A Raman and infrared spectroscopic analysis of the phosphate mineral wardite NaAl3(PO4)(2)(OH)(4)center dot 2(H2O) from Brazil

作者：Frost Ray L^*; Scholz Ricardo; Lopez Andres; Lana Cristiano; Xi Yunfei

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2014, 126: 164-169.

DOI：10.1016/j.saa.2014.02.007

• Wardite
• Cyrilovite
• Phosphate
• Hydroxyl
• Raman spectroscopy

A wardite mineral sample from Lavra Da Ilha, Minas Gerais, Brazil has been examined by vibrational spectroscopy. The mineral is unusual in that it belongs to a unique symmetry class, namely the tetragonal-trapezohedral group. The structure of wardite contains layers of corner-linked -OH bridged MO6 octahedra stacked along the tetragonal C-axis in a four-layer sequence and linked by PO4 groups. Consequentially not all phosphate units are identical. Two intense Raman bands observed at 995 and 1051 cm(-1) are assigned to the v(1) PO43- symmetric stretching mode. Intense Raman bands are observed at 605 and 618 cm(-1) with shoulders at 578 and 589 cm-1 are assigned to the v(4) out of plane bending modes of the PO43-. The observation of multiple bands supports the concept of non-equivalent phosphate units in the structure. Sharp infrared bands are observed at 3544 and 3611 cm(-1) are attributed to the OH stretching vibrations of the hydroxyl units. Vibrational spectroscopy enables subtle details of the molecular structure of wardite to be determined.

• 出版日期2014-5-21