MnAs系列化合物的磁熱效應(yīng)計(jì)算

④得到的兩組數(shù)據(jù)在同一坐標(biāo)系中繪圖可得到圖3.2，分別繪圖則可得到圖3.3和3.4。在圖3.2、3.3、3.4中，我們發(fā)現(xiàn)曲線在某個(gè)點(diǎn)便發(fā)生了突變，這是因?yàn)镸nAs中發(fā)生了一級(jí)磁相變。3.3MnAs化合物的等溫熵變曲線圖3.5、3.6、3.7分別為MnAs化合物的磁熵變實(shí)驗(yàn)曲線、升磁磁熵變曲線、降磁磁熵變曲線。圖3.6、3.7是由圖3.3、3.4中的數(shù)據(jù)通過(guò)公式（2.9）計(jì)算而得到的。由于MnAs的磁滯比較大，所以同實(shí)驗(yàn)數(shù)據(jù)相比要大。而圖(b)則由于外加磁場(chǎng)取間隔太大而導(dǎo)致在M-H圖中S型曲線取值不精確，因而計(jì)算所得曲線與實(shí)驗(yàn)曲線[48]有所偏差。如果外加磁場(chǎng)步長(zhǎng)取的小一些，可能會(huì)和實(shí)驗(yàn)數(shù)據(jù)吻合的比較好。圖3.5熵變隨溫度變化的實(shí)驗(yàn)曲線圖3.6熵變隨溫度的變化曲線圖3.7熵變隨溫度的變結(jié)論本文主要研究了MnAs型化合物的磁性能，通過(guò)Bean-Rodbell模型對(duì)磁熱效應(yīng)的計(jì)算，其結(jié)果表明：1、由Bean-Rodbell模型獲得的理論熱磁曲線與實(shí)驗(yàn)曲線較為吻合。2、由Bean-Rodbell模型獲得的等溫熵變的最大值小于實(shí)驗(yàn)值。而計(jì)算所得曲線與實(shí)驗(yàn)曲線有偏差。4、通過(guò)對(duì)MnAs型化合物磁性的研究為制備出居里溫度在室溫附近的、廉價(jià)的、易得到的、磁熱效應(yīng)大的、可實(shí)用性強(qiáng)的磁制冷材料提供理論指導(dǎo)。參考文獻(xiàn)[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]丁少華.具有手性特征的2-D,3-D稀土硫酸鹽的水熱合成、結(jié)構(gòu)表征及性質(zhì)研究，遼寧師范大學(xué)，[J]2008，34-35[8]鄧曉軍，Mn2-xFexP1-yGey化合物室溫磁制冷材料制備工藝與磁熱性能的研究，北京工業(yè)大學(xué)，[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]門德，松林，伊博樂(lè)，劉璟芳，伊日勒?qǐng)D，特古斯，《稀土金屬》.[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]陳偉，鐘偉等，室溫磁制冷最新進(jìn)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]都有為等，高溫磁致冷工質(zhì)的新進(jìn)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]財(cái)喜雅拉圖，劉建，金永軍.退火溫度對(duì)La0.4Nd0.1Sr0.5MnO3薄膜結(jié)構(gòu)及CMR的影響，中國(guó)稀土學(xué)報(bào)，[J]2011，2[33]暴雨梅，張康達(dá)，磁制冷技術(shù)和納米磁制冷工質(zhì)的研究進(jìn)展，杭州師范學(xué)院報(bào)，[J]2003，2(1)：56-59[34]吳衛(wèi)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