Showing papers in "Physica B-condensed Matter in 2001"
TL;DR: In this article, temperature-dependent resistivity measurements of the irradiated samples have been found to follow ρ ( T )∝exp√( T 0 / T ) in the temperature range of 80 −280 K. The observed behaviour of ρ T is consistent with charge transport due to hopping between isolated, conducting islands.
Abstract: Silver nanoclusters embedded in glass matrices have been obtained by the combined use of ion exchange and subsequent ion implantation. XRD and UV-visible spectro-photometric analysis have confirmed the formation of Ag nano-clusters in the ion-irradiated samples. Temperature-dependent resistivity measurements of the irradiated samples have been found to follow ρ ( T )∝exp√( T 0 / T ) in the temperature range of 80–280 K. The observed behaviour of ρ ( T ) is consistent with charge transport due to hopping between isolated, conducting islands. The separation distance between the conducting islands has been found to be a function of fluence.
365 citations
TL;DR: In this article, it is shown that the maximum free electron or hole concentration that can be achieved by doping is an intrinsic property of a given semiconductor and is fully determined by the location of the semiconductor band edges with respect to a common energy reference, the Fermi level stabilization energy.
Abstract: Doping limits in semiconductors are discussed in terms of the amphoteric defect model (ADM). It is shown that the maximum free electron or hole concentration that can be achieved by doping is an intrinsic property of a given semiconductor and is fully determined by the location of the semiconductor band edges with respect to a common energy reference, the Fermi level stabilization energy. The ADM provides a simple phenomenological rule that explains experimentally observed trends in free carrier saturation in a variety of semiconductor materials and their alloys. The predictions of a large enhancement of the maximum electron concentration in III–N–V alloys have been recently confirmed by experiment.
335 citations
PARC1
TL;DR: In this paper, a first-principles investigation, based on density functional theory, shows that native defects are unlikely to be the cause of the unintentional n-type conductivity of ZnO.
Abstract: Zinc oxide has numerous applications in electronic and optoelectronic devices. Progress is currently hampered by a lack of control over electrical conductivity: ZnO is typically n-type conductive, the cause of which has been widely debated. A first-principles investigation, based on density functional theory, shows that native defects are unlikely to be the cause of the unintentional n-type conductivity. Detailed results for the oxygen vacancy show that it is a deep donor, and that its paramagnetic state is metastable. An investigation of likely donor impurities reveals that hydrogen acts as a shallow donor. Experimental results are discussed in the light of these new insights.
272 citations
TL;DR: The elastic constants c11, c12 and c44 of U, Np, Pu, and Am telluride single crystals have been obtained by Brillouin scattering from the measured sound velocities in prominent crystallographic directions.
Abstract: The elastic constants c11, c12 and c44 of U, Np, Pu, and Am telluride single crystals have been obtained by Brillouin scattering from the measured sound velocities in prominent crystallographic directions. In case of the U chalcogenides also by ultrasound techniques. The Cauchy pressure, the Poisson ratio, the anisotropy ratio, the bulk modulus and the Debye temperature have been derived from these data. U and Pu telluride have a negative c12, implying intermediate valence. AmTe has a very low bulk modulus, but a positive c12. It is extremely soft, with a very low sound velocity. For AmTe also the LO and TO phonon frequencies could be determined. The elastic data point to a divalent Am state. The optical reflectivity of the light actinide tellurides (and sometimes of all chalcogenides) has been measured between UV and infrared wavelengths, in the case of AmTe down to the far infrared. The plasma edge of the free carriers has been determined, which yields the ratio of n/m*. Together with the γ value of the specific heat and magnetic data a consistent proposal for the electronic structure of the light actinide chalcogenides can be given. Thus, the Pu chalcogenides are intermediate valent and represent the high-pressure phase of the corresponding Sm chalcogenides. AmTe, as judged by the electronic, optic and magnetic properties seems to be in the 5f7 configuration, i.e. divalent Am, but with a narrow, half-filled (24 meV) wide 5f band, about 0.1 eV below the bottom of the 6d conduction band. We thus propose a new kind of unhybridized heavy fermion. Also AmTe seems to represent a high-pressure phase of EuTe.
241 citations
TL;DR: In this article, the state-of-the-art ZnO substrate material grown by seeded chemical vapour transport was investigated and the bound exciton lines were identified as donor related.
