Analytical grade
bismuth (III) nitrate pentahydrate (assay 98% Merck), ferric nitrate
(assay 98% Merck), dysprosium (III) nitrate pentahydrate (assay 99.9%
Alfa Aesar), copper (II) nitrate trihydrate (assay 99% Merck) citric acid
anhydrous (assay 99.5% Merck) and nitric acid (assay 70% Merck) were
used as starting materials