By calcining ferric acetylacetonate (Fe(ACAC)₃), Fe(NO₃)₃·9H₂O and FeCl₃·6H₂O in air at 300 °C for 5 h, maghemite (γ-Fe₂O₃) nanoparticles, hematite (α-Fe₂O₃) nanoparticles and α-Fe₂O₃ nanoflakes were synthesized, respectively. The γ-Fe₂O₃ nanoparticles demonstrated far stronger magnetism (remanent magnetization (Mr) = 9.9 emu/g) than α-Fe₂O₃ nanoparticles (Mr = 0.06 emu/g) and nanoflakes (Mr = 0.13 emu/g) at room temperature. For photocatalytic reduction of aqueous Cr(VI) in the presence of visible-light and citric acid, the performance of different Fe₂O₃ samples was found to be in the order of α-Fe₂O₃ from FeCl₃·6H₂O > γ-Fe₂O₃ from Fe(ACAC)₃ > hydrothermally synthesized α-Fe₂O₃ nanorods > α-Fe₂O₃ from Fe(NO₃)₃·9H₂O > hydrothermally synthesized α-Fe₂O₃ nanoparticles. This work reveals the decisive role of precursors in the phase, magnetic and photocatalytic properties of low temperature calcination-synthesized Fe₂O₃. The phase-tunable synthesis of nano Fe₂O₃ by low temperature calcination of easily available precursors is simple, cost-effective and practical for large scale industrial production.

通过将乙酰丙酮铁（Fe（ACAC）₃）、Fe（NO ₃）₃ ·9H ₂ O 和 FeCl ₃ ·6H ₂ O 在空气中在 300°C 下煅烧 5 小时，磁赤铁矿（γ-Fe ₂ O ₃）纳米颗粒，分别合成了赤铁矿（α-Fe ₂ O ₃）纳米颗粒和α-Fe ₂ O ₃纳米薄片。γ-Fe ₂ O ₃纳米颗粒表现出比 α-Fe ₂ O ₃强得多的磁性（剩磁 (Mr) = 9.9 emu/g）纳米颗粒 (Mr = 0.06 emu/g) 和纳米薄片 (Mr = 0.13 emu/g) 在室温下。对于在可见光和柠檬酸存在下光催化还原 Cr(VI) 水溶液，发现不同 Fe ₂ O ₃样品的性能按FeCl ₃ ·6H ₂ O的 α-Fe ₂ O ₃顺序>来自Fe(ACAC) _{3 的}γ-Fe ₂ O ₃  > 水热合成的α-Fe ₂ O ₃纳米棒 >来自Fe(NO ₃ ) ₃ ·9H ₂ O 的α-Fe ₂ O ₃ > 水热合成的α-Fe ₂O ₃纳米粒子。这项工作揭示了前体在低温煅烧合成的 Fe ₂ O ₃的相、磁和光催化性能中的决定性作用。通过低温煅烧容易获得的前体来相位可调合成纳米Fe ₂ O ₃简单、经济且适用于大规模工业生产。