Showing papers on "Atmospheric temperature range published in 1990"
TL;DR: The partial molar heat capacities of various peptides and various organic compounds that model the amino acid side-chains or their parts in aqueous solution have been determined by precise scanning microcalorimetry in the temperature range from 5 to 125 degrees C and this leads to a hydrophobicity scale of the amino acids side- chains based upon the temperature dependences of their heat capacities.
491 citations
TL;DR: The analysis shows that the temperature dependence of the ac conductivity is consistent with the simple quantum-mechanical tunneling model at low temperatures; however, this model completely fails to predict the observed temperature dependent of the frequency exponent.
Abstract: The first measurements are reported for the frequency-dependent (ac) conductivity (real as well as imaginary parts) for various compositions of the bismuth-vanadate glassy semiconductors in the frequency range 10 2 -10 5 Hz and in the temperature range 77-420 K. The behavior of the ac conductivity is broadly similar to what has been observed previously in many other types of amorphous semiconductors, namely, nearly linear frequency dependence and weak temperature dependence. The experimental results are analyzed with reference to various theoretical models based on quantum-mechanical tunneling and classical hopping over barriers. The analysis shows that the temperature dependence of the ac conductivity is consistent with the simple quantum-mechanical tunneling model at low temperatures; however, this model completely fails to predict the observed temperature dependence of the frequency exponent. The overlapping-large-polaron tunneling model can explain the temperature dependence of the frequency exponent at low temperatures. Fitting of this model to the low-temperature data yields a reasonable value of the wave-function decay constant. However, this model predicts the temperature dependence of the ac conductivity much higher than what actual data showed. The correlated barrier hopping model is consistent with the temperature dependence of both the ac conductivity and its frequency exponent. This model provides reasonable values of the maximum barrier heights but higher values of characteristic relaxation times.
341 citations
TL;DR: The magnetization in ultrathin Fe layers (2.5-3.5 atomic layers) on Cu(100) reversibly switches between perpendicular and in-plane magnetization over a temperature range of 20-30 K and shows evidence for a canted-spin configuration.
Abstract: The magnetization in ultrathin Fe layers (2.5-3.5 atomic layers) on Cu(100) reversibly switches between perpendicular (at low temperature) and in-plane magnetization (at higher temperature). The switching temperature decreases with increasing film thickness. The switching transition is attributed to the temperature dependence of the perpendicular anisotropy. The transition is accompanied by a loss of magnetization over a temperature range of 20-30 K and shows evidence for a canted-spin configuration
308 citations
TL;DR: The analysis shows that at high temperatures the temperature dependence of the dc conductivity is consistent with Mott's model of phonon-assisted polaronic hopping conduction in the adiabatic approximation, while the variable-range-hopping mechanism dominates at lower temperatures.
Abstract: Measurements are reported for the dc as well as frequency-dependent (ac) conductivities (real and imaginary parts) for various compositions of the vanadium germanate glassy semiconductors in the temperature range 80--450 K. The experimental results are analyzed with reference to various theoretical models proposed for electrical conduction in amorphous semiconductors. The analysis shows that at high temperatures the temperature dependence of the dc conductivity is consistent with Mott's model of phonon-assisted polaronic hopping conduction in the adiabatic approximation, while the variable-range-hopping mechanism dominates at lower temperatures. Schnakenberg's model predicts the temperature dependence of the observed activation energy in the intermediate temperature range. The temperature dependence of the ac conductivity is consistent with the simple quantum-mechanical tunneling model at lower temperatures, although this model cannot predict the observed temperature dependence of the frequency exponent. The overlapping-large-polaron tunneling model can explain the temperature dependence of the frequency exponent at low temperature; however, this model predicts a temperature dependence of the ac conductivity much higher than the observed data show. On the other hand, the correlated-barrier-hopping model is consistent with the temperature dependence of both the ac conductivity and its frequency exponent over the entire temperature range of measurements.
268 citations
IBM1
TL;DR: The solid state reaction between copper and silicon has been studied using Rutherford backscattering, glancing-angle x-ray diffraction, scanning electron microscopy, and x−ray photoemission spectroscopy as discussed by the authors.
