Berlin, Humboldt-University, Diss., 2001.

Microbeam Radiation Therapy (MRT) is an experimental form of radiation treatment which has the potential to improve the treatment of many types of cancer. In MRT, the radiation is applied as a grid by passing the collimated X-ray beam from a synchrotron through a microplane collimator, which is a stack of parallel plates of two materials with dramatically different X-ray transparencies. The peak-to-valley dose ratio (PVDR) is the difference between the dose in the microbeams and the dose delivered between the beams. It is the PVDR that is of biological importance in MRT. Therefore a dosimeter for MRT requires a combination of a large dynamic range for dose response into the kilo-Gray regime, and high spatial resolution on the micron scale. This project characterizes fluorophosphate glasses doped with trivalent samarium ions as a potential valency conversion dosimeter for MRT using the conversion of Sm3+→Sm2+ to measure the delivered dose. Samples irradiated at the Canadian Light Source synchrotron showed X-ray induced conversion that could be optically characterized by changes in the photoluminescence emission spectra to obtain irradiation dose. The conversion efficiency depends almost linearly on the irradiation dose up to 150 Gy and saturates at doses exceeding 1500 Gy. The conversion shows a strong correlation with an observed increase in absorbance of the glass in the range of 200-750 nm. The absorbance increases with X-ray dose and is related to the formation of phosphorous-oxygen hole centers (POHC) and POn electron centers. The presence of these defects within the irradiated glass was determined by examination of the induced optical absorbance and electron paramagnetic resonance (EPR) spectra. The formation of these hole centers along with the conversion of Sm3+→Sm2+ under X-ray irradiation suggests that the X-rays cause the formation of electron-hole pairs in the glass. The electrons are then primarily captured by the Sm3+ ions, becoming Sm2+ ions, with some of the electrons being captured by POn electron centers. The holes are captured by the POHCs. This process can be represented chemically as Sm3+ + e-→ Sm2+ and PO + h+→POHC. The stability of the Sm conversion under illumination was examined using photoluminescence spectra and the stability of the X-ray induced defects was examined via the induced optical absorbance and EPR spectra.

O presente trabalho aborda o estudo de correlações entre estrutura e propriedade de uma nova composição de vidros fluorofosfato. O trabalho compreende na síntese e caracterização de vidros fluorofosfatos com a seguinte composição: [80Ba(PO3)2 - 20Al(PO3)3]1-x[80BaF2 - 20AlF3]x(0 ≤ x ≤ 40 - mol%).Ressonância Magnética Nuclear e Espalhamento Raman são técnicas indicadas no estudo estrutural de materiais amorfos, como por exemplo, os vidros. Através dos resultados obtidos por difração de raios-X (DRX) e análise térmica diferencial (DTA) confirmam a formação de um sólido amorfo com concentrações de íons fluoretos de até 30 mol%. No entanto, a partir dos resultados da quantificação dos íons fluoretos via 19F RMN sugerem que houve uma quantidade significativa de perda de fluoreto ou ainda troca dos íons fluoretos por óxidos. Os espectros de 31P e Raman indicam uma gradual conversão das unidades Q2m em Q1m com o aumento de x. 19F RMN indica que os átomos de flúor estão em dois ambientes químicos distintos, onde os íons fluoretos estão ligados com átomos de fósforo ou distribuídos em um ambiente misto de Al/Ba. Resultados obtidos via 19F{31P}-REDOR confirmam a formação da ligação P-F. Os espectros de 27Al mostram a predominância dos átomos de alumínio com geometria octaédrica e ainda os resultados de 27Al{31P}-REDOR sugerem uma coordenação preferencial dos Al com unidades fosfato. Através dos resultados dos acoplamentos dipolares homonucleares via 31P{31P}-DRENAR corroboram com a deconvolução dos espectros de 31P na atribuição das espécies Q1m e Q2m. / In this work was studied the development of structure/property correlations for new fluorophosphate