Cu-substituted strontium-hexaferrites with chemical compositions SrFe_12-xCu_xO₁₉ (0 ≤ x ≤ 0.8, x = 0, 0.2, 0.4, 0.6 and 0.8) were synthesized successfully by the tartrate-gel route, followed by calcination at 850 °C for 2 h. All the Cu-substituted compositions have single phase with hexagonal crystal structure and P6₃/mmc space group, but parent compound shows a small amount of hematite impurity phase. This suggests that introduction of Cu helps in reducing the calcination temperature to obtain a single phase compound. Furthermore, all the samples are nanocrystalline in nature with average crystallite size ranging from 40 to 50 nm. The variations in the magnetic parameters with increase in the copper content in the Sr-hexaferrite structure indicate the occupation of Cu at octahedral interstitial site. The above nanocrystalline-hexaferrite powders were employed as catalysts for the reduction of 4-nitrophenol to 4-aminophenol, in aqueous medium. The progress of the catalytic reaction was examined by UV-visible absorbance spectroscopy at different intervals of time. The results indicated that the parent compound (SrFe₁₂O₁₉) was catalytically inactive, while all other Cu-substituted samples exhibited good catalytic activities in transforming 4-nitrophenol into 4-aminophenol. Our results reveal that the catalytic property could be induced in Sr-hexaferrite samples by Cu-substitution at octahedral site.

的Cu-取代的锶铁氧体的具有化学组成的SRFE _12-X的Cu _X Ø ₁₉（0≤  X  ≤0.8，X = 0，0.2，0.4，0.6和0.8）是由酒石酸-凝胶途径成功合成，接着煅烧在850°C持续2 h。所有的Cu取代的组合物都具有具有六方晶体结构和P6 _3的单相。/ mmc空间基团，但母体化合物显示少量赤铁矿杂质相。这表明Cu的引入有助于降低煅烧温度以获得单相化合物。此外，所有样品本质上都是纳米晶体，平均微晶尺寸为40至50 nm。随Sr-六方铁氧体结构中铜含量的增加，磁参数的变化表明Cu在八面体间隙位置处的占有率。上述纳米晶-六价铁氧体粉末用作在水性介质中将4-硝基苯酚还原为4-氨基苯酚的催化剂。通过紫外可见吸收光谱在不同的时间间隔检查催化反应的进程。结果表明母体化合物（SrFe ₁₂ O₁₉）是无催化活性的，而所有其他Cu取代的样品在将4-硝基苯酚转化为4-氨基苯酚中均表现出良好的催化活性。我们的结果表明，在八面体位点，Cu取代可在Sr-六价铁氧体样品中诱导催化性能。