Abstract: The solid state reaction between copper and silicon has been studied using Rutherford backscattering, glancing‐angle x‐ray diffraction, scanning electron microscopy, and x‐ray photoemission spectroscopy. Schottky‐barrier‐height measurements on n‐type Si (100) have also been performed in the temperature range of 95–295 K with the use of a current‐voltage technique. The results show that a metal‐rich compound with a composition in the Cu3Si range forms at low temperatures (473 K). The electronic properties of the compound are dominated by the hybridization between the Cu(d) and Si(p) valence states. A direct consequence of this hybridization is the peculiar oxidation behavior of the compound surface; both Cu and Si have been found to oxidize at room temperature. The oxidation of Si in the silicide is enhanced as compared with the oxidation of the elemental single‐crystalline Si surface. Upon annealing the oxidized surface, a solid state reaction takes place: Cu2O disappears and a thicker SiO2 layer grows, o...
193 citations
TL;DR: In this paper, the authors studied the recombination O+O2+M→O3+M in the bath gases M=He, Ar, and N2 over the temperature range 90-370 K and the pressure range 1-1000 bar.
Abstract: The recombination O+O2+M→O3+M in the bath gases M=He, Ar, and N2 was studied over the temperature range 90–370 K and the pressure range 1–1000 bar. The temperature and pressure dependences of the reaction rates show an anomalous behavior which is attributed to superpositions of mechanisms involving energy transfer, complex formation and participation of weakly bound electronically excited O3 states. The results also show an analogy to oxygen isotope enhancements observed in ozone recombination and dissociation. Experiments in compressed liquid N2 were also made showing a transition to diffusion control.
166 citations
TL;DR: In this paper, the authors investigated the silicidation process of the Ni/a-Si:H system on a fused silica substrate mainly by in situ electric resistance measurement.
Abstract: We have investigated the silicidation process of the Ni/a-Si:H system on a fused silica substrate mainly by in situ electric resistance measurement. A rise of the resistance is observed in the temperature range of 480–510°C of the resistance curve at a heating rate of 2 K/min. The results of the RBS measurements and the XRD measurements show that the rise of the resistance originates from the diffusion of Ni from the NiSi2 layer to a-Si:H film, and that the a-Si:H crystallizes during the diffusion. Noting that the crystallization temperature of a-Si:H film is higher than 700°C, the present crystallization occurs at a much lower temperature. It is suggested that this low-temperature crystallization is induced by heterogeneous nucleation, where the NiSi2 becomes the nucleus for Si crystallization.
158 citations
TL;DR: The analysis shows that the correlated-barrier-hopping model is the most appropriate for the material under consideration and predicts quantitatively the temperature dependence of both the ac conductivity and its frequency exponent.
Abstract: The first measurements are reported for the frequency-dependent ac conductivity for the iron bismuthate glassy semiconductors in the frequency range ${10}^{2}$--${10}^{5}$ Hz and in the temperature range 80--450 K. The experimental data have been analyzed with reference to various theoretical models based on quantum-mechanical tunneling through the barrier and classical hopping over the barrier. The analysis shows that the correlated-barrier-hopping model is the most appropriate for the material under consideration. This model predicts quantitatively the temperature dependence of both the ac conductivity and its frequency exponent. However, other models, such as the quantum-mechanical tunneling model, are consistent with the low-temperature ac conductivity, but completely fail to interpret the observed temperature dependence of the frequency exponent. Similarly, the overlapping-large-polaron tunneling model can explain the temperature dependence of the frequency exponent at low temperature, although this model predicts the temperature dependence of the ac conductivity to be much higher than what the experimental data show.
150 citations
TL;DR: In this article, the temperature-dependent Sellmeier equations were used to predict noncritical phase matching for wavelengths as short as 976 nm to generate blue at 488 nm at room temperature.
