Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / As cerâmicas piesoelétricas estudadas neste trabalho (Pb1,03Zr0,53Ti0,47O3, Pb1,03Zr0,525Nb0,05Ti0,465Fe0,005O3, Pb1,03Zr0,515Nb0,015Ti0,465Fe0,005O3, Pb1,03Zr0,525Nb0,005Ti0,455Fe0,015O3 e Pb1,03Zr0,515Nb0,015Ti0,455Fe0,015O3) foram sinterizadas a 1200oC e 1250oC por 3,5 h a fim de que suas propriedades piesoelétricas fossem investigadas. Nas composições dos PZT obtidas, a matriz e os dopantes empregaram óxidos como matérias primas. As misturas dos óxidos precursores foram calcinadas a 850oC por 3,5 h para obtenção da fase PZT. Os precursores, os pós e os corpos de prova de PZT foram caracterizados quanto às microestruturas, densidades e propriedades físicas. Após a conformação dos pós e a sinterização, os materiais cerâmicos foram polarizados para caracterização de suas propriedades piesoelétricas através de um impedancímetro na faixa de freqüência de 100 KHz a 200 KHz. Os resultados de dispersão de laser dos precursores revelaram aglomeração do óxido de chumbo e óxido de zircônio. As composições calcinadas apresentaram tamanho de partícula na faixa de 0,44 μm a 0,63 μm. As análises de densidade por método de Arquimedes indicaram uma boa densificação dos corpos de prova sinterizados e pouca influência da temperatura de sinterização com uma escala de valores de 95,73 a 97,65% da densidade teórica. As análises de microscopia eletrônica de varredura revelaram que os sinterizados contendo concentrações diferentes de dopantes exibem uma correlação do tipo e teor de dopante com a natureza da fratura, sendo transgranular, quando dopante ferro for predominante e intergranular, quando o dopante Nb for predominante. Também, o aumento da temperatura de sinterização resultou em fratura transgranular independente do tipo e da concentração de dopante, exceto para baixo teor de dopante da composição equimolar, cujos resultados não foram consistentes com a literatura sobre o material. No que diz respeito às propriedades piesoelétricas, revelou-se que a combinação da variação da composição com a temperatura foi favorável para o aumento dos valores da constante dielétrica da formulação equimolar com maior percentual de dopantes. Já o efeito da temperatura com a composição surtiu um efeito muito negativo para os valores de fator de qualidade mecânica da formulação dopada com mais ferro. Para os valores de constante de freqüência da formulação com maior percentagem de nióbio, o efeito da temperatura com a composição gerou um efeito positivo. / The piezoelectric ceramics studied in this work, Pb1.03Zr0.53Ti0.47O3, Pb1.03Zr0.525Nb0.05Ti0.465Fe0.005O3, Pb1.03Zr0.515Nb0.015Ti0.465Fe0.005O3, Pb1.03Zr0.525Nb0.005Ti0.455Fe0.015O3 and Pb1.03Zr0.515Nb0.015Ti0.455Fe0.015O3, were all of them sintered between 1200oC and 1250oC for 3.5h. After that, their piezoelectric properties were investigated. In the present work, oxides were used as raw material in both, matrices and dopants. The mixture of the precursor oxides were calcinaned at 850oC during 3.5h for obtaining the PZT phase. The precursor oxides, the powders and the PZT samples went through characterization tests in order to have their microstructures, densities and physical properties correctly determined. After the powders had been conformed and performed the sinterization process, the PZT ceramics were polarized and their piezoelectric properties determined by using an impedancemeter working in the frequency from 100 KHz to 200 KHz. The obtained results from laser dispersion had revealed agglomeration of lead and zirconium oxide. The calcined samples presented particle sizes from 0.44 μm to 0.63 μm. The density analyses using the Archimedes method indicated a good densification of the sintered samples and a weak influence of the sintering temperature on the obtained density values, whose values ranged from 95.73 to 97.65 % of the theoretical density value. Analysis performed using the scanning electron microscopy technique (MEV) revealed that the sintered samples had showed a correlation between the type and concentration of the dopant with their fracture mode, which were transgranular when Fe prevails over the Nb as dopant, and intergranular, when is the Nb that prevails over the Fe as dopant. By the other side, from increasing the sintering temperature resulted transgranular fractures, independently of which type and content of dopant had been used, except for the equimolar case with relatively low content of dopant, whose results were not consistent with the literature related to this material. About the piezoelectric properties, the results had showed that the combination of the dopant composition with the sintering temperature had brought better values of dielectric constant for the equimolar formulation with more content of dopant. Relating to the mechanical quality factor, from the combination of the dopant composition with the sintering temperature had decreased the factor when Fe prevails over Nb and increased the frequency factor when is the Nb that prevails over the Fe.

