Righi-Leduc Effect in InSb between 25°C and 300°C

The Righi-Leduc effect has been measured for n-type InSb crystals of various mobilities and was found to increase with temperature in a manner to indicate that the unipolar contribution is prevalent over the bipolar part of the effect. The experimental values measured over the temperature range between 25°C and 300°C agree well withPutley's theory. The Righi-Leduc coefficient was also determined as a function of the magnetic field and the strong decrease observed is explained in terms of the magnetoresistance.     

The structure of liquid methanol revisited: a neutron diffraction experiment at −80 °C and +25 °C

Pulsed neutron diffraction with isotope substitution on the hydroxyl hydrogens (H) is used to study the structure of pure liquid methanol at ?80 °C and +25 °C. Although this liquid has been studied with neutrons several times in the past this is the first time that the composite partial structure factors, XX, XH and HH, are derived from the diffraction data. Here X represents a weighted sum of correlations from carbon (C), oxygen (O), and methyl hydrogen (M) atoms on the methanol molecule. The data are used in an empirical potential structure refinement (EPSR) computer simulation of the liquid at both temperatures. Model distributions of molecules consistent with these data are used to estimate the individual site—site radial distribution functions, the coefficients of the spherical harmonic expansion of the orientational pair correlation function, and the length of possible chains of methanol molecules formed in the liquid. Although the results are qualitatively similar to those of earlier computer simulation studies of this liquid, they do differ in detail from previous work. In particular, although most molecules in the liquid are found as part of chains up to 10 molecules long, the average chain length is only about 2.7 molecules at both temperatures, there are about 1.3 hydrogen bonds per molecule on average, and the chains are highly nonlinear on average.     

Manifestation of phase transformations in optical spectra of Na0.5Bi0.5TiO3 crystals between 25°C and 350°C

The pseudo dielectric function ?ε? (E) = ?ε ₁? (E) + i?ε ₂? (E) of sodium bismuth titanate Na_0.5Bi_0.5TiO₃, has been obtained in the spectral range of electronic excitations (2–9.5 eV) by spectroscopic ellipsometry using the synchrotron radiation source BESSY II. The spectrum contains a broad absorption band at 4.2–4.5 eV. The temperature dependence in the range of 25–350°C is presented by the related susceptibilities ?χ ₁? (T) and ?χ ₂? (T) at 5 eV. A clear peculiarity in the temperature behavior of ?χ ₁? (T) and ?χ ₂? (T) between 180 and 320°C has been revealed and discussed. In this range an extremum-like temperature dependence of intensity of the light reflected from the sample surface, has been revealed and can be explained by the diffraction of light on the grid of the elastic domain structure of the sample.     

Anomalies of the natural convection of water near 3.98°C

Natural convection of water in a cylindrical cavity with an open surface at a temperature of about 3.98°C (temperature of the maximum water density) is accompanied by typical anomalies on time dependences of temperatures of water layers. In particular, stabilization of temperature T_st is observed in the bottom region of the cavity and duration of such stabilization t_st may reach several hours depending on the experimental conditions. The results for solutions of sodium chloride and ethanol at a relatively low rate of water cooling show that temperature T_st coincides with temperature T_max corresponding to the maximum density of solutions.     

110°C thermoluminescence glow peak of quartz — A brief review

The 110°C glow peak of quartz, though unstable at room temperature, has worked wonderfully in archaeology and retrospective dosimetry due to its pre-dose sensitization property. Various aspects of the peak, like its nature, defect centres involved, the impact of different stimuli and its application have been extensively studied. The main aims of this review are to (i) summarize briefly the work carried out on the various facets of this TL glow peak during the last four decades and (ii) identify the areas which need further attention in order to have a better understanding of the luminescence characteristics of this TL peak.      

CSR60°二极C型铁磁场特性的研究

兰州重离子加速器冷却储存环主环注入线二极C型磁铁首次采用了磁极头中埋置垫补线圈调整磁场均匀度的设计.在其磁场测量中,使用了点测和积分测量的方法对其各方面特性参数进行了测量,并对积分场的测量结果以及内置垫补线圈对均匀场的垫补效果进行了详细的非线性分析.     

