Showing papers by "ICM Partners published in 1986"

Perovskites oxynitrurees utilisees en tant que materiaux dielectriques

Abstract: Introduction of nitrogen into the anionic network of a ABX3 type perovskite leads to a new family of materials. The consequent increase of charges has to be compensated with cationic substitutions. The up to now obtained materials have a cubic cell and we noticed a statistical disorder between oxygen and nitrogen, they are characterized by high and stable dielectric constants in a large scale of temperature or frequency. Perovskites usually used in multilayer ceramic capacitors have to be sintered in an oxydizing atmosphere that leads to the use of noble inner electrode metals. On the contrary, the present materials are stable at high temperature under neutral or reducing atmosphere. Les matériaux diélectriques pour condensateurs céramiques sont constitués essentiellement d'oxydes de type pérovskite. Ces matériaux doivent être frittes obligatoirement dans une atmosphère oxydante. Dans le cadre de l'élaboration de condensateurs multicouches, ceci limite les métaux utilisés comme électrodes internes au palladium ou aux alliages palladium argent. L'idée directrice des recherches entreprises est d'obtenir des matériaux diélectriques azotés ou oxyazotés qui ne nécessitent plus pour leur frittage une atmosphère oxydante mais neutre, constituée d'azote par exemple. Cela permet d'utiliser des métaux ou alliages non nobles. Les composés nitrurés qui sont stables sous atmosphère d'azote ou d'ammoniac remplissent cette condition. L'introduction d'azote dans le réseau anionique d'un oxyde provoque une augmentation de charge négative qui nécessite parallèlement dans le réseau cationique le remplacement d'un élément de degré d'oxydation donné par un autre de degré d'oxydation plus élevé. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19861139

The law of migrants.

Abstract: While it is acknowledged that international migration law is attracting increased interest this law merely describes the conditions of admission sojourn employment and exit of migrants thus amounting in many respects to a restatement of the law of aliens considered in a different perspective. This article concentrates on the humanitarian aspects of migration law in an attempt to determine the possibility of joint promotion and dissemination of human rights international humanitarian law refugee law law of migrants and relief law. Refugees are protected by a series of international legal instruments both universal and regional which are complemented if need be by resolutions of the competent bodies. 2 reasons why the law of migrants deserves to be highlighted and developed are: 1) we have seen that the characteristic aspects of migration are either ignored or only partially taken into account by existing law and 2) it is important that individuals should be protected in every circumstance. There exists a relatively narrow basis for joint action; since this must be built on points of convergence a preliminary step consists of identifying this common denominator. The forms which joint action may take can be less structured and reflected in the individual practice of each organization The sine qua non of successful joint action is an awareness of the enterprises ultimate goal: to assure in every circumstance better protection for human beings whatever their legal status may be.

Nouveaux materiaux dielectriques a base de perovskites au plomb pour condensateurs multicouches de type ii

Abstract: The pyrochlore phase always observed besides the lead perovskites, by direct synthesis from the oxides, in the diagrams Pb(Mg, ,,Nb_ .,)0,l/2l/23 a n d l/32/33~'l/32n'3 w a s e l i m l n £ d. \" results in higher dielectric constants greater than 15000 for sintering temperatures as low as 1000°C. The addition of alcaline salts in small amounts allows to increase the dielectric constants and to decrease the sintering temperature.