MnAs系列化合物的磁热效应计算

④得到的两组数据在同一坐标系中绘图可得到图3.2，分别绘图则可得到图3.3和3.4。在图3.2、3.3、3.4中，我们发现曲线在某个点便发生了突变，这是因为MnAs中发生了一级磁相变。3.3MnAs化合物的等温熵变曲线图3.5、3.6、3.7分别为MnAs化合物的磁熵变实验曲线、升磁磁熵变曲线、降磁磁熵变曲线。图3.6、3.7是由图3.3、3.4中的数据通过公式（2.9）计算而得到的。由于MnAs的磁滞比较大，所以同实验数据相比要大。而图(b)则由于外加磁场取间隔太大而导致在M-H图中S型曲线取值不精确，因而计算所得曲线与实验曲线[48]有所偏差。如果外加磁场步长取的小一些，可能会和实验数据吻合的比较好。图3.5熵变随温度变化的实验曲线图3.6熵变随温度的变化曲线图3.7熵变随温度的变结论本文主要研究了MnAs型化合物的磁性能，通过Bean-Rodbell模型对磁热效应的计算，其结果表明：1、由Bean-Rodbell模型获得的理论热磁曲线与实验曲线较为吻合。2、由Bean-Rodbell模型获得的等温熵变的最大值小于实验值。而计算所得曲线与实验曲线有偏差。4、通过对MnAs型化合物磁性的研究为制备出居里温度在室温附近的、廉价的、易得到的、磁热效应大的、可实用性强的磁制冷材料提供理论指导。参考文献[1]WARBURGE.MagnetischeUntersuchungen[J].Ann.Phys.Chem.1881,13(2):141-156.[2]PecharskyV.K.,GschneidnerK.A.,Magnetocaloriceffectandmagntic[J]J.M.M.M,1999.200(I).44-56[3]LangevinP.Magnétismeerthéoriedeselectrons[J],AnnalsChimicaPhysics.,1905,5,70[4]WeissP.andPiccardA.Surunnouveauphénomènrmagétocaloriqueet,ComptesRendus,[J]1918,166,325[5]DebyeP.EinigeBemerkungezurMagnetisierungbeitiefertemperature[J],AnnalsofPhysics.,1926,81,1154[6]GiauqueW.F.Ahermodynamictreatmentofcertainmagneticeffects.Aproposedmethodofproducingtemperaturesbelow1°absolute[J],JournalofAmericanChemicalSociety.,1927,49,1864[7]丁少华.具有手性特征的2-D,3-D稀土硫酸盐的水热合成、结构表征及性质研究，辽宁师范大学，[J]2008，34-35[8]邓晓军，Mn2-xFexP1-yGey化合物室温磁制冷材料制备工艺与磁热性能的研究，北京工业大学，[J]2012，1[9]PecharskyV.K.,GschneidnerK.A.,Jr.Tunablemagneticregeneratoralloyswithagiantmagnetocaloriceffectformagneticrefrigerationfrom20to-290K.[J]AppliedPhysLett,1997,70(24):3299-3301[10]PecharskyV.K,.GschneidnerK.A.,Jr.GiantmagnetocaloriceffectinGd5(Si2Ge2)[J].Phys.Rev.Lett.,1997,78:4494-4497.[11]PecharskyV.K.,GschneidnerK.A.,Jr.EffectofalloyingonthegiantmagnetocaloriceffectofGd5(Si2Ge2).[J]MangMangMater,1997,(167):L179-184[12]GschneidnerK.A.Jr.PecharskyV.K.,PecharskyA.O.,etal.Recentdevelopentinmagneticrefrigeration.Materialsscienceforum315,[J]TrasTechPubl.1999:69-76[13]门德，松林，伊博乐，刘璟芳，伊日勒图，特古斯，《稀土金属》.[J]2010，1，27-28[14]WadaH.,Morikawa.Taniguchi.K.,Shibata.Y.,Yamada,Y.andAkishige.Y.,GiantmagnetocaloriceffectofMnAs1-xSbxinthevicinityoffirst-ordermagnetictransition[J],PhysicaB-CondensedMatter,2003,328,114[15]PalaciosE.,TocadoL.,BurrielR.,etal.HeatcapacityanddirectdeterminationofthemagnetocaloriceffectinMnAs1-xSbx(x=0,0.1,0.3,0.4)[C]//FirstIIF-IIRInternationalConferenceonMagneticRefrigerationatRoomTemperatureMontreux,Switzerland,[J]27-30September,2005.[16]WadaH.,FunabaC.H.,AsanoT.,RecentprogressofmagnetocaloriceffectofMnAs1-xSbx[C]//FirstIIF-IIRInternationalConferenceonMagneticRefrigerationatRoomTemperatureMontreux,Switzerland,[J]27-30September,2005.