Given rising concern over elevated lead in drinking water in the aftermath of the Flint Water Crisis, forthcoming revisions to the U.S. EPA Lead and Copper Rule (LCR), and federal funding designated for replacing lead service lines, lead-tin solder corrosion control will become increasingly important. Lead-tin solder is often a dominant source of lead in drinking water for homes built before 1986 and has been the source of several recent high-profile water lead contamination events. This dissertation advances fundamental understanding of lead-tin solder corrosion by demonstrating that 1) elevated nitrate in water can trigger severe solder corrosion associated with very high LCR action level exceedances, 2) spallation of metallic solder to water is a source of lead contamination, 3) zinc orthophosphate offers superior corrosion control to mitigate nitrate attack, and 4) free chlorine can inhibit solder corrosion by electrochemical reversal. These principles were also applied to an exemplary related problem of lead contamination of food stored in tin cans. The conventional understanding is that lead-tin solder corrosion is worsened by low pH, low alkalinity, and elevated chloride relative to sulfate, but a utility that recently switched to a source water previously classified as non-corrosive suffered severe contamination from lead solder. The incident was characterized by the detachment of large chunks of metallic, lead-bearing solder particles from copper pipe joints that sometimes clogged aerators of consumers' faucets. It also caused a 90th percentile lead level of 131 ppb, which was much higher than reported for the 2001-2004 Washington D.C. lead crisis (79 ppb) or the 2014- 2016 Flint, MI water lead crisis (29 ppb). An exhaustive investigation of possible causes eventually revealed a strong correlation (r2=0.79) between seasonal fluctuations in surface water nitrate levels and the 90th percentile lead. The association of high lead with nitrate was unambiguously proven in bench-scale experiments using both copper coupons with new 50:50 lead-tin solder and harvested pipes with aged solder (extracted from a home with ongoing lead release issues) that replicated the characteristic spallation of solder particles (up to 7-mm in length) to water. Lead levels were occasionally >1,000 ppb in homes and >100,000 ppb in the bench experiments with harvested pipe after exposure to high nitrate above 8 mg/L. This finding is especially concerning given that nitrate is not currently identified as a factor affecting solder corrosion in EPA corrosion control guidance and source water contamination by nitrate is increasingly problematic. It was critically important to identify the mechanism by which nitrate caused solder spallation. Analysis of lead-tin solder surfaces in the bench-scale tests and harvested pipes indicated that nitrate preferentially attacked tin in the solder alloy. Nitrate severely detinned solder alloys > 40% tin by weight, causing cracking and detachment of metallic chunks of lead-tin solder from copper surfaces in a matter of weeks. Pure lead and alloys with less than 30% tin corroded more uniformly in the presence of nitrate and were not subject to spallation. Nitrate is reduced to a combination of ammonia and other nitrogenous compounds via reduction reactions that drove lead-tin solder corrosion at the anode. Nitrate also caused 1.3 times more metal weight loss by corrosion than could be explained by Faraday's law even in short-term 32-hour experiments, consistent with a previously identified "chunk effect" and anomalously high tin anode weight loss in nitrate solutions. This severe solder spallation mechanism has never been reported previously in drinking water environments and seems to be unique to nitrate for high tin-content alloys. This discovery also raises concerns about the possibility of pipe joint failures using lead-free tin-based solders that became more commonplace after the federal ban on lead solder in 1986. Common corrosion control strategies, including the use of phosphate corrosion inhibitors, failed to adequately reduce 90th percentile lead levels at the utility affected by runoff water with high nitrate after 6 months of application. Studies using new lead-tin solder and harvested pipes with aged solder demonstrated that zinc orthophosphate outperformed orthophosphate in controlling corrosion in high nitrate water and reduced lead release by 82-90% compared to phosphate alone or no inhibitor. The benefits of zinc orthophosphate improved with time and the dose of zinc delivered to the pipes. When zinc orthophosphate was applied at the water treatment plant, the 90th percentile lead levels in the affected community fell below the action level within 6 months. Analysis of the pipe scale demonstrated that zinc orthophosphate works by coating the interface usually subject to intense galvanic corrosion between copper and solder. Disinfectants may also play a role in controlling lead contamination