摘要
Moleculardynamics(MD)simulationsoftheconsecutivecompression-decompressioncyclesofhexagonalzincsulfide(wurtzite)nanoparticlespredictanirreversiblephasetransformationtothecubicpolymorph.Thephasetransformationcommencesatthecontactareabetweentheparticleandtheindenterandproceedswiththenumberofcompressioncycles.Dislocationsarevisibleforaparticlesizeabove5nm.ResultsfromwetgrindinganddrypowdercompressionexperimentsonacommercialwurtzitepigmentagreequalitativelywithMDsimulationpredictions.X-raydiffractionpatternsrevealthattheamountofcubicpolymorphinthecompressedsamplesincreaseswithpressureappliedtothepowder.Incomparisonwithpowdercompression,wetmillingleadstoamorepronouncedphasetransformation.Thisoccursbecausetheparticlesareexposedtoalargenumberofstresseventsbycollisionwiththegrindingmedia,whichleadstotheformationofdefectsandnewsurfacecrystallitesbyparticlefracture.AccordingtotheMDsimulations,phasetransformationisexpectedtooccurpreferentiallyinsurfacecrystallitesbecausetheyexperiencethehighestmechanicalload.Becauseofthephasetransformation,thewetgroundandcompressedsamplesexhibitalowerphotoluminescenceintensitythanthefeedmaterial.Incomparisonwithpowdercompression,millingreducesthephotoluminescenceintensitymoresubstantially.Thisoccursbecauseahigherdefectconcentrationisformed.Thedefectscontributetothephasetransformationandphotoluminescencequenching.
出版日期
2015年01月11日（中国期刊网平台首次上网日期，不代表论文的发表时间）