Abstract: We investigate the state-of-the-art ZnO substrate material grown by seeded chemical vapour transport. The low-temperature photoluminescence (PL) spectra are dominated by very sharp bound exciton lines, which are followed by two-electron satellite transitions. This identifies the major bound exciton lines as donor related and allows us to derive a binding energy of ≈40 meV for the very similar donors observed here. From a donor–acceptor pair transition at ≈3.22 eV and its associated band-acceptor line emerging at sample temperatures above 40 K, we calculate the acceptor binding energy as ≈195 meV. Hall data confirm these findings.
238 citations
TL;DR: In this paper, the p-type ZnOfilms were fabricated by passing N 2Ogas through an electron cyclotron resonance (ECR) or RF plasma source.
Abstract: We have demonstrated the possibility of growing p-type ZnOfilms by a pulsed laser deposition technique combined with plasma gas source. The p-type ZnOfilm has been fabricated by passing N 2Ogas through an electron cyclotron resonance (ECR) or RF plasma source. N2Ogas is effective to prevent ‘‘O’’ vacancy from occurring and introduce ‘‘N’’ as an acceptor, at the same time. With Ga and N codoping technique, we have observed a room temperature resistivity of 0.5O cm and a carrier concentration of 5 � 10 19 cm � 3 in ZnOfilm on glass substrate. Two-step growth, with a thin ZnOtemplate layer formed at high temperature, is quite effective to realize a well crystallized growth at low temperature. The observed p-type ZnOfilms will open the door for practical applications in various oxide electronic devices. # 2001 Elsevier Science B.V. All rights reserved. PACS: 7361Ga; 7155Gs; 7220� i; 8115Fg
222 citations
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TL;DR: An overview of the present state of the art on the preparation techniques, outstanding magnetic properties and applications of soft magnetic micro and nanowires is presented in this article, where magnetic behaviours of interest are related to the different hysteresis loops of samples: square-shaped loops typical of bistable behaviour, and nearly non-hysteretic loop with well-defined transverse anisotropy field.
Abstract: An overview of the present state of the art on the preparation techniques, outstanding magnetic properties and applications of soft magnetic micro and nanowires is presented. Rapid solidification techniques (in-rotating-water quenching and drawing methods) to fabricate amorphous microwires with diameter in the range from 100 down to 1 μm are first described. Electrodeposition is also employed to prepare composite microtubes (magnetic coatings) and to fill porous membranes (diameter of the order of 0.1 μm). Magnetic behaviours of interest are related to the different hysteresis loops of samples: square-shaped loops typical of bistable behaviour, and nearly non-hysteretic loop with well-defined transverse anisotropy field. The role played by magnetic dipolar interactions in the magnetic behaviour of arrays of micro and nanowires is described. A particular analysis is done on the giant magnetoimpedance (GMI) effect in the radio and microwave frequency ranges exhibited by ultrasoft microwires. Finally, a few examples of applications are introduced for magnetostrictive and non-magnetostrictive wires, they are: “magnetoelastic pens”, micromotors; DC current-sensors based on GMI, and sharpened amorphous wire tips in spin polarised scanning tunneling microscopy.
199 citations
TL;DR: In this article, the unipolarity in ZnO was investigated based on ab initio electronic band structure calculations, and a codopant pair including Ga-reactive donors and N-acceptors was proposed for use in the codoping.
Abstract: We investigate unipolarity in ZnO based on ab initio electronic band structure calculations. We find that p-type doping using Li, N or As species causes an increase in Madelung energy, n-type doping using B, Al, Ga, In or F species gives rise to a decrease in Madelung energy. In order to solve the unipolarity, to fabricate p-type ZnO, we propose a codoping method using acceptors and reactive donors simultaneously. A codopant pair including Ga-reactive donors and N-acceptors is eminently suitable for use in the codoping. For Li-acceptors, F species is a good candidate for reactive donors. For As-acceptors, Ga species is a preferable codopant.
156 citations
TL;DR: In this article, a change in the impurity states of N acceptors between ZnS:N and ZnsS:(2N, In), based on calculated results using ab initio electronic band structure calculations, was found.
Abstract: We use In species as reactive codopants for N acceptors to realize p-type ZnS. We find a change in the impurity states of N acceptors between ZnS : N and ZnS : (2N, In), based on the calculated results using ab initio electronic band structure calculations: while we find highly localized states of N acceptors for ZnS : N, we verify delocalized states for ZnS : (2N, In).
