Work

Thermo-structural investigations on Beryl using Vibrational Spectroscopy and X-Ray Diffraction techniques

Year: 2025

Type: article

Abstract: Molecular orientations and structural distortions are essential properties of minerals that help us understand their response under varying thermodynamic conditions of temperature ( T ) and pressure ( P ). Understanding such properties under varying thermodynamic conditions is helpful in material and geological science. The study of Beryl (Be 3 Al 2 (SiO 3 ) 6 ) under high temperature (high- T ) aids in understanding its effect on atomic vibrations, bonding environment, and overall structural integrity. Here, we present the detailed molecular response of Beryl at high- T from 25 °C to 1200 °C probed using Raman, infrared (IR), and Terahertz-Time Domain (THz-TD) spectroscopic techniques in the 16–4000 cm −1 wide spectral range. Upon heating above 900 °C, minor changes in the full width half maxima (FWHM) of symmetric stretch of Be O and Si O Raman active modes were observed in the 200–1200 cm −1 spectral range. Signatures of two types of water (H 2 O) molecules were observed in the IR spectra, type-I around 3699 cm −1 and type-II at around 3596 cm −1 and 1632 cm −1 , which disappeared upon heating around 900 °C. These subtle changes in vibrational spectra indicate minor distortions at the molecular level in Beryl at high- T s. However, no changes were observed in the lattice region in the 16–66 cm −1 spectral range when probed using THz-TDS. This fact is well supported by high- T X-Ray Diffraction (XRD) studies, which suggest a stable structure up to 1200 °C. • High-temperature Raman, infrared, Terahertz, and X-ray diffraction studies on the Beryl mineral were reported. • No symmetry changes were observed in Beryl up to 1200 °C. • Subtle changes around 900 °C reflected in IR and Raman studies show the disappearance of Type-I and Type-II water molecules entrapped in Beryl. • No structural changes were observed up to 1200 °C, which is well supported by XRD studies.

Source: Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy

DOI: 10.1016/j.saa.2025.127249

Authors: Naini Bajaj, Amartya Sengupta, Aparajita Bandyopadhyay

Institutions: Indian Institute of Technology Delhi, The University of Queensland, Goethe University Frankfurt

Language: English

Topic: Mineralogy and Gemology Studies

Subfield: Geochemistry and Petrology

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,750

Funders: Defence Research and Development Organisation, Indian Institute of Technology Delhi, Board of Research in Nuclear Sciences