Electronegativity, Charge Transfer, Crystal Field Strength, and the Point Charge Model Revisited

Abstract

Although the optical spectra of LnCl(6)(3-) systems are complex, only two crystal field parameters, B(40) and B(60), are required to model the J-multiplet crystal field splittings in octahedral symmetry. It is found that these parameters exhibit R(-5) and R(-7) dependence, respectively, upon the ionic radius Ln(3+)(VI), but not upon the Ln-Cl distance. More generally, the crystal field strengths of LnX(6) systems (X = Br, Cl, F, O) exhibit linear relationships with ligand electronegativity, charge transfer energy, and fractional ionic character of the Ln-X bond.

Optical Properties of Ce-Doped Li4SrCa(SiO4)2: A Combined Experimental and Theoretical Study

“…To proceed, we have performed spectral measurements of Eu 3+ in LSCSO at low temperatures (Figure S3 of the SI). Two distinct excitation bands with maxima at 280 nm (4.43 eV) and 240 nm (5.17 eV) are assigned to the charge transfer transitions (CTs) of Eu 3+ at the Sr and Ca sites, respectively, on the basis of the observation that a larger crystal field strength usually leads to a higher CT transition energy . These CT transition energies of Eu 3+ can be taken as the energy differences between the 4f ground levels of Eu 2+ and the host VBM .…”

Site Occupation of Eu2+ in Ba2–xSrxSiO4 (x = 0–1.9) and Origin of Improved Luminescence Thermal Stability in the Intermediate Composition

“…Accordingly, synchrotron radiation VUV–UV excitation spectra of the 5 D 0 → 7 F 2 emission (at ∼609 nm) of Eu 3+ at the AE2 site of Ba 2– x Sr x SiO 4 :Eu 3+ ,Na + were recorded at 25 K (see Figure S6 the SI). It shows that the CT transition band shifted gradually to the shorter wavelength side with increasing Sr content, as expected from the decrease of the AE2 site size, which should produce an enlarged CT transition energy of Eu 3+ . From the maxima of the CT transition bands, the E vf values for Eu 2+ at the AE2 site were estimated and are listed in the third row of Table .…”

“…It shows that the CT transition band shifted gradually to the shorter wavelength side with increasing Sr content, as expected from the decrease of the AE2 site size, which should produce an enlarged CT transition energy of Eu 3+ . 34 From the maxima of the CT transition bands, the E vf values for Eu 2+ at the AE2 site were estimated and are listed in the third row of Table 1. Third, the ZPL energies E fd were determined from the excitation and emission spectra of Ba 2−x Sr x SiO 4 :Eu 2+ (x = 0−1.9) at 4 K by employing the mirror image method, as shown in Figure 4b, and the results are listed in the fourth row of Table 1.…”

Breakdown Voltage SF6 Versus CF3CHCl2 Gas as Alternative for Gas Insulation Applied

“…The output voltage of the gas in the chamber was 2 kV/s. The breakdown voltage in gas using Paschen law was an equation that provides breakdown voltage that was the voltage needed to start an electric arc between two electrodes in a gas as a function of pressure and gap [21] - [24].…”