glasses compositions: [80Ba(PO3)2 - 20Al(PO3)3]1-x[80BaF2 - 20AlF3]x(0 ≤ x ≤ 40 - mol%). Most suitable techniques for the structural analysis in case of disordered and amorphous material are Nuclear Magnetic Resonance (NMR) Spectroscopy and Raman scattering. Results from X-ray diffraction (XRD) and differential thermal analysis (DTA) reveal that amorphous samples were obtained for all glass compositions up to x ≤ 30. However, the fluorine quantification via 19F MAS NMR suggests significant fluoride loss and/or fluoride/oxide replacement. Both 31P and Raman results indicate gradual conversion of Q2m units to Q1m units with increasing the fluorine concentration. 19F MAS NMR spectra indicate fluorine atoms in two different chemical environments bonded wither covalently to P-atoms or located in a mixed Al/Ba environment. The P-F assignment is confirmed by 19F{31P}-REDOR experiments. 27Al NMR spectra shows dominantly six-coordinated aluminium, and the 27Al{31P}-REDOR data suggest nearly exclusive coordination of Al with phosphate species. The dipolar coupling constant obtained by 31P{31P}-DRENAR are roughly consistent with 31P spectral deconvolution suggesting the presence of Q1and Q2 species.

O presente trabalho aborda o estudo de correlações entre estrutura e propriedade de uma nova composição de vidros fluorofosfato. O trabalho compreende na síntese e caracterização de vidros fluorofosfatos com a seguinte composição: [80Ba(PO3)2 - 20Al(PO3)3]1-x[80BaF2 - 20AlF3]x(0 ≤ x ≤ 40 - mol%).Ressonância Magnética Nuclear e Espalhamento Raman são técnicas indicadas no estudo estrutural de materiais amorfos, como por exemplo, os vidros. Através dos resultados obtidos por difração de raios-X (DRX) e análise térmica diferencial (DTA) confirmam a formação de um sólido amorfo com concentrações de íons fluoretos de até 30 mol%. No entanto, a partir dos resultados da quantificação dos íons fluoretos via 19F RMN sugerem que houve uma quantidade significativa de perda de fluoreto ou ainda troca dos íons fluoretos por óxidos. Os espectros de 31P e Raman indicam uma gradual conversão das unidades Q2m em Q1m com o aumento de x. 19F RMN indica que os átomos de flúor estão em dois ambientes químicos distintos, onde os íons fluoretos estão ligados com átomos de fósforo ou distribuídos em um ambiente misto de Al/Ba. Resultados obtidos via 19F{31P}-REDOR confirmam a formação da ligação P-F. Os espectros de 27Al mostram a predominância dos átomos de alumínio com geometria octaédrica e ainda os resultados de 27Al{31P}-REDOR sugerem uma coordenação preferencial dos Al com unidades fosfato. Através dos resultados dos acoplamentos dipolares homonucleares via 31P{31P}-DRENAR corroboram com a deconvolução dos espectros de 31P na atribuição das espécies Q1m e Q2m. / In this work was studied the development of structure/property correlations for new fluorophosphate glasses compositions: [80Ba(PO3)2 - 20Al(PO3)3]1-x[80BaF2 - 20AlF3]x(0 ≤ x ≤ 40 - mol%). Most suitable techniques for the structural analysis in case of disordered and amorphous material are Nuclear Magnetic Resonance (NMR) Spectroscopy and Raman scattering. Results from X-ray diffraction (XRD) and differential thermal analysis (DTA) reveal that amorphous samples were obtained for all glass compositions up to x ≤ 30. However, the fluorine quantification via 19F MAS NMR suggests significant fluoride loss and/or fluoride/oxide replacement. Both 31P and Raman results indicate gradual conversion of Q2m units to Q1m units with increasing the fluorine concentration. 19F MAS NMR spectra indicate fluorine atoms in two different chemical environments bonded wither covalently to P-atoms or located in a mixed Al/Ba environment. The P-F assignment is confirmed by 19F{31P}-REDOR experiments. 27Al NMR spectra shows dominantly six-coordinated aluminium, and the 27Al{31P}-REDOR data suggest nearly exclusive coordination of Al with phosphate species. The dipolar coupling constant obtained by 31P{31P}-DRENAR are roughly consistent with 31P spectral deconvolution suggesting the presence of Q1and Q2 species.

