Theoretical Investigation of the EPR G-Factor for the Axial Symmetry Ce3+ Center in the BaWO4 Single Crystal

The parameters g-factor (g||  and  g⊥) together with the local structure of the Ce3+ center in BaWO4 single crystal (scheelite structure crystals) were theoretically investigated using a complete diagonalization procedure of energy matrix (CDM method). The intrinsic parameters were calculated. It is shown that the experimental and the calculated values of the g-factors are in good agreement. The angular distortion has also been calculated. It was found that the polar angles of the impurity–ligand bonding are smaller than in BaWO4 single crystal (Δθ≈1.0° ) . The validity of the results and the changing in the local environment of the impurity–cerium ion is also discussed

Pentavalent Manganese Luminescence: Designing Narrow-Band Near-Infrared Light-Emitting Diodes as Next-Generation Compact Light Sources

Manganese in the pentavalent state (Mn5+) is both rare and central in materials exhibiting narrow-band near-infrared (NIR) emission and is highly sought after for phosphor-converted light-emitting diodes as promising candidates for future miniature solid-state NIR light source. We develop the Ca14Zn6Ga10-xMnxO35 (x = 0.3, 0.5, 1.0, 1.25, 1.5, and 3.0) series that exhibit simultaneous Mn4+ (650-750 nm) and Mn5+ (1100-1250 nm) luminescence. We reveal a preferential occupancy of Mn in regular octahedral and tetrahedral environments, with the short bond length between these responsible for luminescence. We present a theoretical spin-orbital interaction model in which breaking the spin selection rule permits the luminescence of Mn4+ and Mn5+. A total photon flux of 87.5 mW under a 7 mA driving current demonstrates its potential for real-time application. This work pushes our understanding of achieving Mn5+ luminescence and opens the way for the design of Mn5+-based narrow-band NIR phosphors

Crystallographic-Site-Specific Structural Engineering Enables Extraordinary Electrochemical Performance of High-Voltage LiNi0.5Mn1.5O4 Spinel Cathodes for Lithium-Ion Batteries

The development of reliable and safe high-energy-density lithium-ion batteries is hindered by the structural instability of cathode materials during cycling, arising as a result of detrimental phase transformations occurring at high operating voltages alongside the loss of active materials induced by transition metal dissolution. Originating from the fundamental structure/function relation of battery materials, the authors purposefully perform crystallographic-site-specific structural engineering on electrode material structure, using the high-voltage LiNi0.5Mn1.5O4 (LNMO) cathode as a representative, which directly addresses the root source of structural instability of the Fd (Formula presented.) m structure. By employing Sb as a dopant to modify the specific issue-involved 16c and 16d sites simultaneously, the authors successfully transform the detrimental two-phase reaction occurring at high-voltage into a preferential solid-solution reaction and significantly suppress the loss of Mn from the LNMO structure. The modified LNMO material delivers an impressive 99% of its theoretical specific capacity at 1 C, and maintains 87.6% and 72.4% of initial capacity after 1500 and 3000 cycles, respectively. The issue-tracing site-specific structural tailoring demonstrated for this material will facilitate the rapid development of high-energy-density materials for lithium-ion batteries

Pentavalent Manganese Luminescence: Designing Narrow-Band Near-Infrared Light-Emitting Diodes as Next-Generation Compact Light Sources

Manganese in the pentavalent state (Mn5+) is both rare and central in materials exhibiting narrow-band near-infrared (NIR) emission and is highly sought after for phosphor-converted light-emitting diodes as promising candidates for future miniature solid-state NIR light source. We develop the Ca14Zn6Ga10–xMnxO35 (x = 0.3, 0.5, 1.0, 1.25, 1.5, and 3.0) series that exhibit simultaneous Mn4+ (650–750 nm) and Mn5+ (1100–1250 nm) luminescence. We reveal a preferential occupancy of Mn in regular octahedral and tetrahedral environments, with the short bond length between these responsible for luminescence. We present a theoretical spin–orbital interaction model in which breaking the spin selection rule permits the luminescence of Mn4+ and Mn5+. A total photon flux of 87.5 mW under a 7 mA driving current demonstrates its potential for real-time application. This work pushes our understanding of achieving Mn5+ luminescence and opens the way for the design of Mn5+-based narrow-band NIR phosphors