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81.
We have used the perturbed angular correlation (PAC) method and extended X-ray absorption fine structure spectroscopy (EXAFS),
along with microscopic methods to investigate the implantation induced disorder and characterize the ion-induced amorphisation
of elemental and compound semiconductors. 相似文献
82.
181Hf and 111In ions were implanted into AlN-layers in order to investigate their immediate lattice site environment and its temperature
dependence by means of the Perturbed Angular Correlation (PAC) technique. After rapid thermal annealing at 1273 K up to 50%
of the probe atoms were incorporated on undisturbed lattice sites defined by an electric field gradient (EFG) of 33 MHz for
In and 572 MHz for Hf for measurement at room temperature. PAC-spectra taken at temperatures between 25 and 1200 K show that
the EFG measured at the site of the undisturbed probes changes with temperature. While for Hf it decreases by 3%, for In it
increases by 25% within the measured temperature range. Thus, the change cannot be due only to the thermal lattice expansion.
In the case of In the fraction of probe atoms on substitutional sites increases with temperature until it reaches nearly 100%
at 973 K. These effects are fully reversible. For the Hf probe, an additional EFG was detected at temperatures above 300 K. 相似文献
83.
高浓度高Al13含量聚合氯化铝溶液的制备 总被引:1,自引:0,他引:1
通过快速加碱在82 ℃下合成0.2 mol·L-1、Alb为60%~70%的低浓度高Alb聚合氯化铝(L-PAC),在热侧温度为50~95 ℃,冷侧温度约9~12 ℃的条件下进行膜蒸馏浓缩,制备出总铝浓度在2 mol·L-1以上,Alb含量大于90%,Al13含量约为70%的高浓度高Alb含量的聚合氯化铝溶液。对膜蒸馏浓缩过程中热侧温度、PAC的碱化度和初始pH值等因素对最终聚合氯化铝溶液产品中聚铝形态分布、总铝浓度的影响进行了初步研究,发现在热侧温度低于70 ℃、碱化度为2.47、初始pH值为5.0 ± 0.2的条件下,可以得到高浓度、高Alb含量的聚合氯化铝溶液,纳米Al13形态在较高的浓度下可以存在;低温贮存条件下,高浓度PAC中Alb相当稳定。 相似文献
84.
A polyaluminum chloride (PAC) sample was prepared using a slow alkaline titration method. The Bio-Gel P-100 gel column chromatographic technique was used to separate and characterize the various forms of aluminum present in the prepared PAC solution. The effluents from a gel column were monitored using online chemical method: Al-Ferron timed complexation spectrophotometry and by 27Al nuclear magnetic resonance (NMR) spectroscopy. Effects of different experimental conditions such as eluent flow rate, ionic strength and pH on separation of Al13 were investigated. Experimental results indicated that molecule size exclusion was not the only parameter affecting the column chromatographic separation efficiency of Al13 but molecule charge as well. Reducing the eluent flow rate, increasing the ionic strength and suitable pH resulted in increase in the separation efficiency. Experimental results clearly indicated that by varying the experimental conditions, it is possible to produce pure Al13 species using a gel column chromatographic technique. 相似文献
85.
D. Bucurescu C. A. Ur D. Bazzacco C. Rossi-Alvarez P. Spolaore C. M. Petrache M. Ionescu-Bujor S. Lunardi N. H. Medina D. R. Napoli M. De Poli G. de Angelis F. Brandolini A. Gadea P. Pavan G. F. Segato 《Zeitschrift für Physik A Hadrons and Nuclei》1995,352(4):361-362
High spin states have been observed for the first time in the odd-odd nucleus80Y, by using the24
Mg(58
Ni,pn) reaction at 180 MeV. Eight rotational bands have been established, indicating a nucleus with appreciable deformation.Supported by CNPq, Brazil 相似文献
86.
Linearised augmented plane wave (LAPW) calculations are performed in order to determine the electric field gradients (EFG)
induced by group V and group Ib acceptors in CdTe at the nearest neighbour (NN) atomic site. Experimentally, the EFG are measured
by the perturbed γγ-angular correlation spectroscopy using the radioactive probe isotopes 111In and 77Br. Besides the identification of the experimentally observed defects, the LAPW calculations provide information about fundamental
properties of the EFG. For the group Ib acceptors, the dependence of the EFG on the NN distance is opposite to the expectation
from the simple point charge model.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
87.
R. Caruso N. Pellegri O. de Sanctis M. C. Caracoche P. C. Rivas 《Journal of Sol-Gel Science and Technology》1994,3(3):241-247
Zirconia coating film and powder obtained by the sol-gel route using zirconium n-propoxide as starting material and acid catalyst were investigated by the Perturbed Angular Correlations method, X-Ray Diffraction and Differential Scanning Calorimetry and Differential Thermal Analyses. The hyperfine interaction, measured after annealing the samples at increasing temperatures up to 1100°C, allowed to distinguish five different zirconium neighborhoods. Two of them describe rather disordered material which, on heating, crystallizes to the tetragonal phase and end finally in monoclinic zirconia. As compared with the powder, the film exhibits a minor fraction of an unidentified ordered form and a higher and more stable fraction of tetragonal phase. In addition, the tetragonal to monoclinic conversion takes place at higher temperatures and with a larger activation energy.Researcher for CONICET-ArgentinaResearcher for CICPBA-Argentina 相似文献
88.