Abstract: Lithium-rich lithium niobate of excellent optical homogeneity can be fabricated by a vapor transport equilibration (VTE) technique The high-optical-quality, uniformly birefringent crystals noncritically phase match for second-harmonic generation of 532-nm radiation from 1064-nm Nd:YAG radiation at 238 degrees C The refractive indexes and their temperature dependence have been measured and used to derive temperature-dependent Sellmeier equations, which predict noncritical phase matching for wavelengths as short as 976 nm to generate blue at 488 nm at room temperature The Sellmeier equations accurately predict experimental phase-matching temperatures over a wide temperature range >
147 citations
TL;DR: The addition of small amounts of elements such as silicon, aluminium and titanium to LaNi2.5Co2 greatly influenced anode performance characteristics such as usable temperature range, capacity and its decay rate during repeated cycles, rate capability, low temperature dischargeability and self-discharge rate as discussed by the authors.
Abstract: The addition of small amounts of elements such as silicon, aluminium and titanium to LaNi2.5Co2.5 greatly influenced anode performance characteristics such as usable temperature range, capacity and its decay rate during repeated cycles, rate capability, low temperature dischargeability and self-discharge rate. The capacity decay was suppressed by the addition of silicon, but the rate capability decreased and the self-discharge rate increased. The alloy containing titanium exhibited a much longer cycle life, but much lower storage capacity and worse low temperature dischargeability. The addition of aluminium was very useful for improving the usable temperature range, cycle life and charge retention, and it did not cause too great a decrease in capacity and/or increase in overpotentials.
137 citations
TL;DR: In this paper, Ramaman scattering measurements have been carried out on poly(propylene oxide) complexed with NaCF3SO3 salt of concentration O:M=30:1 over a temperature range of 186-360 K in order to study ion-ion associations of the dopant salt and their temperature dependence.
Abstract: Raman scattering measurements have been carried out on poly(propylene oxide) complexed with NaCF3SO3 salt of concentration O:M=30:1 (where O:M is the PO:Na ratio) over a temperature range of 186–360 K in order to study ion–ion associations of the dopant salt and their temperature dependence. Splitting of the symmetric stretching mode of the CF3SO−3 anion into a double band was observed and attributed to the existence of different environments of the anions. A two‐component band analysis led to the identification of coexisting dissociated free ions and ion pairs, suggested to be in contact. Below the glass transition temperature, Tg, the intensity of the mode corresponding to the free ions was more or less constant with temperature; the amount of free ions in the glassy state was found to be about 84% of the total salt concentration. Above Tg the amount of dissociated free ions decreased rapidly with temperature in an Arrhenius‐type behavior. The resulting reduction of the number of charge carriers has lit...
TL;DR: In this paper, the temperature dependence of the room pressure Raman spectra of the GeO2 (hexagonal and tetragonal) and SiO2 polymorphs is presented.
Abstract: The temperature dependence of the room pressure Raman spectra of the GeO2 (hexagonal and tetragonal) and SiO2 (quartz, coesite, and stishovite) polymorphs is presented. Several transformations upon heating are reported: a-(l quartz, coesite-cristobalite, stishovite-silica glass (with Si in four-fold coordination). For all the compounds, Raman frequencies decrease linearly with temperature and the measured shifts are used in conjunction with available high-pressure Raman data to calculate for each compound intrinsic mode anharmonicity through the parameter ai=(31nvi/3T)v. In quartz the modes related to the a- transition (128 and 207 cm -1 modes) are highly anharmonic (ai=-20x10 -5 K-l). In coesite many bands are unaffected by temperature and only two modes (77 and 116 cm-1) show significant anharmonic behaviour. Tetragonal GeO2 and stishovite behave similarly under temperature. Vibrational modeling of the specific heat and entropy, including anharmonic corrections deduced from the ai parameters, are presented and compared to available calorimetric measurements. For the GeO2 polymorphs the agreement between calculated and measured values is within 1-3% in the temperature range 100 to 1500 K. For quartz the agreement is similar over the range 50-850 K. For coesite and stishovite the models reproduce existing low temperature measurements. High-temperature values of Cp and entropy are proposed for coesite and stishovite.
TL;DR: In this article, the effect of Cu and/or Nb addition on crystallization processes and soft magnetic properties for Fe•Si•B alloys has been investigated, and it is concluded that the combined addition ofCu and Nb makes the α•Fe single phase stable in a broad temperature range, which is considered to be the necessary condition for the superior soft magnetic property.
