A Silicon–Silica Nanocomposite Material

The synthesis and characterization of a novel silicon–silica nanocomposite material are reported. A self‐assembly method allows the encapsulation of silicon nanoclusters within the channels of a periodic mesoporous silica thin film. The result is the formation of a silicon–silica nanocomposite film with bright, room‐temperature photoluminescence in the visible range, and a nanosecond luminescence lifetime. The properties of the nanocomposite material have been studied by several analytical techniques, which collectively show the existence within the channels of non‐diamondoid‐structure‐type silicon nanoclusters with various hydrogenated silicon sites. It is estimated that the silicon nanoclusters in the silica mesoporous films occupy up to 39 % of the accessible pore volume. The nanocomposite film shows improved resistance to air oxidation compared to crystalline silicon. The high loading and chemical stability to oxidation under ambient conditions are important advantages in terms of the development of silicon‐based light‐emitting diodes from this class of materials.     

多孔硅发光的物理机制——纳米量子限制效应及表面态在发光中的作用

采用阳极氧化腐蚀的方法制备了多孔硅（ＰＳ），这种ＰＳ的微结构为纳米量级的，并具有光致发光特性，这无疑将对全硅光电子学的发展具有很大意义。根据大量实验与理论分析，提出了这种ＰＳ发光的物理机制：纳米量子限制效应和表面态及其物质在发光中的作用，从量子力学的薛定锷方程出发，用沟道势阱的近似模型，推导得到进入量子线的电子和空穴的能量势垒，ＰＳ的有效带宽Ｅ＝Ｅ＿０＋ΔＥ，对于Ｓｉ（Ｅ＿０＝１．１２ｅｖ）。完美地解释了目前在ＰＳ研究中的ＰＬ谱的篮移现象。     

Photoluminiscent Manganese Nanoparticles from Solid State Polyphosphazenes Organometallic Derivatives

Pyrolysis in air at 800°C of [{NP(OC₁₂H₁₀)}_0.6{NP(OC₆H₄PPh₂·(π-CH₃C₅H₄)−Mn(CO)₂)₂}_0.4] _n (1) in the solid state affords product 2 containing nanoclusters of Mn₂P₂O₇ with sizes ranging from 50 to 90 nm and averaging about 74 nm. The egg-shape of the unpyrolyzed organometallic polymer is retained but with increased particle size after pyrolysis. The pyrolytic material shows near-infrared photoluminescence attributed to the emission of tetrahedral Mn²⁺ embedded in a matrix of Mn₂P₂O₇. The solid-state pyrolysis of organometallic derivatives of polyphosphazenes may be a useful and general route to nano-structured Mn₂P₂O₇. An erratum to this article can be found at     

Simultaneous synthesis and densification of transparent,photoluminescent polycrystalline YAG by current activated pressure assisted densification (CAPAD)

We report a method for the synthesis and processing of transparent bulk polycrystalline yttrium aluminum garnet (YAG) and photoluminescent Ce-doped YAG ceramics via solid-state reactive-current activated pressure assisted densification (CAPAD). The process uses commercially available γ-Al₂O₃, Y₂O₃, and CeO₂ nanopowders. The nanopowders were reacted and densified simultaneously at temperatures between 850 °C and 1550 °C and at a maximum pressure of 105 MPa. The solid-state reaction to phase pure YAG occurs in under 4 min at processing temperatures 1100 °C which is significantly faster (on the order of tens of hours) and occurs at much lower temperatures (∼600 °C) compared to conventional reaction sintering. We found that the reaction significantly improves densification – the shrinkage rate of reaction-produced YAG was three times higher than that of YAG using pre-reacted powder. The Ce additions were found to retard the reaction driven shrinkage kinetics by a factor ∼3, but are still faster (by a factor ∼1.6) than those associated with direct densification (no synthesis). Densities >99% were achieved in both pure YAG and Ce doped YAG (Ce:YAG). Results of optical measurements show good transparency in the visible and photoluminescence (PL) in the Ce:YAG. The PL peak is broad and appears white when excited using blue light confirming that the ceramics can be used in solid state lighting to produce white light.     

