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Conditions for the formation of an explosive atmosphere when using a flammable liquid

J.Petit , J.Chaineaux , A.Janes , B.Salle


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When employing a flammable liquid, the conditions in which an explosive atmosphere can form depend to a great extent on the liquid itself ; if the liquid is in an open space, they are also linked to the evaporation flow rate, which in turn depends on the air renewal conditions at the surface of the liquid. An evaporation model has been established from the results of a series of measurements carried out with volatile solvents, where the vaporization flow rate and the vapor concentration at the surface of the liquid were measured. Knowledge of these different features permits the implementation of the ATEX regulations in a precise and realistic way. Resume : Au cours de la mise en oeuvre d'un liquide inflammable, les conditions de formation d'une atmosphere explosive dependent au moins des caracteristiques du liquide ; dans le cas ou le liquide se trouve en milieu ouvert, les conditions de formation d'une ATEX sont egalement liees au debit d'evaporation du liquide, lui-meme associe aux conditions de renouvellement de l'air a sa surface. Un modele d'evaporation a ete etabli d'apres les resultats d'une campagne de mesures effectuees sur des solvants volatils courants, au cours de laquelle le debit d'evaporation du liquide et la concentration en vapeur a proximite de sa surface ont ete mesures. La connaissance de ces differents elements permet une application precise et realiste de la reglementation ATEX.

Effects of Substrate-Induced Strain on Transport Properties of LaMnO[sub 3+] and CaMnO Thin Films Using Ferroelectric Poling and Converse Piezoelectric Effect

C.HLW , C.CL , Z.RK , H.H , L.HS


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We have investigated the effects of the strain induced by ferroelectric poling (or the converse piezoelectric effect) on the transport properties of LaMnO[sub 3+δ] and CaMnO₃ thin films grown on ferroelectric 0.67Pb(Mg[sub 1/3]Nb[sub 2/3])O₃-0.33PbTiO₃ single-crystal substrates. The ferroelectric poling of the substrate gives rise to a reduction in the in-plane tensile strain of the LaMnO[sub 3+δ] film, which results in a significant decrease in the resistance and increase in the insulator-to-metal transition temperature T[sub P] of the film. The ferroelectric poling also leads to opposite effects on the magnetoresistance (MR) below and above T[sub P], namely, MR is reduced for T<T[sub P] while MR is enhanced for T>T[sub P]. These strain effects are explained in terms of coexisting phases whose volume fractions are modified as a result of the reduction in the Jahn-Teller (JT) distortion due to ferroelectric poling. An investigation of the effects of the strain induced by the converse piezoelectric effect on the resistance of the LaMnO[sub 3+δ] and CaMnO₃ films shows that the resistance-strain coefficients (ΔR/R)/(Δc[sub film]/c[sub film]) of the LaMnO[sub 3+δ] film is much larger than those of the CaMnO₃ film. This result may imply that the strain-induced modification of the electronic bandwidth alone cannot account for the large (ΔR/R)/(Δc[sub film]/c[sub film]) observed in the LaMnO[sub 3+δ] film, and highlights that the strong coupling of charge carriers to JT distortion is crucial for understanding the effects of the substrate-induced strain in manganite thin films.Department of Applied PhysicsMaterials Research CentreAuthor name used in this publication: H. L. W. ChanAuthor name used in this publication: C. L. Cho
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