简介：K2NbOF5·H2OandK2TaF7werepreparedthroughmeltingNb2O5andTa2O5respectivelywithFHF2·2H2O,followedbyrecrystallizing.ThehydrolysispropertiesofK2NbOF5andK2TaF7weredeterminedagainbyusingarapidlyquenchvessel.Astemperature(from250to550℃)andpressure(from500to1500bars)increase,thedegreeofhydrolysisofbothK2NbOF5andK2TaF7willincrease.Nb-andTa-fluorinecomplexcompoundsareinstableinsupercriticalaqueousfluids.ThedegreeofhydrolysisofbothK2NbOF5andK2TaF7decreaseswithincreasingconcentra-tionofHF,independentoftheconcentrationofNaF.ThepartitioncoefficientsofNbandTabetweengraniticmeltandfluidphasearelessthan0.15,ie.,mostofNbandTaareleftingraniticmelt.ThepartitioncoefficientofTaismoredependentontheconcentrationofHFthanthatofNb.ThesignificanceofhydrolysisinNb-ansTamineralizationisalsodiscussedinthepresentpaper.

简介：CassiteritesfromboththeBeauvoirandMontebrasgeanitedofFrancearetypicallyrichintraceelementssuchasNbandTa,andcontainquiteanumberofinclusionsofcolumbite(dominantlymanganocolumbite).TwothinsectionsofcassiteritecrystalshavebeenpreparedforRamanmicroprobeanalysis).Thespectraobtainedfromdifferentpartsofthecassiteritesshowthatthevibra-tionfrequencyoftheA1gpeakdecreaseswithincreasingNb,Ta,FeandMnatomiccontents.Itisworthytonotethatanewpeak(namedthe“Anpeak”)hasbeenreportedforthefirsttimeinthepartwithorientedcolumbiteinclusions.Thevibrationfrequencyvariesfrom827to830cm^-1.ThepresenceofthenewpeakmaybeattributedtostructuralchangesofcassiteriteduetotheexcessofNbandTainthelatticeandtheexsolutionofcolumbiteinclusionsincassiterite.