Synthesis of Ba sub 2 YCu sub 3 O sub 7 powder by anionic oxidation (NO sup minus sub 3 )-reduction (RCOO sup minus , where R is H, CH sub 3 , and CH sub 3 CH sub 2 )

Journal Article · Fri Dec 01 04:00:00 EST 1989 · Journal of Solid State Chemistry; (USA)

DOI:https://doi.org/10.1016/0022-4596(89)90172-2· OSTI ID:6717205

Kourtakis, K; Robbins, M; Gallagher, P K ^[1]

---

1. AT T Bell Laboratories, Murray Hill, NJ (USA)

A new method for synthesizing homogeneous oxide powder, reported earlier, is studied. This technique involves spray drying a solution containing an oxidizing and reducing salt into an intimately mixed powder. The spray-dried powder undergoes an internal oxidation-reduction reaction which completely converts it into the mixed oxide at <300{degree}C. The resulting powder is homogeneous on a fine scale and can be reacted to form the final oxide compound at much shorter times than those using the usual ceramic methods. Single phase (>95%) Ba{sub 2}YCu{sub 3}O{sub 7-x} is formed in 10 min at 910{degree}C. Previously, mixtures of nitrate (oxidizing) and acetate (reducing) salts were studied. This is now extended to include other organic reducing agents such as formates and propionates and comparisons are made for RCOO{sup {minus}}, where R = H, CH{sub 3}, and CH{sub 2}CH{sub 3}. The formate/nitrate and propionate/nitrate precursors are completely converted into their oxides at temperatures as low as 210{degree} and 260{degree}C, respectively (as opposed to 270{degree}C for the acetate/nitrate precursors). The enthalpy of the low-temperature reaction is dependent on the organic fraction in the mixture. In addition, the reaction enthalpies of the formate/nitrate precursors are less than that of the propionate/nitrate or acetate/nitrate precursors: {minus}{Delta}H (7:6, propionate:nitrate) = 3,184, {minus}{Delta}H (7:6, acetate:nitrate) = 3,473, and {minus}{Delta}H (8:5, formate:nitrate) = 958 kj/mole. Hence, control over both the reaction enthalpy of the decomposition temperature can be achieved by the choice of organic ligand reducing agent and the nitrate/reducing agent ratios.

• OSTI ID: 6717205
• Journal Information: Journal of Solid State Chemistry; (USA), Journal Name: Journal of Solid State Chemistry; (USA) Vol. 83:2; ISSN JSSCB; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals &amp; Alloys-- Preparation &amp; Fabrication
360104 -- Metals &amp; Alloys-- Physical Properties
ALKALINE EARTH METALS
BARIUM
CHALCOGENIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
COPPER COMPOUNDS
COPPER OXIDES
DATA
DATA ANALYSIS
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
MATERIALS
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
REDOX REACTIONS
SUPERCONDUCTING COMPOSITES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
YTTRIUM