Search Results

You are looking at 1 - 4 of 4 items for

  • Author: J. Plewa x
Clear All Modify Search
Open access

D. Michalik, M. Sopicka-Lizer, J. Plewa and T. Pawlik

Application of Mechanochemical Processing to Synthesis of YAG: Ce Garnet Powder

The paper presents the method of preparation YAG: Ce precursor powder with ability for synthesis at lower temperature. Mechanochemical processing of an initial powder mixture was used as a preliminary step for subsequent high-temperature treatment of the precursor. The specific surface area, phase composition and luminescence properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. It has been shown that YAG structure formed at lower temperature by 300°C in comparison to the reference specimen but luminescence intesity was dependant on temperature of powder synthesis. The highest luminescence intensity was observed for powders synthesised at 1650°C.

Open access

D. Michalik, T. Pawlik, J. Plewa and M. Sopicka-Lizer

Abstract

Manufacturing high purity polycrystalline YAlO3 (YAP) ceramics could replace monocrystalline YAP thus recently it is an interesting task for low cost producers of scintillators. The paper presents influence of different source of initial oxide powders (micro/nano powders of Y2O3 and Al2O3) and the method of their homogenization on the formation of a YAP phase. The solid state reaction method was used to prepare YAP powder or ceramic pellets. After preheating, all samples in the form of powders and pellets were heat-treated in the temperature range of 1050-1650 °C. DTA method was applied for examination of the phase crystallization in the tested system. X-ray diffraction method (XRD) was used for characterization of the phase composition. X-ray microanalysis (EDS) was used to control homogeneity in the small areas. Morphology of the resultant samples are presented on SEM pictures. The results show a significant influence of the starting powders on the homogeneity, purity and temperature of formation of the main phase.

Open access

D. Czekaj, A. Lisińska-czekaj and J. Plewa

Abstract

In the present research technology of compositionally graded barium strontium titanate Ba1-xSrxTiO3 thin films deposited on stainless steel substrates by sol-gel spin coating followed with thermal annealing at T = 650°C is reported. Results of thermal behavior of the sol-gel derived powders with compositions used for fabrication of graded structure (i.e. with Sr mole fraction x = 0.5, 0.4 and 0.3) are described. X-ray diffraction studies of the phase composition and crystal structure of such complex thin film configuration are given. It was found that gel powders exhibited a large total weight loss of about Δm ≈ 44-47%. Three stages of weight loss took place at temperature ranges: below T ≈ 300°C, at ΔT ≈ 300-500°C and between T = 600°C and T = 800°C. Phase analysis has shown that the dominating phase is Ba0.67Sr0.33TiO3 compound while the second phase is Ba0.7Sr0.3TiO3 or Ba0.5Sr0.5TiO3 for “up-graded” and “down-graded” structure, respectively.

Open access

Tomasz Jaworski, Jacek Hilszczański, Radosław Plewa and Andrzej Szczepkowski

Abstract

New records for twenty species of saproxylic tineid moths (Lepidoptera, Tineidae) from the Białowieża Forest (NE Poland) are presented. Most species were recorded on the basis of laboratory breeding of the adult moths from the sporocarps of wood-decaying fungi inhabited by the larvae. Some species were captured using barrier traps or were collected at light. One species, Dryadaula irinae (Savenkov, 1989), is recorded for the first time from Poland and three others, Nemaxera betulinella (Paykull, 1785), Nemapogon fungivorella (Benander, 1939) and Elatobia fuliginosella Lienig & Zeller, 1846, are recognized as new for the fauna of the Białowieża Forest. The current distribution in Poland of each species is briefly discussed, and some remarks on its biology are given