from solder. Two water utilities in the Pacific Northwest experienced lead action level exceedances for decades due to solder corrosion while using the same source water with chloramine disinfectant. After one utility switched to a similar water source using free chlorine disinfectant, lead release dropped to low levels within months. This was consistent with laboratory experiments conducted at the second utility more than three decades ago that indicated much lower lead release using free chlorine versus chloramine using the water utility's source water. There was previously no explanation for the benefits from free chlorine, but it was recently demonstrated that chlorine can cause electrochemical reversal of a copper-lead pipe galvanic cell, which dramatically reduced lead release to water. It was hypothesized that a similar reaction could occur for lead-tin solder as well. This was confirmed when lead-tin solder and copper connections exposed to 4 mg/L free chlorine in circulating rigs experienced electrochemical reversal in some waters over a period of weeks. The electrochemical reversal was accompanied by dramatic decreases in lead release, concomitant with the formation of insoluble lead (IV) oxide scale. In some situations where traditional corrosion inhibitors are not effective, it is possible that electrochemical reversal due to free chlorine may control lead solder corrosion, either unintentionally or purposefully. This new understanding of nitrate's ability to exacerbate lead contamination from lead-tin alloys in drinking water was then extended to concerns about lead contamination of food stored in tin-plated cans. Fruits and their juices can contain nitrate, and if lead is present in the tin plating, the resulting corrosion is predicted to cause significant contamination. Twenty-one brands of canned pears from across the U.S. were assessed for lead content, and one brand was found to contain 2-3 times higher lead in the fruit (average=14 ppb, max=38 ppb) and syrup (average=7 ppb, max=15 ppb) than other brands. The brand of cans with higher lead in the fruit also had higher levels of lead in the can materials: surface lead levels in the interior tin-plate was 0.1% by mass on average (max=0.60%) and 7.5% by mass on average (max=29%) in the interior seam, which is up to 146 times the 0.2% value advised in FDA guidelines for lead in food-contact surfaces. Follow-up testing with three brands of canned pears confirmed lead levels in the syrup were also associated with higher levels of ammonia in the juice—ammonia is a reaction product of nitrate corrosion of tin in the can. To confirm that the can material was the source of the lead contamination, the pear cans were emptied and then refilled with a variety of synthetic solutions containing up to 50 mg/L NO3-N. The higher nitrate levels always formed ammonia and were associated with higher lead release in some cases. The use of lead-tin alloys (either lead-bearing tin-plate or solder) in unlined canned goods with solutions known to contain nitrates can create unnecessary lead exposure for consumers. This dissertation provides novel insights into lead-tin solder corrosion with profound implications for water lead contamination, the integrity of potable water infrastructure, and corrosion control strategies in potable water. Rising concerns about nitrate contamination of source waters underscore the importance of understanding these effects on lead and public health. As illustrated by the application of these principles to lead contamination of tin-lined fruit cans, the results may also enhance understanding of corrosion of tin-based materials in electronics, museum artifacts, electrochemical water treatment, and in the automotive and aerospace industries. / Doctor of Philosophy / Given rising concern over elevated lead in drinking water in the aftermath of the Flint Water Crisis, forthcoming revisions to the U.S. EPA Lead and Copper Rule (LCR), and federal funding designated for replacing lead service lines, the issue of lead-tin solder corrosion control will become increasingly important. Lead-tin solder is often a dominant source of lead in drinking water for homes built before 1986 and has been the source of several recent high-profile water lead contamination events. This dissertation advances the fundamental understanding of lead-tin solder corrosion by demonstrating that 1) high source water nitrate levels can trigger severe solder corrosion associated with elevated lead release in drinking water, 2) detachment (i.e., spallation) of metallic solder to water is a source of lead contamination, 3) zinc orthophosphate offers superior corrosion control to mitigate nitrate attack, and 4) free chlorine disinfectant can inhibit solder corrosion by electrochemical reversal. These principles were also applied to an exemplary related problem of lead contamination of food stored in tin cans. It is understood that lead-tin solder corrosion can be affected by water