Using of Photoluminescent Tile for Evacuation of the Buildings During Electrical Failure

Photoluminescent pigments could be successfully applied on the wall tiles, floor tiles and porcelain tiles as well as glass substrates （glass mosaics, borders, and cutted glass with various designs）. For this applications, these products can be used for different purposes. In this study, these pigments are applied on the ceramic tiles and glass mosaics/tiles with traditional ceramic production line. These products are intentended to provide guidance in the event of a power failure. With this study also aimed to prevent potential accidents and injury during evacuation of building.     

A 3D interpenetrating coordination polymer based on a T-shaped linker of [Cu3Br6]

A new photoluminescent copper(I) polymer [(Cu₆Br₆)(bix)₃]_n (bix = 1,4-bis(imidazole-l-ylmethyl)benzene) (1) has been hydrothermally synthesized and structurally characterized. The structure of 1 features a 3D interpenetrating network with a novel (Cu₃Br₆) cluster unit acting as a T-shaped module. The present compound was characterized using IR, Elemental analysis and X-ray single-crystal analysis. The photoluminescent property of the title compound was also investigated.     

A new (3,4,7)-connected topology framework based on [Cd2(CO2)3O4N2] second building unit

A new 3D coordination polymer [Cd₂(L³)(BTC)(H₂O)] (1) (HL³ = 3,5-bis(pyridin-3-ylmethoxy)benzoic acid, H₃BTC = 1,3,5-benzenetricarboxylic acid), has been isolated under hydrothermal condition and characterized by single-crystal X-ray diffraction. Compound 1 is constructed from Cd₂-based second building units (SBUs) [Cd₂(CO₂)₃O₄N₂] and displays a 3D (3,4,7)-connected net with (4²·6)(4³·6³)(4⁵·6¹¹·8⁵) topology. In addition, the photoluminescent spectra indicate compound 1 may be a good candidate for blue-luminescent materials.     

Three metal-organic frameworks prepared from mixed solvents of DMF and HAc

Three metal-organic framework compounds [HZn₃(OH)(BTC)₂(2H₂O) (DMF)] · H₂O (MOF-CJ3), [Co₆(BTC)₂(HCOO)₆(DMF)₆] (MOF-CJ4), and [Co₁₈(HCOO)₃₆] · 3H₂O (MOF-CJ5) have been solvothermally synthesized in mixed solvents of DMF and HAc, respectively. These MOFs are characterized by single-crystal X-ray diffraction, X-ray powder diffraction, ICP, TG analyses, IR, and photoluminescence spectroscopy analyses. MOF-CJ3 crystallizes in tetragonal, space group I4cm (No. 108) with a = 20.588(3) Å, b = 20.588(3) Å, c = 17.832(4) Å. Its framework can be described as a 3D decorated (3, 6)-connected net based on the assembly of trigonal prismatic SBUs and triangular links. MOF-CJ4 crystallizes in hexagonal, space group P-3 (No. 147) with a = 13.975(2) Å, b = 13.975(2) Å, c = 8.1650(16) Å. The 2D network of MOF-CJ4 is constructed from [Co₆(R(CO₂)₃)₂(HCO₂)₆(DMF)₆] (R = C₉H₃–) clusters and 1,3,5-benzene-tricarboxylates linkers. MOF-CJ5 crystallizes in triclinic, space group (No. 2) with a = 15.205(3) Å, b = 18.005(4) Å, c = 21.500(4) Å,  = 71.21(3)°, β = 84.47(3)°, γ = 67.15(3)°. MOF-CJ5 has a diamond framework with Co-centered CoCo₄ tetrahedra as nodes. It is noteworthy that the formic ligands in MOF-CJ4 and MOF-CJ5 are generated by the decomposition of DMF under acid conditions and incorporated into these two compounds.     

Growth of Wurtzite ZnS Micrometer‐Sized Diskettes and Nanoribbon Arrays with Improved Luminescence

We report on the synthesis of wurtzite ZnS micrometer‐sized diskettes (including those lined up with ZnS nanowires) and ZnS nanoribbon arrays. Using ZnS powder as a source material, a vapor–solid growth based on a two‐stage temperature‐controllable thermal evaporation and condensation process is realized. Significant enhancement of luminescence compared to the ZnS source material is observed from these ZnS micro‐ and nanometer‐sized structures. The structures may serve as ideal model systems in the nano‐ to micrometer range for studying the optical and electronic properties of ZnS material. They can also be treated as prospective building blocks of two‐ and/or three‐dimensional arrays and are promising candidates for fabricating novel electronic and optoelectronic devices.