We have investigated the effect of the long-range Coulomb interaction on the one-particle excitation spectrum of n-type germanium, using tunneling spectroscopy on mechanically controllable break junctions. At low temperatures, the tunnel conductance shows a minimum at zero bias voltage due to the Coulomb gap. Above 1 K, the gap is filled by thermal excitations. This behavior is reflected in the variable-range hopping resistivity measured on the same samples: up to a few degrees Kelvin the Efros-Shklovskii lnR infinity T(-1/2) law is obeyed, whereas at higher temperatures deviations from this law occur. The type of crossover differs from that considered previously in the literature. 相似文献
In this work, we report the results of magnetoresistance studies of variable range hopping down to 30 mK in isotopically engineered Ge with low compensation, and in n-CdTe crystals. Experimentally we find a decrease and disappearance of the negative magnetoresistance with decreasing temperature down to 200 mK, in weak magnetic fields. Such behaviour is in disagreement with the quantum interference theory of Nguen, Spivak and Shklovskii. 相似文献
Perovskite-type mixed oxides with the formula La1−xAxMe1−yByO3±δ (x=0.01...0.2; y=0.01...0.5; A=Ca, Sr; Me=Cr, Mn, Fe, Co; B=Mg, Ga) were investigated with the aim to use the oxides as electrode
materials for galvanic cells with Y2O3-stabilized ZrO2 solid electrolytes (YSZ). The catalytic activity of the oxides for the oxidation, reduction and decomposition of gas components
was varied by changing the transition metal and by partial substitution of lanthanum and the metal.
The behaviour of different substituted lanthanum chromite/YSZ and manganite/YSZ electrodes in the presence of nitric oxides
(NOx) and combustible components (CHx) in gases containing oxygen was investigated. Various electrode combinations were tested in gas-symmetrical cells.
For the NO determination cells with a catalytically active Pt electrode and a La0.8Sr0.2MnO3 electrode with a low catalytic activity for the decomposition of NO were used. The results show the possible quantitative
measurement at low and constant p(O2) on the basis of a calibration.
For the determination of C3H6 a CHx-sensitive Au and an O2-sensitive La0.99Sr0.01CrO3 electrode were combined in a potentiometric thick film sensor. In gases containing oxygen with small amounts of C3H6 the sensor provided a utilizable voltage in dependence of the C3H6 concentration.
Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996 相似文献
Investigations on lanthanum gallium chromium mixed oxides of the compositions La1.0Ga0.2Cr0.8O3−d and La0.9Ga0.2Cr0.8O3-d are presented regarding their structure, redox stability, conductivity and catalytic activity for the oxidation of propene.
The mixed oxide has perovskite-type structure, high redox stability, an electronic p-type conductivity and low catalytic activity.
If the perovskite-type compound has a deficiency of lanthanum, the electronic conductivity, surface area and catalytic activity
are significantly higher. The catalytic activity is likely comparable to that of gold. Similar to gold electrodes of solid
electrolytes, oxygen electrodes formed with gallium doped lanthanum chromite show a relatively high sensitivity to hydrocarbons
such as propene at temperatures of about 700 °C. The mixed oxide is possibly suitable as electrode material for exhaust gas
sensors using oxide-ion conducting solid electrolytes.
Paper presented at the 5th Euroconference on Solid State Ionics, Benalmádena, Spain, September 13–20, 1998. 相似文献
A LabVIEW®-based software for the control of the fully automated multi-sequential flow injection analysis Lab-on-Valve (MSFIA-LOV) platform AutoRAD performing radiochemical analysis is described. The analytical platform interfaces an Arduino®-based device triggering multiple detectors providing a flexible and fit for purpose choice of detection systems. The different analytical devices are interfaced to the PC running LabVIEW®VI software using USB and RS232 interfaces, both for sending commands and receiving confirmation or error responses. The AUTORAD platform has been successfully applied for the chemical separation and determination of Sr, an important fission product pertinent to nuclear waste.
From September 15th – 22nd, 1996 the 3rd Euroconference on Solid State Ionics took place in the Hotel “Baia delle Ginestre„ near Teulada, which is situated on the
marvellous island of Sardinia.
About 100 participants came from countries like Russia, the Czech Republic, Poland, Bulgaria, Japan, China, Scotland, England,
France, Belgium, Portugal, Greece, Italy, Spain, Israel and Germany and had to deal with almost all fields of Solid State
Ionics. The conference and its atmosphere, which was very nice indeed, will be described in detail using some models for the
processes which were taking place. Some conclusions will be drawn as well. 相似文献