Protected Vacuum Annealing Effect on Single Crystals of Pr 1- x LaCe x CuO 4 in the Overdoped Regime

Insani

et al. 2021

MSF

We report the possible existence of defect recovery and the magnetic behavior in the T’-Pr2-xCexCuO4 (T’-PCCO) with x = 0.10 nanoparticles through the partially reduction annealing process. The powders of T’-PCCO nanoparticles were synthesized by using the chemically dissolved method followed by partially reduction annealing at 700 °C for 5 h in argon atmosphere. The high-resolution neutron powder diffraction (HRPD) technique has been employed to study the nuclear structure, vacancy, and the magnetic properties of the T’-PCCO nanoparticles. It is found that there is an increase of oxygen occupancy at the in-plane oxygen, O(1), and the apical oxygen, O(3), which signifies the decrease of the number of the vacancy on their sites. Meanwhile, the out plane oxygen, O(2), seems to be unchanged in the partially reduced samples. The Fourier difference profile shows an enhancement of the neutron scattering density at all the critical sites of O(1), O(3), and the Cu site. This may lead to the idea of the defect recovery affecting the whole magnetic moments which is responsible for the absence of weak ferromagnetism in the T’-PCCO nanoparticles.

Section: Resultsmentioning

confidence: 89%

Possible Defect Recovery in T’-Pr2-xCexCuO4 with x = 0.10 Nanoparticles Analyzed by Neutron Diffraction

Insani

et al. 2021

MSF

“…This is important to achieve superconductivity as reported in Refs. [18,19]. However, it should be noted that not only oxygen at this site can be removed, but also oxygen at the other sites in the T'-structure, namely in O( 1 In this research, a low annealing temperature with a short holding time was carried out to maintain the nano-sized particles and avoid the phase decomposition as much as possible.…”

Section: Resultsmentioning

confidence: 97%

“…Therefore, the oxygen reduction in the atmosphere with a low partial pressure or in vacuum is very crucial to achieve its superconductivity [17]. Thus, it has been suggested that superconductivity will not occur only by Ce-doping, but an annealing process in vacuum must be carried out to reduce the oxygen content [18][19][20]. In order to obtain superconducting samples and to observe the enhancement of magnetization, in this work, the PCCO nanoparticles were reduced in vacuum with increasing annealing temperature.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Room-Temperature Ferromagnetism in Superconducting Pr2-xCexCuO4 Nanoparticles

Baqiya

et al. 2019

MSF

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.

“…Moreover, it is responsible for the enlargement of c-axis length in the structure [5]. Some previous studies have been successfully reduced the excess oxygen by an advanced reduction annealing process [3,[6][7][8].…”

Section: Re 2 Cementioning

confidence: 99%

Oxygen Reduction Effect on T’-Pr2-xCexCuO4 Nanopowders in the Underdoped Regime Studied by X-Ray Absorption near Edge Structure

Triono

et al. 2018

MSF

This research is aimed to examine oxidation state of Copper (Cu) in both as-synthesized and reduced T’-Pr2-xCexCuO4 (T’-PCCO) with x = 0, 0.10, and 0.15 using Cu K-edge x-ray absorption near edge structure (XANES). The T‘-PCCO nanopowders were successfully synthesized by the chemically dissolved method with HNO3 as a dissolving agent continued by calcination at 1000°C for 15 h. The reduced T’-PCCO nanopowders were obtained by reduction annealing process at 700°C for 5 h under Ar gas atmosphere. The analyses of XANES spectra show that oxidation states of the Cu ions in all of the T'-PCCO nanopowders have values between +1 and +2. This indicates the existence of electron doping in the CuO2 planes, even in the undoped T’-structure. It is found that the oxidation states of the Cu ions change after reduction annealing depending on the existence of apical oxygen in the T'-structure. Based on the XANES analyses, it is revealed that the change of oxidation state is influenced by the presence of both electron and hole carriers in the two-carrier model of T’-structure.