Organophosphates (OPs) are a major class of pesticides and nerve agents that elicit acute toxicity by inhibiting acetylcholinesterase (AChE), the enzyme responsible for the degradation of the neurotransmitter acetylcholine in the central and peripheral nervous systems. Acetylcholine accumulation following extensive AChE inhibition leads to an acute cholinergic syndrome characterized by autonomic dysfunction, involuntary movements, muscle fasciculations, respiratory distress, and seizures. Despite their classification as moderate to highly toxic, OP pesticides are the most widely used class of insecticides in the U.S., and are even more commonly used worldwide. Additionally, there is a growing concern that OP nerve agents could be used to cause mass civilian casualties. It is well known that the survivors of acute nerve gas poisoning and chronic OP pesticide exposure exhibit neurobehavioral deficits including mood changes, depression, and memory impairments. Despite this, there are very few treatments available for OP-intoxication survivors and this topic is under-researched. In this study we investigated whether animals surviving a single severe OP exposure exhibited long-term neurological impairments, using two OP agents: paraoxon (POX) and diisopropyl fluorophosphates (DFP), as well as a non-OP chemoconvulsant, pilocarpine (Pilo), which acts as a muscarinic agonist. Exposure to POX, DFP, or Pilo led to overt signs of cholinergic toxicity. POX and DFP rats were rescued with an optimized atropine, 2-PAM, and diazepam therapy per current OP-exposure treatment guidelines, while Pilo rats were given only diazepam. Saline was administered to control rats at all pharmacological timepoints. Surviving rats were studied using established behavioral assays for identifying symptoms of depression and memory impairment 3-6 months after exposure to toxic agents. In the forced swim test, POX, DFP, and Pilo animals exhibited increased immobility time indicative of a despair-like state. In the sucrose preference test, POX, DFP, and Pilo rats did not display a preference for sucrose water, indicating an anhedonia-like condition. POX, DFP, and Pilo rats also displayed increased anxiety as characterized by significantly lower performance in the open arm of the elevated plus maze. Furthermore, when tested with a novel object recognition paradigm, POX, DFP, and Pilo rats exhibited a significantly lower discrimination ratio, indicating impaired recognition memory. The results indicate that these models of survival from severe POX and DFP exposure can be employed to study chronic behavioral and cognitive comorbidities and to further investigate the molecular bases for these comorbidities, potentially leading to the development of pharmacological therapies.

