Recrystallization of amorphous and nanocrystalline NdBa/sub 2/Cu/sub 3/O/sub 7-x/ and GdBa/sub 2/Cu/sub 3/O/sub 7-x/

Abstract

Using a novel melt-spinning technique, we have produced both amorphous and nanocrystalline NdBa~Cu307-~ and GdBa2C~307-~ materials. Samples melt-spun in 0 2 consist' of nanocrystals with the tetragonal 123 structure while those processed in N2 show an amorphous matrix with small amounts of crystalline BaCu202, as shown by XRD and TEM studies. The difference is due to the strong dependence of the phase relations on the 0 2 partial pressure. Superconductivity can be fully restored by heating above 1000°C followed by a 450°C anneal in 0 2 . High temperature XRD studies show that the 123 phase crystallizes directly from the amorphous matrix below 800°C. Restoration of the orthorhombic 123 phase does not necessarily insure good superconducting properties, a result attributed to disorder on the heavy metal sites.

Formation of NdBa2Cu3O7−δ amorphous phase by combining aero-acoustic levitation and splat quenching

“…Moreover, the amorphouslike phase was more reactive to the atmospheric gasses than the Nd123 phase, which is subject to decomposition. [9][10][11] As discussed in Sec. This is also associated with the fact that XRD results at room temperature did not indicate any distinct features of the amorphous phase.…”

“…[9][10][11] It was suggested that the amorphous phase was obtained and the Nd123 phase crystallized from the amorphous phase around 630°C by high-temperature x-ray diffrac-tion (HTXRD) at heating condition of 6.5°C/min. [9][10][11] It was suggested that the amorphous phase was obtained and the Nd123 phase crystallized from the amorphous phase around 630°C by high-temperature x-ray diffrac-tion (HTXRD) at heating condition of 6.5°C/min.…”

High-temperature phase relationships for YxNd1–xBa2Cu3Oy(0.7 ≤ x ≤ 1.0) superconductors via containerless processing

“…[3][4][5][6][7] One particularly interesting finding is that the substitution of Nd and other RE elements for yttrium, either full or partial, has been found to have little or no deleterious effect on the electronic properties of the material. A great deal of work has been put into fully characterizing REsubstituted 1:2:3 in terms of the crystal structure and the phase transformations that occur.…”