152 citations
TL;DR: The paper proposes the identification and compensation of the hysteretic behavior of an actuator constituted by a Terfenol-D magnetostrictive material and the idea of pseudo-compensator is introduced for compensation of hysteresis and nonlinearity of a magnetstrictive actuator.
Abstract: The paper proposes the identification and compensation of the hysteretic behavior of an actuator constituted by a Terfenol-D magnetostrictive material. Hysteresis is modeled by applying the classical Preisach model whose identification procedure is performed by the adoption of both a fuzzy approximator and a feed-forward neural network. This allows to analytically reconstruct either Everett integrals and the Preisach distribution function, without any special smoothing of the measured data, owing to the filtering capabilities of the neuro-fuzzy interpolators. The idea of pseudo-compensator is introduced for compensation of hysteresis and nonlinearity of a magnetostrictive actuator.
149 citations
TL;DR: In this paper, the stability of the ferromagnetic state compared with that of the spin-glass state is systematically investigated by calculating the total energy difference between them based on first principles calculations.
Abstract: The ferromagnetism in ZnO-based diluted magnetic semiconductors (DMSs) is investigated based on the first principles calculations. The electronic structure of a ZnO-based DMS is calculated using the Korringa–Kohn–Rostoker method combined with the coherent potential approximation based on the local density approximation. The stability of the ferromagnetic state compared with that of the spin-glass state is systematically investigated by calculating the total energy difference between them. It is found that the ferromagnetic state is more stable than the spin-glass state in V-, Cr-, Fe-, Co- or Ni-doped ZnO without any additional carrier doping treatments. In the case of the Mn-doped ZnO, the spin-glass state is stable at a carrier concentration of 0%, but the ferromagnetic state is stabilized by the hole doping treatment. Analyzing the calculated density of states, it is proposed that the origin of the stabilization of the ferromagnetism is a double-exchange mechanism.
TL;DR: In this article, the authors used EPR and ODMR to study state-of-the-art bulk ZnO single crystals and observed a center due to residual nitrogen (g∥=1.9551).
Abstract: We have used EPR and ODMR to study state-of-the-art bulk ZnO single crystals. Most of the samples are n-type; however, under certain conditions (e-irradiated or annealed), we observe a center due to residual nitrogen (g∥=1.9953, g⊥=1.9633 and Aiso=1.225 mT, Aaniso=0.864 mT). The N center is a nitrogen p-orbital along the c-axis, very similar to P or As in ZnSe, which have a Jahn-Teller distorted, deep state, seen in EPR. The intensity of the N center is strongly anisotropic, as would be expected for shallow heavy-hole acceptors with m J =± 3 2 in which the magnetic dipole transition is forbidden for B ∥ c and becomes allowed away from that orientation due to mixing with m J =± 1 2 states. The EPR spectra for the n-type samples are dominated by delocalized donors (g∥=1.9570 and g⊥=1.9551). In one sample, the donor appears to be localized. These crystals also exhibit a broad PL band at 2.5 eV. ODMR on the 2.5 eV “green” PL band reveals an S=1 triplet center (not seen in EPR) with spin-Hamiltonian parameters of D=0.763 GHz, g∥=1.9710, and g⊥=2.0224. ODMR of shallow donors is also observed as a luminescence-decreasing feature on the 2.5 eV green emission band.
TL;DR: In this paper, the potential distribution of a two-dimensional electron system (2DES) under quantum Hall conditions at a temperature T = 1.4 K was mapped out for the Landau level filling factor range 1 < v < 14 with submicron resolution.
Abstract: A low-temperature scanning force microscope sensitive to electrostatics is used to investigate the potential distribution of a two-dimensional electron system (2DES) under quantum Hall conditions at a temperature T = 1.4 K. We mapped out the Hall potential profiles for the Landau level filling factor range 1 < v < 14 with submicron resolution. At integer filling factors, the potential drop is rather nonlinear, but depends strongly on the scan position. Obviously inhomogeneities of the sample strongly affect the Hall potential profile if the bulk of the 2DES is nonconductive and cannot screen. At filling factors slightly above an even integer value, the Hall potential drops at prominent positions at both edges which are associated with the positions of the incompressible strips as confirmed by comparison with theoretical predictions. With these broad incompressible strips electrically decoupling the edge region from the compressible bulk region, a nearly vanishing Hall potential drop is observed in the compressible bulk region, suggesting that most of the current is flowing close to the edges. In addition, potential profiles near the current injecting contacts reveal the well known hot spot region in the direct vicinity of the contact, but recover to the described shape within a distance of only 6 μm.