chemistry, but a utility that recently switched to a new source water previously classified as non-corrosive was surprised to discover severe water lead contamination from solder. The contamination was characterized by the detachment of large chunks of lead-bearing solder particles from copper pipe joints that sometimes clogged aerators of consumers' faucets. It also caused a 90th percentile lead level of 131 ppb, a level much higher than reported for the 2001-2004 Washington D.C. lead crisis (79 ppb) or the 2014-2016 Flint, MI water lead crisis (29 ppb). The presence of such large chunks of lead-bearing solder is contrary to the belief that water lead contamination occurs by the dissolution of lead rust from solder. An exhaustive investigation of possible causes eventually revealed that lead release in this community was strongly related to seasonal fluctuations in surface water nitrate levels. The association of high lead with nitrate was unambiguously proven in experiments using both copper coupons with new 50:50 lead-tin solder and harvested pipes with aged solder that had been extracted from a home with ongoing lead release issues, which replicated the characteristic spallation of solder particles (up to 7-mm in length) to water. Lead levels were occasionally >1,000 ppb in homes and >100,000 ppb in the bench experiments with harvested pipe after exposure to high nitrate above 8 mg/L. These levels of water lead contamination are amongst the highest ever recorded. This discovery is especially concerning given that nitrate is not currently identified as a factor affecting solder corrosion in EPA corrosion control guidance and source water contamination by nitrate is increasingly problematic. It was critically important to better understand the mechanism by which nitrate caused solder spallation. Analysis of lead-tin solder surfaces in the bench-scale tests and harvested pipes indicated that nitrate preferentially attacked tin in the solder alloy. Nitrate is reduced to a combination of ammonia and other nitrogenous compounds while contributing to lead-tin solder corrosion at the anode. Nitrate severely degraded solder alloys with >40% tin by weight, causing cracking and detachment of metallic chunks of lead-tin solder from copper surfaces in a matter of weeks. Pure lead and alloys with less than 30% tin corroded more uniformly in the presence of nitrate and were not subject to spallation. Nitrate corrosion also caused 1.3 times more water contamination than predicted by conventional chemical reactions that do not consider spallation, even in short-term 32-hour experiments. This severe solder spallation mechanism has never been reported previously in drinking water environments and at present seems to be unique to nitrate for solder alloys with high tin content. This discovery also raises concerns about the possibility of pipe joint failures, and associated pipe bursting and water damage, when using lead-free tin-based solders that became more commonplace after the federal ban on lead solder in 1986. Common corrosion control strategies, including the use phosphate corrosion inhibitors, failed to adequately reduce 90th percentile lead levels at the utility affected by runoff water with high nitrate after 6 months of application. Studies using new lead-tin solder and harvested pipes with aged solder demonstrated that zinc orthophosphate outperformed orthophosphate in controlling corrosion in high nitrate water, reducing lead release by 82-90% compared to phosphate alone or no inhibitor. The benefits of zinc orthophosphate improved with time and the dose of zinc delivered to the pipes. When zinc orthophosphate was applied at the water treatment plant, the 90th percentile lead levels in the affected community fell below the action level within 6 months. Analysis of the pipe scale demonstrated that zinc orthophosphate works by coating the interface usually subject to the most intense galvanic corrosion between copper and solder. Disinfectants used to kill bacteria in drinking water may also play a role in controlling lead contamination from solder. Two water utilities in the Pacific Northwest experienced lead action level exceedances for decades due to solder corrosion while using the same source water with chloramine disinfectant. After one utility switched to a similar water source using free chlorine disinfectant, lead release dropped to low levels within months. This was consistent with results from a laboratory study conducted more than three decades ago at the second utility that indicated much lower lead release using free chlorine versus chloramine using this water utility's source water. There was previously no explanation for the benefits from free chlorine, but it was recently demonstrated that chlorine can control lead pipe corrosion by reversing normal electrochemical reactions which dramatically reduced lead release to water. It was hypothesized that chlorine could have a similar effect for lead-tin solder