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The spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) material is considered as a promising cathode in high-voltage lithium-ion batteries due to its advantageous voltage and capacity. Previous results indicate that the electrodes constructed by LNMO with the same compositions while differing in the crystallite geometries always exhibit various electrochemical performances. Here, to probe the relationships between the crystalline geometry of the obtained cathodes and their electrochemical properties, we synthesized different facet-exposed LNMOs with the same compositions using a template method. We demonstrate that the crystallite geometries of the hydroxide precursors can be tuned easily via varying the synthesize parameters, while the tuned precursors can be employed as the templates during the final product preparation. LNMOs enclosed by single {111} facets (LNMO-OH) and both {110} and {100} facets (LNMO-HP) are obtained and employed to elucidate the particle geometry-dependent electrochemical properties. Despite better rate capabilities exhibited for LNMO-HP because of the higher lithium diffusion coefficients along these crystal orientations, inferior cycling performance is released compared with its LNMO-OH counterpart. These insights can provide informative guidance in particle geometry-dependent material construction, thus helpful in realizing high-performance LNMO cathode. • Different facet-exposed LNMOs with the same compositions were synthesized. • The crystallite geometries of the hydroxide precursors can be tuned easily via varying the synthesize parameters. • Facet-exposed LNMOs exhibit various electrochemical properties. • Working mechanism of different LNMOs was investigated. [ABSTRACT FROM AUTHOR]

Abstract A series of Bi3+ ions activated blue-emitting phosphors Gd 2-x ZnTiO 6 :xBi3+ (0 ≤ x ≤ 0.015) were synthesized by high-temperature solid-state procedure. The Density Functional Theory (DFT) calculations demonstrated that the host lattice Gd 2 ZnTiO 6 possessed a direct band gap of 3.07 eV which agreed well with the optical band gap of about 3.80 eV obtained from the diffuse reflection spectrum. Moreover, the Gd 2-x ZnTiO 6 :x Bi3+ crystallizes in a monoclinic space group P 2 1 / n (# 14) and the representative Gd 1.9925 ZnTiO 6 :0.0075Bi3+ phosphor presents an irregular crystal shape with smooth surface, clear edges and corner. All of them emit bright blue light with the emission peak at 419 nm under 375 nm excitation and the optimum Bi3+ ion doping concentration is 0.0075. In addition, the thermal quenching properties and PL decay test show that the Gd 1.9925 ZnTiO 6 :0.0075Bi3+ possess good thermal stability and an efficient energy transfer between Bi3+ ions. Finally, we explored the application of Gd 1.9925 ZnTiO 6 :0.0075Bi3+ phosphor by fabricating the warm pc-WLED device. Notably, the device presents good luminescence properties with the International Commission on Illumination (CIE) coordinates of (0.4485, 0.4222), a high color rendering index (CRI) of 89.4 and low corresponding color temperature (CCT) of 2956 K under 60 mA current. Graphical abstract Image 1 Highlights • Gd 2 ZnTiO 6 :Bi3+ were synthesized as blue-emitting phosphors. • Gd 1.9925 ZnTiO 6 :0.0075Bi3+ possess efficient energy transfer between Bi3+ ions. • The Gd 1.9925 ZnTiO 6 :0.0075Bi3+ based WLED presents excellent luminescence properties. [ABSTRACT FROM AUTHOR]

SrMoO 4 : Sm3+ orange red-emitting phosphors for novel application in temperature measurement were prepared by solid-phase synthesis method. SrMoO 4 : Sm3+ phosphor with scheelite structure was assigned to tetragonal system and I 4 1 /a space group. Sm3+ ions could occupy Sr2+ lattice sites of SrMoO 4. SrMoO 4 : Sm3+ consisted of irregular microparticle with well-crystallized pomegranate seed-like morphology and Sm3+ ions can be evenly distributed in the SrMoO 4 matrix. The band gap value of SrMoO 4 : 1.0%Sm3+ (∼4.228 eV) is less than that of SrMoO 4 (∼4.267 eV), which is due to generation of defective energy levels in band gap. The appropriate quenching concentration of Sm3+ was 1.0%, the critical distance is ∼25.57 Å and θ is 7.1, close to 8, which was attributed to dipole−quadrupole interaction type of electric multipolar interaction. SrMoO 4 :1.0%Sm3+ had excellent thermal stability of the PL peak at 598 nm and 644 nm and anti-thermal quenching property of the PL peak at 530 nm and 563 nm. The activation energy based on the intensity of the PL peak at 598 nm is 0.318 eV. The new dual-model thermometry strategy base on exponential function and modified Boltzmann population distribution would be proposed. SrMoO 4 :Sm3+ phosphor had the absolute sensitivities of 0.108 K−1 based on exponential function and the relative sensitivities of 0.601% K−1 based on modified Boltzmann population distribution. The excellent anti-thermal quenching and good thermal stability of SrMoO 4 : Sm3+ phosphors indicate that it has a potential for applications as pc-WLEDs and optical thermometry. [Display omitted] • SrMoO 4 : Sm 3+ thermometric phosphors were prepared by solid state reaction method. • The excellent anti-thermal quenching and good thermal stability of SMO: Sm3+ phosphors. • The new dual-model thermometry strategy would be proposed. • SrMoO 4 : Sm3+ has a potential for application as optical thermometry. [ABSTRACT FROM AUTHOR]

Highlights: [•] We have synthesized the layered LiNi0.5Mn0.5O2−xF x (0⩽ x ⩽0.04) by hydroxide co-precipitation method. [•] The structure, morphology and electrochemical performance of LiNi0.5Mn0.5O2 are influenced by F doping effect. [•] The cations mixing of pure LiNi0.5Mn0.5O2 decreases and Li+ diffusion coefficient increases with doping F. [•] The reversible capacity of LiNi0.5Mn0.5O1.96F0.04 is 155.0mAhg−1 after 50 cycles at 0.2 C, 0.5 C and 1.0 C ratios between 2.8 and 4.6V. [ABSTRACT FROM AUTHOR]

A series of red emitting phosphors Mg 3 Y 2-x Ge 3 O 12 :xSm3+ (0≤x ≤ 0.06) were successfully synthesized. Samples Mg 3 Y 2-x Ge 3 O 12 :Sm3+ exhibited a cubic structure pertaining to the I a-3d (230) space group and the particle sizes range from 1 μm to 5 μm. The optical properties displayed that the optimum doping concentration of Sm3+ is 4%. The phosphor Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm3+ not only exhibited a broad band gap of 5.54 eV but also showed a high color purity of 97.6%. In addition, the strongest emission intensity located at 566 nm belonged to the 4G 5/2 → 6H 5/2 transition when excited at 405 nm. Thermal quenching test revealed that the sample Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm3+ are excellent powders with splendid thermal stability, in which only 3.6% of the PL intensity is quenched at 473 K in comparison with that of 298 K. As a result, the W-LEDs based on Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm3+ yielded a high R a of 91.1, a low CCT of 4881 K, and CIE coordinates of (0.3476, 0.3466) in a 20 mA driven current. This research work provided important guidance for the synthesis of Sm3+ doped red component with excellent luminesce properties and high thermal stability characteristics used in W-LEDs. • The phosphor Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm3+ not only exhibited a broad band gap of 5.54 eV but also showed a high color purity of 97.6%. • The sample Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm3+ are excellent powders with splendid thermal stability. • The W-LEDs based on Mg 3 Y 1.96 Ge 3 O 12 :0.04Sm3+ exhibited an excellent electroluminesce performance in a 20 mA driven current. [ABSTRACT FROM AUTHOR]