Oxygen Reduction Effect on T’-Pr&lt;sub&gt;2-&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Ce&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;CuO&lt;sub&gt;4&lt;/sub&gt; Nanopowders in the Underdoped Regime Studied by X-Ray Absorption near Edge Structure

Triono

et al. 2020

KEM

Self Cite

The coexistence of ferromagnetism and paramagnetism of T’-Pr2-xCexCuO4+α-δ (T’-PCCO) nanoparticles with x = 0, and 0.10 have been studied intensively in the normal state. All samples were synthesized by a chemically dissolved method using HNO3 as a dissolving agent. The calcination process was performed at 1000°C for 15 h in air and followed by reduction annealing at 700°C in argon atmosphere for 10 h. All samples were first characterized by an x-ray diffraction (XRD) measureemnts followed by Rietveld and Maximum Entropy Method (MEM) analyseis. The result confirms the Ce-dependence and reduction annealing effect on the electron density at around the Cu site. The magnetic characterization was performed by using vibration sample magnetometer (VSM) indicating weak ferromagnetic properties at x = 0 and dominant paramagnetic properties at x = 0.10 at room temperature. Moreover, the weak ferromagnetic feature seems to remain after the annealing process. This signifies the coexist of weak ferromagnetism and paramagnetism at the normal state due to a number of oxygen vacancies in the crystal structure.

Section: Introductionsupporting

confidence: 93%

Section: Samplementioning

confidence: 99%

Coexistence of Weak Ferromagnetism and Paramagnetism in T’-Pr2-xCexCuO4+α-δ Nanoparticles

Triono

et al. 2020

KEM

Self Cite

Synchrotron X-Ray Absorption Spectroscopy (XAS) Studies on Structural and Magnetic Properties of T’-Pr2-xCexCuO4 Nanocrystals

Triono

et al. 2020

KEM

Self Cite

We have succeeded in synthesizing electron-doped cuprates T’-Pr2-xCexCuO4 (PCCO) with x = 0 and 0.10 nanocrystals prepared by the chemically dissolved method. Reduction annealing of the PCCO samples at 700°C under a flowing argon gas atmosphere has been performed for the removal of excess oxygen in the apical sites. The XRD data showed that the reduction annealing process decreases c-axis length indicating successful removal of the excess oxygen. The bond distortion of PCCO including coordination number and bond distance between the absorber atoms with the nearest neighboring atoms (Cu-O) was investigated by extended x-ray absorption fine structure (EXAFS) using Cu K-edge. The implication of our results is discussed on the basis of tremendous influence of oxygen vacancies on the magnetism of the nanosized T’-cuprates at the normal state.

Enhanced Room-Temperature Ferromagnetism in Superconducting Pr2-xCexCuO4 Nanoparticles

Baqiya

et al. 2019

MSF

Self Cite

Recently, the so-called room-temperature ferromagnetism in any nanoparticles has been studied intensively. It is well known that the properties of ferromagnetism and superconductivity are contradictory in a superconducting high-Tc cuprate. The existence of ferromagnetism in the nanoparticles has been suggested to occur on the surface. This magnetism has been expected to come from defects inducing magnetic moments on oxygen vacancies at the surface of the nanoparticles. This work is to observe magnetism in nanosized superconducting Pr2-xCexCuO4 (PCCO) with x = 0.15 by means of a superconducting quantum interference device (SQUID). The magnetization curves of the reduced PCCO nanoparticles with the superconducting transition temperature, Tc, of ~25 K have revealed that there is weak ferromagnetism observed at room temperature. The magnitude of magnetization could be enhanced by oxygen reduction annealing in vacuum with increasing annealing temperature. A non-linear magnetization occurring in the reduced PCCO nanoparticles through the vacuum annealing process is probably due to a strong oxygen reduction producing more oxygen vacancies in the T'-structure.