as well. That hypothesis was confirmed when lead-tin solder and copper connections exposed to 4 mg/L free chlorine in circulating rigs experienced electrochemical reversal in a synthesized version of this water within weeks. The electrochemical reversal was accompanied by dramatic decreases in lead release, along with the formation of protective lead (IV) oxide pipe scale. These unexpected benefits of free chlorine may help explain why some water utilities with water normally considered corrosive have not been experiencing lead solder corrosion problems or lead action level exceedances. This new understanding of nitrate's ability to exacerbate lead contamination from lead-tin alloys in drinking water was then applied to concerns about lead contamination of food stored in tin-plated cans. Fruits and their juices can contain nitrate, and if lead is present in the tin plating, the resulting corrosion is predicted to cause significant contamination. Twenty-one brands of canned pears from across the U.S. were assessed for lead content, and one brand was found to contain 2-3 times higher lead in the fruit (average=14 ppb, max=38 ppb) and syrup (average=7 ppb, max=15 ppb) than other brands. The brand of cans with higher lead in the fruit also had higher levels of lead in the can materials: surface lead levels in the interior tin-plate was 0.1% by mass on average (max= 0.60%) and 7.5% by mass on average (max=29%) in the interior seam, which is up to 146 times the 0.2% value advised in FDA guidelines for lead in surfaces that contact food. Follow-up testing with three brands of canned pears confirmed lead levels in the syrup were also associated with higher levels of ammonia (a reaction product formed by nitrate corrosion of tin in the can) in the juice. To confirm that the can material and high levels of nitrate in the original food contributed to the lead contamination, the pear cans were emptied and then refilled with a variety of synthetic solutions containing up to 50 mg/L nitrate. The higher levels of nitrate always formed ammonia and were associated with higher lead release in some cases. The use of tin alloys (either lead-bearing tin-plate or solder) to package acidic food containing nitrate can create unnecessary lead exposure for consumers. This dissertation provides novel insights into lead-tin solder corrosion with profound implications for water lead contamination, the integrity of potable water infrastructure, and corrosion control strategies in potable water. Rising concerns about nitrate contamination of source waters underscore the importance of better understanding these effects on lead and public health. As illustrated by the application of these principles to lead contamination of tin-lined fruit cans, these results may also enhance understanding of corrosion of tin-based materials in electronics, museum artifacts, electrochemical water treatment, and in the automotive and aerospace industries.

Clay minerals have widespread application in industry and play an important role in plant life (2, 17). It is the adsorptive capacity of clay which determines largely its importance to man (2). The purpose of this investigation is to interpret the mechanism of adsorption of the phosphate anion by the two clay minerals montmorillonite and kaolinite. This particular system was singled out for two reasons: 1. It has agricultural significance. 2. It is believed that if the particular phosphate adsorption mechanism is understood it will aid in an understanding of many other adsorption phenomena associated with clay.

An economical process for the elimination of nutrients to receiving waters.is a major problem now facing modern wastewater treatment. The purpose of this investigation was to determine the feasibility of soluble phosphate removal in a flyash contact system. The investigation consisted of experiments involving batch adsorption studies and continuous flow studies. Removal kinetics and relationships between contact time, “t” , and flyash concentration, “D_f”, were evaluated using batch adsorption techniques. Of the two flyash samples tested the high alumina content flyash exhibited the best rate of phosphate removal. The high alumina content flyash yielded an average removal capacity of 2.47 x l0⁻⁴ grams of phosphorus per gram of flyash, whereas the low alumina content flyash yielded an average capacity of only 1.61 x 10⁻⁴ grams of phosphorus per gram of flyash. Continuous flow operations were conducted using both types of flyash so as to observe the removal in an actual process situation. The phosphate removal was concluded to be both physical and chemical in nature, with two removal mechanisms predominating. The primary physical mechanism involved the phosphate adsorption on the alumina surface found in the flyash. The chemical removal mechanism was postulated to be the precipitation of phosphate as Mg₃(PO₄)₂ and Ca₃(PO₄)₂ at pH levels above 8.0. / Master of Science

no abstracts provided by author / Ph. D.

