In the article, the characterization of the microstructure, phase composition and distribution of elements in the Eu2O3-ZrO2 sintered materials obtained by four different ways of powders’ homogenization (mixing) process and different temperature of sintering process is shown. The feedstock powders with an average mole ratio of ZrO2 to Eu2O3 equal 74% to 26% were used as an initial material. The principal aim of the investigation was characterization of differences in the microstructure of the same type of ceramics, however, prepared via different mixing and manufacturing processes. The range of the investigation covered a characterization of these materials via phase identification of all samples by XRD (X-ray diffraction) and characterization of internal morphology of the specimens with detailed analysis of elements distributions by SEM (scanning electron microscopy) and EDS (energy dispersive spectrometry). The aim of the following investigation is to characterize the possibilities of the solid state synthesis of the europium zirconate based materials, dedicated for TBC applications.
Worldwide commercial interest in the production of cerium doped yttrium aluminium garnet (YAG:Ce) phosphors is reflected in the widespread use of white light emitting devices. Despite of the fact that YAG:Ce is considered a “cool phosphor” it is the most important in white LED technology. This article reviews the developed techniques for producing phosphors with superior photoluminescence efficiency, including solid-state reaction, sol-gel and (co)precipitation methods. Also, by co-doping with rare earth elements, a red/blue shift is reached in the spectrum. The characteristics of YAG:Ce phosphors are investigated because the properties of the phosphors are strongly influenced by the synthesis routes and the sintering temperature treatment. After the phase analysis, morphology and emission studies of the phosphors there may be seen the conditions when the transition from the amorphous phase to the crystalline phase appears, when luminescent properties are influenced by the crystalline form, purity, average size of the particles, co-doping and so on.
The aim of these studies was to obtain single phase cubic modification of Li7La3Zr2O12 by mechanical milling and annealing of La(OH)3, Li2CO3 and ZrO2 powder mixture. Fritsch P5 planetary ball mill, Rigaku MiniFlex II X-ray diffractometer, Setaram TG-DSC 1500 analyser and FEI Titan 80-300 transmission electron microscope were used for sample preparation and investigations. The applied milling and annealing parameters allowed to obtain the significant contribution of c-Li7La3Zr2O12 in the sample structure, reaching 90%. Thermal measurements revealed more complex reactions requiring further studies.
Al and Nb-doped Li7La3Zr2O12 (LLZO) and W-doped LLZO lithium ion conducting electrolyte samples were prepared and their H2O stability was investigated. The LLZO samples were exposed to 50% humidified air for 48 h. After H2O exposure, a cubic to tetragonal transformation occurred and acquired SEM images exhibited the presence of reaction phases at the grain boundaries of Al and Nb-LLZO. As a result, the lithium ion conductivity significantly decreased after H2O exposure. On the contrary, W-LLZO showed good stability against H2O. Although the cubic to tetragonal transformation was also observed in H2O-exposed W-LLZO, the decrease in lithium ion conductivity was found to be modest. No morphological changes of the W-LLZO samples were confirmed in the H2O-exposed W-LLZO samples.
In this paper, explain the preparation of CaTiO3 ceramics synthesized by the solid-state reaction method. Calcium carbonate and titanium dioxide were high energy mixed in stoichiometric amounts, and the obtained mixture was calcined at different temperatures (800, 900, 1000 and 1300ºC) for 2 h. The obtained samples were characterized by measurement of particle size, Energy Dispersive X-Ray (EDX) Analysis; differential thermal analysis, X-ray diffraction and SEM images. XRD patterns indicated that CaTiO3 ceramics with the structure of perovskite is obtained from calcined powders at 1,300°C for 2 h. SEM images show the formation of a very fine and homogeneous morphology. The measured values of electrical resistivity were within the typical range of insulating materials and approach values corresponding to insulating ceramics.
An efficient operation of a Ho:YLF laser pumped by a Tm-doped fibre laser is reported. The research in a continuous-wave (CW) operation was done for two crystals of the same 0.5 at.%Ho dopant concentration and with different lengths (3×3×30 mm3 and 3×3×50 mm3). For an output coupling transmission of 20% and a crystal length of 50 mm, the maximum CWoutput power of 38.9 W for 81.4 W of incident pump power, corresponding to the slope efficiency of 52.3% and optical-to-optical conversion efficiency of 47.8% (determined with respect to the incident pump power) was achieved. The highest opti- cal-to-optical conversion efficiency of 70.2% with respect to the absorbed pump power was obtained. The influence of a heat-sink cooling water temperature on theCWlaser performance was studied. For a Q-switched operation the pulse repe- tition frequency (PRF) was changed from 2 to 10 kHz. The maximum average output power of 34.1 W at the PRF of 10 kHz was obtained for a 50 mm holmium crystal length. For 2 kHz PRF and 71.9 W of incident pump power, pulse energies of 13.7 mJ with a 21 ns FWHM pulse width corresponding to 652 kW peak power were recorded.
49th Winter School on Wave and Quantum Acoustics constituted platforms for sharing the results and achievements obtained in different branches of physical acoustics, as molecular acoustics, quantum acoustics, acousto-optics, magnetoacoustics, photoacoustics, acoustics of solid state, acoustic emission, and others. Moreover, researches in some selected topics related to those mentioned above (e.g. optoelectronics, relaxation processes) were presented during the school.
The conference consisted of the 16th Workshop on Acoustoelectronics and the 16th Workshop on Molecular Acoustics, Relaxation and Calorimetric Methods. However, the organizers are opened to organizing workshops on other subjects in future. We would like to invite scientific centers and other professional groups to cooperate in organizing workshops on the subjects of their interests.
XLVIIIth Winter School on Environmental Acoustics and Vibroacoustics was a forum for all environmental and vibroacoustics fields. Particularly it was concerned with traffic noise, vibroacoustics of machines, room acoustics, building acoustics, noise protection and similar problems. During the Conference, seminars on “Measurement of noise and vibration at the workplace” and Environmental noise monitoring”, combined with measurement workshops, were organised in association with SVANTEK.
The Conferences began with the special, joined session dedicated to celebration of the 15th Jubilee Conference Integrated Optics – Sensors, Sensing Structures and Methods. In summary, 48 people participated in Conferences and seminars, presenting 37 lectures, reports and posters. In this issue one can find abstracts of some lectures and posters, which were presented during the Conferences.