The control of the growth of hematite nanoparticles from iron chloride solutions under hydrothermal conditions in the presence of two different structure promoters has been studied using a range of both structural and spectroscopic techniques including the first report of photo induced force microscopy (PiFM) to map the topographic distribution of the structure-directing agents on the developing nanoparticles. We show that the shape of the nanoparticles can be controlled using the concentration of phosphate ions up to a limit determined to be ~6 × 10⁻³ mol. Akaganéite (β-FeOOH) is a major component of the nanoparticles formed in the absence of structure directors but only present in the very early stages (< 8 h) of particle growth when phosphate is present. The PiFM data suggest a correlation between the areas in which phosphate ions are adsorbed and areas where akaganéite persists on the surface. In contrast, goethite (α-FeOOH) is a directly observed precursor of the hematite nanorods when 1,2-diamino propane is present. The PiFM data shows goethite in the center of the developing particles consistent with a mechanism in which the iron hydroxide re-dissolves and precipitates at the nanorod ends as hematite.

在水热条件下，在两种不同的结构促进剂的存在下，从氯化铁溶液中赤铁矿纳米粒子的生长控制已使用一系列结构和光谱技术进行了研究，包括光诱导力显微镜（PiFM）的第一篇报道结构导向剂在正在发展的纳米颗粒上的形貌分布。我们表明，可以使用磷酸根离子的浓度控制纳米颗粒的形状，直至确定​​为〜6×10 ^-3的极限 摩尔 赤铁矿（β-FeOOH）是在不存在结构导向器的情况下形成的纳米颗粒的主要成分，但仅在存在磷酸盐时才存在于颗粒生长的非常早期阶段（<8小时）。PiFM数据表明，吸附磷酸根离子的区域与表面残留高铝矾石的区域之间存在相关性。相反，当存在1,2-二氨基丙烷时，针铁矿（α-FeO​​OH）是赤铁矿纳米棒的直接观察到的前体。PiFM数据显示针铁矿位于显影颗粒的中心，这与氢氧化铁以赤铁矿形式重新溶解并沉淀在纳米棒末端的机理一致。