Synthesis of Nanocrystalline BaCeO₃ by Oxalate Coprecipitation for YBa₂Cu₃O₇ Bulk Superconductors

Abstract

Barium cerate (BaCeO3) is one of the preferred additions to bulk YBa2Cu3O7 single-grain superconductors to inhibit the growth of Y2BaCuO5 particles. The present paper investigates synthesis of very fine barium cerate powder and its use in YBa2Cu3O7 bulk superconductor growth. The crystalline barium cerate was synthesized by oxalate co-precipitation from barium and cerium nitrates. X-ray diffraction in air and vacuum was performed to understand the formation of barium cerate as well as to determinate its crystal structure. Size and shape of BaCeO3 particles were studied by scanning electron microscopy. The BaCeO3 was used to grow YBa2Cu3O7 bulk superconductor. Microstructure of prepared YBa2Cu3O7 crystal shows that the barium cerate in the final product is very fine and uniformly distributed throughout the whole YBa2Cu3O7 crystal.

Hydrazine-nitrate combustion synthesis of BaCeO3 preceramic powders: structure, morphology and thermophysical properties

“…As a consequence of thermal processing at 600 °C several changes were observed in the composition of the sample due to the decomposition of barium nitrate, which is in line with the results of thermal analysis (Fig. 2); also there occurs cerium oxide (IV) (crystallization of amorphous cerium oxide in the range of 500-600 °C) and the decomposition of barium carbonate BaCO3 [14]. The composition of the sample processed thermally at 700 °C is in close correspondence with rhombic barium cerate, however, large amounts of barium carbonate and cerium oxide(IV) are also observed and their elimination occurs only at 1000 °С.…”

“…The main disadvantages of this method are low homogeneity, the complexity of size control for material particles high sintering temperatures, and long sintering time [10][11][12]. The second group of technologies is solution-based methods including co-precipitation, combustion methods (fuel-nitrate combustion), sol-gel Pechini methods, cryochemical and hydrothermal syntheses, and others [11,[13][14][15][16][17][18][19]. The main advantages of these technologies are the considerably smaller size of particles of prepared powders and their high homogeneity, which favors the decrease in synthesis temperature and duration of phase formation of multicomponent compounds, as well as preparation of gastight ceramic products at lower sintering temperatures.…”

Influence of addition of nanosize barium cerate on the microstructure and properties of top‐seeded melt growth YBCO bulk superconductors

“…The calcination of BaCeO 3 samples in air and vacuum was controlled by X‐ray powder diffraction (XRD) (Rigaku Ultima IV, Cu Kα radiation λ = 0.15417 nm) (~ 2 × 10 ‐3 mbar) at temperatures from 25 to 1100°C and by differential thermal analysis and thermogravimetry performed using a NETZSCH STA 449 F1 Jupiter instrument. The results of these studies have already been published 26 …”

“…The results of these studies have already been published. 26 The studied bulk YBCO samples were produced by a top-seeded melt growth process from a mixture of Y123, Y211 and BaCeO 3 powders. The powders were mixed in appropriate amounts by a mixer for 30 minutes and subsequently were milled for 15 minutes in a friction mill.…”