Les matériaux luminescents sensibles à la température ou l’exposition auxrayons ultra-violets sont de plus en plus recherchés. Dans ces travaux, deux famillesde composés ont été synthétisés et caractérisés.La première famille est celle des composés ZnAl2O4 dopés aux ionsmanganèse de structure spinelle. Ces composés présentent des propriétés dethermo-chromo-luminescence irréversible avec une variation d’émission du rouge auvert en fonction de l’histoire thermique subie par le matériau. Ici les variations delongueurs d’onde d’émission sont dues au changement de l’environnement des ionsluminescents manganèse en fonction de la température. Il a été démontré que lagamme de température de commutation peut être modulée par une variation de lacomposition de la matrice hôte. La seconde famille est celle des elpasolites decomposition Rb2KInF6 dopé au cérium. Ces composés présentent des propriétés dephoto-chromo-luminescence réversible par oxydo-réduction entre les ions cérium etindium. Sous irradiation UV, il est possible de créer des espèces (In+) quiluminescent dans le rouge. Nous avons montré que le retour aux propriétés initialespeut avoir lieu sous irradiation UV à plus hautes longueurs d’onde ou par chauffage.La spécificité du phénomène associé à cette structure et cette compositionparticulière peut s’expliquer par des considérations structurales, la situation spatialedes ions cérium et indium permettant des échanges électroniques par recouvrementorbitalaire de ces deux ions. / Research for luminescent materials sensitive to temperature or UV exposurevariation are increasing. Here we manage to synthesized and characterized materialswhich show such properties.First, spinel structure materials as ZnAl2O4 doped with manganesecompounds exhibit irreversible thermo-chromo-luminescence properties. Thismaterial shows a variation of emission wavelength from red to green with a variationof the thermal history of the sample. These variations are due to a modification of themanganese environment in the structure with the temperature. It was demonstratedthat the temperature range of the luminescence switch can be tuned by themodification of the matrix composition. Secondly, cerium-doped Rb2KInF6compounds with elpasolite structure exhibit reversible photo-chromo-luminescenceproperties. Under UV irradiation, new luminescent species (In+), created by redoxreaction between Ce3+ and In3+ species, and which emits in the red range, can beproduced. We demonstrate the reversibility of the phenomenon by UV irradiation orafter a thermal treatment. The specificity of these properties with this structure andthis composition can be explained by structural consideration: Ce3+ and In3+positioning in the cell allowing electronic exchanges between these ions thanks toorbital overlap.

O interesse no estudo de materiais isolantes dopados com metais de transição do grupo do ferro se origina no fato destes sistemas apresentarem largas bandas de emissão nas regiões espectrais do visível e do infravermelho próximo, o que os torna atrativos como meios ativos sintonizáveis. Neste trabalho apresentaremos medidas de fotoluminescência, absorção e excitação a temperatura ambiente, a 77K e a 4K da elpasolita K2LiAlF6 contendo a fração de 0,01 de Cr3+ em sítio do Al3+. A luminescência a 300K se compõe de uma larga banda que varia entre 650 e 850nm, com máximo de intensidade localizado em 734nm e tempo de vida de 0,48ms. O espectro a 77K, localizado também entre 650 e 850nm, apresenta uma banda larga com máximo de intensidade de 708nm e tempo de vida de 0,58ms, enquanto o espectro a 4K apresenta uma intensa transição em 665nm, com tempo de vida de 0,98ms e uma rica estrutura de fônons sobreposta à banda de base. Estas emissões são associadas à transição permitida por spin 4T2(4F)→ 4A2(4F) do íon Cr3+ em sítio coordenado octaedricamente. A eficiência quântica calculada a partir dos resultados experimentais é de 0,58. Os espectros de absorção e excitação também foram obtidos a temperatura ambiente, a 77K e a 4K. Estes espectros apresentam duas bandas, também características do Cr3+, associadas à transição do nível 4A2(4F) para os níveis excitados 4T1(4F) e 4T2(4F). / The interest in the study of insulating materials doped with transition metals arises from the fact that these systems present wide emission bands in the visible and near infrared regions, which turns them especially attractive as active media for tunable radiation. In this work we will present photoluminescence, absorption and excitation measurements at room temperature, 77K and 4K temperature of the elpasolite K2LiAlF6 containing 0,01 of Cr3+ Al3+ sites. The luminescence at 300K is composed of a wide band between 650 and 850nm with barycenter at 734nm and lifetime of 0,48ms. The spectrum at 7K also located between 650 and 850nm, presents a wide band with maximum at 708nm and lifetime of 0,58nm , while the spectrum at 4K presents an intense transition at 665nm, with lifetime of 0,98ms and a rich phonon structure. These emissions are associated to the allowed-spin transition 4T2(4F)→ 4A2(4F) of the íon Cr3+ in octahedrally coordinated site. The obtained quantum efficiency is 0,58. This value indicates that the K2LiAlF6 : C3+ is an attractive candidate as active media for tunable radiation. The absorption spectra were also obtained at room temperature, 77K and 4K. These spectra present two bands, also characteristic of octahedrally coordinated Cr3+ associated to the transition from 4A2 (4F) level to excited 4T1 (4F) and 4T2 (4F) levels.

