The Use of Thermal Analysis for the Study of the Calcinationprocess of Oxalateprecursors for the Synthesis of High T_c Superconductors

Abstract

The decomposition of the oxalateprecursors Y2(C204)3.4BaC204 . (6 + n)CuCgO4 . xH20 for the synthesis of high Tc superconductors and the individual Y-, Ba-, Cu-oxalate components is investigated by DTA and by TGA coupled with FTIR. INTRODUCTIONA common route for the preparation of the YBa2Cu3076 superconductor is the solid state reaction of physically mixed oxides or carbonates. Several disadvantages of this method have been mentioned such as inhomogeneities at atomic level (1) resulting in long calcination and sintering times. Therefore several other techniques have been checked for the synthesis of high Tc superconductors. One of these methods is the thermal treatment of coprecipitated oxalates (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)). An important difficulty in this method is the control of the stoichiometric ratio of the metalions, because, due to side reactions, the metalion ratio in solution is not necessarily the one found in the precipitate. In a previous publication (12) we reported a method by which it is possible to obtain a simultaneous precipitation of the metal ions in any desired ratio; the method has been succesfully used for the preparation of YBa2Cu307 (12), YBa2Cu3,507.5 (13) and YBa2Cu408 (13).

Growth aspects of barium oxalate monohydrate single crystals in gel medium

“…Most oxalate compounds have shown to exhibit interesting applications such as precipitation agent [6], precursor for superconductive oxides [7], nano particles synthesis [8,9], magnetic and luminescent devices [10][11][12]. In addition, microporous oxalate materials have open-framework structure and are layered with honeycomb like apertures [13].…”

Growth of strontium oxalate crystals in agar–agar gel

“…Oxalates play a vital role in increasing the hardness of barium titanate and to achieve decreased layer thickness in multilayer ceramic capacitors (Bera and Sarkar 2003). They also have good ionic conductivity (George et al 1990), exhibit applications as precipitation agent (Mullens et al 1993) as well as used in nano particle synthesis, in magnetic and luminescent devices (Vos et al 1992;Ye et al 1999;Ahmad et al 2004). Synthesis of rare earth oxalates (Bhat et al 1995;Jayakumari et al 1995;Raju et al 1998) and transition metal oxalates has been * Author for correspondence (paresh10dalal@gmail.com) carried out using gel method (Arora and Tony 1981).…”

Morphological and FTIR Studies of Barium Oxalate Single Crystals

“…2,3 Oxalate ions (C 2 O 4 ) 2-are employed in constructing a large variety of molecular structures and frameworks by incorporating suitable metal ions in the crystal lattice, which can act like monodentate, bidentate, tridentate or tetradentate donor ligand. 4,5 The oxalate compounds are exhibiting interest due to versatile applications like precipitation agent, 6 precursor for superconductive oxides, 7 nanoparticles synthesis, 8 magnetic and luminescent devices. 9 Among the metallic ions studied, Sm cadmium oxalate crystals.…”