2024/12/19 by Garrett Zeff, Quentin Williams · 1 voice
Materials Science · Chemistry · #Solid-state spectroscopy and crystallography #Crystal Structures and Properties #Inorganic Fluorides and Related Compounds
paper · doi:10.2138/am-2024-9500
openalex publication_date 2024/12/19 · openalex created_date 2024/12/20 · openalex updated_date 2026/08/01
Abstract Raman spectra of Na2Ca2(CO3)3 shortite and K2Ca(CO3)2 bütschliite were measured to 715 and 740 °C, respectively, under vacuum. The vibrational spectra demonstrate that shortite converts to nyerereite [Na2Ca(CO3)2] and calcite at 535 °C. This assemblage remains stable up to ∼700 °C, at which point nyerereite begins to decompose. Bütschliite converts to the isochemical phase fairchildite at 570 °C, which is stable to 665 °C, where it decomposes to an assemblage of K2CO3 and CaO. The variation of anharmonicity between different vibrational modes of each of the low-temperature phases is assessed, and these yield insights into inter-carbonate group couplings. Both fairchildite and nyerereite exhibit spectral features consistent with extensive disordering.