Rare earth RE3+ doped fluorophosphates glasses and glass ceramics are among the most promising candidates for high efficiency laser generation in the near-infrared spectral region. Glass ceramics are polycrystalline materials of fine microstructure that are produced by the controlled crystallization (devitrification) of a glass. By developing fluorophosphate base glasses with appropriate compositions and by controlling crystal nucleation and growth in them, glass ceramics with special properties can be fabricated combining the advantages of fluorides (low phonon energy, low refractive indexes, extensive optical window, lower hygroscopicity) and oxides (high chemical and mechanical stability and high dopant solubility), resulting in enhancement of the RE3+ emissive properties. In this study, we present the synthesis by melting/quenting and structural/spectroscopic investigation of new glasses and glass ceramics with composition 25BaF225SrF2(30-x)Al(PO3)3xAlF3(20-z)YF3: zREF3, where x = 15, 20 or 25, RE = Er3+ an/or Yb3+ and Nd3+. A detailed structural investigation of a series of this glasses has been conducted, using Raman, solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopies. / Vidros e vitrocerâmicas fluorofosfatos dopados com íons terras raras (TR3+) estão entre os candidatos mais promissores para a geração de laser de alta eficiência na região espectral do infravermelho próximo. As vitrocerâmicas são materiais policristalinos com microestrutura bem definida obtida a partir da cristalização controlada do vidro base. Desenvolvendo vidros base de fluorofosfato com composições apropriadas e controlando a nucleação e crescimento de cristais, vitrocerâmicas com propriedades especiais podem ser fabricadas combinando as vantagens dos fluoretos (baixa energia de fônons, baixos índices de refração, janela ótica extensa, baixa higroscopicidade) e óxidos (alta estabilidade química e mecânica e alta solubilidade dopante), resultando no aumento das propriedades emissoras dos íons TR3+. Neste estudo, apresentamos a síntese por fusão/resfriamento e investigação estrutural/espectroscópica de novos vidros e vitrocerâmicas com composição 25BaF225SrF2(30-x)Al(PO3)3xAlF3(20-z)YF3: zREF3, onde x = 15, 20 ou 25, RE = Er3+ an / ou Yb3+ e Nd3+. Uma investigação estrutural detalhada de uma série destes vidros foi conduzida utilizando espectroscopias Raman, de ressonância magnética nuclear de estado sólido (RMN) e de ressonância paramagnética eletrônica (EPR).

Atualmente, vidros e vitrocerâmicas dopados com íons terras raras trivalentes TR3+ constituem a mais importante classe de materiais para aplicações laser e em outros dispositivos ópticos, na região do infravermelho próximo e visível. Neste contexto, um dos desafios está em encontrar uma matriz hospedeira adequada que assegure qualidade óptica e um ótimo desempenho dos íons dopantes (altas seções de choque de absorção e emissão, baixa probabilidade de decaimentos não radiativos, tempos de vida de estado excitado suficientemente longos), mantendo estabilidade térmica e mecânica. Entre os possíveis candidatos, estão os vidros fosfatos com alta capacidade de dispersão dos dopantes, baixo índice de refração e propriedades termo-ópticas superiores aos silicatos, calcogenetos e fluoretos. Contudo, estes vidros apresentam alta energia de fônons, menor estabilidade química e mecânica e são higroscópicos, o que pode constituir um significativo mecanismo de supressão da luminescência devido ao acoplamento de transições dos TR3+ com vibrações de grupos hidroxila. Se por um lado vidros fluoretos podem ser obtidos com baixas energias de fônon e alta estabilidade química, os mesmos são mecanicamente frágeis e apresentam más características termo-ópticas. Para superar estas limitações, vidros oxifluoretos como fluorofosfatos têm sido explorados com a promessa de combinar os méritos dos fluoretos (baixas energias de fônon, baixos índices de refração, extensa janela de transmissão óptica) e dos óxidos (alta estabilidade química e resistência mecânica, maior solubilidade dos TR3+). Do ponto de vista das aplicações, considerando a transmissão e amplificação de sinais em telecomunicação em torno de 1,5 µm, e geração de ação laser de alta potência em torno de 1,0 µm, materiais dopados com Er3+ e Yb3+ estão entre os mais importantes. Neste trabalho apresenta-se a síntese e caracterização estrutural e espectroscópica de novos vidros fluorofosfatos dopados com Er3+ ou Yb3+ e co-dopados com ambos, no sistema composicional 