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dc.contributor.author |
CHAOUCHE, Yassine |
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dc.date.accessioned |
2021-04-06T08:08:31Z |
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dc.date.available |
2021-04-06T08:08:31Z |
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dc.date.issued |
2017-01-22 |
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dc.identifier.uri |
http//localhost:8080/jspui/handle/123456789/100 |
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dc.description.abstract |
Wehavestudiedthestructural,dynamicalandthermodynamicalpropertiesofYttrium
Pnictides YX(X=N,P,AsandSb)inbothphasesB1(NaCl)andB2(CsCl).Weuse¯rst-
principles calculations,bymeansofthepseudopotentialmethodusingthegeneralized
gradientapproximation(GGA).Wecalculatedstructuralparameters;thelatticeconstant
are obtainedbyminimizingtheenergyasfunctionofvolumeandbulkmodulusandits
derivativeforYX(X=N,P,AsandSb)compoundsinbothphasesB1andB2.Theyarein
goodagreementwiththepublisheddata.wahaveobtainedthetransitionpressure Pt from
B1 toB2whentheenthalpyareequalanditisabout171,72,75and34GPaforYN,YP,
YAsandYSbcompoundsrespectively.Weevaluatedtheelasticconstants C11,C12 et C44
whichsatisfythemechanicalstabilitiescriteria.DensityFunctionalPerturbationTheory
(DFPT) isappliedtodeterminethephonondispersionrelationsalongthehighsymmetry
lines withcorrespondingphonondensityofstates.InB1phase,thefrequenciesarepositive
valuesthatshowthestabilityofthisstructure.InB2phase,thefrequenciesarenegative
valuesthatshowthatthisstructureisunstableat0GPa.Byusingthecalculatedphonon
frequencies, weobtainedthethermodynamicproperties;constant-volumespeci¯cheat Cv
whichincreasewithtemperatureandapproachesthelimitingDulong-Petit,theentropy
S increasewithtemperatureatdi®erentpressures. |
en_US |
dc.language.iso |
fr |
en_US |
dc.title |
Etude ab initio des Spectres des Phonons et les Propriétés Thermodynamiques des Semi-Conducteurs |
en_US |
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