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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. Michalik, M. Sopicka-Lizer, T. Pawlik and R. Lisiecki

Abstract

The goal of this study was to investigate influence of the synthesis parameters on the luminescence properties of Ca- α -Sialon doped with Eu2+. The compound of Eu0:07Ca0:73Si9:6Al2:4O0:8N15:2 was prepared by the solid state reaction method from the mixture of the relevant oxides, Si3N4 and CaCO3. Synthesis was carried out in the temperature range of 1600-1700°C for 2-8 h in a reduction atmosphere (N2+CO). The structure and morphology of obtained powders were analyzed by XRD and SEM/EDS methods, respectively. Content of nitrogen/oxygen was also measured. Optical properties were investigated by excitation, emission and reflection spectra. Obtained results show strong influence of synthesis temperature on the phase composition and intensity of emission of Ca- -Sialon:Eu2+ powder compound.

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

T. Pawlik, M. Sopicka-Lizer, D. Michalik and T. Włodek

Characterization of the Mechanochemically Processed Silicon Nitride-Based Powders

Nanostructured silicon nitride and aluminium nitride powder mixtures have been successfully produced by high-energy mechanical activation in the planetary mill. The effect of planetary milling parameters (time, ball-to-powder ratio, surfactants addition) and means of deagglomeration by the ultrasound disintegration (type of dispersant, the ultrasonic action) were studied. The resultant powders were examined by XRD, SEM and TEM as well as the specific surface area (BET) was measured and grain size distribution was analyzed. It has been found that significant agglomeration occurred in the samples milled with the highest energy accompanied by the severe destruction of the crystal lattice. The results show the crucial effect of dispersant action for a one-modal distribution of the milled powders.

Open access

T. Pawlik, D. Michalik, J. Barzowska, K. Szczodrowski, T. Lesniewski, M. Sopicka-Lizer and M. Grinberg

Abstract

This paper presents the results of the synthesis temperature on the properties of the ceramic powders of SrSi2O2N2:Eu2+ obtained by the solid-phase reaction. Synthesis was carried out in the temperature range of 1250-1650°C for 2 hours in nitrogen flow in the reducing atmosphere of the graphite furnace. The phases present in the resultant powders were identified by X-ray structural analysis (XRD). Scanning electron microscopy (SEM) was used to examine the changes in the powder morphology as a result of the synthesis. The excitation and emission spectra measurements let to study phosphor photoluminescence properties. The results show the strong influence of temperature synthesis on the formation and purity of expected phases. The synthesis temperature also affects the luminescent properties of SrSi2O2N2:Eu2+ ceramic powders.