A novel terbium–mercury compound: Preparation, structure, and properties

Using a hydrothermal reaction, a novel 4f–5d isonicotinic acid complex {[Tb2(IA)6(H2O)4](Hg3Cl7)} n( nHgCl4)· nCl·4 nH3O (1, HIA = isonicotinic acid) was synthesized and it was characterized by single crystal X-ray diffraction technique. Compound 1 is characterized by a two-dimensional layer-like structure. The photoluminescence measurement using solid-state samples uncovered that it shows four emission peaks at 489, 546, 587, and 622 nm, of which the peak at 546 nm is the strongest. These peaks could be assigned to the 5 D4 → 7 F6, 5 D4 → 7 F5, 5 D4 → 7 F4, and 5 D4 → 7 F3 transitions of the Tb3+ ions, respectively. The energy transfer mechanism of the photoluminescence emission was described by means of the energy level scheme of the Tb3+ ions and the isonicotinic acid ligand. Compound 1 shows remarkable CIE (Commission Internationale de I’Éclairage) chromaticity coordinates of (0.3633, 0.5038) in the yellowish green region. Compound 1 possesses a wide semiconductor band gap of 2.97 eV, as unveiled by the solid-state UV-Vis diffuse reflectance experiment.

Designing a novel red to near-infrared persistent phosphor CaMgGe2O6:Mn2+,Sm3+based on a vacuum referred binding energy diagram

We constructed an empirical energy level scheme of the CaMgGe2O6:Ln2+/Ln3+phosphors and improved the persistent luminescent properties of the sample, which the persistence duration was three times that of the red commercial phosphor Y2O2S:Eu3+.

Inelastic Neutron Scattering Studies on the Crystal Field Excitations in Superconducting NdFeAsO0.85F0.15

Inelastic neutron scattering experiments were performed on polycrystalline samples of NdFeAsO0.85F0.15over a wide temperature range (3 K–250 K). Based on the analysis of the experimental data, a Nd3+CF energy level scheme is proposed to give a consistent explanation about the observed CF transitions. The observed extra ground-state CF transitions could not be simply explained by the transitions between five Kramers doublets split from the Nd3+ 4I9/2ground state in theC4vpoint symmetry. A reliable explanation would be a superposition of crystal fields due to different local symmetries around the Nd3+ions induced by the fluorine doping.