Abstract: The effect of Cu and/or Nb addition on crystallization processes and soft magnetic properties for Fe‐Si‐B alloys has been investigated. For Fe‐Si‐B, Fe‐Cu‐Si‐B, and Fe‐Nb‐Si‐B alloys annealed at various temperatures, the effective permeabilities were very low and decreased considerably as they crystallized, while for Fe‐Cu‐Nb‐Si‐B alloy annealed at a temperature above Tx , a very good soft magnetic property was obtained. From DTA analysis of Fe‐Cu‐Nb‐Si‐B alloys, it became clear that the combined addition of Cu and Nb expanded largely the temperature range over 100 °C where a single phase of α‐Fe solid solution can exist. Above 580 °C, the second crystalline phase such as Fe2 B and some unidentified phases other than the α‐Fe phase precipitated, and soft magnetic properties deteriorated rapidly. It is concluded that the combined addition of Cu and Nb makes the α‐Fe single phase stable in a broad temperature range, which is considered to be the necessary condition for the superior soft magnetic properties.
TL;DR: In this paper, the loss peak of the AC susceptibility in polycrystalline high-T c superconductors shifts slightly to higher temperatures with increasing frequency of the applied AC magnetic field, and the magnitude of peak shift is predicted to increase with decreasing average grain size and decreasing grain boundary junction current density.
Abstract: The loss peak of the AC susceptibility in polycrystalline high- T c superconductors shifts slightly to higher temperatures with increasing frequency of the applied AC magnetic field It is shown that a flux creep term, added to the current density term in the critical state equation, can account for the observed frequency dependence The magnitude of the peak shift is predicted to increase with decreasing average grain size and decreasing grain boundary junction current density The model predictions are compared with the experimental data of Nikolo et al Some of the parameters used in the calculation are determined by fitting data for χ′ and χ″ over the full temperature range using a recently developed model for granular superconductors In addition, the relation between the intergranular pinning potential and the activation energy, which is extracted from log-frequency versus inverse χ″-peak temperature data, is clarified
TL;DR: In this paper, the symmetry of the three first order Raman active phonons has been determined and a broad peak occurs at approximately 1100 cm−1 and is assigned to multiphonon scattering on the basis of the observed temperature dependence.
Abstract: Raman scattering experiments have been carried out on single crystals of cupric oxide (CuO) in the temperature range from 15 K to 300 K. The symmetry of the three first order Raman active phonons has been determined. A broad peak occurs at approximately 1100 cm−1 and is assigned to multiphonon scattering on the basis of the observed temperature dependence. Another peak appears in the Raman spectrum as the temperature of the sample is lowered below the Neel temperature. The frequency, intensity and linewidth of this peak have been studied as a function of temperature. The frequency of this peak cannot be reconciled with the known spin wave spectrum of CuO and thus, on the basis of the measured temperature dependence, it has been assigned to scattering from a magnetic exciton. The Raman spectrum also contains a background continuum which is weakly peaked at about 2000 cm−1 and the possible origin of this scattering is discussed. The observed optical and magnetic properties of CuO are compared, where possible, to results that have been obtained for the high-Tc cuprates.
TL;DR: The temperature dependence of the dipole polarizability α(λ, T) of free atoms and molecules was determined by precise measurements of the refractive index n of gases in the extended temperature range between 300 K and 1100 K for wavelength λ = 632·99 nm, using a specially constructed Michelson twin interferometer as mentioned in this paper.
Abstract: The temperature dependence of the dipole polarizability α(λ, T) of free atoms and molecules is determined by precise measurements of the refractive index n of gases in the extended temperature range between 300 K and 1100 K for wavelength λ = 632·99 nm, using a specially constructed Michelson twin interferometer. α of the noble gases is observed to be independent of T. α of the molecular gases H2, N2, O2, and CH4 increases with increasing temperature by an amount of approximately 1 per cent per 1000 K. These results are in excellent agreement with theoretical predictions. They will be compared to previously measured temperature dependent polarizabilities.
