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1、VerneuilCrystalGrowthTheVerneuilprocess,alsocalledflamefusion,isamethodofmanufacturingsyntheticgemstones,developedin1902bytheFrenchchemistAugusteVerneuil.Itisprimarilyusedtoproducetherubyandsapphirevarietiesofcorundum,aswellasthediamondsimulantsrutileandstrontiumtitanat
2、e.Theprincipleoftheprocessinvolvesmeltingafinelypowderedsubstanceusinganoxyhydrogenflame,andcrystallisingthemelteddropletsintoaboule.Theprocessisconsideredtobethefoundingstepofmodernindustrialcrystalgrowthtechnology,andremainsinwideusetothisday.(MTIstillusesthismethodto
3、growSrTiO3crystal)AsketchofanearlyfurnaceusedbyVerneuiltosynthesiserubiesusingtheVerneuilprocessAsimplifieddiagramoftheVerneuilprocessHistorySincethetimeofthealchemists,therehavebeenattemptstosyntheticallyproducepreciousstones,andruby,beingoneofthefivehighlyprizedcardin
4、algems,haslongbeenaprimecandidateforsynthesis.Inthe19thcentury,thoseattemptsstartedtobearfruit,withthefirstrubyproducedbymeltingtwosmallerrubiestogetherin1817,andthefirstmicroscopiccrystalscreatedfromalumina(aluminiumoxide)inalaboratoryin1837.By1877,chemistEdmondFremyha
5、ddevisedaneffectivemethodforcommercialrubymanufacturebyusingmoltenbathsofalumina,yieldingthefirstgemstone-qualitysyntheticstones.TheParisianchemistAugusteVerneuilcollaboratedwithFremyondevelopingthemethod,butsoonwentontoindependentlydeveloptheflamefusionprocess,whichwou
6、ldeventuallycometobearhisname.OneofVerneuil'ssourcesofinspirationfordevelopinghisownmethodwastheappearanceofsyntheticrubiessoldbyanunknownGenevanmerchantin1880.These"Genevarubies"weredismissedasartificialatthetime,butarenowbelievedtobethefirstrubiesproducedbyflamefusion
7、,predatingVerneuil'sworkontheprocessby20years.Afterexaminingthe"Genevarubies",Verneuilcametotheconclusionthatitwaspossibletorecrystallisefinelygroundaluminiumoxideintoalargegemstone.Thisrealisation,alongwiththeavailabilityoftherecentlydevelopedoxyhydrogentorchandgrowing
8、demandforsyntheticrubies,ledhimtodesigntheVerneuilfurnace,wherefinelygroundpurifiedaluminaandchromiumoxidewere