TL;DR: Erbium is a lanthanide ion with unique electronic and optical properties as discussed by the authors, which can be used to probe point defects, oxygen, OH, Er, radiation defects, network structure, excitons, optical density of states, optical modes, and photonic bandstructure.
Abstract: Erbium is a lanthanide ion with unique electronic and optical properties. In its trivalent state it is composed of an incompletely filled 4f inner shell and two closed outer shells. By employing these properties in specific material systems, Er can be used to probe point defects, oxygen, OH, Er, radiation defects, network structure, excitons, optical density of states, optical modes, and photonic bandstructure.
TL;DR: In this article, the barrier height and ideality factor of Au/n-GaAs Schottky diodes grown by metal-organic vapor phase epitaxy (MOVPE) on undoped and Si-doped n-GAAs substrates were determined in the doping range of 2.5 � 10 15 − 1.
Abstract: The barrier height and ideality factor of Au/n-GaAs Schottky diodes grown by metal-organic vapor-phase epitaxy (MOVPE) on undoped and Si-doped n-GaAs substrates were determined in the doping range of 2.5 � 10 15 – 1 � 10 18 cm � 3 at low temperatures. The thermionic-emission zero-bias barrier height for current transport decreases rapidly at concentrations greater than 1 � 10 18 cm � 3 . The ideality factor also increases very rapidly at higher concentration and at lower temperature. The results agree quite well with thermionic field emission (TFE) theory. The doping dependence of the barrier height and the ideality factor were obtained in the concentration range of 2.5 � 10 15 – 1.0 � 10 18 cm � 3 and the results are well described using TFE theory. An excellent match between the homogeneous barrier height and the effective barrier height was observed which supports the good quality of the GaAs film. The observed variation in the zero-bias barrier height and the ideality factor can also be explained in terms of barrier height inhomogeneities in the Schottky diode. r 2001 Elsevier Science B.V. All rights reserved.
TL;DR: The hardness of single crystals α-SiC, AlN, GaN, ZnO and ZnSe at elevated temperatures was measured by the Vickers indentation method in the temperature range 20-1400°C as mentioned in this paper.
Abstract: The hardness of single crystals α-SiC, AlN, GaN, ZnO and ZnSe at elevated temperatures was measured by the Vickers indentation method in the temperature range 20–1400°C. The hardness of SiC, AlN, GaN, ZnO and ZnSe is about 25, 18, 11, 5 and 1 GPa, respectively, at room temperature. SiC, AlN and GaN show a decrease in hardness, originating in the beginning of macroscopic dislocation motion and plastic deformation, only at temperature 1200°C. A high thermo-mechanical stability for SiC, GaN and AlN is deduced.
TL;DR: In this paper, the structural properties of boron doped and undoped zinc oxide (ZnO) thin films were studied by using X-ray diffraction and the results showed that both the doped, undoped and non-doped ZnO thin films exhibit hexagonal wurtzite structure with strong c-axis orientation.
Abstract: Boron doped and undoped zinc oxide (ZnO) thin films were prepared by pyrolytic decomposition of methanolic solution of zinc acetate onto glass substrates. The structural properties of the films were studied by using X-ray diffraction. The results show that both the boron doped and undoped films exhibit hexagonal wurtzite structure with strong c-axis orientation as evidenced by X-ray diffraction patterns. The crystallite size wanes with increasing doping concentration. The electrical resistivity studies were carried out using the four-probe method. It is found that the films with 0.8 wt% boron doping concentration attains the lowest resistivity (10−4 Ω m), whereas for higher and lower doping concentrations resistivity increases. The thermoelectric power studies showed that the doped and undoped films exhibit n-type conductivity, optical studies revealed that with increase in doping concentration the transmittance of the film increases in the wavelength range 400–600 nm. The optical absorption data were used to determine band gap energy and it is found to be 3.22 eV for undoped ZnO films and 3.32 for boron doped films.
TL;DR: In this paper, a comparison between the energy separation of the several groups of near band edge photoluminescence emission bands and energy separation between the free exciton resonances observed in reflectivity is made.
