Structural and vibrational properties of carbonophosphates: Na3MCO3PO4 (M = Mn, Fe, Co and Ni)

A Raman spectroscopic study of the natural carbonophosphates Na<sub>3</sub><i>M</i>CO<sub>3</sub>PO<sub>4</sub> (<i>M</i> is Mn, Fe, and Mg)

“…The Raman spectral profiles of all investigated minerals (i.e., sidorenkite, bonshtedtite, and bradleyite) are similar (Fig. 3) and generally cor-respond to the information reported in Amaral et al (2019) and Frost et al (2015). The low-frequency spectral region from 70 to 350 cm −1 shows a series of external (translational lattice) modes.…”

“…The standard group theory analysis shows the presence of 78 vibrational modes for carbonophosphates, of which 39 can be expected in Raman spectra (Amaral et al, 2019). In the Raman spectra of the phases examined in this study, from 21 to 24 pronounced bands were detected.…”

“…The first band is interpreted as a υ 1 (P-O) mode from the [PO 4 ] 3− group (Amaral et al, 2019;Frost et al, 2015). The second band was described as a υ 1 (C-O) mode from the [CO 3 ] 2− group (Amaral et al, 2019;Frost et al, 2015). The Raman bands between 1010-1050 cm −1 are identified as the υ 3 (P-O) antisymmetric stretching mode of the phosphate units.…”

“…Because these species are capable of incorporating large-ion lithophile and rare earth elements (REEs) into their structure, they can participate in the transport of these elements (Gao et al, 2015). It is also noteworthy that bonshtedtite is one of the minerals obtained in recent experiments on the mobility of REEs in carbonatite systems (Anenburg et al, 2020), which indicates its value for petrological modeling of carbonatite evolution. Moreover, due to the presence of both [PO 4 ] 3− and [CO 3 ] 2− groups in carbonophosphates, these mineral phases can play an important role in the Earth's global carbon and phosphate cycles.…”

“…A thorough study of the Raman spectrum has only been made for natural sidorenkite (Frost et al, 2015). For the synthetic analog of bonshtedtite, the position of the lattice modes in the 140-240 cm −1 spectral range and the two main modes of the [PO 4 ] 3− and [CO 3 ] 2− groups have been described (Amaral et al, 2019;Gao et al, 2018). Positions of only two main modes have previously been determined for synthetic bradleyite (Gao et al, 2015).…”