Ce travail est consacré à l’élaboration de luminophores à base de polyphosphates d’ions alcalins et de terres rares, stœchiométriques ou activés en ions Eu3+ et Sm3+, émetteurs de fluorescence sous excitation VUV. Ces matériaux, de formulation LixNa1-xY1-yEuy(PO3)4 (x = 0 ; 0,25 ; 0,5 ; 0,75 ; 1 et 0,01 ≤ y ≤ 1), LixNa1-xLa(PO3)4 : 5 % Eu3+ (x = 0 ; 0,1 ; 0,2 ; 0,8 ; 0,9 ; 1), NaxK1-xLa(PO3)4 : 5 % Eu3+ (x = 0 ; 0,1 ; 0,2 ; 0,8 ; 0,9 ; 1) et LixNa1-xSm(PO3)4 (x = 0 ; 0,5 ; 1), ont été synthétisés par voie céramique et caractérisés principalement par diffraction des rayons X, spectroscopies infrarouge et Raman et analyses thermiques. Les analyses physico-chimiques et optiques, notamment grâce aux propriétés de sonde structurale de l’ion Eu3+, démontrent que la substitution croisée des ions alcalins Li+, Na+ et K+ n’est possible que dans une proportion relativement faible, ce qui lié aux différences de structures cristallographiques de ces matériaux. L’analyse des données spectroscopiques de l’ion Eu3+ selon la théorie de Judd et Ofelt confirme le lien étroit existant entre les propriétés optiques et structurales dans ces matériaux. Les spectres d’excitation sont caractérisés par une bande intense localisée dans le domaine VUV, respectivement due au mécanisme de transfert de charge Y3+-O2- et Eu3+-O2- dans les phases à l’yttrium dopées en ions Eu3+ et aux bandes 4f-5d pour les matériaux concentrés en ions Sm3+. Les matériaux concentrés en ions Eu3+ et Sm3+ sont émetteurs d’une intense fluorescence rouge et orange respectivement, démontrant l’absence d’extinction par concentration. / This work is devoted to the development of phosphors based on polyphosphates of alkaline and rare earth ions, stoichiometric or activated with Eu3+ and Sm3+ ions, considered as light emitters under VUV excitation. These materials, with formula LixNa1-xY1-yEuy(PO3)4 (x = 0; 0.25; 0.5; 0.75; 1 and 0.01 ≤ y ≤ 1), LixNa1-xLa(PO3)4 : 5 % Eu3+ (x = 0; 0.1; 0.2; 0.8; 0.9; 1), NaxK1-xLa(PO3)4 : 5 % Eu3+ (x = 0; 0.1; 0.2; 0.8; 0.9; 1) and LixNa1-xSm(PO3)4 (x = 0; 0.5; 1), were synthesized in the solid state and characterized mainly by X-ray diffraction, infrared and Raman spectroscopies and thermal analysis. Physical-chemical and optical analyses, in particular using the Eu3+ ion as a structural probe, show that the cross-substitution of Li+, Na+ and K+ alkaline ions is possible only in a relatively small proportion, which is linked to the differences in crystallographic structures of these materials. The analysis of the Eu3+ ion spectroscopic data according to Judd and Ofelt theory confirms the close link between optical and structural properties in these materials. Excitation spectra are characterized by an intense band localized in the VUV domain, respectively due to the charge transfer mechanism Y3+-O2- and Eu3+-O2- for the Eu3+ doped yttrium materials and to the 4f-5d inter-configuration for the Sm3+ concentrated materials. Materials concentrated in Eu3+ and Sm3+ ions emit intense red and orange fluorescence respectively, demonstrating the absence of concentration quenching.

