Synthesis of Vertically Aligned Manganese-Doped Fe₃O₄ Nanowire Arrays and Their Excellent Room-Temperature Gas Sensing Ability

Vertically aligned Mn (10%)-doped Fe 3 O 4 (Fe 2.7 Mn 0.3 O 4 ) nanowire arrays were produced by the reduction/substitution of pregrown Fe 2 O 3 nanowires. These nanowires were ferromagnetic with a Verwey temperature of 129 K. X-ray magnetic circular dichroism measurements revealed that the Mn 2+ ions preferentially occupy the tetrahedral sites, substituting for the Fe 3+ ions. We observed that the Mn substitution decreases the magnetization, but increases the electrical conductivity. We developed highly sensitive gas sensors using these nanowire arrays, operating at room temperature, whose sensitivity showed a correlation with their bond strength of diatomic/triatomic molecules.