Advances in solid state white lighting technologies witness the explosive development of phosphor materials (down-conversion luminescent materials). A large amount of evidence has demonstrated the revolutionary role of the emerging nitride phosphors in producing superior white light-emitting diodes for lighting and display applications. The structural and compositional versatility together with the unique local coordination environments enable nitride materials to have compelling luminescent properties such as abundant emission colors, controllable photoluminescence spectra, high conversion efficiency, and small thermal quenching/degradation. Here, we summarize the state-of-art progress on this novel family of luminescent materials and discuss the topics of materials discovery, crystal chemistry, structure-related luminescence, temperature-dependent luminescence, and spectral tailoring. We also overview different types of nitride phosphors and their applications in solid state lighting, including general ...

Down-Conversion Nitride Materials for Solid State Lighting: Recent Advances and Perspectives.

Based on the concept of band bending at metal/semiconductor interfaces as an energy filter for electrons, we present a theory for the enhancement of the thermoelectric properties of semiconductor materials with metallic nanoinclusions. We show that the Seebeck coefficient can be significantly increased due to a strongly energy-dependent electronic scattering time. By including phonon scattering, we find that the enhancement of $ZT$ due to electron scattering is important for high doping, while at low doping it is primarily due to a decrease in the phonon thermal conductivity.

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Theory of enhancement of thermoelectric properties of materials with nanoinclusions.

High-rate lithium (Li) ion batteries that can be charged in minutes and store enough energy for a 350-mile driving range are highly desired for all-electric vehicles. A high charging rate usually leads to sacrifices in capacity and cycling stability. We report use of black phosphorus (BP) as the active anode for high-rate, high-capacity Li storage. The formation of covalent bonds with graphitic carbon restrains edge reconstruction in layered BP particles to ensure open edges for fast Li+ entry; the coating of the covalently bonded BP-graphite particles with electrolyte-swollen polyaniline yields a stable solid-electrolyte interphase and inhibits the continuous growth of poorly conducting Li fluorides and carbonates to ensure efficient Li+ transport. The resultant composite anode demonstrates an excellent combination of capacity, rate, and cycling endurance.

Black phosphorus composites with engineered interfaces for high-rate high-capacity lithium storage.

We present a new type of large-scale computational screening approach for identifying promising candidate materials for solid state electrolytes for lithium ion batteries that is capable of screening all known lithium containing solids. To be useful for batteries, high performance solid state electrolyte materials must satisfy many requirements at once, an optimization that is difficult to perform experimentally or with computationally expensive ab initio techniques. We first screen 12 831 lithium containing crystalline solids for those with high structural and chemical stability, low electronic conductivity, and low cost. We then develop a data-driven ionic conductivity classification model using logistic regression for identifying which candidate structures are likely to exhibit fast lithium conduction based on experimental measurements reported in the literature. The screening reduces the list of candidate materials from 12 831 down to 21 structures that show promise as electrolytes, few of which have been examined experimentally. We discover that none of our simple atomistic descriptor functions alone provide predictive power for ionic conductivity, but a multi-descriptor model can exhibit a useful degree of predictive power. We also find that screening for structural stability, chemical stability and low electronic conductivity eliminates 92.2% of all Li-containing materials and screening for high ionic conductivity eliminates a further 93.3% of the remainder. Our screening utilizes structures and electronic information contained in the Materials Project database.

Holistic computational structure screening of more than 12 000 candidates for solid lithium-ion conductor materials

The isotypic compounds M[Mg3SiN4] (M = Ca,Sr,Eu) have been synthesized by solid-state reactions in sealed tantalum ampules or in a radio-frequency furnace. The nitridomagnesosilicates crystallize in space group I41/a (No. 88). Crystal structures were solved and refined from single-crystal X-ray diffraction data (Z = 16, Ca[Mg3SiN4]:Ce3+, a = 11.424(2), c = 13.445(3) A, R1 = 0.040, wR2 = 0.106; Sr[Mg3SiN4]:Eu2+, a = 11.495(2), c = 13.512(3) A, R1 = 0.036, wR2 = 0.102; Eu[Mg3SiN4], a = 11.511(4), c = 13.552(4) A, R1 = 0.016, wR2 = 0.039). The nitridomagnesosilicates are isotypic to Na[Li3SiO4], containing a condensed tetrahedra network with a high degree of condensation (i.e., atomic ratio (Mg,Si):N) κ = 1. The crystal structures were confirmed by Rietveld refinement, lattice energy (MAPLE) calculations, and further investigated by 29Si-MAS NMR. Ce3+-doped samples of Ca[Mg3SiN4] show yellow emission (λmax = 530 and 585 nm, fwhm ∼3900 cm–1 (∼130 nm)), while Sr[Mg3SiN4]:Eu2+ exhibits red luminescence (λmax = ...

Toward New Phosphors for Application in Illumination-Grade White pc-LEDs: The Nitridomagnesosilicates Ca[Mg3SiN4]:Ce3+, Sr[Mg3SiN4]:Eu2+, and Eu[Mg3SiN4]

Sr(Mg3Ge)N4 and Sr(Mg2Ga2)N4: New isostructural Mg-containing quaternary nitrides with nitridometallate anions of [(Mg3Ge)N4]2−∞3 and [(Mg2Ga2)N4]2−∞3 in a 3D-network structure

Transport properties of undoped and Br-doped PbTe sintered at high temperature and pressure> 4.0 GPa

The crystal structure of Li3P has been reinvestigated and confirmed by single-crystal data. The structure is built of Li+ and P3− ions stacked in two kinds of layers perpendicular to the c axis. Atoms Li1, Li2 and P reside at positions of \overline{6}m2, 3m and \overline{6}m2 site symmetry, respectively. The only free parameter, z, for Li2 is found to be 0.5839 (4).

Reinvestigation of trilithium phosphide, Li3P

Synthesis and single crystal structures of ternary phosphides Li4SrP2 and AAeP (A=Li, Na; Ae=Sr, Ba)

The structure of tris­odium phosphide, Na3P, known from X-ray powder diffraction data, has been refined based on single-crystal data. The compound crystallizes in the hexa­gonal A3B (A = alkali metal and B = group 15 element) structure type and is isotypic with the homologous potassium phase. The framework is built of Na+ and P3− ions arranged in two kinds of layers perpendicular to the c axis. Two of the Na atoms and the P atom reside at positions of \overline{6}m2 (2b), 3m (4f) and \overline{6}m2 (2c) site symmetry, respectively.

Yongkwan Dong

Papers

Sr(Mg3Ge)N4 and Sr(Mg2Ga2)N4: New isostructural Mg-containing quaternary nitrides with nitridometallate anions of [(Mg3Ge)N4]2−∞3 and [(Mg2Ga2)N4]2−∞3 in a 3D-network structure

Transport properties of undoped and Br-doped PbTe sintered at high temperature and pressure> 4.0 GPa

Reinvestigation of trilithium phosphide, Li3P

Synthesis and single crystal structures of ternary phosphides Li4SrP2 and AAeP (A=Li, Na; Ae=Sr, Ba)

Reinvestigation of Na3P based on single‐crystal data