagnetic characteristics. The superconductivity phase disappears with y = 0.01. The effective magnetic moments in samples with y = 0 are smaller than those in samples with y = 0.01. The effective magnetic moment in ECCZO can be contributed by Cu2+. When the amount of Cu2+ decreases due to the addition of nonmagnetic Zn2+ atoms, the overall effective magnetic moment value also decreases. Another possibility that causes a decrease in the value of the magnetic moment of the ECCZO is the existence of stripe-pinning model, which results in suppressed superconductivity by Zn.
The samples of Eu2-xCexCuO4 (ECCO) with x = 0.09 (Eu1.91Ce0.09CuO4) and x = 0.16 (Eu1.84Ce0.16CuO4) have been synthesized by the solid reaction method without annealing. Each sample is covered with CuO to prevent excess oxygen entering the sample. The purity and electrical resistivity were investigated by x-ray Diffraction (XRD) and resistivity measurements. From the XRD analysis, it was found that the purity of ECCO phase was 93.5% with tetragonal structure of T’ for x = 0.09 while 96.1% for x = 0.16. These results show that the synthesis method with CuO covering has succeeded in synthesizing materials with high purity. From the electrical measurements, the trace of superconductors was not observed in all samples. It is probably the existence of excess oxygen, which was not fully absorbed by CuO Covering.
Superconductors are materials with the unique characteristics when the temperature of the material is below its critical temperature, namely zero resistivity. There are many superconducting phenomena that need to be explained theoretically. One of them is the effect of addition of impurities on the physical properties of superconducting materials. In this study, the addition of 0.01 Ni magnetic impurities in the Eu2-xCexCuO4+α-δ material has been carried out to form the structure Eu2-xCexCu0.99Ni0.01O4+α-δ, in an under-doped area with a concentration of Ce (x) = 0.09 and 0.10. Material synthesis was carried out by the solid reaction method with prefire at 900 °C for 20 hours, sintering at 1,000 °C for 16 hours, and annealing at 900 °C for 10 hours by flowing argon (Ar) gas. The XRD measurements were carried out to investigate the crystal structure, while the magnetic properties were carried out by SQUID measurement at temperature of 2 K to 30 K. From the XRD measurements, it was found that the crystals formed had a tetragonal crystal structure T’ which was indicated by the appearance of two main peaks with Miller indices (103) and (110), lattice parameter a is 3,904 Å in both samples, lattice c is 11.8752 Å and 11.9738 Å for the concentrations of Ce (x) = 0.09 and 0.10. The volume of unit cells obtained were 181.0178 Å3 and 181.0244 Å3 with the bond distance between Cu-O of 1.9521 Å and 1.9523 Å. It was also obtained that the crystal size were 86.2604 nm and 91.6735 nm. From the SQUID measurement, it was found that the material Eu2-xCexCu0.99Ni0.01O4+α-δ has paramagnetic properties. The value of the effective magnetic moment was decreased by reducing the addition of Ni impurities of 0.0057 and 0.0051.
Structure and magnetic properties of electron-doped superconducting cuprates have been investigated in order to study the effect of magnetic impurity to its physical properties. Here, we reported structure and magnetic properties of Eu1.88Ce0.12Cu1-yZnyO4+α-δ (ECCZO) with y = 0 and 0.03. The properties of ECCZO have been studied from X-ray diffraction data and temperature dependence of magnetic susceptibility data, to elucidate the effect of partial substitution of non-magnetic impurity Zn for Cu to its structure, Tc and the value of magnetic moments per unit volume extracted from susceptibility data in normal state. Magnetic-susceptibility measurements were carried out down to 2 K on-field cooling at 5 Oe for Eu1.88Ce0.12Cu1-yZnyO4+a-d with y = 0 and 0.03. For ECCZO sample with y = 0 and d = 0.0669 indicated the change of magnetic behavior from paramagnetic to diamagnetic below 12 K which is addressed to the Tc onset of this samples. Diamagnetic behavior is observed starting from about 12 K. Above 12 K, all samples show paramagnetic behavior with the values of the magnetic moment in every volume unit increased with increasing Zn.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.