Magnetic properties of Sn/1-x/Cr/x/Te diluted magnetic semiconductors

We present the studies of Sn/1-x/Cr/x/Te semimagnetic semiconductors with chemical composition x ranging from 0.004 to 0.012. The structural characterization indicates that even at low average Cr-content x < ?0.012, the aggregation into micrometer size clusters appears in our samples. The magnetic properties are affected by the presence of clusters. In all our samples we observe the transition into the ordered state at temperatures between 130 and 140 K. The analysis of both static and dynamic magnetic susceptibility data indicates that the spin-glass-like state is observed in our samples. The addition of Cr to the alloy seems to shift the spin-glass-like transition from 130 K for x = 0.004 to 140 K for x = 0.012.Comment: 4 pages, 4 figure

Point defects and p-type conductivity in Zn1-xMnxGeAs2

Positron annihilation spectroscopy is used to study point defects in Zn1–xMnxGeAs2 crystals with low Mn content 0≤x≤0.042 with disordered zincblende and chalcopyrite structure. The role of negatively charged vacancies and non-open-volume defects is discussed with respect to the high p-type conductivity with carrier concentration 10exp19≤p≤10exp21cm−3 in our samples. Neutral As vacancies, together with negatively charged Zn vacancies and non-open-volume defects with concentrations around 10exp16−10exp18 cm−3, are observed to increase with increasing Mn content in the alloy. The observed concentrations of defects are not sufficient to be responsible for the strong p-type conductivity of our crystals. Therefore, we suggest that other types of defects, such as extended defects, have a strong influence on the conductivity of Zn1–xMnxGeAs2 crystals.Peer reviewe

Determination of density and classification of post-coagulation sediment

The coagulation process is one of the water and wastewater treatment processes. It results in the precipitation of sediment. After the coagulation process, the density of the sediment has a significant impact on the sedimentation rate of particles. These particles have different shapes, sizes and structures, and they settle in a different way. The particle density has an impact on the settling rate. The structure of particles results in two types of pores. Micropores are characteristic features of the sediment, but macropores should not be considered while determining the density. In this paper sediment samples were prepared and the density was determined using the gravimetric method by means of the press. The number of press strokes should not destroy the microstructure of sediment. The authors determined the degree of sample compression to minimize errors while determining the density. The volume of samples was obtained using X-ray tomography and image processing. The correct determination of the sample volume depends on the correct number of the threshold. Image processing was performed using LabVIEW software and Vision module. The paper presents the statistic classification of post-coagulation particles and the results of tests