CNRS, Université de Bordeaux, Bordeaux INP, ICMCB, UMR 5026, F-33600 Pessac, France.
Université de Limoges, IRCER─Centre Européen de la Céramique, UMR CNRS 7315, F-87068 Limoges, France.
Inorg Chem. 2022 Sep 12;61(36):14377-14388. doi: 10.1021/acs.inorgchem.2c02212. Epub 2022 Aug 31.
In this fundamental solid-state chemistry study, two sample series were investigated in depth: iron(III)-doped hydroxyapatite (HA) compounds obtained from a co-sintering process of hematite and pure HA under air and iron(III)-doped HA compounds obtained from a co-sintering process from iron(II) acetate and pure HA under an argon atmosphere. X-ray diffraction, UV-visible, Fourier transform infrared, H and P NMR, electron paramagnetic resonance (EPR,) and Mössbauer spectroscopy methods were coupled to unravel the Fe valence states, the interactions with other anionic species (OH and PO), and finally the complex local environments in hexagonal channels in both the series. In particular, we highlighted the associated mechanism to ensure electroneutrality with a focus on deprotonation versus calcium substitution. By diverging mechanisms, Fe and Fe ions were found to be located in different coordinated sites: 4(+1) coordinated site for Fe and 2(+3) coordinated site for Fe and clearly associated with very different Mössbauer and EPR signatures as various absorption bands (leading to different sample colors).
在这项基础的固态化学研究中，我们深入研究了两个样品系列：在空气氛围下通过赤铁矿和纯羟基磷灰石（HA）共烧结得到的掺铁(III)羟基磷灰石（HA）化合物，以及在氩气氛围下通过二醋酸铁和纯 HA 共烧结得到的掺铁(III)HA 化合物。我们采用 X 射线衍射、紫外-可见吸收光谱、傅里叶变换红外光谱、H 和 P 核磁共振、电子顺磁共振（EPR）和穆斯堡尔谱学方法相结合，以揭示 Fe 价态、与其他阴离子（OH 和 PO）的相互作用，以及这两个系列中六方通道中复杂的局部环境。特别地，我们强调了确保电中性的相关机制，重点关注去质子化与钙取代。通过不同的机制，Fe 和 Fe 离子被发现位于不同的配位位置：Fe 为 4(+1)配位，Fe 为 2(+3)配位，并且与非常不同的穆斯堡尔和 EPR 特征明显相关，表现为各种吸收带（导致不同的样品颜色）。
