Images and graphs from a Raman and infrared spectroscopic study of the vivianite-group phosphates vivianite, baricite and bobierrite

The molecular structure of the three vivianite-structure, compositionally related phosphate minerals vivianite, baricite and bobierrite of formula M32+(PO4)2.8H2O where M is Fe or Mg, has been assessed using a combination of Raman and infrared (IR) spectroscopy.

Figure 1 is Raman spectra of the hydroxyl-stretching region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 2 is IR spectra of the hydroxyl-stretching region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 3 is IR spectra of the water HOH-bending region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 4 is Raman spectra of the phosphate-stretching region of (a) vivianite, (b) baricite and (c) bobierrite.

Figure 5 is IR spectra of the PO4-stretching region of (a) vivianite, (b) baricite and (c) bobierrite

Figure 6 is Raman spectra of the low-wavenumber region of (a) vivianite, (b) baricite and (c) bobierrite.

本研究结合拉曼（Raman）光谱与红外（Infrared, IR）光谱技术，对三种具有蓝铁矿（vivianite）结构、成分相关的磷酸盐矿物——蓝铁矿、重晶磷镁石（baricite）与纤磷镁石（bobierrite）的分子结构进行了表征分析。上述三种矿物的统一化学式为M²⁺₃(PO₄)₂·8H₂O，其中M为二价铁（Fe）或二价镁（Mg）。
图1为三种矿物羟基伸缩振动区域的拉曼光谱，其中(a)为蓝铁矿，(b)为重晶磷镁石，(c)为纤磷镁石。
图2为三种矿物羟基伸缩振动区域的红外光谱，其中(a)为蓝铁矿，(b)为重晶磷镁石，(c)为纤磷镁石。
图3为三种矿物水分子HOH弯曲振动区域的红外光谱，其中(a)为蓝铁矿，(b)为重晶磷镁石，(c)为纤磷镁石。
图4为三种矿物磷酸盐伸缩振动区域的拉曼光谱，其中(a)为蓝铁矿，(b)为重晶磷镁石，(c)为纤磷镁石。
图5为三种矿物PO₄伸缩振动区域的红外光谱，其中(a)为蓝铁矿，(b)为重晶磷镁石，(c)为纤磷镁石。
图6为三种矿物低波数区域的拉曼光谱，其中(a)为蓝铁矿，(b)为重晶磷镁石，(c)为纤磷镁石。