Grüneisen parameters, bulk modulus, and thermal expansion coefficient of Na₃MCO₃PO₄ (M = Mn, Fe, Co, and Ni) carbonophosphates

Abstract

Technological advances in recent decades have made the growing demand for energy one of the main bottlenecks for the development of more complex equipment and processes, requiring a constant search to more efficient materials and techniques that increase the efficiency of energy storage devices.Making use of Raman, X-ray diffraction (XRD), and first-principles calculation techniques, applied in Na 3 MCO 3 PO 4 (M = Mn, Fe, Co, Ni) carbonophosphates in a wide range of pressure and temperature, several thermoelastic and structural parameters were determined. Grüneisen parameters, bulk modulus, and thermal expansion coefficient, as well as the anisotropy under pressure and temperature change, were satisfactorily quantified, characterizing the distinct molecular ambient from the carbonate and phosphate groups of these materials. The results indicate an increasing stiffness and a greater anharmonic contribution as we move towards a more compact structure, indicating an increase in its phonon-phonon interaction.