25BaF225SrF2(30-x)Al(PO3)3xAlF3 (20-z)YF3:zTRF3 com x = 20 ou 15, TR = Er3+ e/ou Yb3+ e z = 0,25, 0,5, 1,0, 2,0, 3,0, 4,0 e 5,0 mol%. As amostras foram obtidas pelo método convencional de fusão e resfriamento e caracterizadas por Raman, Ressonância Magnética Nuclear de estado sólido e espectroscopia UV-VIS. Dos estudos por RMN de 19F verificou-se que há uma perda máxima de fluoreto de ~20% nas amostras. Ainda assim, a quantidade remanescente foi suficiente para garantir um ambiente químico favorável às emissões e poucas diferenças foram notadas entre as amostras com 20 e 15 mol% AlF3 contendo a mesma concentração de dopantes. Para o Er3+, tempos de vida do estado emissor 4I13/2 da ordem de 10 ms implicam em altos valores de eficiência quântica (&#951= 85%) e para o Yb3+ tempos de vida do estado emissor 2F5/2 similarmente longos (&#964 = 1,7 ms) foram medidos. Em amostras co-dopadas com 4,0 mol% YbF3 e 0,25, 1,0 e 2,0 mol% ErF3 o decréscimo do tempo de vida do Yb3+ e acréscimo do tempo de vida do Er3+ indicam que a transferência Yb&#8594Er foi eficiente neste sistema. De maneira geral, os resultados indicam que os vidros estudados são potenciais candidatos a aplicações ópticas como as mencionadas acima. / Currently, glasses and glass ceramics doped with trivalent rare earth ions RE3+ represent the most important class of materials for laser and other optical applications in the visible and near-infrared spectral regions. In this context, one of the challenges is to find host matrices that assure good optical quality and optimum performance of the dopant ions (high absorption and emission cross sections, low probability of non-radiative decays, sufficiently long excited state lifetimes), while still maintaining thermal and mechanical stabilities. Among the candidates, phosphate glasses with high capacity for RE3+ dispersion, low refractive index and superior thermo-optical properties than silicate, chalcogenide and fluoride glasses are largely studied. However, phosphates present high phonon energies, lower chemical and mechanical stabilities and they are hygroscopic, which can imply in significant luminescence quenching effects. If on one hand fluoride glasses may be designed with low phonon energies and higher chemical stability, they are frail and present less than ideal thermo-optical properties. In order to overcome these drawbacks, oxyfluoride glasses such as fluorophosphates have been explored with the promise to combine the merits of fluorides (low phonon energies and refractive index, extensive optical window) and of oxides (high chemical stability and chemical resistance, higher solubility of RE3+). From the viewpoint of applications, when it comes to the transmission and amplification of signal in telecommunications around 1.5 µm, and the generation of high power lasers around 1.0 µm, materials doped with Er3+ and Yb3+ are among the favorite. Furthermore, because Yb3+ presents higher absorption cross-section than Er3+ at the preferred excitation wavelength for both these ions (980 nm), the former can act as an efficient sensitizer of excitation energy with subsequent transfer to the latter. We present the synthesis, and structural and spectroscopic characterization of new flurophosphate glasses doped with Er3+ or Yb3+ and co-doped with both, in the compositional system 25BaF225SrF2(30x)Al(PO3)3 xAlF3 (20- z)YF3:zREF3 with x = 20 or 15, RE = Er3+ and/or Yb3+ and z = 0.25, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mol%. The samples were obtained by conventional melt quenching technique and characterized by Raman, solid state NMR and UV-VIS spectroscopy. From the NMR studies of 19F, it was shown that there is a maximum fluoride loss of 20% in the samples. Even so, the remaining quantity was enough to assure a favorable chemical environment to the RE3+ emissions. Little differences were detected between the samples with 20 and 15 mol% AlF3 for the same dopant concentration. For Er3+, lifetimes of the emitting level 4I13/2 of the order of 10 ms result in fluorescence quantum efficiency values (&#951 = 85%), and similarly, for Yb3+, long lifetimes of the excited state 2F5/2 (&#964 = 1,7 ms) were measured. In co-doped samples with 4.0 mol% YbF3 and 0.25, 1.0 and 2.0 mol% ErF3 the decrease in lifetime of Yb3+ and increase in lifetime of Er3+ indicate that the Yb&#8594Er energy transfer is efficient in this system. In general, the results indicate that the studied glasses are potential candidates for optical applications.

