Processing and Optimization of Bulk La₁₋ₓCaₓMnO3±δ
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Date
1998
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Abstract
The following explores the first systematic research conducted at Texas A&M University studying preparation techniques of the bulk La₁₋ₓCaₓMnO3±δ colossal magnetoresistance (CMR) family. Three sample sets of bulk La₁₋ₓCaₓMnO3±δ were fabricated using different preparation techniques. Details of each technique and the subsequent sample characterization are presented. Focus of the study was directed to compositions in the range 0.25<x<0.55 because these compositions exhibit a insulator-to-metal transition associated with the paramagnetic-to-ferromagnetic (FM) transition upon cooling. Resistance, susceptibility, wavelength dispersion (WDS), x-ray diffraction and BSE photograph data is presented and compared for compositions of different sample sets. In all three sets, unexpected trends and inconsistencies in resistance and susceptibility were observed. BSE photographs confirm sample inhomogeneity, although WDS and x-ray diffraction data suggests that the bulk of the samples are the correct composition. Future changes in preparation techniques are explored. In conclusion, more research is needed to optimize reaction/annealing temperatures and duration parameters to fabricate more homogeneous bulk La₁₋ₓCaₓMnO3±δ magnetoresistance materials.
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Includes bibliographical references: leaf 34.
Program year: 1997/1998
Includes bibliographical references: leaf 34.
Program year: 1997/1998
Keywords
colossal magnetoresistance, La₁₋ₓCaₓMnO3±δ, insulator-to-metal transition, Resistance, susceptibility, wavelength dispersion, x-ray diffraction