Journal De Physique Iii最新文献

{"title":"Interaction of Copper with Dislocations in GaAs","authors":"H. Leipner, R. Scholz, F. Syrowatka, H. Uniewski, J. Schreiber","doi":"10.1051/JP3:1997202","DOIUrl":"https://doi.org/10.1051/JP3:1997202","url":null,"abstract":"The interaction of copper with dislocations was studied in silicon-doped gallium arsenide by means of cathodoluminescence, analytical, and transmission electron microscopy. Several structures of defect complexes or microdefects surrounding the dislocations were found depending on the diffusion temperature and cooling rate. The results could be explained by considering the local nonequilibrium of intrinsic point defects induced by Cu in- or outdiffusion. The appearance of a bright or dark dislocation contrast in the cathodoluminescence pictures is related for different diffusion conditions: i) to the enrichment of copper acceptors at dislocations, ii) to the distribution of silicon-vacancy complexes, and iii) to non-radiative recombination at Cu-As precipitates or clouds of small dislocation loops.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124087009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Réfraction des ondes sonores émises par une torche à plasma","authors":"R. Pauvit, C. D. Izarra, O. Vallée","doi":"10.1051/JP3:1997208","DOIUrl":"https://doi.org/10.1051/JP3:1997208","url":null,"abstract":"Dans cette publication est rapportee l'existence d'un phenomene de cone de silence dans l'axe du jet d'une torche a plasma d'arc qui est mis en evidence par l'application de la transformation en ondelettes sur les enregistrements de l'emission sonore de la torche. Apres une description du comportement dynamique de l'arc electrique, cette observation est justifiee par la refraction des rayons sonores sous l'action des gradients de la vitesse d'ecoulement du gaz en sortie de torche.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132164427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Étude d'un plasma de SF6 hors d'équilibre thermique","authors":"P. André","doi":"10.1051/JP3:1997191","DOIUrl":"https://doi.org/10.1051/JP3:1997191","url":null,"abstract":"L'influence des parametres suivants : temperature de vibration, desequilibre thermique, pression et vapeurs de cuivre sur la composition et la capacite calorifique d'un plasma de SF 6 hors d'equilibre thermique est etudiee. Les effets de ces parametres sur les reactions chimiques et le comportement du plasma sont discutes. Par exemple, nous montrons que la concentration des especes chimiques chargees negativement diminue a mesure que le desequilibre thermique augmente.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128329856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Piezoelectric Ceramics Nonlinear Behavior. Application to Langevin Transducer","authors":"D. Guyomar, N. Aurelle, L. Eyraud","doi":"10.1051/JP3:1997183","DOIUrl":"https://doi.org/10.1051/JP3:1997183","url":null,"abstract":"Des changements importants de comportement sont observes sur des transducteurs de puissance utilisant des ceramiques de type PZT. Une meilleure caracterisation des materiaux piezoelectriques sous hauts niveaux s'avere alors necessaire. En effet, des phenomenes caracteristiques d'un comportement non lineaire tels que le decalage de la frequence de resonance avec hysteresis ou la generation d'harmoniques ont ete observes experimentalement. Ceci se traduit par des effets de saturation du niveau de deplacement de la face avant, une limitation des performances du systeme et un fonctionnement instable. Afin d'interpreter de tels comportements, une theorie non lineaire est proposee. Ce modele a ensuite ete applique a notre structure de transducteur. Une comparaison entre simulations et resultats experimentaux a permis de valider cette nouvelle approche. Les effets de saturation observes ont ete jusqu'a present toujours relies a la variation du coefficient d'amortissement, notre etude a permis de demontrer qu'une autre explication liee aux non linearites etait possible et permettait en meme temps d'expliquer d'autres phenomenes observes.