O processo de conversão ascendente de energia (infravermelho ao visível) é amplamente estudado em materiais dopados com íons terras raras trivalentes (TR3+) devido as várias possibilidades de aplicações tecnológicas. Tal processo consiste na emissão de fótons de maior energia (usualmente no visível) mediante excitação com fótons de menor energia (infravermelho) via mecanismo de absorção de dois fótons e/ou transferência de energia entre os íons TR3+. Entre os materiais estudados destacam-se vidros e vitrocerâmicas dopados com Er3+ com emissões nas regiões do verde e do vermelho, que podem ser eficientemente excitadas por lasers de diodo na região do infravermelho próximo (980 nm). Uma das aplicações possíveis para este processo é a de um sensor óptico de temperatura baseado na dependência da razão de intensidades de emissão dos níveis 2H11/2 e 4S3/2 do Er3+ com a temperatura, vantajoso para operação em ambientes hostis como transformadores de alta tensão, em processos industriais, etc. Como a eficiência das emissões depende também da matriz hospedeira, os vidros fluorofosfatos com composição 25BaF225SrF2(30-x)Al(PO3)3xAlF3(20-z)YF3:zErF3 com x = 20 e z = 1,0 a 5,0 mol% foram escolhidos por apresentarem alta estabilidade química e mecânica, e energia de fônon relativamente baixa. Assim, amostras vítreas dopadas com várias concentrações de Er3+ foram previamente caracterizadas e selecionadas para desenvolver o protótipo que emprega a variação de intensidade relativa das emissões 2H11/2 → 4I15/2 e 4S3/2 → 4I15/2 do vidro fluorofosfato dopado com Er3+ na medição de temperaturas. Este protótipo apresenta as características de baixo custo, alta sensibilidade e rápida resposta. / The infrared-to-visible upconversion process is widely studied in materials doped with trivalent rare earth ions (RE3+) due to the various possibilities of technological applications. The process is based on the emission of photons with higher energy (in the visible) than the excitation photons (in the infrared) via the mechanisms of two-photon absorption and/or energy transfer between RE3+ ions. Among the studied materials emphasis is given to glasses and glass ceramics doped with Er3+, exhibiting intense emissions in the green and red, which can be efficiently excited by diode lasers in the near infrared region (980 nm). One application of this process is an optical temperature sensor based on the dependence of the ratio of the emission intensities of levels 2H11/2 and 4S3/2 of Er3+ on the temperature of the sample. Such sensor would be advantageous for operation in hostile environments, such as high voltage transformers, industrial processes, etc. Because the efficiency of upconversion also depends on the host matrix composition, flurophosphate glasses are interesting candidates due to their high chemical stability, good mechanical properties and relatively low phonon energy. Glasses with composition 25BaF225SrF2(30-x)Al(PO3)3xAlF3(20-z)YF3:zErF3 with x = 20 and z varying from 1.0 to 5.0 mol% were characterized and selected to develop the prototype employing the fluorescence of fluorophosphate glass doped with Er3+ for measuring temperatures with the following characteristics: low cost, high accuracy and fast response.

