MgO基片上的YBCO高温超导薄膜生长分析

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1、ABSTRACTABSTRACTLarge-areadouble-sidedYBCOhightemperaturesuperconductor(HTS)thinfilmswithexcellentelectricalandmicrowaveproperties,whichcanimprovetheperformanceofthemicrowavepassivedevices,havebeenpaidintensiveattention.MgOsubstratewithisotropicdielectricconstantandverylowdielectric

2、lossisverysuitablefortheapplicationofthemicrowavedevices.ItisdifficulttoprepareYBCOfilmonMgOsubstratebecauseofthelargelatticemismatchbetweenMgOandYBCO,andthedeliquescencyofMgOintheair.ThegrowthofYBCOthinfilmonMgOsubstrateaimingatthesedifficultissueswasstudiedinthisthesis.Thecontenti

3、ndetailisasfollows:1.Theinfluenceofthesubstratetemperature,andsputteringpressure,etc.onthefilmstructure,surfacestateandperformancehasbeenstudied.Byanalyzingthemicrostructure,orientationandsurfacestate,optimumprocessparameterswereobtained:substratetemperaturebeing650℃,sputteringpower

4、being0.5(×2)A,sputteringpressurebeing30Pa,andPO2:PArbeing1:2.2.YBCOself-epitaxymethodandMgOhomogenousepitaxymethodwereadoptedtoimproveitsproperties.Thecriticalcurrentdensity(Jc)ofYBCOfilmwasrelativelyhigherthanthatofYBCOthinfilmpreparedbycommonsputteringmethod.3.TheimprovementofJcan

5、din-plainandout-of-plaingrainorientationofYBCOfilmhadbeenrealisedbypre-annealingofMgOsubstrates.ThepropertiesofYBCO2filmsdepositedontheannealedsubstratesweregreatlyimproved,withJc=2.3MA/cm,andRs(microwaveresistance)≈0.16m,whichmettherequirementofhighperformancemicrowavedevice.4.The

6、stabilityofYBCOfilmindifferentenvironmentswasdiscussedandfurthersuggestionhasbeengivenforpreservingthefilms.Key-words:YBCOsuperconductivefilm,MgOsubstrate,annealling,stabilityII目录目录第一章概述.................................................................................................

7、...................11.1高温超导简介....................................................................................................11.2高温超导薄膜及应用........................................................................................21.3超导薄膜的制备技术........................................

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