三斜水钠锰矿层间阳离子交换作用的拉曼谱学

水钠锰矿为自然界中常见的锰氧化物矿物，其离子交换作用及结构转变理解尚不深刻，矿物表征手段较为局限.为探究水钠锰矿的离子交换特性以及结构转变在拉曼光谱上的反映，利用MnSO₄和NaOH合成了三斜晶系的Na型水钠锰矿，进行了NH₄+、K+、Mg2+、Ca2+、Ba2+、Co2+、Zn2+的离子交换实验，使用ICP-OES、XRD、拉曼光谱等手段对离子交换水钠锰矿进行表征.拉曼光谱分析表明，570~585 cm-1与640~655 cm-1两个锰氧八面体伸缩振动模式的相对强度及570~585 cm-1附近拉曼峰峰位指示水钠锰矿的结构对称型；570~585 cm-1拉曼峰强度大、振动频率高指示三斜对称型.280 cm-1与500 cm-1附近的拉曼峰是层间离子种类的识别标志.水钠锰矿层间若为Na+、K+、Mg2+、Ca2+、Ba2+等碱金属、碱土金属离子，则在280 cm-1附近存在1个峰值，500 cm-1存在2个分立的峰值；其他种类的层间离子仅500 cm-1处有1个孤峰，指示层间离子排列无序. 

Raman Spectroscopy of Ion Exchange in Interlayer of Triclinic Birnessite

Birnessite is a group of manganese oxide minerals widely found in nature. However, its ion exchange behavior and structural transformation have not been fully understood, and the characterization techniques are limited. To study the ion exchange behavior of birnessite and the reflection of structural transformation in Raman spectroscopy, triclinic Na-birnessite was synthesized using MnSO₄ and NaOH, and ion exchange experiments on NH₄+, K+, Mg2+, Ca2+, Ba2+, Co2+, and Zn2+ were carried out. Ion exchange birnessite samples were characterized using ICP-OES, XRD, and Raman spectroscopy. Raman study shows the relative strength of two stretching vibration modes inMnO₆] octahedra around 570-585 cm-1 and 640-655 cm-1 and the band location of the mode around 570-585 cm-1 are indicators of the symmetry of birnessite. High strength and frequency of the mode around 570-585 cm-1 are signs of triclinic symmetry. Raman bands around 280 cm-1 and 500 cm-1 are indicators of interlayer cations. If alkalis and alkaline-earth metals (i.e., Na+, K+, Mg2+, Ca2+, Ba2+, etc.) are in the interlayer of birnessite, a band around 280 cm-1 and two separate bands around 500 cm-1 will appear; whereas other interlayer cations only give rise to one single band at 500 cm-1, indicating disorder in the interlayer.