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Evolution of the infrared emissivity of Ni during thermal oxidation until oxide layer opacity
摘要： The mid-infrared (3–22 μm) emissivity of high-purity Ni has been studied in its pure state, during an isothermal oxidation in air at 730 °C and in the fully oxidized state. Measurements in pure Ni were performed in Ar between 200 and 800 °C and a change of slope in the temperature dependence of the total normal emissivity around its Curie temperature (354 °C) was observed. An oxidation process was carried out at 730 °C for 33 days, when the emissivity stopped evolving and the results were representative of NiO. During the ?rst stages, the emissivity evolved forming the usual interference patterns of semi-transparent ?lms. A mixture of oscillatory and monotonic behaviours of the emissivity as a function of wavelength and oxide layer thickness was found, which manifests as a non-trivial evolution of the total normal emissivity, di?erent than that reported in previous studies. Finally, the emissivity of NiO was measured from below its Néel temperature (252 °C) to 850 °C. It showed the typical shape of a ceramic material with an extra vibrational mode due to two-phonon processes and an additional absorption band around 5 μm in the antiferromagnetic phase produced by magnons. The temperature dependence of its total normal emissivity di?ers signi?cantly from that of a lightly oxidized nickel sample from the literature. Overall, the in?uence of the surface characteristics on the thermal radiative properties of oxidized Ni is thoroughly discussed and highlights the importance of accounting for all possible sources of infrared emissivity evolution in order to make accurate radiative heat transfer calculations.
关键词： Nickel oxide,Infrared emissivity,Radiometry,Radiative heat transfer,Magnetic phase transition,Nickel,Oxidation
更新于2025-09-23 15:23:52
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Preparation and magnetic properties for FeSe <sub/><i>x</i> </sub> /Bi <sub/>2</sub> Se <sub/>3</sub> bilayer films on silicon substrates by RF magnetron sputtering
摘要： FeSex/Bi2Se3 bilayer thin films were grown by RF magnetron sputtering on silicon substrates with different thicknesses of Bi2Se3 and the structural, morphological and magnetic properties were investigated. FeSex/Bi2Se3 bilayer films had Bi2Se3 crystallites oriented with c-axis perpendicular to the film plane, and exhibited weak ferromagnetism at low temperature due to the ferromagnetic FeSe2. The thickness of Bi2Se3 layer affected both crystalline structure of Fe–Se layer and the magnetic property.
关键词： magnetic phase,RF magnetron sputtering,paramagnetism,Topological insulator,bilayer films
更新于2025-09-19 17:15:36
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Magnetic phase transitions of insulating spin-orbit coupled Bose atoms in one-dimensional optical lattices
摘要： We consider the insulating spin-orbit coupled Bose atoms con?ned within one-dimensional optical lattices and explore their ground-state magnetic phase transitions. Under strong interactions, the charge degrees of atoms are frozen and the system can be described by an anisotropic XXZ Heisenberg chain with Dzyaloshinskii-Moriya interaction and transverse ?eld. We apply the matrix product state method to obtain the ground states, and analyze spiral correlation functions, spin-spin correlation functions, and ?rst energy gap. Under weakly transverse ?elds, the ground state is a ferromagnetic phase if the interspin s-wave interaction strength is stronger than that of the intraspin ones, otherwise, it is a paramagnetic phase, an antiferromagnetic phase, or a gapless spiral phase with algebraic decaying spin correlations. When the transverse ?eld is strengthened, the gapless spiral phase is broken and a new spiral phase with long-range spin-spin correlations emerges.
关键词： optical lattices,XXZ Heisenberg chain,Bose atoms,magnetic phase transitions,Dzyaloshinskii-Moriya interaction,spin-orbit coupling,matrix product state method,transverse ?eld
更新于2025-09-12 10:27:22
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[IEEE 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Erlagol (Altai Republic), Russia (2018.6.29-2018.7.3)] 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Multifunctional Magnetophotonic Structure Creation Based on Magnetic Properties of Micro and Nanoscale Clusters
摘要： The optical and magnetic properties, phenomena and effects of nano- and microparticles of clusters and other formations can potentially influence the propagation and processing of optical signals in magnetophotonic structures. The analysis of existing devices and the ones proposed for interpretation of their implementation allows the correct operation algorithm in correlation to structural characteristics and to multi-functional magnetophotonic structures of micro- and nanoscale. The magnetophotonic structure models are considered and analyzed, which makes it possible to find the correct approaches for their implementation. The choice of the specific magnetophotonic medium for a functional simulator is determined by the requirements of functional orientation, simplicity and efficiency, manufacturability and other factors.
关键词： nanoclusters,magnetic phase transitions,superparamagnetism,Photonics,resonance
更新于2025-09-04 15:30:14