简介:ThephaseandmorphologytransformationduringthehydrothermaltreatingprocessofY2O3wasevaluatedwithX-raydiffcrcnce(XRD),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM),particlesizeandspecificsurfaceareadetermination.TheresultsshowedthatthecubicY2O3didnottransferintohexagonalY(OH)3inpurewater.Therefore,purehexagonalY(OH)3withnanotubeandmicrorodmorphologieswereobtainedbyhydrothermaltreatingY2O3at150℃for12hin15mlof2mol/LNaOHsolutionwithandwith-outPVAorPEGItwassuggestedthatthecharacteristicpreferentialgrowthofY(OH)3wasattributedtothestructureanisotropyofhexahedronY(OH)3.TheadditionofPVAorPEGcouldpromotetheformingprocessofnanotubesbyselectiveadsorptionondifferentcrystalplanes,whichalteredthegrowthratealongdifferentdirectionsandresultedinthediffusionlimitofconstructingionsinthecentertopofrods.Finally,Y(OH)3:EuandY2O3:Eunanotubeswerealsosynthesizedbyusingthismethod,andtheirphotoluminescencepropertieswereevaluated.
简介:Inthispaper,analmostP-stabletwo-stepsixth-orderHybridmethodwithphase-lagoforderinfinityandaclassexpliciteighth-orderObreckoffmethodswithphase-lagoforder10-24aredevelopedforthenumericalintegrationofthespecialsecond-orderperiodicinitial-valueproblems.Thesemethodshavetheadvantageofhigheralgebraicorderandconsiderablysmallerphase-tagcomparedwithsomemethodsin[1-6].Numericalexamplesindicatethatthesenewmethodsaremoreaccuratethanmethodsdevelopedby[1-6].