Abstract: The similarities between ZnO and GaN samples reveal that the semiconductor oxide is a potential material as a promising material for optoelectronic devices. In this work, we study by spectroscopic and RBS techniques the characteristics of bulk ZnO. A comparison between the energy separation of the several groups of near band edge photoluminescence emission bands and the energy separation between the free exciton resonances observed in reflectivity is made. We report on the luminescence dependence from temperature and the variation of the relative intensities of the lines. From the data, an assignment of recombination centers is discussed.
TL;DR: The electron effective mass of n-type ZnO obtained recently by the cyclotron resonance is compared with the quasiparticle mass predicted by the GW approximation which takes into account the dynamical screening effects within the random phase approximation.
Abstract: The electron effective mass of n-type ZnO obtained recently by the cyclotron resonance is compared with the quasiparticle mass predicted by the GW approximation which takes into account the dynamical screening effects within the random phase approximation. The bare electron effective mass has been determined to be about 0.23 m 0 ( B ∥ c -axis) by cyclotron resonance experiments excluding electron–phonon coupling. On the other hand, the calculated quasiparticle mass has been obtained as about 0.24 m 0 . We have found that the dynamical screening effect enhances the mass obtained by the conventional local density approximation by about 17% and the predicted quasiparticle mass is in good agreement with the experiment.
TL;DR: In this article, a spray pyrolysis process was used to pre-process thin films of ZnO onto glass substrate at different substrate temperatures, ranging from 180°C to 450°C, and a relative permittivity of 9.8 is calculated from the capacitance measurements.
Abstract: Thin films of ZnO onto glass substrate at different substrate temperatures Ts, ranging from 180°C to 450°C, have been prepared using a spray pyrolysis process. X-ray diffraction showed that the films prepared at Ts greater than 300°C exhibit the hexagonal wurtzite structure with a preferential orientation along (0 0 2) direction. All electrical properties have been investigated for films at Ts=400°C. A relative permittivity of 9.8 is calculated from the capacitance measurements. Thermally generated electron concentration, n0=(2.8–6.7)×1010 m−1, and trapping factor, θ=(8.02–18.22)×10−12 have been evaluated from the analysis of current–voltage characteristics at room temperature assuming a plausible value of carrier mobility, 1.8 m2 V−1 s−1. The obtained values n0 and θ are correlated with the crystallite size.
TL;DR: In this paper, rare earth (RE) ions implanted GaN films were studied by optical spectroscopy and RBS techniques, and the authors reported on the temperature dependence of the intra-ionic emissions as well as on the lattice site location of the RE detailed angular scans through the / 00 0 1S and / 10 % S axial directions; which indicates that complete substitutionality on the Ga sites was achieved while for Eu a Ga displaced site was found.
Abstract: Rare earth (RE) ions implanted GaN films were studied by optical spectroscopy and RBS techniques. Sharp emission lines due to intra-4f n shell transitions can be observed even at room temperature for the Eu 3+ and Pr 3+ .Th e photoluminescence spectra recorded by the above band gap excitation reveal dominant transitions due to the 5 D0- 7 F1,2,3 lines at 6004, 6211 and 6632 ( A for the Eu 3+ and 3 P0,1- 3 F2,3 at 6450 and 6518 ( A, respectively, for the Pr 3+ . We report on the temperature dependence of the intra-ionic emissions as well as on the lattice site location of the RE detailed angular scans through the / 00 0 1S and / 10 % S axial directions; which indicates that for Pr, complete substitutionality on the Ga sites was achieved while for Eu a Ga displaced site was found. r 2001 Elsevier Science B.V. All rights reserved.
TL;DR: In this paper, a review on the recent advances in theoretical and experimental studies of itinerant electron metamagnetism (IEM) found in 3d and 5f intermetallic compounds without magnetic rare-earth elements is presented.
Abstract: A review is presented on the recent advances in theoretical and experimental studies of itinerant electron metamagnetism (IEM) found in 3d and 5f intermetallic compounds without magnetic rare-earth elements. These compounds exhibit various peculiar magnetic properties characteristic of IEM under high magnetic fields and high pressures. The observed IEM and peculiar properties are found to be qualitatively explained very well by theories of IEM based on the spin fluctuation model.
TL;DR: In this paper, different glasses in the system xCeO2-(1−x)B2O3 were prepared and characterized and infrared measurements of the glasses were carried out.
