28229.過(guò)渡金屬mo高壓物性的數(shù)值模擬和實(shí)驗(yàn)研究

1、獨(dú)創(chuàng)性聲明本人聲明所呈交的學(xué)位論文是本人在導(dǎo)師指導(dǎo)下進(jìn)行的研究工作及取得的研究成果。據(jù)我所知，除了文中特別加以標(biāo)注和致謝的地方外，論文中不包含其他人已經(jīng)發(fā)表或撰寫(xiě)過(guò)的研究成果，也不包含為獲得中國(guó)工程物理研究院或其他教育機(jī)構(gòu)的學(xué)位或證書(shū)使用過(guò)的材料。與我一同工作的同志對(duì)本研究所做的任何貢獻(xiàn)均已在論文中作了明確的說(shuō)明并表示謝意。學(xué)位論文作者簽名：奄勃砼簽字日期：沙忙鄉(xiāng)月沖曰學(xué)位論文版權(quán)使用授權(quán)書(shū)本學(xué)位論文作者完全了解并接受中國(guó)工程物理研究院

2、研究生部有關(guān)保存、使用學(xué)位論文的規(guī)定，允許論文被查閱、借閱和送交國(guó)家有關(guān)部門(mén)或機(jī)構(gòu)，同時(shí)授權(quán)中國(guó)工程物理研究院研究生部可以將學(xué)位論文全部或部分內(nèi)容編入有關(guān)數(shù)據(jù)庫(kù)進(jìn)行檢索，可以影印、縮印或掃描等復(fù)制手段保存、匯編學(xué)位論文。學(xué)位論文作者簽名：匙刎簽字日期：沙葉年歲月沖日導(dǎo)師簽名：j箕皋釤，’V’1一簽字日期珈J年年朗哆號(hào)過(guò)渡金屬M(fèi)o高壓物性的數(shù)值模擬和實(shí)驗(yàn)研究AbstractTherehasbeenalongstandingcontrove

3、rsyonthehighpressurephasediagramoftransitionmetals，forthegreatdifferencebetweentheresultsobtainedfromdynamicandstatichighpressureexperimentsAsoneoftheoftenusedpressurecarlibrationmaterials，thehi【ghpressurephasetransition

4、ofMo(akindof4dmetal)isstillundertobeclarifiedBesides，itisalsonecessarytodeterminethestnIctI】reconfigurationbeforeinvestigatingotherphysicalpropertiesBasedonthepreheatedshockwaveexperimentsandnumericalsimulations，wewoulda

5、ttempttoexplainthetransitionpathsofphasesforMo，andinvestigateitsthermodynamic，mechanicandsomeotherpropertiesThemaincontentsofthisdissertationarelistedasfollows：1Basedonthedensityfunctionaltheory(DFT)，therelativestablenes

6、sofbcc，fcc，hcp，anddhcpsnuctlIfesforMoissystematicallyinvestigatedAbccdhcptransitionWasfoundat～620GPa，whichislowerthanformerreportedresult[PhysRevLett101(2008)049602】by～40GPaThequasiharrnonicDebye(QHD)modelwasusedtoinvest

7、igatethethermodynamicpropertiesofbccanddhcpphasesTheresultsshowthatanobviousjumpat—620GPaisobservedalong293Kisothermandthereisalsoobviouschangeofthermodynamicsnearthecriticalpointofslmcturaltransition2Bytakingthethermoel

8、ec臼onexcitationintoconsideration，theHflgoniotshocktemperatureswithdifferentinitialtemperatures(293，933，1698，and2600K)arccalculatedrespectivelyWecangettheconclusionthattheTECcouldreducetheshocktemperatureeffectivelyBasedo

9、ntheLLNLanalyticalmodelforcalculatingelasticconstantsatfinitetemperamre，theHiigoniotsoundvelocitiesfromdifferentinitialtemperaturesattherangeof0—。400GPaalecalculatedrespectivelyThecalculationsagreewiththenewestexperiment

10、alresultsmRevB89(2014)174109]Besides，themethoddevelopedinthisdissertationcanbeusedtocalculatetheHfigoniotsoundvelocityofothermetals，andprovidepredictionsforexperiments3BasedontheEAMmanybodypotential，theSOlidliqmdcoexiste

11、ncetechnologyhasbeenemployedtoperformthemoleculardynamics(MD)smlationofthemeltingcurveforMowithinNPTensembleTheMDresultsagreewiththemeltingtemperatures(MT)obtainedfromreporteddynamicexperimentsandtheoreticalcalculations，

12、butareobviouslyhigherthantheMTderivedfiomDACexperimentsByusingtheadaptivecommonneighboranalysis(CNA)technologythephasetransitionofMoathighPTisinvestigatedItisobservedthatthebccstructureisstablebeforemeltingupto——200GPa；w

13、henhigherthan200GPa，Moisunderastablemultiphasescoexistencestateatlowertemperature，andtransformsintobccstructureathighertemperaturebeforemelting4BasedonthepreheatedSWloadingtechnique，theshockMT(at3246and3733GPa)andrelease

14、MT(at1531and1766GPa)ofpreheatedMo(T0=933K)aremeasured，respectivelyTheresultsagreewithreportedtheoreticalcalculationswell，andprovidenewdatatoclarifythegreatdifferenceofmeltingCIEVeSobtainedfromdynamicandstatichigh／experim