简介:Basedonthethermodynamicallyself-consistentanalysisandoptimizationofthreesub-binarysystemsoftheternarysystemPrCl3-CaCl2-MgCl2,thethermodynamicsofthisternarysystemhasbeenstudied.UsingHillertmodelandtakingMgCl2asanasymmetriccomponent,thePrCl3-CaCl2-MgCl2phasediagramhasbeencalculated.Theagreementbetweencalculatedandmeasuredcompositionsandtemperaturesatdeflectingpointsonliquidusisgood.Thesystemisasimpleeutecticonewithaeutecticpointat26.0mol%PrCl3,41.5mol%CaCl2,32.5mol%MgCl2;560℃(calculated)and26.0mol%PrCl3,39.4mol%CaCl2,34.6mol%MgCl2;546℃(measured),respectively.
简介:Y3Al5O12:Ce3+isthemostfamousphosphormaterialduetoitsexcellentphotolumincentproperties.Here,throughfirst-principlescalculation,theeffectofcarboninterstitialdefectsonY3Al5O12:Ce3+phosphorwasinvestigated.Itisfoundthatthecarboninterstitialstendtooccupythenext-nearestsitesofCe3+ioninY3Al5O12:Ce3+lattice.Specially,theseinterstitialdefectscanshortentheCe3+-O2-bondlength,leadingtoalargercrystalfieldsplittingof5dorbitaloftheCe3+atomandbigger5dcentroidshift.ThesetwofactorscausetheemissionspectrumofY3Al5O12(C):Ce3+redshiftcomparedwiththatofY3Al5O12:Ce3+.Moreover,withourcomparisonexperiment,wefindthattheY3Al5O12(C):Ce3+hasanobviousredshiftcomparedwiththatofY3Al5O12:Ce3+system,whichisinaccordwithourfirstprinciplescalculation.OurworksystematicallyinvestigatestheimpactofthecarboninterstitialdefectonY3Al5O12:Ce3+,andprovidesanewroutetotunetheemissionspectruminY3Al5O12:Ce3+.
简介:有色金属的分类很多,大约有80多种,大致按其比重、价格、在地壳中的储量及分布情况和被人们发现与使用情况的早晚等分为五大类。(1)重有色金属;指比重大于4.5的有色金属。包括铜,镍,锢,铅,锌,锑,汞,镉和铋。(2)轻有色金属;指比重小于4.5的有色金属。包括铝,镁,钙、钾、锶和钡。(3)贵金属;指在地壳中含量少,开采和提取都比较困难,对氧和其它试剂稳定,价格比一般金属贵的有色金属。包括金、银。和铂族元素。一般比重都较大,熔点较高在916—3000度,有很好的化学稳定性、优良的抗氧化性及耐腐蚀性。(4)半金属;一般指硅、硒、碲、砷和硼五种元素。其物理化学性质介于金属和非金属之间。如砷是非金属,但它能传热和导电。