Rapid nickel diffusion in cold-worked carbon steel at 320–450 °C

The diffusion coefficient of nickel in cold-worked carbon steel was determined with the diffusion couple method in the temperature range between 320 and 450 °C. Diffusion couple was prepared by electro-less nickel plating on the surface of a 20% cold-worked carbon steel. The growth in width of the interdiffusion zone was proportional to the square root of diffusion time to 12,000 h. The diffusion coefficient (D_Ni) of nickel in cold-worked carbon steel was determined by extrapolating the concentration-dependent interdiffusion coefficient to 0% of nickel. The temperature dependence of D_Ni is expressed by D_Ni = (4.5 + 5.7/?2.5) × 10^?11 exp (?146 ± 4 kJ mol^?1/RT) m²s^?1. The value of D_Ni at 320 °C is four orders of magnitude higher than the lattice diffusion coefficient of nickel in iron. The activation energy 146 kJ mol^?1 is 54% of the activation energy 270.4 kJ mol^?1 for lattice diffusion of nickel in the ferromagnetic state iron.     

110 °C range athermalization of wavefront coding infrared imaging systems

110 °C range athermalization is significant but difficult for designing infrared imaging systems. Our wavefront coding athermalized infrared imaging system adopts an optical phase mask with less manufacturing errors and a decoding method based on shrinkage function. The qualitative experiments prove that our wavefront coding athermalized infrared imaging system has three prominent merits: (1) working well over a temperature range of 110 °C; (2) extending the focal depth up to 15.2 times; (3) achieving a decoded image being approximate to its corresponding in-focus infrared image, with a mean structural similarity index (MSSIM) value greater than 0.85.     

Sealing of bore-holes in Si crystals by epitaxial overgrowth below 560° C

Liquid phase epitaxy (LPE) is applied to seal small bore-holes (diameter 250–400 m) in Si crystals by lateral overgrowth. The overgrowth layers have a typical thickness of 20 m, are mechanically stable and gas-tight. Using Ga as solvent for the LPE process the overgrowth can be performed at temperatures as low as 560°C.     

60°C lead salt laser emission near 5-μm wavelength

A IV–VI double heterostructure laser made from molecular beam epitaxy grown PbSrSe/PbSe/PbSrSe has been operated in pulsed mode up to 333 K (60°C) at a wavelength of 4.78 μm. This is the highest mid-infrared diode laser operation temperature observed to date.     

Thermal expansion of ChS-139 steel in temperature range 20–720 °C

The article presents the results of investigation of thermal expansion of ChS-139 steel in the temperature range 20–720 °C. Measurements were carried out by dilatometric method with DIL-402C unit manufactured by NETZSCH (Germany) with the error (1.5–2)×10^?7 K^?1. The approximation dependences of thermal coefficient of linear expansion on temperature have been obtained and reference tables have been calculated. The abnormal change of expansion coefficient above 550 °C is shown, and the explanation of the phenomenon is given.     

Low-Temperature (<100°C) Poly-Si Thin Film Fabrication on Glass

Polycrystalline silicon (poly-Si) thin-film is fabricated on Al-coated planar glass substrates at the temperature below 100°C, using aluminium-induced crystallized (AIC) amorphous silicon (a-Si) deposited by dc-magnetron sputtering under an electric field. The properties of NA poly-Si films (AIC of dc-magnetron sputtered silicon non-annealing) are characterized by Raman spectroscopy and x-ray diffraction (XRD) spectroscopy. A narrow and symmetrical Raman peak at a wave number of about 521cm^-1 is observed for samples, showing that the films are fully crystallized. XRD spectra reveal that the films are preferentially (111) oriented. Furthermore, the XRD spectrum of the sample prepared without electric field does not show any XRD peaks for poly-Si, which only appears at about 38°for Al (111) orientation. It is indicated that the electric field plays an important role in crystallization of poly-Si during the dc-magnetron sputtering. Thus, high quality poly-Si film can be obtained at low temperature and separate post-deposition step of AIC of a-silicon can be avoided.     

Emissivity measurements of opaque gray bodies up to 2000 °C by a dual-frequency pyrometer

In the framework of the SPES project at LNL-INFN a method for emissivity measurements by a double-frequency pyrometer in the infrared region at high temperatures on opaque gray bodies of SiC and graphite is presented. The measurement method proposed in this work reveals a good fitting with literature values. Moreover, the effect of surface finishing on emissivity values has been investigated.