Dissertation
Dissertation > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Metal elements and their compounds > Section III group metal elements and their compounds > Lanthanides ( rare earth elements ) > Lanthanum La

Synthesis and Characterization of Double Perovskite La-K-Fe-Mo-O Series Compound by Sol-Gel Method

Author ZhangHongRui
Tutor HuoGuoYan
School Hebei University
Course Materials Physics and Chemistry
Keywords Giant magnetoresistance Double perovskite Crystal structure Fullprof full spectrum fitting
CLC O614.331
Type Master's thesis
Year 2009
Downloads 17
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This paper using the sol - gel reaction the synthesis series the compound LaKFe2 - x , MoxO6 and La2- xKxFe2 - xMoxO6 ( x = 0.6,0.7,0.8,0.9 ) , respectively, using powder X -ray diffraction to determine the crystal structure of the compounds measuring , using a vibrating sample magnetometer sample magnetic properties of the electrical properties of the sample was measured and the four-probe method to obtain the main results are as follows : right LaKFe1.2Mo0.8O6 sample for analysis , the sample of the powder X-ray diffraction pattern , full spectrum fitting procedure with Fullprof fitting determine the sample for the monoclinic system , space group P21 / n , and the sample contains a small amount of impurity phase K2MoO4 ; calculated fitting of Fe valence 3.077 Mo valence -bit 5.215 . In measuring the temperature in the range of 80-300K does not appear Curie temperature; the sample field cooling thermal demagnetization curve (MT) is higher than the field - free cooling curve . Sample resistivity curve varies with temperature (ρ-T) showed samples have semiconducting properties , the sample conductivity mechanism in line with the small polaron variable range hopping model . Series LaKFe2-xMoxO6 (x = 0.6,0.7,0.8,0.9) oxide analysis , X - ray diffraction patterns of the samples belong to the monoclinic system , space group P21 / n ; reduction of the cell parameters of the calculation of the sample with x small decreases. MT curves of the series of samples of the sample in 80-300K temperature range of magnetic moment is decreased slowly with temperature , there was no Curie temperature , and the sample is increased by the magnetic moment decreases with x . All samples have semiconducting properties , and the conductive mechanism complies with the small polaron variable range hopping model . La2- xKxFe2 - xMoxO6 (x = 0.6,0.7,0.8,0.9 ) series oxides analysis , X - ray diffraction patterns of the samples belong to the monoclinic system , space group P21 / n ; calculate the cell parameters of the sample with x the reduction first increases and then decreases. All samples have semiconducting properties . The magnetic properties and electrical properties of the sample in this series with LaKFe2-xMoxO6 (x = 0.6,0.7,0.8,0.9) series compounds .

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