Synthesis and morphological characterization of CaSO$$_{4}$$: low-temperature Raman spectroscopy analysis of vibrational modes

Abstract

This study delves into the synthesis of CaSO$$_{4}$$ 4 materials using the Pechini and sol-gel methods, followed by heat treatment up to 900 $$^{\circ }$$ ∘ C. X-ray analysis discerned distinct phases, with one method yielding pure orthorhombic anhydrite and the other predominantly producing a mixture of orthorhombic anhydrite and bassanite. Scanning electron microscopy (SEM) showcased homogeneous columnar morphologies for the anhydrite samples and irregularly sized particles for the alternative method. Photoluminescence (PL) measurements demonstrated emissions in the visible range (approximately 400 nm to 700 nm) with differences noted between synthesis methods. Low-temperature Raman spectroscopy (20 K to room temperature) unveiled unique vibrational modes, notably with the orthorhombic phase of anhydrite exhibiting the most intense peak at 1017 cm$$^{-1}$$ - 1 . These powders, intended for thin film applications, bear significance in electronics, optoelectronics, and nanotechnology. A thorough comprehension of their structural and vibrational properties at the microscopic level is paramount for material and device design and optimization.