简介：Moleculardynamics(MD)simulationsoftheconsecutivecompression-decompressioncyclesofhexagonalzincsulfide(wurtzite)nanoparticlespredictanirreversiblephasetransformationtothecubicpolymorph.Thephasetransformationcommencesatthecontactareabetweentheparticleandtheindenterandproceedswiththenumberofcompressioncycles.Dislocationsarevisibleforaparticlesizeabove5nm.ResultsfromwetgrindinganddrypowdercompressionexperimentsonacommercialwurtzitepigmentagreequalitativelywithMDsimulationpredictions.X-raydiffractionpatternsrevealthattheamountofcubicpolymorphinthecompressedsamplesincreaseswithpressureappliedtothepowder.Incomparisonwithpowdercompression,wetmillingleadstoamorepronouncedphasetransformation.Thisoccursbecausetheparticlesareexposedtoalargenumberofstresseventsbycollisionwiththegrindingmedia,whichleadstotheformationofdefectsandnewsurfacecrystallitesbyparticlefracture.AccordingtotheMDsimulations,phasetransformationisexpectedtooccurpreferentiallyinsurfacecrystallitesbecausetheyexperiencethehighestmechanicalload.Becauseofthephasetransformation,thewetgroundandcompressedsamplesexhibitalowerphotoluminescenceintensitythanthefeedmaterial.Incomparisonwithpowdercompression,millingreducesthephotoluminescenceintensitymoresubstantially.Thisoccursbecauseahigherdefectconcentrationisformed.Thedefectscontributetothephasetransformationandphotoluminescencequenching.