TL;DR: In this paper, the authors present Raman spectroscopic measurements in the OH stretch region of water (2900 to 3800 cm−1) for the temperature range 80 to −33°C.
Abstract: We present Raman spectroscopic measurements in the OH stretch region of water (2900 to 3800 cm−1) for the temperature range 80 to −33 °C. This latter temperature represents the homogeneous limit of nucleation for our bulk samples. We find that the temperature dependence of both our intensity and depolarization ratio measurements are well described by a two‐state model in which both states have frequency dependent depolarization ratios. We argue that the hydrogen bonded mode of the spectrum begins to develop a collective nature at both its low and high frequency ends. This collective nature can explain a breakdown in isosbestic behavior at low temperature. It is suggested that these collective modes may be due to in‐ and out‐of‐phase motions of OH oscillators. Their intensity approaches those seen in amorphous solid water as the liquid is cooled to the apparent singular temperature Ts≂−45 °C, for a variety of bulk properties. We use our Raman data to make an estimate of hydrogen bond probability and show that four bonded molecules would percolate near the singularity. We then argue that the collective mode grows because clusters of four bonded molecules grow in extent until at Ts percolation occurs to yield an infinite cluster with the amorphous solid’s collective spectrum.
TL;DR: In this article, the thermal conductivity, diffusivity and emissivity of a sandwich-system of low pressure chemically vapour-deposited SiO2 and Si3N4 films were investigated in the temperature range 80 −400 K.
TL;DR: In this article, the adsorption of NO on Pd(111) was studied by means of HREELS, LEED, UPS and Δo measurements in the temperature range between 20 and 300 K.
TL;DR: In this paper, the temperature dependence of the fundamental absorption edge of a series of Hg1−xCdxTe alloys was investigated in the light of the three-dimensional theory of direct-allowed excitons, and precise values for the fundamental Γ8−Γ6 interband transition energy in a temperature range extending from 0 to 300 K were obtained.
Abstract: We have investigated the temperature dependence of the fundamental absorption edge of a series of Hg1−xCdxTe alloys (with composition x ranging from 0.5 to 1). Analyzing our data in the light of the three‐dimensional theory of direct‐allowed excitons, we find precise values for the fundamental Γ8‐Γ6 interband transition energy in a temperature range extending from 0 to 300 K. All experimental results, including previous data for HgTe and mercury‐rich Hg1−xCdxTe alloys, are well accounted for using a simple empirical formula: Eg (eV)=−0.303(1−x)+1.606x−0.132x(1−x)+[6.3(1−x) −3.25x −5.92x(1−x)]10−4T2/[11(1−x)+78.7x+T]. This expression, which is valid for all compositions 0≤x≤1 and temperatures 0≤T≤500 K, predicts an alloy composition such that the band‐gap energy is temperature independent: We find x=0.505. Finally, it can be used for technological application purpose (far‐infrared detection as well as optical‐fiber communications performed at realistic values of the temperature) and gives accurate values f...
01 May 1990
TL;DR: In this article, the authors measured the mechanical damping and resonant frequency of a material over a temperature range and calculated the dynamic loss modulus, storage modulus and loss tangent from these data.
Abstract: Polymeric materials exhibit mechanical behavior which is dependent on temperature. Dynamic mechanical analysis measures the mechanical damping and resonant frequency of a material over a temperature range. Values of the dynamic loss modulus, storage modulus, and loss tangent can be calculated from these data. The glass transition temperature and onset temperature are obtained from curves of the dynamic moduli versus temperature.
TL;DR: In this article, the optimal salinity of three different anionic microemulsions was found to increase as a function of increased hydrostatic pressure, which is equivalent to a phase transition from an upper Winsor II(+)(WII(+)) microemulsion to a lower Winsor I(minus) (WII({minus}) micro emulsion.
Abstract: This paper reports that optimal salinity of three different anionic microemulsions was found to increase as a function of increased hydrostatic pressure. This is equivalent to a phase transition from an upper Winsor II(+)(WII(+)) microemulsion to a lower Winsor II({minus})(WII({minus})) microemulsion. Increased pressure induces a compressibility effect that is consistent with the observed phase transition. Increasing temperature also leads to increasing optimal salinity. Prediction of temperature effects is complicated by temperature-dependent interactions and entopic contributions caused by dispersion. Fluid models that account for temperature effects are needed; therefore, no attempt was made to develop a theoretical interpretation of this effect. The temperature range is 0 to 100{degrees}C, and the pressure was varied from 0.1 to 50 MPa.