Microbeam radiation therapy (MRT) is an experimental form of radiation treatment which causes less damage to normal tissue in comparison with customary broad-beam radiation treatment. In this method the synchrotron generated X-ray beam is passed through a multislit collimator and applied to the tumor in the form of an array of planar microbeams. MRT dosimetry is an extremely challenging task and no current detector can provide the required wide dynamic rang and high spatial resolution. In this thesis, fluorophosphate (FP) and fluoroaluminate (FA) glass plates doped with trivalent samarium (Sm3+) are characterized towards developing a potential X-ray detector suitable for MRT dosimetry. The detection is based on the difference in the photoluminescence signatures of Sm3+ ions and Sm2+ ions; the latter are formed under X-ray irradiation. This valency conversion is accompanied by the formation of defects including hole centers (HCs) and electron centers (ECs) in the glass structure which absorb light in the UV and visible regions (induced absorbance). Both FP and FA glasses show promising dynamic range for MRT and may be used as a linear sensor up to ~150 Gy and as a nonlinear sensor up to ∼2400 Gy, where saturation is reached. X-ray induced defects saturate at the same dose. The optimum doping concentration is in the 0.001˗ 0.2 at.% range. Doping with higher concentrations will decrease the conversion efficiency. The glass plates also show a very promising spatial resolution (as high as a few microns) for recording the dose profile of microbeams which is readout using a confocal fluorescence microscopy technique. These plates are restorable as well and the response is reproducible. The effects of previous X-ray exposure including samarium valency conversion as well as induced absorbance may be erased by annealing at temperatures exceeding the glass transition temperature Tg while annealing at TA < Tg enhances the response. This enhancement is explained by a thermally stimulated relaxation of host glass ionic matrix surrounding X-ray induced Sm2+ ions. Optical erasure is another practical means to erase the recorded data. Nearly complete Sm2+ to Sm3+ reconversion (erasure) is achieved by intense optical illumination at 405 nm. While, existing X-ray induced bands would be only partially erased. Electron spin resonance (ESR) and optical absorbance spectroscopy are used to investigate the nature of X-ray induced defects and their correlation with Sm valency conversion. A model based on competition between defect center formation and the Sm3+ ⇆ Sm2+ conversion successfully explains the different processes occurring in the glass matrix under X-ray irradiation.

Atualmente, vidros e vitrocerâmicas dopados com íons terras raras trivalentes TR3+ constituem a mais importante classe de materiais para aplicações laser e em outros dispositivos ópticos, na região do infravermelho próximo e visível. Neste contexto, um dos desafios está em encontrar uma matriz hospedeira adequada que assegure qualidade óptica e um ótimo desempenho dos íons dopantes (altas seções de choque de absorção e emissão, baixa probabilidade de decaimentos não radiativos, tempos de vida de estado excitado suficientemente longos), mantendo estabilidade térmica e mecânica. Entre os possíveis candidatos, estão os vidros fosfatos com alta capacidade de dispersão dos dopantes, baixo índice de refração e propriedades termo-ópticas superiores aos silicatos, calcogenetos e fluoretos. Contudo, estes vidros apresentam alta energia de fônons, menor estabilidade química e mecânica e são higroscópicos, o que pode constituir um significativo mecanismo de supressão da luminescência devido ao acoplamento de transições dos TR3+ com vibrações de grupos hidroxila. Se por um lado vidros fluoretos podem ser obtidos com baixas energias de fônon e alta estabilidade química, os mesmos são mecanicamente frágeis e apresentam más características termo-ópticas. Para superar estas limitações, vidros oxifluoretos como fluorofosfatos têm sido explorados com a promessa de combinar os méritos dos fluoretos (baixas energias de fônon, baixos índices de refração, extensa janela de transmissão óptica) e dos óxidos (alta estabilidade química e resistência mecânica, maior solubilidade dos TR3+). Do ponto de vista das aplicações, considerando a transmissão e amplificação de sinais em telecomunicação em torno de 1,5 µm, e geração de ação laser de alta potência em torno de 1,0 µm, materiais dopados com Er3+ e Yb3+ estão entre os mais importantes. Neste trabalho apresenta-se a síntese e caracterização estrutural e espectroscópica