GUILHOT , Bernard

LaPO4:Ce, Tb (LaCeT) is a green phosphor used in fluorescent lamps and plasma display panels. In order to improve the fabrication process of this phosphor, different fluxes have been used. Their influence on the particles size and shape is described thanks to SEM analyses. Fluxes were found to control the morphology of particles : LaCeT...

Data concerning thermostimulated luminescence (TL) and fluorescence spectra are given for a scries of ruby monocrystals obtained by Verneuil's method, and containing several values of Cr3+concentration, up to 12000 ppm.

The properties of thermoluminescence (TL) observed from various mixed rare earth (RE) phosphate powders La1−x−yCexTbyPO4 are reported. TL peaks appear around −175°C, −135°C, −80°C, −35°C and +25°C and the TL emission spectra of La1−x−yCexTbyPO4 are mainly composed of characteristic line transitions of Tb3+ ions. The results show that the...

Az alumínium-oxid alapú kerámiaanyagok tekinthetok az elsö modern kerámiáknak, melyek mind technológíai mind tudományos szempontból kiemelkedö fontosságúak. Feldolgozási technológiájuk és tulajdonságaik javulása igen szoros kapcsolatban van a szinterelésük mechanizmusára vonatkozó ismeretek bóvülésével1. A szinterclés a szilárd anyagok...

Thanks to its high thermal conductivity, aluminum nitride may be a serious candidate as fuel coating for the Gas Fast Reactor. However, its behavior under irradiation is not entirely well understood. In order to catch a glimpse of this behavior, specimens were irradiated with swift heavy ions of different energies then characterised by both...

Thanks to its high thermal conductivity, aluminum nitride may be a serious candidate as fuel coating for the Gas Fast Reactor. However, its behavior under irradiation is not entirely well understood. In order to catch a glimpse of this behavior, specimens were irradiated with swift heavy ions of different energies then characterised by both...

Thanks to its high thermal conductivity, aluminum nitride may be a serious candidate as fuel coating for the Gas Fast Reactor. However, its behavior under irradiation is not entirely well understood. In order to catch a glimpse of this behavior, specimens were irradiated with swift heavy ions of different energies then characterised by both...

Ce travail porte sur l'amélioration du procédé de fabrication des luminophores et en particulier un phosphate de lanthane : LaPO4:Ce,Tb (LaCeT). L'influence de fondants carbonatés (Li2CO3, Na2CO3, K2CO3, ...) sur la taille et la forme des grains du luminophore y est décrite. Pour ce faire des analyses par microscopie électronique à balayage ont...

The dependence of the firing conditions on the crystal structure formation of ZnGa2 O4 has been investigated. The effects of temperature and atmosphere were examined and gave evidence of the instability of the zinc gallate under a reducing atmosphere at temperatures above 600°C. A new preparation route has allowed to synthesize ZnGa2 O4 at...

The formation of SrAl2O4 by solid state reaction between SrCO3 and Al2O3 has been studied. The firing conditions, namely the time, the atmosphere and the temperature, have been optimized so as to obtain pure well crystallized SrAl2O4, allowing the further study of the influence of the atmosphere on the optoelectronic properties of the phosphor....

Alpha alumina powders have been produced by thermal treatment under controlled atmosphere of highly pure gamma alumina. The influence of the atmosphere and the addition of dopants (Mg2+, Cr3+, Th4+) were studied by thermoluminescence (TL). TL is a technique which gives information about point defects. It allowed to reveal the presence of oxygen...

The various possibilities of thermoluminescence and thermostimulated exoelectronic emission in ceramic investigations are presented. Numerous examples are given.

Doped alpha-alumina powders have been synthesised by thermal treatment of gamma-alumina under a controlled atmosphere. Two TL peaks, located at 200°C and 365°C, have been detected in almost all samples. Their intensity is strongly dependent on the atmosphere and on the nature of introduced dopants. The influence oh these parameters on point...

Two parameters were studied upon the thermoluminescence (TL) properties and the sintering behaviour of α-alumina: the atmosphere during the heat treatment used to transform γ-Al2O3 into α-Al2O3 and the doping by Zr and Th. It appears that a reducing atmosphere tends to delay the sintering compared with the oxidising atmosphere until 1600°C....

The thermoluminescence method (TL), or the thermostimulated luminescence is one of the techniques which correlate thermal and optical methods and usually used to characterize the defects occuring in insulating or semiconductors materials. After a brief description of the TL phenomenon based on the example of alpha alumina, we present some...

The dependence of the firing conditions on the crystal structure formation of ZnGa2O4 has been investigated. The effects of temperature and atmosphere were examined and gave evidence of the instability of the zinc gallate under a reducing atmosphere at temperatures above 600 degrees C. A new preparation route has allowed to synthesize ZnGa2O4...

Pure alpha alumina powders have been synthesized under oxidizing or reducing atmosphere. They have been characterized by specific surface area measurements, scanning electron microscopy and X-Ray diffraction. No differences have been detected. However the sintering rate of these powders depends on the synthesis atmosphere. The densification of...

Two parameters were studied upon the thermoluminescence (TL) properties and the sintering behaviour of a-alumina: the atmosphere during the heat treatment used to transform gamma -Al2O3 into alpha -Al2O3 and the doping by Zr and Th. It appears that a reducing atmosphere tends to delay the sintering compared with the oxidising atmosphere until...

La synthèse hydrothermale d'hydroxyapatite à faible teneur en chlore ou en fluor a été obtenue selon la réaction: Ca5 (PO4)3 OH+xNH4 Cl ou +x NH4F. Les spectres IR de ces échantillons ont été enregistrés, la bande à 3 498 cm-1 pour les OH, Cl apatites et 3 545 cm-1 pourles OH, F apatites permet de détecter respectivement 350 ppm de chlore et...

For Generation IV reactors, and more particularly the Gas Fast Reactor, aluminum nitride is an interesting candidate for the application as fuel coating; actually, its great thermal conductivity should allow efficient thermal transfer between the fuel pellets and the coolant. Unfortunately, few data are available on its behavior under...

Pure Al2O3 powders have been prepared by thermal decomposition of ammonium alum (NH4Al(SO4)2. 12H2O). The calcinations were performed at different temperatures, and under flowing oxygen or nitrogen or hydrogenated argon. The thermoluminescence of these powders after X ray irradiation at room temperature is studied from room temperature to 780...

The thermoluminescence (TL) and fluorescence spectra of magnesium aluminium oxynitride "MgAlON" and magnesium aluminate MgAl2O4 spinel powders have been analysed. Two broad peaks at about 100 and 300 °C appear in the TL spectra of MgAl2O4 and seem to be related to electron and hole release from [AlMg√] and [MgAl′] traps, respectively. The...

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The thermoluminescence (TL) after excitation by UV or X-rays radiation of alumina-zirconia powders is investigated. The composites present five of the characteristic peaks of zirconia at −170, −145, −90, 0 and 95 °C. After a thermal treatment of mixed oxides, a new peak is observed at −35 °C in TL. This peak reveals the presence of stabilized...

Comme pour tout système nucléaire, le concept du combustible pour les réacteurs de IVème génération consiste en des pastilles de combustible conditionnées dans une matrice qui doit contenir les produits de fission. De par leur excellente réfractarité, les carbures sont pressentis pour constituer cette barrière de confinement. Parmi ceux...