Découvert dans les années 1970 sur le site palafitte aujourd’hui immergé du Crêt de Châtillon (lac d’Annecy, Haute-Savoie, France), le four de Sévrier, daté de l’âge du Bronze, est considéré comme un des plus anciens fours de potier d’Europe occidentale. Il incarne l’arrivée d’une nouvelle technologie qui marquera la disparition progressive des modes de cuisson en fosse ou en meule en usage depuis l’invention de la poterie. En cette fin de l’âge du Bronze l’acmé de l’art céramique, représenté par les productions de poteries fines, pouvait donc être lié à l’utilisation d’un tel dispositif. Le caractère unique de cette construction en argile, de dimensions modestes et à parois étonnamment minces, réside dans sa conception modulaire et portable. La découverte publiée en 1975 (Bocquet et Couren 1975) recueille aussitôt un échoeuropéen et près de quarante ans après, elle reste pratiquement sans équivalent. L’utilisation de fours de potier à l’âge du Bronze, dans un contexte occidental, demeure pourtant une question ouverte et depuis les années 80, l’interprétation avancée pour le four de Sévrier alimente régulièrement ce débat. L’objectif de cette thèse de doctorat est de porter un nouveau regard sur cet objet de référence quelque peu voilé par sa célébrité et réexaminer les hypothèses fonctionnelles non encore étudiées. Après une présentation du contexte et de l’historique de la découverte, un premier volet aborde différents aspects de l’objet archéologique: sa morphologie, sa conception, sa restauration, son comportement lors d’expérimentations de cuissons de céramiques, ses traits singuliers qui le rapprochent ou le distinguent des fours de potiers plus tardifs ou des structures d’argile à parois fines diversement interprétées. Notre analyse du four de Sévrier comporte trois volets : a) l’inventaire du matériel découvert sur le Crêt de Châtillon et l’intégration éventuelle d’éléments non pris en compte dans la reconstruction, b) une analyse archéométrique (minéralogie des argiles) portant sur les tessons du four et sur des argiles des gisements situés à proximité du Crêt de Châtillon. Une analyse des changements de phases des argiles cuites en fonction de l’intensité de la température, c) l’évaluation de la température minimale et maximale subie par le four afin de confirmer ou exclure certaines utilisations. L’analyse fonctionnelle du four aborde, en premier lieu, l’hypothèse privilégiée, celle consacrée à la cuisson des poteries. Une méthode expérimentale comparative permet de préciser les avantages et inconvénients de différents procédés de cuisson de poteries noires et cherche à évaluer l’apport technologique supposé avoir été introduit par le four de Sévrier. D’autres alternatives sont abordées, en particulier la fonction culinaire. Cette interprétation est confortée par la découverte d’inédits indices d’usages observés lors de cette étude sur des matériels similaires de même époque et provenance. L’inventaire des structures comparables constitue un autre volet de cette recherche. Elle témoigne de l’usage courant des structures de cuisson en argile de faible épaisseur aux âges du Bronze et du Fer. Leur diffusion géographique s’étend des Balkans à l’Espagne et de la Grande Bretagne à la Grèce. Le recensement d’une famille large et multiforme de dispositifs portables en argile à vocation domestique nous permet de poser les bases d’une typologie et de proposer un scénario d’évolution et d’influences entre des régions parfois très éloignées. / This study focuses on a unique archaeological finding from the Crêt de Châtillon, a late Bronze Age lacustrine village situated on a now submerged island in Lake Annecy (Haute-Savoie, France). The Sévrier kiln is considered to be one of the oldest pottery kiln in Western Europe. Over the years it has become internationally known and still forms the basis of research projects and experiments relating to Bronze Age ceramic technology. It embodies the arrival of a new technology that would mark the gradual disappearance of the open fire or pit firing modes that had been used since the invention of pottery. As such, the acme of ceramic art which marks the end of the Bronze Age, may therefore be related to the use of such a device. The uniqueness of this clay building of modest proportions and surprisingly thin walls, lies in it modular and portable design. The discovery, published in 1975 (Bocquet and Couren 1975) soon received a valuable feedback in Europe and nearly forty years later remains virtually unparalleled. However, the use of pottery kilns in the Bronze Age in a Western context remains an open question. Since the 1980s, several arguments will gradually undermine this interpretation. The purpose of this study is to take a fresh look at this inescapable object, somewhat veiled by its celebrity and review functional hypotheses hitherto not studied. After describing the background and the history of the discovery, we discuss various aspects of the archaeological kiln: morphology, design, restoration, use, experimentations and singular features that approximate or distinguish this furnace from later pottery kilns or thin-walled clay structures wich have been variously interpreted. This analysis of the kiln of Sévrier has been threefolds: (a) an inventory of the findings from the Crêt de Châtillon and a discussion about the integration of many components excluded from the reconstruction ; (b) archaeometric analysis (clay mineralogy) of the kiln and the clay deposits located near the site and (c) identification of the changing phases in clays, subjected to high temperatures and determination of the temperature experienced by the furnace. The functional analysis, reviews different hypotheses : (a) pottery firing : a comparative experimental method that aims to highlight the benefits and disadvantages of different processes to produce black pottery. The purpose is to underscore the technological contribution assumed to have been introduced by the Sévrier kiln. (b) Other functional alternatives will be discussed, especially the culinary function. This interpretation is supported by the discovery of unprecedented indices discovered during this study. The inventory of comparable structures is another aspect of this research. The relatively widespread use of such thin-walled clay structures during the Bronze and Iron ages is highlighted. Their geographical distribution extends from the Balkans to Spain and from Great Britain to Greece. The census of a multiform family of domestic portable clay ovens allows us to propose a new typology and a scenario of diffusion between regions sometimes very remote, completes this new outlook and draw new perspectives for the research.

