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Electronic, Magnetic, and Thermal properties of lead(A)chromium oxide (A = potassium or lanthanum)

Posted on:2012-03-20Degree:M.ScType:Thesis
University:Brock University (Canada)Candidate:Indovski, BiljanaFull Text:PDF
GTID:2461390011968430Subject:Physics
Abstract/Summary:
Lead chromium oxide is a photoconductive dielectric material that has great potential of being used as a room temperature photodetector. In this research, we made ceramic pellets of this compound as well as potassium doped compound Pb2-xKxCrO 5, where x=0, 0.05, 0.125. We also investigate the properties of the lanthanum doped sample whose chemical formula is Pb1.85La 0.15CrO5. The electronic, magnetic and thermal properties of these materials have been studied. Magnetization measurements of the Pb 2CrO5 sample indicate a transition at about 310 K, while for the lanthanum doped sample the transition temperature is at about 295 K indicating a paramagnetic behavior. However, the potassium doped samples are showing the transition from paramagnetic state to diamagnetic state at different temperatures for different amounts of potassium atoms present in the sample. We have studied resistivity as a function of temperature in different gas environments from 300 K to 900 K. The resistivity measurement of the parent sample indicates a conducting to insulating transition at about 300 K and upon increasing the temperature further, above 450 K the sample becomes an ionic conductor. As temperature increases a decrease in resistance is observed in the lanthanum/potassium doped samples. Using Differential Scanning Calorimetry experiment an endothermic peak is observed for the Pb2CrO 5 and lanthanum/potassium doped samples at about 285 K.
Keywords/Search Tags:Potassium, Lanthanum, Doped samples, Temperature
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