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71.
Temperature and magnetic-field dependences of the static magnetization of polycrystalline cobaltite GdCoO3 have been measured. The magnetic properties of the GdCoO3 sample have been studied in the paramagnetic and antiferromagnetic states. The magnetic phase diagram has been constructed. The exchange field between the Gd-Gd sublattices and the anisotropy field have been estimated.  相似文献   
72.
This paper reports on the results of studies of small particles of the superionic conductor AgI embedded in MCM-41 and SBA-15 molecular sieves with different sizes of pores (channels). The studies are performed by the dielectric and nuclear magnetic resonance techniques. The temperature of the superionic phase transition is shown to increase monotonically with decreasing pore size. The enthalpy of activation of the ion motion in β-AgI in restricted geometry is determined. It is shown that introduction of AgI into pores does not noticeably affect its structure.  相似文献   
73.
Terahertz Time Domain Imaging has been used in the last few years for the investigation of cultural heritage. In this article, the authors demonstrate the possibility to apply it for the investigation of clay artifacts. Tomographic images were obtained of a model in reflection, and an Egyptian vessel in transmission.  相似文献   
74.
This paper describes three inexpensive and fast analytical methods to characterise grafted particle surfaces. The reaction of silica with (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane and N-(phosphonomethyl)iminodiacetic acid hydrate, respectively, leads to NH2-, SO3H- or COOH-functionalised silica, which were characterised by X-ray photoelectron spectrometry and titration in nonaqueous media as well as with two titration methods in a water-based environment. In the work presented, factors influencing the titrations are pointed out and solutions are presented to overcome these limiting factors are shown.  相似文献   
75.
The transport properties of half-metallic ferromagnetic Heusler alloys Co2MeAl (Me = Ti, V, Cr, Mn, Fe are transition 3d metals) have been measured in the temperature range of 4–900 K. The specific features of the behavior of the resistivity have been considered in the framework of the two-current model of conductivity that takes into account the existence of the energy gap in the electronic spectra of the alloys near the Fermi level of one of electron subbands that differs in the spin direction.  相似文献   
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Gettering of metallic impurities in photovoltaic silicon   总被引:5,自引:0,他引:5  
 This work addresses the issue of structural defect-metallic impurity interactions in photovoltaic silicon and their effect on minority carrier diffusion length values. Aluminium and phosphorus segregation gettering studies were performed on photovoltaic silicon in order to gain insight into these interactions and quantify the effect of gettering on solar cell performance. Integrated circuit grade silicon was also studied for comparative purposes. Additionally, a novel rapid thermal annealing technique, designed to dissolve metallic impurity precipitates, and Deep Level Transient Spectroscopy were utilized to determine the as-grown impurity concentration in both grades of materials. Significant differences in gettering responses between the two grades of silicon are observed. Gettering treatments greatly improve I.C. grade silicon with a specific gettering temperature providing the optimal response. Photovoltaic grade silicon does not respond as well to the gettering treatments and, in some cases, the material degrades at higher gettering temperatures. The degradation is primarily observed in dislocated regions of multicrystalline photovoltaic silicon. Additionally, these dislocated regions were found to possess the highest as-grown metallic impurity concentration of all the materials studied. The dislocation-free photovoltaic silicon has a higher diffusion length relative to dislocated silicon but could not be improved by the gettering methods employed in this study. A model is presented to describe these phenomena where the high concentration of metallic impurities at dislocations produce relatively low minority carrier diffusion lengths as well as the degrading response with higher gettering temperatures while microdefects create an upper limit to the photovoltaic grade material’s diffusion length. Received: 21 June 1996/Accepted: 2 September 1996  相似文献   
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The automated real-time detection and classification of cetacean and anthropogenic sounds from deep-sea observatories can play a key role to study cetaceans in the field, to quantify the impact of anthropogenic sounds or to initiate mitigation measures during potentially harmful human activities. In the area of the NEMO-ONDE deep-sea observatory, sperm whales are often present together with heavy shipping. The spatial coincidence of both sound sources allows for the long term monitoring of their interaction. Some ships produce impulsive sounds and the automated separation of these impulses from sperm whale clicks is not a trivial task. As part of a detection, classification and localisation system for acoustic data from marine observatories, we present four modules performing the automated real-time classification of clicks from sperm whales and impulsive sounds produced by ships. First, two modules detect segments that contain impulsive sounds within a specifiable frequency band and return the impulses’ positions. Then, two modules classify the detected impulses as sperm whale clicks or ship impulses. Finally, at the level of 22 s segments, the classification outputs from individual impulses are combined into a decision on the presence of sperm whale clicks or ship impulses. The modules’ reliability was tested on data from the NEMO-ONDE observatory. Training and testing data were separated by more than 2 months, enabling to assess the consistency of the predictions over the long term. The automated separation between segments of the two classes was high with area under the ROC curve (AUC) values between 0.94 and 0.98.  相似文献   
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