Consequences of anisotropy in electrical charge storage: application to the characterization by the mirror method of TiO2 rutile

This article is devoted first to anisotropic distributions of stored electric charges in isotropic materials, second to charge trapping and induced electrostatic potential in anisotropic dielectrics. On the one hand, we examine the case of anisotropic trapped charge distributions in linear homogeneous isotropic (LHI) insulators, obtained after an electron irradiation in a scanning electron microscope. This injection leads to the formation of a mirror image

Adhesion forces due to nano-triboelectrification between similar materials

Contact electrification and triboelectrification are well-known in the case of dissimilar materials, however the case of charge exchange during friction between nominally identical insulating materials is less documented. We experimentally investigated the triboelectrification between two smooth monocrystalline α-Al 2O 3 (sapphire) antagonists by surface force measurements with a Surface Force Apparatus (SFA). The force between a sphere and a plane, both in sapphire, was measured as a function of the sphere-plane distance D, before and after nano-friction tests, under dry argon atmosphere. Respective contributions of van der Waals, water meniscus and electrostatic forces were determined. The estimated Hamaker constant was in good agreement with the Lifshitz theory, and the dominant meniscus attraction at low separation could be overcome with small radius sphere. We demonstrated that electrostatic forces were generated by the nano-friction test and we quantified the adhesion that results from this contact-electrification. In the first stage of the unloading process, the short range electrostatic force was found to vary both with time and distance D. Experimental results were correlated with surface densities of mobile charges on the two surfaces, and the time-dependence was related to classical surface transport phenomena on alumina surfaces

Electron Beam Charging of Insulators with Surface Layer and Leakage Currents

International audienceThe electron beam induced selfconsistent charge transport in layered insulators is described by means of an electron-hole fight-drift model FDM and an iterative computer simulation. Ballistic secondary electrons and holes, their attenuation and drift, as well as their recombination, trapping, and detrapping are included. Thermal and field-enhanced detrapping are described by the Poole-Frenkel effect. Furthermore, an additional surface layer with a modified electric surface conductivity is included which describes the surface leakage currents and will lead to particular charge incorporation at the interface between the surface layer and the bulk substrate

Electron beam charging of insulators: A self-consistent flight-drift model

International audienceElectron beam irradiation and the self-consistent charge transport in bulk insulating samples are described by means of a new flight-drift model and an iterative computer simulation. Ballistic secondary electron and hole transport is followed by electron and hole drifts, their possible recombination and/or trapping in shallow and deep traps. The trap capture cross sections are the Poole-Frenkel-type temperature and field dependent. As a main result the spatial distributions of currents j(x,t), charges, the field F(x,t) and the potential slope V(x,t) are obtained in a self-consistent procedure as well as the time-dependent secondary electron emission rate sigma(t) and the surface potential V0(t) For bulk insulating samples the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and sigma=1. Especially for low electron beam energies E0=4 keV the incorporation of mainly positive charges can be controlled by the potential VG of a vacuum grid in front of the target surface. For high beam energies E0=10, 20, and 30 keV high negative surface potentials V0=−4, −14, and −24 kV are obtained, respectively. Besides open nonconductive samples also positive ion-covered samples and targets with a conducting and grounded layer (metal or carbon) on the surface have been considered as used in environmental scanning electron microscopy and common SEM in order to prevent charging. Indeed, the potential distributions V(x) are considerably small in magnitude and do not affect the incident electron beam neither by retarding field effects in front of the surface nor within the bulk insulating sample. Thus the spatial scattering and excitation distributions are almost not affected

Koinon

Koinon, followed by the genitive plural of an ethnic may be used in the sense of πόλις and of δήμος as applied to Thucydide's expression, IV, 78, 3 : άνευ τοΰ πάντων κοινοΰ, which has often puzzled translators and commentators. We suggest a new interpretation of the dedication commemorating the battle of Sellasie (IG, XI 4, 1097) whose authors, Philip V, the Macedonians and the allies are named for contributing their shares of buty to the erection of the votive offering. The same interpretation is valid for a large number of dedicative royal statues among which T. singles out IG, XI 4, 1102, which brings back to the word Koinon and shows how delusive is an alleged sharing of Macedonian authority between the king and the people as well as the obstinately postulated distinction between an assembly of the people and an assembly of the army.Koɩvóv, suivi du génitif pluriel d'un ethnique, peut s'employer au sens de πόλις ou δήμος : application à l'expression de Thucydide, IV, 78, 3 : άνευ τοΰ πάντων κοινού, qui a plusieurs fois embarrassé les traducteurs et les commentateurs. Interprétation nouvelle de la dédicace commémorative de la bataille de Sellasie, IG, XI 4, 1097, dont les auteurs, Philippe V, les Macédoniens et les alliés sont nommés pour avoir participé de leur part de butin à l'érection de l'ex -voto. La même interprétation vaut pour un grand nombre de dédicaces de statues royales parmi lesquelles l'Α. isole IG, XI 4, 1 102, qui ramène au mot κοινόν et montre combien sont illusoires un prétendu partage de l'autorité en Macédoine entre le roi et les Macédoniens et la distinction, obstinément postulée, entre une assemblée du peuple et une assemblée de l'armée.Tréheux Jacques. Koinon. In: Revue des Études Anciennes. Tome 89, 1987, n°1-2. pp. 39-46

Επ' αμφότερα

Tréheux Jacques. Επ' αμφότερα. In: Bulletin de correspondance hellénique. Volume 77, 1953. pp. 155-165

L'inventaire des Clérouques d'Imbros

Tréheux Jacques. L'inventaire des Clérouques d'Imbros . In: Bulletin de correspondance hellénique. Volume 80, 1956. pp. 462-479

Ἐπιπροσθεῖν

L'A. revient sur une correction proposée par M. Mugler, REG, LXIX (1956), p. 20-28, au texte traditionnel du Parménide, 137 ·, où Platon définit la ligne droite. Il montre que la forme έπιπροσθέον, forgée par M. M., est irrecevable, que l'adverbe έπάτροσθεν contient déjà, contre l'avis de M. M., l'image de l'éclipsé et qu'il n'y a lieu de modifier ni la leçon des manuscrits ni l'interprétation qu'on en donne. Έπιπροσθεΐν n'a sûrement rien à voir avec θέω, « je cours », mais le rapport linguistique entre ἐπιπροσθεΐν et ἐπίπροσθεν reste à préciser.Tréheux Jacques. Ἐπιπροσθεῖν. In: Revue des Études Grecques, tome 70, fascicule 331-333, Juillet-décembre 1957. pp. 356-360