Crystallographic study of mixture Ba 0.6 Nd 0.4 CuO y , in the range of annealing temperatures 860 o - 910 o C

2016-02-08T15:37:47Z (GMT) by I. Kerasiotis
A powder mixture of BaCO3, Nd2O3 and CuO was prepared according to the chemical formula Ba0.6Nd0.4CuOy. The mixture was heated successively for several hours (52 to 75h) in free atmosphere at temperatures 860 oC, 870 oC, 880 oC, 890 oC, 900 oC and 910 oC. The products were cooled at room temperature and measured by an X-Ray powder diffractometer with Bragg-Brentano geometry and CuKα radiation. Each of the samples was characterized with the help of the “Powder Diffraction File” (PDF). The initial crystal structure parameters of found crystalline phases were taken from ICSD data base and refined, using the Rietveld’s method, “Powder Profile Analysis”. The refinement took place progressively, with constant temperature factors for all atoms. Six phases were found for whole of the samples: A=Ba1.78Nd1.22Cu3O6.70, B=BaCO3, C=BaCuO2, D=BaCuNd2O5, E=CuO, F=Nd2CuO4. All phases, except the A, decrease progressively and disappear in 910 oC. The phase A is the main phase, and is the unique phase in the sample of 910 oC. Its space group is P4/mmm and the mean unit cell constants are a=b=3.893 Å, c=11.690 Å. The percentage of the main phase varies from 38.78% to 100% (w/w), as the temperature increases from 860 oC to 910 oC.