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129910819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"VDF-TrFE Copolymer Pyroelectric Sensor","authors":"P. Bauer, L. Audaire, J. Simonne, F. Bauer","doi":"10.1051/JP3:1997184","DOIUrl":"https://doi.org/10.1051/JP3:1997184","url":null,"abstract":"Une nouvelle generation de matrice infrarouge non refroidie a ete developpee pour la detection d'obstacle dans le cadre de l'application automobile et dans le contexte du programme europeen PROMETHEUS PROCHIP . La detection infrarouge utilise l'effet pyroelectrique dans le copolymere VDF-TrFE. Les senseurs matriciels pyroelectriques a base de VDF-TrFE ont maintenant atteint la maturite d'un produit et peuvent etre consideres comme un systeme complet avec une technologie de detection monolithique directement realisee sur le circuit de lecture de type CMOS. Cet article decrit les etapes principales de l'elaboration d'une matrice dans le plan focal de format 32 x 32 au pas de 100 μm concue pour les applications infrarouges a tres faibles couts. Nous presenterons l'architecture de la matrice, une modelisation complete de la detection pyroelectrique a base de VDF-TrFE ainsi que les performances de la matrice.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116934710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ferroelectric Domain Walls in BaTiO3: Fingerprints in XRPD Diagrams and Quantitative HRTEM Image Analysis","authors":"N. Floquet, C. Valot, M. Mesnier, J. Nièpce, L. Normand, A. Thorel, R. Kilaas","doi":"10.1051/JP3:1997180","DOIUrl":"https://doi.org/10.1051/JP3:1997180","url":null,"abstract":"Une etude de la structure des murs de domaines ferroelectriques dans BaTiO 3 est realisee a travers deux approches complementaires : une approche globale par une methode fine d'analyse des diagrammes de poudre de diffraction des rayons X, et une autre tres locale par une methode quantitative d'analyse des images obtenues par microscopie electronique de haute resolution. Ces deux approches originales convergent vers une description claire des murs de domaines a 90°: c'est une region large de 4-6 nm ou la discontinuite cristallographique est accommodee par des deplacements atomiques irreguliers. Ces resultats montrent que la description structurale theorique communement utilisee pour des calculs d'energies est de loin trop simpliste. Les methodologies developpees, propres a chacune des analyses structurales utilisees, peuvent etre appliquees a l'etude de tout autre materiau ferroelectrique, mais aussi a tout autre materiau cristallise ou des maclages ou interfaces coherentes sont attendues.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126119056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Production of N_2 Radiative States in N_2-H_2 Flowing D.C. Discharge","authors":"S. Popa, L. Hochard, A. Ricard","doi":"10.1051/JP3:1997190","DOIUrl":"https://doi.org/10.1051/JP3:1997190","url":null,"abstract":"La temperature du gaz, le champ electrique et les intensites des bandes de N 2 , deuxieme systeme positif (2 e pos.) et de N 2 + , premier systeme negatif (1 er neg.) ont ete mesures dans une decharge N 2 -H 2 D.C. en ecoulement avec moins de 0,5 % de H 2 . Les variations d'intensites des bandes de N 2 , 2 e pos. et N 2 + , 1 er neg. lorsqu'un peu de H 2 est ajoute a N 2 sont expliquees par un accroissement du champ electrique reduit E/N (N densite du gaz neutre) et par une diminution de la densite de N 2 + .","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125214642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Matériaux diélectriques à base de K2Sr4Nb10O30 présentant des courbes ε'r = f (T) plates avec de hautes constantes diélectriques","authors":"B. Tribotte, G. Desgardin","doi":"10.1051/JP3:1997181","DOIUrl":"https://doi.org/10.1051/JP3:1997181","url":null,"abstract":"Les ceramiques ferroelectriques de type II sont couramment utilisees dans les condensateurs multicouches a forte capacite volumique. Parmi differentes classes concernant la variation de la constante dielectrique en fonction de la temperature, une des plus severes, la X7R, autorise seulement une variation de ±15% de la capacite par rapport a celle a 25 ○C dans un large domaine de temperature, de -55 ○C a +125 ○C. Des etudes recentes ont prouve l'interet de melanger le niobate K2Sr4Nb10O30, de structure de type Bronze Quadratique de Tungstene (BQT), avec des perovskites en faible proportion comme Pb(Mg1/3Nb2/3)O3, pour obtenir des courbes plates e'r = f (T), correspondant a des constantes moyennes superieures a 6000. Pour mettre en evidence le mecanisme conduisant a de telles courbes, nous avons etudie l'influence de l'introduction de differents cations comme Mg2+ ou Pb2+ dans la structure BQT. Dans ce travail, nous montrons que des materiaux a base de K2Sr4Nb10O30, sans presence simultanee de phase perovskite d'apres la diffraction des rayons X, peuvent conduire a des courbes e'r= f (T) a caractere plat.