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.
One of the important characteristics of magnetic materials is the measurement of magnetic characteristics through Superconducting Quantum Interference Device (SQUID) especially magnetization temperature dependence M(T)ZFC and MTFC measurement. In this work, we reported magnetization temperature dependence measurements of magnetite nanoparticles without SiO2 encapsulation (Fe3O4) and magnetite nanoparticles with SiO2 encapsulation (Fe3O4.SiO2) at the application of magnetic fields of 100 Oe. The nanoparticles magnetite was synthesized by co-precipitation method. It was calculated that the blocking temperature of magnetite nanoparticles Fe3O4 without and with SiO2 encapsulation is 118.38 K and 209.03 K, respectively. The blocking temperatures of magnetic nanoparticles increase by SiO2 encapsulation.
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