[17]WadaH.andTanabeY.,GiantmagnetocaloriceffectofMnAs1-xSbx[J],AppliedPhysicsLetters,2001,79,3302[18]RoweA.,Tura.A.Experimentalinvestigationofathree-materiallayeredactivemagneticregenerator.InternationalJournalofRefrigeration[J].29(2006):1286-1293[19]HuF.X.,ShenB.G.,SunJ.R.MagneticentropychangeinNi51.5Mn22.7Ga25.8[J].AppliedPhysLett,2000,76(23):3460-3462.[20]HuF.X.,SunJ.R.,Wu,G.H.andShenB.G.,MagneticentropychangeinNi50.1Mn20.7Ga29.6singlecrystal,[J].Applied.Phys.,90（2001）5216.[21]HuF.X.,ShenB.G.；GreatMagneticEntropyChangeinHeuslerAlloysNi2Mn2GaandNaZn13－TypeCompoundsLa(Fe,Co,M)13,M=Si,Al，JournaloftheGraduateSchooloftheChineseAcademyofSciences,Vol.[J]19No.2,2002.06[22]ZhangZ.,LongY.,WenD..MagnetocaloriceffectandphasetransitioninNi53.6Mn23.2Ga23.2Heusleralloy[C]//FirstIIF-IIRInternationalConferenceonMagneticRefrigerationatRoomTemperatureMontreux,Switzerland,[J]27-30September,2005.[23]HuF.X.,ShenB.G.,SunJ.R.,ChengZ.H.,ZhangX.X..MagneticEntropyChangeinLa(Fe0.98Co0.02)[J].Phys.CondenseMatter,2000,12:L691.[24]HuF.X.,ShenB.G.,SunJ.R.,AhangX.X..LargeMagneticEntropyChangeinLa(Fe,Co)11.7Al1.3[J].Phys.Rev.2001,B64:012409.[25]HuF.X.,ShenB.G.,SunJ.R.,ChengZ.H.,RaoG.H.,ZhangX.X..InfluenceofnegativelatticeexpansionandmetamagnetictransitiononmagneticentropychangeinthecompoundLaFe11.4Si1.6[J].AppliedPhys.Lett,2001,78:3675.[26]HuF.X.,ShenB.G.,SunJ.R.,WangG.J.,ChengZ.H..VeryLargeMagneticEntropyChangenearRoomTemperatureinLaFe11.2Co0.7Si1.1[J].AppliedPhys.Lett.,2002,80:826.[27]RoweA.,Tura.A.Experimentalinvestigationofathree-materiallayeredactivemagneticregenerator.InternationalJournalofRefrigeration[J].29，2006，1286-1293[28]陈伟，钟伟等，室温磁制冷最新进展，功能材料，[J]1998，29(3)：236-239[29]GuoZ.B.,DuY.W..Largemagneticentropychangeinperovskite-typemanganeseoxides.[J]PhysRevLett,1997,78(6):1142-1144[30]都有为等，高温磁致冷工质的新进展，物理，[J]1997，26(7)：385-343[31]HuangH,GuoZ.B..LargemagneticentropychangeinLa0.67-xGdxCa0.33Mn0.3[J].MagnMater,1997,(173):302-304[32]财喜雅拉图，刘建，金永军.退火温度对La0.4Nd0.1Sr0.5MnO3薄膜结构及CMR的影响，中国稀土学报，[J]2011，2[33]暴雨梅，张康达，磁制冷技术和纳米磁制冷工质的研究进展，杭州师范学院报，[J]2003，2(1)：56-59[34]吴卫，刘晓烈，姜自莲等.磁热效应及磁制冷材料的研究现状，四川工业学院学报，[J]2001，20(1)：57-60[35]MorikawaT.,WadaH.,KogureR.andHirosawaS.,EffectofconcentrationDeviationfromstoichiometryonthemagnetismofMn1+δAs0.75Sb0.25[J],JournalofMagnetismandMagneticMaterials,2004,283,322[36]PeterW.AndrejKitanovski,Egolf,Thermodynamicsofmagneticrefrigeration[J],InternationalJournalofRefrigeration,2005,43,1[37]TishinA.M.,SpichkinYu.I.,RelationshipofAsiabat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