Abstract: Different glasses in the system xCeO2–(1−x)B2O3 were prepared and characterized. Density (D), molar volume (Vm), microhardness (Hv), glass transition temperature (Tg), thermal expansion coefficient (α) and infrared measurements of the glasses have been carried out. IR results of CeO2-rich glasses (40–60 mol%) confirm that CeO2 affects the glass network as both a network modifier and a network former. The modifier part of CeO2 is consumed in transformation of BO3 units to BO4 groups. The rest of CeO2 can participate in the network in the form of CeO4 units. Both Tg and Hv increase with increasing the concentration of BO4 and CeO4 units. There is a great change in α with increasing CeO2 content. The increase in both Tg and Hv and the decrease in α are considered as evidences for increasing the total network connectivity. On the other hand, the concentration of BO4 and CeO4 groups in glasses of lower CeO2 content (<40 mol%) is considered to be limited. This was interpreted in terms of the ability of CeO2 to form linkages with BO3 groups rather than forming BO4 units.
TL;DR: In this article, the authors examined the question posed in the literature evidence implying the positive answer and concluded that, in order to prevent further proliferation of the incorrect terminology and thus to increase reliability of the published EMR data, a concerted effort within the EMR community is indispensable.
Abstract: In this paper, the question posed in the title is critically examined on the basis of the available literature evidence implying the positive answer. The distinction between, on the one hand, the actual crystal field (CF) or equivalently ligand field (LF) related quantities and, on the other hand, the actual zero-field splitting (ZFS) or equivalently fine structure (FS) quantities, is elucidated. The origin and possible roots of the incorrect terminology consisting in mixing up the two physically distinct quantities at different levels are examined. Aspects concerning Hamiltonians, parameters, energy level splitting, and nature of the operators involved are taken into account. Problems with the various notations for the operators and parameters used in the electron magnetic resonance (EMR) area are also identified and reviewed. A large number of cases of incorrect terminology and other inconsistencies identified in the course of a comprehensive literature survey are analyzed and systematically classified. Implications of the confusion in question, which go beyond the simple semantic issues, are discussed. The results of the survey reveal that the two most serious categories of this confusion lead to misinterpretation of the experimental EMR data. Several examples of serious misinterpretations found in the books, reviews, and original papers are discussed. The incorrect terminology contributes also to misleading keyword classifications of papers in journals as well as references in scientific literature databases. Thus, the database searches may produce unreliable outcomes. Examples of such outcomes are also shown. It is concluded that, in order to prevent further proliferation of the incorrect terminology and thus to increase reliability of the published EMR data, a concerted effort within the EMR community is indispensable. Various ways in this regard at the international level are suggested.
TL;DR: In this article, the authors focus on the binary compound Cu x S. In order to understand its influence on CuInS 2, they first focus their study on the two compounds, i.e., Cu 2 S, and CuS films were deposited on float glass substrates using a reactive RF sputter process.
Abstract: Cu x S is one of the most prevalent minor phases co-existing in CuInS 2 films. In order to understand its influence on CuInS 2 , we first focus our study on the binary compound Cu x S. Cu 2 S, and CuS films were deposited on float glass substrates using a reactive RF sputter process with optimized sputter parameters, such as power, temperature of the substrate, and the gas flow of the H 2 S. X-ray diffraction spectra showed that the Cu 2 S films have (0 0 2) preferential orientation, and both compounds have a hexagonal structure. The surface morphology and the composition of the layers were analyzed by atomic force microscopy and Rutherford back-scattering spectroscopy, respectively. X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy were used to characterize the layer surfaces, as well as the surface composition. Hall-effect measurements were carried out to determine the electrical properties of the films.
TL;DR: In this paper, it has been shown that the magnetic fields of this range do produce various visible effects on the equilibrium shape, relative distribution of the substances or kinetic processes of the systems.
Abstract: Magnetic fields up to 10 T have been applied on various substances composed of non-magnetic liquids, solids and/or gases. It has turned out that the magnetic fields of this range do produce various visible effects on the equilibrium shape, relative distribution of the substances or kinetic processes of the systems. The phenomena observed are due to the magnetization force that becomes non-significant in determining the mechanical balance of the system. The effects manifest themselves through the deformation of the equilibrium shape of the liquid interfaces, through the change in the effective weight which determines the relative positions occupied in the space by the substances involved and through the creation of convection in a non-uniform gas or liquid phase in terms of the magnetic susceptibility. Some of the processes seem to be utilized for practical purposes.
TL;DR: In this paper, the first backscattering spectrometer of the second generation, called IN16, was presented. But it used focusing optics and a deflection chopper, allowing for the first time for a perfect backscatter condition at the monochromator side.