de novos vidros fluorofosfatos dopados com Er3+ ou Yb3+ e co-dopados com ambos, no sistema composicional 25BaF225SrF2(30-x)Al(PO3)3xAlF3 (20-z)YF3:zTRF3 com x = 20 ou 15, TR = Er3+ e/ou Yb3+ e z = 0,25, 0,5, 1,0, 2,0, 3,0, 4,0 e 5,0 mol%. As amostras foram obtidas pelo método convencional de fusão e resfriamento e caracterizadas por Raman, Ressonância Magnética Nuclear de estado sólido e espectroscopia UV-VIS. Dos estudos por RMN de 19F verificou-se que há uma perda máxima de fluoreto de ~20% nas amostras. Ainda assim, a quantidade remanescente foi suficiente para garantir um ambiente químico favorável às emissões e poucas diferenças foram notadas entre as amostras com 20 e 15 mol% AlF3 contendo a mesma concentração de dopantes. Para o Er3+, tempos de vida do estado emissor 4I13/2 da ordem de 10 ms implicam em altos valores de eficiência quântica (&#951= 85%) e para o Yb3+ tempos de vida do estado emissor 2F5/2 similarmente longos (&#964 = 1,7 ms) foram medidos. Em amostras co-dopadas com 4,0 mol% YbF3 e 0,25, 1,0 e 2,0 mol% ErF3 o decréscimo do tempo de vida do Yb3+ e acréscimo do tempo de vida do Er3+ indicam que a transferência Yb&#8594Er foi eficiente neste sistema. De maneira geral, os resultados indicam que os vidros estudados são potenciais candidatos a aplicações ópticas como as mencionadas acima. / Currently, glasses and glass ceramics doped with trivalent rare earth ions RE3+ represent the most important class of materials for laser and other optical applications in the visible and near-infrared spectral regions. In this context, one of the challenges is to find host matrices that assure good optical quality and optimum performance of the dopant ions (high absorption and emission cross sections, low probability of non-radiative decays, sufficiently long excited state lifetimes), while still maintaining thermal and mechanical stabilities. Among the candidates, phosphate glasses with high capacity for RE3+ dispersion, low refractive index and superior thermo-optical properties than silicate, chalcogenide and fluoride glasses are largely studied. However, phosphates present high phonon energies, lower chemical and mechanical stabilities and they are hygroscopic, which can imply in significant luminescence quenching effects. If on one hand fluoride glasses may be designed with low phonon energies and higher chemical stability, they are frail and present less than ideal thermo-optical properties. In order to overcome these drawbacks, oxyfluoride glasses such as fluorophosphates have been explored with the promise to combine the merits of fluorides (low phonon energies and refractive index, extensive optical window) and of oxides (high chemical stability and chemical resistance, higher solubility of RE3+). From the viewpoint of applications, when it comes to the transmission and amplification of signal in telecommunications around 1.5 µm, and the generation of high power lasers around 1.0 µm, materials doped with Er3+ and Yb3+ are among the favorite. Furthermore, because Yb3+ presents higher absorption cross-section than Er3+ at the preferred excitation wavelength for both these ions (980 nm), the former can act as an efficient sensitizer of excitation energy with subsequent transfer to the latter. We present the synthesis, and structural and spectroscopic characterization of new flurophosphate glasses doped with Er3+ or Yb3+ and co-doped with both, in the compositional system 25BaF225SrF2(30x)Al(PO3)3 xAlF3 (20- z)YF3:zREF3 with x = 20 or 15, RE = Er3+ and/or Yb3+ and z = 0.25, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mol%. The samples were obtained by conventional melt quenching technique and characterized by Raman, solid state NMR and UV-VIS spectroscopy. From the NMR studies of 19F, it was shown that there is a maximum fluoride loss of 20% in the samples. Even so, the remaining quantity was enough to assure a favorable chemical environment to the RE3+ emissions. Little differences were detected between the samples with 20 and 15 mol% AlF3 for the same dopant concentration. For Er3+, lifetimes of the emitting level 4I13/2 of the order of 10 ms result in fluorescence quantum efficiency values (&#951 = 85%), and similarly, for Yb3+, long lifetimes of the excited state 2F5/2 (&#964 = 1,7 ms) were measured. In co-doped samples with 4.0 mol% YbF3 and 0.25, 1.0 and 2.0 mol% ErF3 the decrease in lifetime of Yb3+ and increase in lifetime of Er3+ indicate that the Yb&#8594Er energy transfer is efficient in this system. In general, the results indicate that the studied glasses are potential candidates for optical applications.