TL;DR: In this paper, the resistivity data have been analyzed in terms of the Ziman theory of electron-phonon scattering and the effective Debye temperature Theta p has been estimated by fitting the experimental data to Ziman's equation.
Abstract: Conducting films consisting of silver particles of diameters ranging from 4 to 12 nm have been grown in glass-ceramic by subjecting the latter to a Li+ to or from Ag+ exchange followed by a suitable reduction treatment. The DC electrical resistance of these films has been measured over the temperature range 80-300 K. The resistivity data have been analysed in terms of the Ziman theory of electron-phonon scattering. The effective Debye temperature Theta p has been estimated by fitting the experimental data to Ziman's equation. Theta p is seen to vary from 98 to 192 K for silver particle sizes ranging from 4.3 to 11.0 nm. The silver particle aggregates in the present system have a fractal microstructure with fractal dimensions of around 1.6 and 1.9, respectively.
TL;DR: In this paper, the effects of temperature (4 −400 K), hydrostatic pressure and frequency on the dielectric constant, e.g., loss, and loss of single crystals of LaAlO3 and cubic yttria (9.5 mol) −stabilized zirconia (ZrO2) were investigated.
Abstract: The effects of temperature (4–400 K), hydrostatic pressure and frequency on the dielectric constant, e’, and dielectric loss of single crystals of LaAlO3 and cubic yttria(9.5 mol %)‐stabilized zirconia (ZrO2) were investigated. Both crystals are relatively low‐loss, low‐dispersion dielectrics in the temperature range (T<150 K) of most interest for high‐temperature superconductors. The pressure results make it possible to evaluate the various contributions to the temperature dependence of e’. It is found that this dependence is dominated by the change of polarizability with volume. The dielectric properties of the two crystals are compared with those of other candidate substrate materials.
TL;DR: In this article, a thermogravimetric analysis of chemically vapor-deposited SiC in wet O2 was performed in the temperature range of 1823 to 1923 K. The activation energies of linear and parabolic rate constants were 428 and 397 kJ · mol−1, respectively, and it was shown that the rate controlling step is a chemical reaction at an SiC/SiO2 interface in the linear oxidation regime, and the rate-controlling step is an oxygen diffusion process through the oxide film (cristobalite) in the parabolic
Abstract: The oxidation of chemically vapor-deposited SiC in wet O2 (water vapor partial pressure = 0.01 MPa, total pressure = 0.1 MPa) was examined using a thermogravimetric technique in the temperature range of 1823 to 1923 K. The oxidation kinetics follow a linear-parabolic relationship over the entire temperature range. The activation energies of linear and parabolic rate constants were 428 and 397 kJ · mol−1, respectively. The results suggested that the rate-controlling step is a chemical reaction at an SiC/SiO2 interface in the linear oxidation regime, and the rate-controlling step is an oxygen diffusion process through the oxide film (cristobalite) in the parabolic oxidation regime.
TL;DR: In this article, a simple model from calorimetric data was developed to assess the size distribution of samples with different thermal histories and the morphological characterizations were completed by wide-angle x-ray diffraction measurements.
Abstract: By using an automated low-frequency apparatus, dynamic mechanical experiments are performed on bulk-crystallized high-density polyethylene in the temperature range of the α relaxation. In order to characterize the key morphological features governing the presence of multiple α relaxations, we have developed a simple model from calorimetric data to assess the crystallite size distribution of samples with different thermal histories. The morphological characterizations are completed by wide-angle x-ray diffraction measurements. Isochronal spectrometry and frequency scans performed under isothermal conditions both exhibit two α relaxations designated α1 and α2, with increasing temperature (or increasing frequency). These two relaxations are frequency dependent but they are not thermorheologically simple processes. Some analogy is found between tan ϕ versus temperature or frequency and the biomodal lamellar size distribution curves determined from calorimetric data. Moreover, both the temperature of α2 peak and the most probable lamellar thickness of the larger lamellae depend on the thermal history of the sample: with increasing thickness of the larger lamellae, the α2 peak temperature is shifted toward higher temperature. In contrast, both the temperature of the a peak and the most probable lamellar thickness of the thinner lamellae seem to be independent of thermal history: the thinner lamellae should be formed on cooling from the remaining uncrystallized fraction. From thege findings, it is proposed that the α, and α2 relaxations have the same origins and that they could arise from defect diffusion within the thinner and thicker crystallites, respectively, with some influence of the amorphous matter in the interfacial regions.
