A simple aqueous solution technique utilizing citric acid (CA) as a complexant was applied to prepare PrBa2Cu4O8(Pr124) at ambient oxygen pressure. Heating of a mixed-solution of CA, water (H2O) and ions of Pr, Ba and Cu with a molar ratio of [CA]:[H2O]:[Pr+Ba+Cu] = 3.6:40:1 on a hot-plate set at 200 °C produced a transparent amorphous citrate `gel' without any precipitation, which after heat-treatment at 450 °C was converted to a precursor for Pr124. The Pr124 compound with only minor traces of BaCuO2, PrBaO3 and CuO formed after heat-treating the precursor twice at 850 °C for 60 h under 1 atm oxygen pressure. The amount of impurities in the citrate-derived Pr124 was approximately half of that in the best sample previously prepared by the more elaborate high-pressure technique.
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