A comparable study of the optical spectra and EPR parameters for 3d1‐ and 3d9‐doped MgNH4PO4·6H2O. (11th March 2022)

• Record Type: Journal Article
• Authors: Chen, Baojin; Zhang, Junlong; Li, Rong; Liang, Yajin; Feng, Cuidi; Zhang, Huaming
• Is Part Of: Magnetic resonance in chemistry. Volume 60:Number 6(2022)
• Page Start: 554
• Page End: 562
• Publication Date: 2022-03-11
• Subjects: Cu2+ -- electron paramagnetic resonance (EPR) -- MgNH4PO4·6H2O -- optical spectra -- VO2+; Nuclear magnetic resonance spectroscopy -- Periodicals; Chemistry, Organic -- Periodicals; Magnetic resonance -- Periodicals; 538.36
• DOI: 10.1002/mrc.5264
• Languages: English
• ISSNs: 0749-1581

Abstract

Abstract: VO 2+ (3d 1 ) and Cu 2+ (3d 9 ) are the two complementary states that usually show opposite distortions when they are doped in crystals. In this work, the optical absorption spectra (OAS), electron paramagnetic resonance (EPR) parameters, and local structure (LS) for VO 2+ (and Cu 2+ ) in MgNH4 PO4 ·6H2 O (MPPH) are uniformly investigated on the basis of the high‐order perturbation formulas for a 3d 1 (and 3d 9 ) ion in tetragonally compressed (and elongated) octahedra, respectively. In the calculated formulas, the required crystal‐field parameters can be obtained from the superposition model and reasonably linked with the LS distortion for VO 2+ and Cu 2+ centers. Based on the calculations, the tetragonal compressed [VO(H2 O)5 ] 2+ cluster (and tetragonal elongated [Cu(H2 O)6 ] 2+ cluster) is found to suffer tetragonal compression ratio of 1.65% and tetragonal elongation ratio of 3.8% along C 4 ‐axis, respectively, due to the Jahn–Teller (JT) effect. The theoretical EPR parameters based on the above lattice distortions agree well with the experimental data, and the LS of the VO 2+ and Cu 2+ centers in MPPH is discussed. Abstract : The tetragonal compressed [VO(H2 O)5 ] 2+ cluster (and tetragonal elongated [Cu(H2 O)6 ] 2+ cluster) is found to suffer tetragonal compression ratio of τV (≈1.65%) and tetragonal elongation ratio of τV (≈3.8%) along C4‐axis, respectively, due to the Jahn–Teller effect