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

Two Decades of French Urban Policy: From Social Development of Neighbourhoods to the Republican Penal State

International audienceThis paper provides an overview of French national urban policy for the period 1981–2002, organized around three themes: spatial conceptualizations of intervention areas and changing scales of intervention, discursive articulations of intervention areas, and legitimation of state intervention. By relating the transformations of this policy to the contemporary restructuring of the French state, the paper argues that although there are elements of convergence, the contemporary restructuring of the French state differs remarkably from a US or UK-style neoliberalization, partly because of the republican tradition emphasizing the active role of the state for the well-being of its citizens. This restructuring carries the signs of the strong state tradition in France, and is best understood as an articulation of neoliberalism with established political traditions, an articulation that I try to capture with the notion of a ''republican penal state''

Analysis of thermal detrapping of holes created by electron irradiation in high purity amorphous SiO2 using the induced and secondary current measurements

International audienceIsothermal detrapping of holes after electron irradiation (using a SEM) in high purity amorphous SiO2 is evaluated at different temperatures (in the range 300-663 K) by means of the induced and secondary current measurements. In order to single out the hole detrapping, the specific charging conditions (1 keV defocused electron beam of low density) leading to positive charging are adopted. The thermal detrapping, which stems from a single trap, begins at 523 K and is completed at 663 K. After annealing in air at 973K during 48h, two detrapping stages are revealed: the former is connected with an additional shallow trap, while the latter requires temperatures above 663 K for a complete detrapping. The first order kinetics describes reasonably well the detrapping process. The frequency factors (near 10(10) s(-1)) and the activation energies (about 1.6 eV) deduced from this analysis could be assigned, respectively, to the relaxation connected to detrapping and to the trap energy level of the charged oxygen vacancy. (C) 2015 Elsevier B.V. All rights reserved