ساخت و بررسي خواص ساختاري ، مغناطيسي و الكتريكي تركيب منگنايت La1-xMno3

چكيده انگليسي :

Fabrication and Investigation of Structural Magnetic and Electrical Properties of La1 xMnO3 Manganite Compounds Adam Hosseinzadeh adam hosseinzadeh@gmail com April 13 2011 Department of Physics Isfahan University of technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Dr Hadi Salamati Mail salamati@cc iut ac irAbstractIn this study the effect of doping vacancy in the place of lanthanum and conditions on the construction ofvarious structural characteristics magnetic and electrical of La1 xMnO3 Manganite discussed Samples weremade by heat acetate resolution method To investigate the effect of building hunk temperature in the differentcharacteristics of compounds samples were divided into two series at temperatures 1200 and 1350 degreescentigrade and Hunk were paired samples were low temperature and high temperature were called Withintroducing vacancy in the place of lanthanum La3 ions decrease and some of Mn3 ions convert to Mn4 ionsresult in the double exchange interaction to be stronger in system X ray diffraction pattern analysis of samplesshowed that the majority compounds have rhombohedra structural than samples x 0 15 the low temperaturethat is orthorhombic structure Also For samples x 0 15 of high temperature has appeared Mn3O4 impuritiesphase In the all samples with an increase vacancy in the place of lanthanum has increased lattice parameters andunit cell volume Analysis of SEM images taken from samples showed that grain size with increasing buildinghunk temperature is increases However the vacancy range created in samples here the grain size appears to bewith increasing vacancy here are smaller and more homogeneous Ac magnetic susceptibility diagrams samplesshowed that in both series with increasing vacancy in the place of lanthanum in the first place Curie temperatureincreases and then decreases In samples x 0 01 and x 0 low temperature the system state after the transitionto a phase Ferromagnetic indicate a cluster spin glass state that because the double exchange interaction in theeffect increasing dominance of ferromagnetic phase that this is together with short range order on the supperexchange interaction mode cloud field with antiferromagnetic phases in the sample The samples x 0 05 andx 0 high temperature systems after the transition to a Ferromagnetic state show the spin glass phase In theseexamples contrast to between ferromagnetic interaction and antiferromagnetic interaction leads to be that thesystem in low temperatures to determine owns basic state frustration stricken and suffered a chaotic state Acmagnetic susceptibility samples in the temperature range that is system the spin glass state or a cluster spinglass dependent to the applied frequency With investigation diagrams of electrical resistance of the sampleswas determined that with increasing vacancy in the place of lanthanum specific resistivity samples initiallydecreased and then increased With matching electrical resistance Diagrams of high temperature samples andlow temperature samples by small polaron hopping model indicated that with increase vacancy in the place oflanthanum decreased initially energy of activation Polaron and then increased This trend is contrary Curietemperature are examples Moreover it was found that fast cooling of samples is an appropriate method tocontrol the oxygen content in samples Samples syntheses with fast cooling method show similar properties withLaMnO3 compound This result confirms that the oxygen of samples is close to the stoichiometry amount Keyword Manganite Vacancy La1 xMnO3 Ac Magnetic Susceptibility Spin Glass Cluster Spin Glass

حسين زاده، آدم

ساخت و بررسي خواص ساختاري ، مغناطيسي و الكتريكي تركيب منگنايت La1-xMno3

تهي جا , پذيرفتاري مغناطيسي AC , شيشه ي اسپيني