Ce travail est consacré à l’étude cristallographique et aux propriétés électrochimiques et optiques de phosphates et fluorophosphates de cadmium. L’exploration du système NaF – CdO – NaPO3 a mis en évidence un nouveau fluorophosphate de formule Na2CdPO4F et a permis de reconsidérer le polymorphisme du phosphate NaCdPO4. Les structures cristallines de ces deux phases ont été résolues grâce à des données de diffraction des rayons X, à partir de matériaux obtenus sous forme pulvérulente par voie céramique. La caractérisation du fluorophosphate Na2CdPO4F a également menée par spectroscopie infrarouge, diffusion Raman et Résonance Magnétique Nucléaire. L’étude électrochimique, menée sur des solutions solides de type Na2(Cd/Mn)PO4F, a révélé que la présence simultanée de deux cations divalents était bénéfique pour l’amélioration des taux de sodation/désodation. Les propriétés de luminescence des matériaux NaCdPO4 et Na2CdPO4F dopés en ions Eu3+, ion émetteur d’une fluorescence rouge, sont étroitement corrélées aux propriétés structurales. Certaines formulations de type NaCdPO4 : Eu3+ sont intéressantes en vue d’une application comme composante rouge dans des dispositifs d’émission de lumière. L’étude du système LiF – CdO – NaPO3 a révélé l’existence d’un fluorophosphate inédit de formule Li4Na41Cd30P30O117F20. Sa structure cristalline, déterminée sur monocristal, est caractérisée par la présence d’une entité inédite PO3F2, où le phosphore admet une coordinence 5. / This work is devoted to the crystallographic study and the electrochemical and optical properties of cadmium phosphates and fluorophosphates. The investigation of the NaF - CdO - NaPO3 system revealed a new fluorophosphate of formula Na2CdPO4F and the polymorphism of the phosphate NaCdPO4. The crystal structures of these two phases were solved using XRD powder diffraction data, from materials obtained by a ceramic route. The characterization of the fluorophosphate Na2CdPO4F was also carried out by infrared spectroscopy, Raman scattering and Nuclear Magnetic Resonance. The electrochemical study, carried out on solid solutions of the Na2(Cd/Mn)PO4F type, revealed that the simultaneous presence of two divalent cations was beneficial for the improvement of the sodation/desodation rates. The luminescence properties of the red emitters NaCdPO4: Eu3+ and Na2CdPO4F: Eu3+ are closely correlated with the structural properties. Some formulations of NaCdPO4: Eu3+ type are of interest for application as red components in light emitting devices. The study of the LiF - CdO - NaPO3 system revealed the existence of an original fluorophosphate of formula Li4Na41Cd30P30O117F20. Its crystal structure, determined on monocrystal, is characterized by the presence of a novel entity PO3F2, where the phosphorus admits a five-fold coordination.

L’étude des inositols hautement phosphorylés est un domaine en pleine expansion. Leurs essors ne datent que d’une dizaine d’années, mais de nombreuses fonctions y sont déjà associées bien qu’ils en restent sans doute encore à découvrir. Les inositols phosphates (incluant les inositols hautement phosphorylés) s’inscrivent dans un cycle dont le représentant le plus connu est inositol 1,4,5-trisphosphate (Ins(1,4,5)P3). De ce fait, chaque inositol phosphate influence directement ou indirectement les autres membres de ce cycle.<p>Au cours de la thèse, nous avons pu éclaircir une controverse de la littérature sur la voie de synthèse des inositols hautement phosphorylés. Grâce à un modèle de cellules MEF (mouse embryonic fibroblast) n’exprimant aucune des trois isoformes de l’inositol 1,4,5-trisphosphate 3-kinase (ITPK) et à l’aide des cellules souches déficientes pour l’inositol polyphosphate multikinase (IPMK), nous avons pu révéler le rôle majeur de cette dernière dans la génération de l’InsP5 et l’InsP6.