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126996417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of 0.9PMN–0.1PT Dielectric Behaviour in Relation to the Nanostructure","authors":"E. Lattard, M. Lejeune, D. Imhoff, R. Guinebretière, C. Elissalde, P. Abélard","doi":"10.1051/JP3:1997100","DOIUrl":"https://doi.org/10.1051/JP3:1997100","url":null,"abstract":"(1 - x)PbMg1/3Nb2/3O3-xPbTiO3 ceramics with x = 0, 0.1 were prepared with a 12 mol% MgO excess to obtain dense and perovskite phase materials after sintering. The dielectric characterization has revealed that a local polarization appears at a Td temperature largely above the temperature of the maximum of permittivity (Tm, respectively -13 ○C and +36 ○C for x = 0 and 0.1). This phenomena is consistent with the nucleation of polar clusters. Moreover, a dielectric relaxation is observed for 0.9PMN-0.1PT-0.12MgO, in a large frequency range (100 Hz – 1 GHz), which corresponds to a multi-Debye process with broadening of the relaxation time distribution as the temperature decreases. This suggests a nucleation and growth mechanism of polar clusters with decreasing temperature, which can result from the successive transitions of different compositions. This hypothesis was confirmed by the identification of large chemical heterogeneities on a nanometric scale by TEM using two spectroscopy techniques (EDXS and EELS), because of the association of low and high atomic number elements in the materials, different types of equipment and also the simulation of the patterns with standards. In fact, these quantitative analyses have revealed large fluctuations of the local composition around the nominal one: lead and magnesium deficient areas enriched in niobium coexist with nanodomains largely enriched in lead and slightly in magnesium, which the size depends on the titanium content. The origin of these heterogeneities in correlation with the reactions sequences during calcination and sintering is discussed: in particular the addition of titanium contributes, by stabilizing the perovskite phase, to limit the diffusion of lead oxide, which consequently increases the homogeneity of the ceramics. Due to such heterogeneities, the material remains mainly paraelectric up to very low temperatures. This effect can be balanced by the application of a high electric field which induces the growth of the polar clusters by displacement of their interface with the paraelectric matrix and orientation of their polarization in the direction of the electric field which can lead to a macroscopic ferroelectric transition in specific conditions of temperature and electric field intensity. These different mechanisms relax in a frequency range which depends on the temperature and on the amplitude of the electric field.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131103539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Méthode de prédétermination des caractéristiques électromagnétiques de machines á bobinage global à commutation de flux. Application à un actionneur linéaire","authors":"L. Prevond, A. B. Ahmed, B. Multon, J. Lucidarme","doi":"10.1051/JP3:1997189","DOIUrl":"https://doi.org/10.1051/JP3:1997189","url":null,"abstract":"Cet article presente une methode de predetermination des caracteristiques de machines multicellulaires (bobinage global) a commutation de flux (aimants permanents) en tenant compte de la non linearite des materiaux ferromagnetiques. Cette methode allie le calcul numerique par elements finis et le calcul analytique. Cette etude nous a permis, d'une part, d'effectuer une analyse parametrique intrinseque et, d'autre part, de definir les parametres optimaux de la cellule a commutation de flux. La notion de desaimantation est introduite en calculant le champ demagnetisant dans l'aimant. Les calculs effectues, dans le cas d'un actionneur lineaire a commutation de flux, montrent une bonne correlation avec les essais directs.","PeriodicalId":237595,"journal":{"name":"Journal De Physique Iii","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133221254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}