Exchange charge model of crystal field for 3d ions

Comment on “Oxygen-Vacancy-Induced Midgap States Responsible for the Fluorescence and the Long-Lasting Phosphorescence of the Inverse Spinel Mg(Mg,Sn)O4”

“…Monitoring the B band (λ em = 710 nm, left of Figure a and the inset) shows that the recorded excitation spectrum of the undoped Mg 2 SnO 4 consists of a dominant broadband absorption (∼275 nm, 36.4 × 10 3 cm –1 ) in the ultraviolet (UV) range and several weak bands in the visible range, i.e., C (∼399 nm, 25.1 × 10 3 cm –1 ), D (∼446 nm, 22.4 × 10 3 cm –1 ), E (∼562 nm, 17.8 × 10 3 cm –1 ), and F (∼605 nm, 16.5 × 10 3 cm –1 ) bands. The visible bands are in line with those of Fe 3+ -doped Mg 2 SnO 4 with stronger absorption intensities (Figure e) and are also close to other Fe 3+ -activated oxides. − Thus, these absorptions C ( 4 E­( 4 D)), D ( 4 T 2 ( 4 D)), E ( 4 T 2 ( 4 G)), and F ( 4 T 1 ( 4 G)) are attributed to the Fe 3+ 3d transitions. The Fe 3+ 6 A 1 ( 6 S) → 4 A 1 , 4 E­( 4 G) transitions have not been resolved from the 6 A 1 ( 6 S) → 4 T 2 ( 4 D) one due to weak intensities .…”

Energy levels scheme simulation of divalent cobalt doped bismuth germanate

“…All the notations in Equations (3), (4) are detailed explain in [11,22], so we don't present them in this paper. The CFPs were calculated using the ionic positions obtained from optimized geometry of BGO:Co 2+ system.…”

Eu3+ ions as a crystal-field probe for low-symmetry sites in doped phosphors – a case study: Eu3+ at triclinic sites in Li6RE(BO3)3 (RE = Y, Gd), YBO3 and ZnO and at trigonal sites in YAl3(BO3)4

“…There are two independent techniques, which allow, using the crystal structure data, predicting CFP sets: (i) ab initio calculations based on density functional theory (DFT) and complete active space self-consistent field (CASSCF) 45,46 and (ii) semiempirical models. 36,47–53 In the ab initio methods, the CFPs are deduced from the AILFT ( ab initio ligand field theory), 45,46 and MOLCAS, 54,55 or from the many-electron wave function technique. The above two codes, i.e.…”

“…45,46,54,55 Thus the ab initio results, and those obtained using semiempirical models discussed below, enable studying the structural, electronic, magnetic and optical properties of dopant metal ions in the host crystals, including the CF energy levels. Among several semiempirical models, 36,47–53 the exchange charge model (ECM) 49,50 and superposition model (SPM) 51–53 are two major approaches. In the ECM approach, the CF effects are calculated by incorporating both the electrostatic interactions at the metal site due to ions surrounding the metal ion in the crystal and the exchange effects, which take into account the overlap and covalency of the multi-electronic wave functions of metal ions and ligand ions.…”

“…51–53 The CFPs calculated using the coordinates of atoms surrounding the dopant ion enable correlation of CFPs with the observed optical spectra. 34,49,50 Since the CAS for monoclinic Li 6 RE(BO 3 ) 3 38–40 and YBO 3 15 and hexagonal ZnO 16,17 host crystals do not forms a Cartesian axis system, a modified crystallographic axis system (CAS*) 29,34 was adopted for CFP modelling for these crystals. The CFPs calculated by the ECM (in short: ECM/CFPs or ECM/ B kq ) and SPM (in short: SPM/CFPs or SPM/ B kq ) serve as input to the CF analysis program SPECTRE.…”