abcolt4gt型低损耗微波介质陶瓷新体系

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1、浙江大学硕士学位硷文AbstractTherapiddevelopmentsofmicrowavecommunicationsystemsrequiredielectricmaterialswithhighperformances．Thepurposeofthisworkwastosearchlowlossmicrowavedielectricceramicnewsystem．TheexcellentmicrowavedielectriccermnicsweredevelopedinABC04oxideswithK2NiF4structu

2、re，andtherelationbetweenmicrowavedielectriccharacteristicsandstructurewereinvestigated．Single—phaseSrRAlO-(R=NdandSm)ceramicswerepreparedbyasolidstatereactionmethod．andtheycouldbedensifiedat1450～14750Cinairfor3hours．Obviousgraingrowthwithincreasingsinteringtemperaturewaso

3、bserved，anditdecreasedtheamountofgrainboundaryandcontributedtothesignificantincreaseofQfvalue．Goodmicrowavedielectricpropertieswereachieved：1)8=17．8，Qf=25，700GHz，xf=4ppm／。CforSrNdAl04ceramics；2)e=18．8，Qf=54，880GHz，xf=4pproflCforSrSmAl04ceramics．Goodsinteringcharacterwasal

4、soobservedinCaRAl04(R=Y,NdandSm)ceramics，however,someinhomogeneousareasandsmallamountofsecondphasewereobservedinCaYAl04andCaSmAl04ceramics．ThedielectricconstantofCaRAl04(R2Y，NdandSm)ceramicscouldbewellinterpretedbyClausius-Mosotti(C—M)equation，whilethechangesofQfvaluesand

5、研valueswererelatedtothestretchingandcompressingofoctahedralinK2NiF4structure：RietveldresultsshowedthatthestressinoctahedralofCaSmAl04ceramicswasthesmallest，whichensureditslargestQfvaluecomparingtoCaYAl04andCaNdhl04ceramics．Meanwhile，thespaceinoctahedraldecreasedfromCaNdAl

6、04toCaYAl04，whichreducedthevibrationspaceforA13+．Asaresult，CaNdAl04hadthelargestTfvalue，followedbyCaSmAl04，andCaYAl04hadthesmallestqvalue．GoodmicrowavedielectricpropertieswereobtainedinCaRAl04system：1)￡218．2，Qf217，980GHz，1；f一52pprrdoCforCaNdAl04ceramics；2)￡218．2，Of251，060

7、GHz，可2—3ppm／oCforCaSmAl04ceramics；3)￡218．9，Qf239，960GHz，研=6ppm／oCforCaYAl04ceramics．TherelativetolerancefactordifferencebetweenABC04andAB03structure，l浙江大学硕士学位论文⑧Af％couldbeacriteriatojudgethestabilityofK2NiF4structure．If△f％>4．3％，theK2NiF4structurewasunstable，suchasCaLaAl04

8、andSrYAl04ceramics．TofurtherinvestigateandimprovethestabilityofCaLaAl04，the(Cal．xSrx)LaAl04ceram