X pert apparatus

Petrographical characterization of carbonates was achieved by a combination of optical and scanning electron microscopy techniques. Mineralogy was determined at the Geological Survey of Norway by X-ray diffraction (Philips X'pert apparatus, Cu K_α radiation in 2–70° 2θ range) on bulk carbonate powder. Identification of the main carbonate phases was done using EVA software (Supplementary Table 1). The d₁₀₄ displacement was used to estimate the MgCO₃ mol% in calcite67 .

A Philips X'pert apparatus was used to carry out wide angle X-ray diffraction (WAXD) spectroscopy. Measurements were done using a copper CuKα radiation source (λ = 1.54056 Å). Coatings deposited on silicon wafers were scanned from 2 to 10 degrees at a rate of 0.02° s⁻¹. The MMT interlayer spacing (d₀₀₁) was determined using the Bragg's law and the diffraction angle at the maximum intensity peak in XRD patterns.

The crystal structure of the final product was determined using X-ray diffraction (XRD) with a Philips X’Pert apparatus equipped with a CuK_α X-ray source (λ = 1.54056 Å) in the 2θ range of 10–80°. The morphology of the materials was studied using scanning electron microscopy (SEM) with a JSM-7800F microscope, JEOL, Tokyo, Japan and high-resolution transmission electron microscopy (HRTEM) using a JEOL 2100F microscope operated at 200 kV. X-ray photoelectron spectra were recorded using a scanning X-ray microprobe system (PHI VersaProbe II, Ulvac-Phi, Chanhassen, MN, USA) equipped with a Mg Kα source (λ = 1253.6 eV). Raman spectra were recorded at room temperature with a micro-Raman spectrometer (Renishaw, Wottonunder-Edge, UK) equipped with a confocal Raman microscope in-Via TM system at a 532 nm laser-line excitation. The spectra were calibrated with the reference Si phonon peak at 520 cm⁻¹. Brunauer–Emmett–Teller (BET) specific surface area and pore size distribution of synthesized samples were determined from N₂-adsorption experiments using a Belsorp max version 2.3.2 analyzer (Microstac Retsch GmbH, Haan, Germany).