La transition entre le Sylvicole moyen et le Sylvicole supérieur, vers l’an 1000 de notre ère, correspond à un moment de bouleversements technologiques dans le Nord-Est américain. En Abitibi-Témiscamingue, il s’agit d’une transition entre les cultures Laurel orientale et Blackduck orientale. La poterie blackduckienne semble avoir été rapidement adoptée par les groupes laureliens, sans phase transitoire apparente. Ce mémoire s’intéresse aux technologies céramiques employées par les populations des cultures Laurel et Blackduck en Abitibi-Témiscamingue et cherche à comprendre s’il existe de la continuité ou de la discontinuité entre les deux ensembles. Plus précisément, il est question de voir comment se manifeste la transition entre les deux cultures et comment la technologie céramique permet de caractériser cette transition. Pour ce faire, quatre sites ont été sélectionnés de part et d’autre de la ligne de partage des eaux entre : le site Bérubé (DdGt 5), le site du lac Opasatica (DaGt-4), le site Nault (ClGt-2) et le site Léo-Guay (ClGt-3). Les vases laureliens et blackduckiens provenant de ces sites ont fait l’objet d’une analyse visuelle par attributs morphostylistiques et d’une analyse par attributs technologiques selon les données tomodensitométriques fournies par l’Institut national de recherche scientifique Eau-terre-environnement (INRS-ETE), à Québec. Puisque l’utilisation de la tomodensitométrie dans l’analyse technologique de la céramique est plutôt récente, ce mémoire se veut une contribution modeste, mais originale au développement de cette approche. À la lumière des analyses effectuées, la transition technologique s’est opérée plus lentement que la transition morphostylistique. Les potiers auraient graduellement développé un nouveau savoir-faire, par contact et par expérimentation, produisant un vase mieux adapté à la cuisson des aliments. / The transition between the Middle Woodland and Late Woodland periods, towards 1000 CE, corresponds to a moment of technological upheavals in the American Northeast. In Abitibi-Temiscamingue, it takes the form of a transition between the Eastern Laurel and Eastern Blackduck cultures. Blackduck pottery seems to have been quickly adopted by Laurel groups, with no apparent transitional phase. This masters’ thesis relates to the ceramic technologies employed by the populations of Laurel and Blackduck cultures in Abitibi-Temiscamingue and explors the continuity or lack of continuity between the two groups. More precisely, I ask how this transition between two cultures manifests itself and how ceramic technology allows us to characterize this transition. To that end, four sites have been selected on both sides of the watershed divide between: the Bérubé site, (DdGt-5), the lake Opasatica’s site (DaGt-4), the Nault site (ClGt-2) and the Léo-Guay site (ClGt-3). The Laurel and Blackduck vessels originating from these sites were subjected to a visual analysis using morphostylistic attributes and an analysis using technological attributes based on tomodensitometric data supplied by the Institut National de Recherche Scientifique - Eau Terre Environnement (INRS-ETE) research center located in Quebec City. Since the use of tomodensitometry in ceramic technological analysis is rather recent, this thesis seeks to be a modest but original contribution to the development of this approach. Based on our analyses, the technological transition happened more slowly than the morphostylistic transition. The potters would have gradually developed a new craftmanship, by contact and by experimentation, producing vessels better suited to cooking food.