5114

4804

كارشناسي ارشد

ماده چگال

اصفهان:دانشگاه صنعتي اصفهان،دانشكده فيزيك

1388

[نه]،95ص.:مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

هادي سلامتي

پرويز كاملي

89/1/23

مهدي رنجبر،فرهاد شهبازي

فيزيك

ID4804

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

96 Preparation and investigation phase separation structural electrical and magnetic properties of La0 5Ca0 5Mn1 xMoxO3 x 0 0 02 0 04 0 06 0 08 manganite and Pr0 5Sr0 5MnO3 Student name Vahide Eftekharian Jahromi Email address v eftekharianjahromi@ph iut ac ir Date of submission 1388 12 11 Department of Physics Isfahan University of Technology Isfahan Iran Degree M Sc Language FarsiSupervisor Dr Hadi Salamati salamati@cc iut acAbstractIn this thesis we have investigated the effect of Mo 6 subtitution and preparation conditions on the structural magnetic and electrical properties and phase separation phenomena of La0 5Ca0 5Mn1 xMoxO3 07 x 70 08 andPr0 5Sr0 5MnO3 manganites The samples of La0 5Ca0 5Mn1 xMoxO3 have been prepared by the standars solid ststereaction method for investigation of phase separation and structural magnetic and electrical properties After ofpreparing pellet the samples divided into two series by cooling rate and without cooling rate and sintered Theanalysis of the XRD pattern of samples that hade cooling rate and samples that hade note cooling rate x 0 04 0 06 0 08 showed impurity peaks with Reitveld analysis that note all of compounds hade orthorhombicstructure with space group Pbnm By increasing of doping lattice parameters and unit cell voloum in effect ofenterance of Mn 2 hade not regular behavior For samples of by cooling rate and without cooling rate Thus thisincreasing of lattice parameters and unit cell voloum were the reason of entrance of Mn 2 with ionic radii ofMn 2 Mn 3 when that Mo substituted for Mn and above it we have a impurity phase CaMoO4 So thisincreasing of lattic parameters and unit cell volume in x 0 06 0 08 were the reason of increasing of deficiency inCa site The SEM images for samples of that by cooling rate was given Ac magnetic susceptibility of samplesobserved two transitions that ones in Tco between temperatures 240 270K and ones in between temperatures Tc 140 170K that with increasing of doping in samples of by cooling rate to x 0 04 decreased curietemperature and then increased and in samples of without cooling rate to x 0 02 decreased Tc and thenincreased In sample of x 0 02 that there was samples coexistence of ferromagnetic and chargeorderingantiferromagnetic phases In sample of with cooling rate x 0 02 that Mo was entered in phase hasdecreased transition temperature the reason of double exchange interaction weakens But Mo doping in othersamples has detected as impurity phase of CaMoO4 and with increasing of Ca deficiency causedincreasing of Tcin samples According to the electrical resistivity measurements of with cooling rate samples was in agreementwith the susceptibility data but without cooling rate samples hade note regular behavior For calculation ofsamples oxygen used iodometry titration technique and oxygen decreasing in two series of samples withoutdoping calculated almost 0 05 Other samples Pr0 5Sr0 5MnO3 were prepared by a new method identical with solgel First one series by calcination in 700 C sintered in 900 C 1350 C temperatures and one other series bycalcinations in 900 C sintered in 1100 C 1200 C 1300 C 1450 C temperatures Reitveld analysis of XRDshowed that two series of Pr0 5Sr0 5MnO3 samples have tetragonal structure By increasing of sinteringtemperature increased lattice parameters and unit cell voloum ln effect of increasing of average crystallite sizeand decreasing of surface stress In the Ac magnetic susceptibility measurements of samples observed twotransitions in Tc And TN temperatures that means coexistance of Ferromagnetic and Antiferromagnetic phases In samples by calcinations in 700 C decreased Tc with lncreasing of sintering temperature and increased TN Soin samples by calcinations in 900 C observed that decreased almost Tc with increasing of sintering temperatureand increased TN slightly As we knows With increasing of sintering temperature increased ground state incompound So in this samples by calcinations in 700 C temperature observed

هادي سلامتي

پرويز كاملي

مهدي رنجبر،فرهاد شهبازي