Abstract: IN16 is the first backscattering spectrometer of the second generation: it uses focusing optics and a deflection chopper, allowing for the first time for a perfect backscattering condition at the monochromator side. The high flux of the instrument, combined with a Gaussian resolution function, made the instrument a success. We summarise the technical design, experiments carried out over the 5 yr of operation, recent developments and plans for improving both the neutron flux and the dynamic range in the future.
TL;DR: In this paper, a broad green emission band in ZnO at 2.45 eV originates from a spintriplet-recombination characterised by g || c = 1.984 and g ⊥ c = 2.025 (parallel and perpendicular to the crystallographic c -axis, respectively) and a zero-field splitting of D =260×10 −4 ǫ −1.
Abstract: Optically detected magnetic resonance shows that a broad, green emission band in ZnO at 2.45 eV originates from a spintriplet-recombination characterised by g || c =1.984 and g ⊥ c =2.025 (parallel and perpendicular to the crystallographic c -axis, respectively) and a zero-field splitting of D =260×10 −4 cm −1 . These parameters and the polarisation properties of the emission are very similar to the anion vacancies in CaO but not compatible with the Zeeman results on ZnO : Cu.
TL;DR: In this paper, the authors used modified Judd-Ofelt (JO) intensity parameters to predict radiative properties such as spontaneous emission probabilities (A), lifetimes (τR), and branching ratios (βR) for all the 12 excited states of these Pr3+ doped lithium borate and lithium fluoroborate glasses.
Abstract: Optical absorption and emission spectra of 1 mol% Pr3+ doped lithium borate and lithium fluoroborate glasses have been recorded. The intensities of f–f transitions are parameterized in terms of Judd–Ofelt (JO) intensity parameters Ωλ (λ=2, 4 and 6). The JO parameters obtained with modified JO theory have been used to predict radiative properties such as spontaneous emission probabilities (A), lifetimes (τR) and branching ratios (βR) for all the 12 excited states of these Pr3+ doped glasses along with some of the reported Pr3+ : systems. The predicted βR are compared with the experimental values for the emission from 3P0 and 3P1 levels. The stimulated emission cross-sections are also evaluated for all the observed emission transitions. The βR values for the potential laser transitions including the 1G4→3H5 (1.3 μm) transition useful for fibre amplifier have been compared for 17 Pr3+ : systems. The effect of compositional changes of the glasses on the optical properties of Pr3+ ions have been discussed.
TL;DR: In this paper, a non-destructive pulsed magnet for 100 T has been developed to carry out precise magnetic measurements at extremely low temperatures and under high pressures, which can be used for magnetization measurements under high pressure up to 10kbar.
Abstract: A non-destructive pulsed magnet for 100 T has been developed to carry out precise magnetic measurements at extremely low temperatures and under high pressures Our record magnet has generated 803 T in a 10 mm bore with 7 ms pulse duration and then is called a 80 T magnet The 80 T magnet consists of inner and outer coils, both of these are made by winding with Cu–Ag wire and reinforced by maraging steel The inner coil is a single-layer coil backed up with a thin maraging pipe and the outer coil is made with nine layers reinforced by a thick maraging ring Magnetization and magnetoresistance measurements at 13 K have been carried out up to 70 T in the 80 T magnet The outer coil of the 80 T magnet has an 18 mm bore and can generate 713 T as a record and then is called a 70 T magnet The 18 mm bore of the 70 T magnet is a useful space for introducing an extremely low temperature into high magnetic field; this was used to carry out both magnetization and magnetoresistance measurements at 80 mK up to 60 T We have examined the lifetime of the 70 T magnet at various maximum fields in ordinary use The results show that about 100 shots can be made with 60 T and 500 shots at 55 T We have developed another 70 T magnet with longer pulse duration of about 20 ms for magnetization measurements under high pressure up to 10 kbar The 70 T magnet for high-pressure experiments has an 18 mm bore and an inductance of about 3 mH The magnet consists of an inner five-layer coil backed up with a thick maraging steel pipe and the outer has 11 layers and a maraging ring As the pressure cell used for the measurement is made of Be–Cu, a longer pulse is necessary to allow penetration of the pulsed field into the cell Magnetization measurements under high pressure have been carried out successfully up to 55 T although the pulse duration is not long enough to keep the temperatures very low A new pulsed magnet with higher field and longer pulse duration is proposed