<p>Dans un second temps, nous avons comparé la neurogenèse de ces cellules souches IPMK+/+ et IPMK-/- mises dans un milieu de différenciation par défaut (DDM). Les cellules dépourvues de l’IPMK entrent en apoptose et se différencient très difficilement en progéniteurs neuronaux et en neurones. Afin de comprendre le mécanisme sous-jacent pouvant expliquer ce phénomène, nous avons réalisé des PCRs quantitatives qui ont montré une sous expression des gènes du neuroectoderme ainsi qu’une augmentation de l’expression de gènes du mésoderme dans les cellules IPMK-/- par rapport aux cellules IPMK+/+. De plus, nous avons découvert que le phénomène d’apoptose observé au cours de la différenciation en DDM était spécifique à ce milieu. En effet, nous n’avons pas pu mettre en évidence un tel phénomène au cours de la différenciation en corps embryoïdes.<p>Durant la thèse, nous avons également développé des anticorps dirigés contre l’isoforme B de l’inositol 1,4,5-trisphosphate 3-kinase et contre la forme native de l’IPMK. Ceci nous a permis de mener à bien nos expériences et d’ouvrir de futures perspectives de recherche.<p>En conclusion, nous avons démontré le rôle majeur de l’IPMK dans la voie de synthèse des inositols hautement phosphorylés. Nous avons également découvert que l’IPMK est très importante pour la survie de ces cellules souches en cours de différenciation et nous avons également introduit une nouvelle fonction pour l’IPMK dans la neurogenèse.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

Ce travail est consacré au développement de luminophores de type orthophosphates GdPO4 et ultraphosphates YP5O14 activés par les ions Yb3+, Er3+ et Tm3+, synthétisés sous forme de poudres par voie solvothermale (orthophosphates) et par méthode de flux (ultraphosphates), aptes à émettre une lumière blanche par up-conversion IR-visible. Des orthophosphates GdPO4 : Eu3+ ont également été élaborés par chimie douce afin d’établir le lien entre propriétés optiques et propriétés morphologiques. Les conditions opératoires optimales ont été déterminées. La caractérisation des matériaux obtenus a été menée d’un point de vue structural, par DRX et IR, et morphologique, par MEB. Les orthophosphates GdPO4 ont été obtenu sous forme de nanobâtonnets en condition acide et nanodisques en milieu basique. L’étude des propriétés de luminescence des orthophosphates GdPO4 : Eu3+ a montré que les nanodisques présentent de meilleures performances que les nanofils. L’utilisation de la théorie de Judd et Ofelt a permis de relier les propriétés optiques, structurales et morphologiques de ces orthophosphates. Sous excitation IR, un processus de up-conversion est mis en évidence dans les phosphates YP5O14 : Yb3+, Er3+, Tm3+ et GdPO4 : Yb3+, Er3+, Tm3+. Les processus de transfert d’énergie Yb3+ → Er3+, Tm3+, présidant à l’émission d’une lumière blanche, ont été étudiés. La morphologie des matrices phosphatées a une influence notable sur les propriétés de up-conversion. Ainsi, l’orthophosphate GdPO4 : Yb3+, Er3+, Tm3+ obtenu sous forme de nanobâtonnets en milieu acide est un candidat prometteur pour la lutte anti-contrefaçon. / This work deals with the development of polycrystalline Yb3+/Er3+/Tm3+ activated phosphate phosphors of formula GdPO4 (orthophosphates) and YP5O14 (ultraphosphates) elaborated by a solvothermal method (GdPO4) and by a flux method (YP5O14), able to emit a white light by a IR-visible up-conversion process. Eu3+ doped GdPO 4 samples were also elaborated by soft chemistry in order to establish the relation between optical and morphological properties. The elaborating conditions were determined. The characterization of these materials has been carried out using X-ray diffraction, IR spectroscopy and SEM analysis. GdPO4 orthophosphates were obtained as nanorods and nanoparticles under acidic and basic media respectively. GdPO4 : Eu3+ orthophosphate nanoparticles show better optical performances than nanorods. Moreover, the optical, structural and morphological properties of orthophosphate materials were corroborated by the Judd and Ofelt theory. Under an IR excitation, an up-conversion mechanism is evidenced in YP5O14 : Yb3+, Er3+, Tm3+ and GdPO4 : Yb3+, Er3+, Tm3+ activated phosphates. Yb3+ → Er3+, Tm3+ energy transfer processes leading to a white light emission are investigated. The up-conversion properties are considerably influenced by the morphology of the phosphates. The GdPO4 : Yb3+, Er3+, Tm3+ orthophosphate obtained as nanorods in an acidic medium is a promising candidate for anticounterfeit labels.

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