Search results for " TEMPERATURE"
showing 10 items of 2370 documents
Temperature dependence of luminescence of LiF crystals doped with different metal oxides
2020
Photoluminescence and cathodoluminescence of LiF crystals doped with different binary metal oxides were measured in the wide temperature range of 50-300 K and time interval of 10−8−10−1 s after the nanosecond electron excitation pulse. Both as-grown those and crystals irradiated by an electron beam in range of absorbed dose up to 103 Gy were studied. It is shown that spectral-kinetic characteristics of the luminescence depend on the absorbed dose (type of created/accumulated color centers), the irradiation temperature, the concentration of hydroxyl, which promotes incorporation of the MeO complex (Me: W, Ti, Fe, Li) into the crystal lattice, and the cation-dopants.
Antiferromagnetic NiO thickness dependent sign of the spin Hall magnetoresistance in γ-Fe 2 O 3 /NiO/Pt epitaxial stacks
2019
We study the spin Hall magnetoresistance (SMR) in epitaxial γ–Fe2O3/NiO(001)/Pt stacks, as a function of temperature and thickness of the antiferromagnetic insulating NiO layer. Upon increasing the thickness of NiO from 0 nm to 10 nm, we detect a sign change of the SMR in the temperature range between 10 K and 280 K. This temperature dependence of the SMR in our stacks is different compared to that of previously studied yttrium iron garnet/NiO/Pt, as we do not find any peak or sign change as a function of temperature. We explain our data by a combination of spin current reflection from both the NiO/Pt and γ-Fe2O3/NiO interfaces and the thickness-dependent exchange coupling mode between the …
Gel combustion synthesis and magnetic properties of CoFe2O4, ZnFe2O4, and MgFe2O4 using 6-aminohexanoic acid as a new fuel
2020
Abstract For the first time, 6-aminohexanoic acid is used as an alternative fuel in the synthesis of the spinel ferrites with compositions CoFe2O4, ZnFe2O4 and MgFe2O4 using gel combustion synthesis with different oxidizer-to-fuel (O/F) ratios. The gel precursors were studied by differential thermal analysis and thermogravimetry (DTA/TG), which showed that the ignition temperature depends on the gel precursor, being around 230 °C, 130 °C and 275 °C for CoFe2O4, ZnFe2O4, and MgFe2O4, respectively. These results showed than the 6-aminohexanoic acid has an ignition temperature lower than the urea and the citric acid when were used in the synthesis of the spinel ferrites by gel combustion. More…
Raman characterization of Pb2Na1−xLaxNb5−xFexO15 and Pb0.5(5−x)LaxNb5−xFexO15 (0≤x≤1) solid solutions
2011
Abstract The ferroelectric compounds Pb 2 Na 1− x La x Nb 5− x Fe x O 15 and Pb 0.5(5− x ) La x Nb 5− x Fe x O 15 (0≤ x ≤1) with the tungsten bronze type structure have been investigated using Raman spectroscopy. The evolution of the spectra as a function of composition at room temperature is reported. In the frequency range 200–1000 cm −1 three main A 1 phonons around 240 ( υ 1 ), 630 ( υ 2 ) and 816 ( υ 3 ) cm −1 were observed. The broadening of the Raman lines for high values of x originates from a significant structural disorder. This is in good agreement with the relaxor character of these compositions. The lowest-frequency part of the spectra, below 180 cm −1 , reveals a structural ch…
Spectroscopic study of ion temperature in minimum-B ECRIS plasma
2019
Experimentally determined ion temperatures of different charge states and elements in minimum-B confined electron cyclotron resonance ion source (ECRIS) plasma are reported. It is demonstrated with optical emission spectroscopy, complemented by the energy spread measurements of the extracted ion beams, that the ion temperature in the JYFL 14 GHz ECRIS is 5–28 eV depending on the plasma species and charge state. The reported ion temperatures are an order of magnitude higher than previously deduced from indirect diagnostics and used in simulations, but agree with those reported for a quadrupole mirror fusion experiment. The diagnostics setup and data interpretation are discussed in detail to …
Atomic Layer Deposition of LiF Thin Films from Lithd, Mg(thd)2, and TiF4 Precursors
2013
Lithium fluoride is an interesting material because of its low refractive index and large band gap. Previously LiF thin films have been deposited mostly by physical methods. In this study a new way of depositing thin films of LiF using atomic layer deposition (ALD) is presented. Mg(thd)2, TiF4 and Lithd were used as precursors, and they produced crystalline LiF at a temperature range of 300–350 °C. The films were studied by UV–vis spectrometry, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), atomic force microscopy (AFM), time-of-flight elastic recoil detection analysis (ToF-ERDA), and energy dispersive X-ray spectroscopy (EDX). In addition, film adhesion was t…
Hydrodynamic Modeling of Transport and Noise Phenomena in Bipolar Two-Terminal Silicon Structures
1998
International audience
Annealing behaviour of aluminium-implanted InP
2000
The annealing behaviour of aluminium has been studied in single-crystal InP implanted with 40 and 120 keV 27Al+ ions. The implantation doses were 1 x 1015 and 1 x 1016 cm-2. The aluminium concentration profiles were determined by two techniques, Secondary ion mass spectrometry (SIMS) and the nuclear resonance broadening technique (NRB) which was used for checking purposes. The usability of the SIMS technique for profiling Al rich layers was studied. Significant inconsistencies were observed in the SIMS profiles with the high dose implanted samples. The 120 keV, 1 x 1016 cm-2 implanted samples were subject to annealing in argon atmosphere in the temperature range 380–600°C. Redistribution an…
EPR and optical spectroscopy of neutron-irradiated Gd3Ga5O12 single crystals
2020
Abstract In this paper, we have performed comparative analysis of EPR, optical absorption (OA) and luminescence spectra for a series of Gd3Ga5O12 (GGG) single crystals irradiated with fast neutrons with fluencies varied from 1016 to 1020n/cm2. In a crystal irradiated with the maximum neutron fluence, the EPR spectra demonstrated the formation of several paramagnetic defects. In particular, EPR spectrum shows a strong resonance at (effective) g ≈ 1.4 with practically isotropic behavior in the crystal rotation around the [1 1 1] direction (magnetic field being perpendicular to [1 1 1]) and several weaker lines in the g ≈ 1.1–2.6 region, which show more pronounced angular dependences. While th…
Comparison of the F-type center thermal annealing in heavy-ion and neutron irradiated Al2O3 single crystals
2018
Abstract The optical absorption and thermally stimulated luminescence of Al2O3 (sapphire) single crystals irradiated with swift heavy ions (SHI) 238U with energy 2.4 GeV is studied with the focus on the thermal annealing of the F-type centers in a wide temperature range of 400–1500 K. Its theoretical analysis allows us to obtain activation energies and pre-exponentials of the interstitial oxygen ion migration, which recombine with both types of immobile electron centers (F and F+ centers). A comparison of these kinetics parameters with literature data for a neutron-irradiated sapphire shows their similarity and thus supports the use of SHI-irradiation for modeling the neutron irradiation.