O interesse no estudo de materiais isolantes dopados com metais de transição do grupo do ferro se origina no fato destes sistemas apresentarem largas bandas de emissão nas regiões espectrais do visível e do infravermelho próximo, o que os torna atrativos como meios ativos sintonizáveis. Neste trabalho apresentaremos medidas de fotoluminescência, absorção e excitação a temperatura ambiente, a 77K e a 4K da elpasolita K2LiAlF6 contendo a fração de 0,01 de Cr3+ em sítio do Al3+. A luminescência a 300K se compõe de uma larga banda que varia entre 650 e 850nm, com máximo de intensidade localizado em 734nm e tempo de vida de 0,48ms. O espectro a 77K, localizado também entre 650 e 850nm, apresenta uma banda larga com máximo de intensidade de 708nm e tempo de vida de 0,58ms, enquanto o espectro a 4K apresenta uma intensa transição em 665nm, com tempo de vida de 0,98ms e uma rica estrutura de fônons sobreposta à banda de base. Estas emissões são associadas à transição permitida por spin 4T2(4F)→ 4A2(4F) do íon Cr3+ em sítio coordenado octaedricamente. A eficiência quântica calculada a partir dos resultados experimentais é de 0,58. Os espectros de absorção e excitação também foram obtidos a temperatura ambiente, a 77K e a 4K. Estes espectros apresentam duas bandas, também características do Cr3+, associadas à transição do nível 4A2(4F) para os níveis excitados 4T1(4F) e 4T2(4F). / The interest in the study of insulating materials doped with transition metals arises from the fact that these systems present wide emission bands in the visible and near infrared regions, which turns them especially attractive as active media for tunable radiation. In this work we will present photoluminescence, absorption and excitation measurements at room temperature, 77K and 4K temperature of the elpasolite K2LiAlF6 containing 0,01 of Cr3+ Al3+ sites. The luminescence at 300K is composed of a wide band between 650 and 850nm with barycenter at 734nm and lifetime of 0,48ms. The spectrum at 7K also located between 650 and 850nm, presents a wide band with maximum at 708nm and lifetime of 0,58nm , while the spectrum at 4K presents an intense transition at 665nm, with lifetime of 0,98ms and a rich phonon structure. These emissions are associated to the allowed-spin transition 4T2(4F)→ 4A2(4F) of the íon Cr3+ in octahedrally coordinated site. The obtained quantum efficiency is 0,58. This value indicates that the K2LiAlF6 : C3+ is an attractive candidate as active media for tunable radiation. The absorption spectra were also obtained at room temperature, 77K and 4K. These spectra present two bands, also characteristic of octahedrally coordinated Cr3+ associated to the transition from 4A2 (4F) level to excited 4T1 (4F) and 4T2 (4F) levels.

Le degrè d'oxydation (+III) du palladium a étét mis en évidence dans des composés fluorés de structures dérivant de KBRF4 et de l'elpasolite K2NAALF6. Ce nouveau degrè d'oxydation a été caractérisé par RPE, mesures magnétiques et spectroscopie XPS. Les processus dynamiques intervenant lors des transitions de phases dans la structure elpasolite on été précisés par diffusion Raman et mesures calorimétriques

De nouveaux fluorures A2BMF6 de structure type elpasolite ont été caractérisés. Des déterminations structurales ont été réalisées soit sur des poudres soit sur des monocristaux. Diverses techniques d'analyse (microcalorimétrie, diffraction X, Résonance Paramagnétique Electronique, mesures optiques) ont permis de mettre en évidence des transitions de phases. Ces composés comportent des entites octaédriques MF6 isolés et rigides pouvant présenter des mouvements de rotation, en particulier dans la variété cubique stable a haute température. Lorsque la température diminue, le "gel" des octaèdres dans une de leurs positions instantanées conduit a une distorsion structurale de la maille. Des études par Résonance Magnétique Nucléaire du noyau 19F confirment l'apparition de mouvements des atomes de fluor lorsque la température croit. Les processus dynamiques intervenant dans Rb2KInF6 et Rb2KScF6 lors de la séquence de transitions monoclinique/quadratique/cubique ont été précises par diffusion Raman. Un mécanisme displacif de translation des atomes de rubidium s'accompagne d'une rotation des octaèdres MF6 qui s'effectue selon un processus ordre-désordre.