TL;DR: In this paper, the static magnetic susceptibility of hole-doped oxide superconductors was studied as a function of oxygen content over the temperature range 2-900 K, and a correlation was observed between the magnitude of T c ( y ) and the temperature dependence of the normal-state magnetic susceptibility.
Abstract: The static magnetic susceptibility of Bi 2 Sr 2 CaCu 2 O 8+ y and Tl 2 Ba 2 CuO 6+ y is studied as a function of oxygen content y over the temperature range 2–900 K. With increasing oxygen (hole) content the superconducting transition temperature T c ( y ) passes through a maximum for the Bi-compound and falls monotonically for the Tl-system, reaching a maximal value of c ≅92 K in both systems. As the oxygen content is varied, a correlation is observed between the magnitude of T c ( y ) and the temperature dependence of the normal-state magnetic susceptibility. The fact that this same correlation can also be seen in the published data on La 2- x Sr x CuO 4 and YBa 2 Cu 2 O 6+ y implies that it may be a universal property of hole-doped oxide superconductors.
TL;DR: In this paper, the adsorption of O2 on atomically clean Fe(110) in the temperature range of 90 to 920 K was studied and the correlation between the Auger measurements and O2 uptake measurements was demonstrated.
TL;DR: In this paper, Raman data for the OD stretch mode of 10 mol % HOD in H2O for the liquid phase from −31.5 to 160 °C were presented.
Abstract: We present Raman data for the OD stretch mode of 10 mol % HOD in H2O for the liquid phase from −31.5 to 160 °C. We find that an exact isosbestic does not hold, but rather the crossing of isotherms slowly but uniformly changes with temperature. We present an analysis based on Boltzmann statistics which gives evidence for a distribution of deuterium hydrogen bond strengths with minimum energy near the frequency (2440 cm−1) also found in the solid ice and amorphous solid phases. This analysis also gives evidence for a band of frequencies above 2630 cm−1 due to OD oscillators all at essentially the same high energy relative to the strongest hydrogen bonds, and we interpret this band as due to broken hydrogen bonds. This allows us to calculate hydrogen bond probabilities, and we find this probability increases with decreasing temperature and approaches a value equal to the four bonded percolation threshold near the singular temperature Ts ≂−45 °C for the anomalies of supercooled water. Peak frequency and full width at half‐maximum of the OD stretch band are found to drop precipitously to the amorphous solid values as T→Ts implying the ultimate state of supercooled water is similar to the amorphous solid.
TL;DR: In this article, collisional quenching of the v'=0 vibrational levels of the A 2Σ+ and B 2Π states of nitric oxide has been studied over the temperature range 300 to 750 K.
Abstract: Collisional quenching of the v’=0 vibrational levels of the A 2Σ+ and B 2Π states of nitric oxide has been studied over the temperature range 300 to 750 K. The pressure dependence of the time decay of laser‐induced fluorescence, in a slowly flowing heated cell, furnished the quenching cross sections σQ. NO and O2 quench the A state rapidly but with no temperature dependence; σQ=37 and 21 A2, respectively. σQA for H2O drops from 105 A2 at 300 K to 34 A2 at 750 K. σQB for O2 is independent of temperature but σQB for NO drops twofold and for H2O decreases by a factor of 3 over the temperature range studied. This variation among these colliders cannot be explained by a uniform, simple picture of the collision dynamics. Evidence is seen for B→A transfer proceeding through an intermediate state, perhaps a 4Π.