Journal of Supercritical Fluids 23 (2002) 81 – 87 Tailoring of nano- and micro-particles of some superconductor precursors by supercritical antisolvent precipitation E. Reverchon *, I. De Marco, G. Della Porta Dipartimento di Ingegneria Chimica ed Alimentare, Uniersita ` di Salerno, Via Ponte don Melillo, 84084 Fisciano, SA, Italy Received 12 February 2001; received in revised form 18 September 2001; accepted 24 September 2001 Abstract Semi-continuous supercritical antisolvent (SAS) precipitation has been used to produce europium (EuAc) and gadolinium (GdAc) acetate nano- and micro-particles with the aim of obtaining controlled size and particle size distributions of these superconductor precursors. For both the compounds tailored micro- and nano-particles have been produced from dimethyl sulfoxide (DMSO). Their particle size and particle size distribution were controlled by varying the concentration of the liquid solution injected into the precipitation vessel. Spherical particles with mean diameters ranging from about 0.2 to 10 m were obtained. The mechanisms that control particle size and particle size distribution were explained in terms of the relative relevance of nucleation and growth processes. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Supercritical antisolvent; Micro-particles; Nano-particles; Gadolinium acetate; Europium acetate www.elsevier.com/locate/supflu 1. Introduction High-temperature superconductors (HTS) have large potential applications in the electro-techni- cal industry. Before their industrial development some problems have still to be overcome. For example, how to maintain superconducting char- acteristics in the presence of magnetic fields gener- ated during ordinary operation. Therefore, to avoid the flux motion, pinning centers are gener- ated by the precipitation of a secondary phase that induces fine non-superconducting defects [1]. It has been suggested that micron or submicron inclusions of yttrium, europium, gadolinium, sa- marium or neodymium can be used. During the last 10 years various micronization techniques based on the use of supercritical fluids have been suggested as an alternative to tradi- tional processes. Indeed, supercritical fluids can substitute liquid solvents in producing microparti- cles with controlled diameters and without solvent contamination. In previous work we proposed the supercritical antisolvent (SAS) precipitation as an alternative technique to produce finely com- minuted particles of yttrium and samarium ac- * Corresponding author. Tel.: +39-089964116; fax: +39- 089964057. E-mail address: reverch@dica.unisa.it (E. Reverchon). 0896-8446/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0896-8446(01)00129-2