Search results for " Temperature dependence"

showing 4 items of 4 documents

A field induced ferromagnetic-like transition below 2.8 K in Li2CuO2: An experimental and theoretical study

1998

The low temperature magnetic properties of the Li2CuO2 compound have been investigated by means of superconducting quantum interference device magnetometry. We find in addition to an antiferromagnetic phase below 9.5 K a ferromagnetic-like steep rise of the magnetization around 2.8 K. The observed low temperature behavior is discussed by considering second and fourth order magnetocrystalline effective anisotropy coefficients, in addition to the exchange couplings reported in the literature. Work at the Institut de Ciencia dels Materials was supported by the Spanish Comisión Interministerial de Ciencia y Technología Grant No. CICYT MAT 96-1037.

Field (physics)MagnetometerExchange InteractionsGeneral Physics and AstronomyExchange Interactions (Electron)Magnetizationlaw.inventionMagnetizationMagnetisationAntiferromagnetism:FÍSICA [UNESCO]lawPhase (matter)Magnetic propertiesFerromagnetic MaterialsCopper OxidesLi2CuO2AntiferromagnetismAntiferromagnetic MaterialsLithium OxidesAnisotropyCondensed matter physicsTemperature Range 0000-0013 KChemistryTemperature DependenceUNESCO::FÍSICALithium Compounds ; Ferromagnetic-Antiferromagnetic Transitions ; Ferromagnetic Materials ; Antiferromagnetic Materials ; Magnetisation ; Magnetic Anisotropy ; Exchange Interactions (Electron) ; Lithium Oxides ; Copper Oxides ; Magnetization ; Exchange Interactions ; Antiferromagnetism ; Ferromagnetism ; Temperature Dependence ; Temperature Range 0000-0013 KMagnetic AnisotropyMagnetic anisotropyFerromagnetismLithium CompoundsFerromagnetismFerromagnetic-Antiferromagnetic TransitionsJournal of Applied Physics
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A Methodology for Protection of Trees Against Lightning Strikes as a Measure to Prevent Fires and Loss of Human Life

2021

Some regions may be characterized by a very low annual lightning ground flash density, and yet lightning strikes seem to have been in those areas the cause of widespread wildfires in forested areas. Due to global climate change, these occurrences seem to be an increasing threat. In this paper, the authors discuss the withstand capability of trees against lightning and introduce the criteria for the deployment of tree lightning protection systems (TLPS) to protect forested areas, where deemed necessary by the tree risk assessment. This work analytically identifies the critical trunk radius of the tree below which the tree may explode in the case of a lightning strike and ignite the surroundi…

collection areaHuman lifeflash densityFiresLightningIndustrial and Manufacturing Engineeringwood resistivityElectrical and Electronic EngineeringLightning protectionMoistureform factorConductivityVegetationbusiness.industryGlobal warmingEnvironmental resource managementtreesVegetationwood densityProtection systemcollection area; Conductivity; Fires; flash density; form factor; lightning; Lightning; Lightning protection; Moisture; resistivity; Temperature dependence; trees; Vegetation; wood density; wood resistivityLightningSettore ING-IND/33 - Sistemi Elettrici Per L'EnergiaresistivityCollection area Conductivity Fires flash density form factor lightning Lightning protection Moisture resistivity Temperature dependence trees Vegetation wood density wood resistivityTree (data structure)Lightning strikeTemperature dependenceControl and Systems EngineeringEnvironmental sciencebusinessIEEE Transactions on Industry Applications
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Transport properties of nitrogen doped p‐gallium selenide single crystals

1996

Nitrogen doped gallium selenide single crystals are studied through Hall effect and photoluminescence measurements in the temperature ranges from 150 to 700 K and from 30 to 45 K, respectively. The doping effect of nitrogen is established and room temperature resistivities as low as 20 Ω cm are measured. The temperature dependence of the hole concentration can be explained through a single acceptor‐single donor model, the acceptor ionization energy being 210 meV, with a very low compensation rate. The high quality of nitrogen doped GaSe single crystals is confirmed by photoluminescence spectra exhibiting only exciton related peaks. Two phonon scattering mechanisms must be considered in orde…

Electron mobilityOptical PhononsPhotoluminescenceMaterials scienceNitrogen AdditionsPhononExcitonGallium SelenidesHole MobilityGeneral Physics and AstronomyMonocrystalsCondensed Matter::Materials ScienceP−Type Conductors:FÍSICA [UNESCO]Condensed Matter::SuperconductivityDoped MaterialsHall EffectCondensed matter physicsPhonon scatteringScatteringDopingTemperature DependenceUNESCO::FÍSICAAcceptorDoped Materials ; Excitons ; Gallium Selenides ; Hall Effect ; Hole Mobility ; Monocrystals ; Nitrogen Additions ; Optical Phonons ; P−Type Conductors ; Temperature Dependence ; Transport ProcessesTransport ProcessesExcitons
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High‐temperature behavior of impurities and dimensionality of the charge transport in unintentionally and tin‐doped indium selenide

1993

A systematic study of the electron transport and shallow impurity distribution in indium selenide above room temperature or after an annealing process is reported by means of far‐infrared‐absorption and Hall‐effect measurements. Evidences are found for the existence of a large concentration of deep levels (1012–1013 cm−2), related to impurities adsorbed to stacking faults in this material. Above room temperature impurities can migrate from those defect zones and then become shallow in the bulk. The subsequent large increase of 3D electrons can change the dimensionality of the electron transport, which in most cases was 2D. The temperature dependence of the resistivity parallel to the c axis…

Electron mobilityInfrared SpectraAnnealing (metallurgy)Analytical chemistryGeneral Physics and Astronomychemistry.chemical_elementAnnealingchemistry.chemical_compound:FÍSICA [UNESCO]Hall effectImpurityElectrical resistivity and conductivityTin AdditionsSelenideDoped MaterialsIndium SelenidesHall EffectCondensed matter physicsTemperature DependenceDopingUNESCO::FÍSICAElectric ConductivityIndium Selenides ; Tin Additions ; Impurities ; Annealing ; Electric Conductivity ; Infrared Spectra ; Hall Effect ; Deep Energy Levels ; Temperature Dependence ; Doped MaterialsDeep Energy LevelschemistryIndiumImpuritiesJournal of Applied Physics
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