Structural features of the congruently melting compounds MLi (NO 3) 2 (M=K, Rb, Cs) inferred from their Raman spectra

• Published in: The Journal of physics and chemistry of solids 1999, Vol.60 (3), p.317-324
• Main Authors: Xu, Kangcheng, Chen, Yang
• Format: Article
• Language: English
• Subjects: A. Inorganic compounds; C. Raman spectroscopy; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Crystal binding; cohesive energy; Crystalline state (including molecular motions in solids); D. Crystal structure; Exact sciences and technology; Infrared and raman spectra and scattering; Lattice dynamics; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other nonmetallic inorganics; Phonon states and bands, normal modes, and phonon dispersion; Phonons and vibrations in crystal lattices; Physics; Structure of solids and liquids; crystallography
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/S0022-3697(98)00291-1

Raman spectroscopy was applied to interpret the structure of the congruently melting compounds KLi(NO 3) 2, RbLi(NO 3) 2 and CsLi(NO 3) 2. They have similar Raman spectra in both the external and internal vibrational regions, indicating the same structure of the crystals and the same coordination environment of the nitrate ion. The two peaks of comparable intensity in the non-degenerate ν 1 region suggest two crystallographically different sites of the nitrate ion. These compounds appeared to have the same Li–NO 3 complexes as in molten LiNO 3: lithium ions and are tetrahedrally coordinated to nitrate ions to form polymeric complexes in which the nitrate ions act as either unidentate or bidentate ligands. This work confirms that KLi (NO 3) 2 is a congruently melting compound.