Effect of Surfactant Polyvinyl Pyrrolidone on the Properties of Microporous Carbon Nanospheres Reinforced Magnesium Matrix Composites.

Microporous carbon nanospheres (PCNS)-reinforced magnesium (Mg) composites were prepared using polyvinyl pyrrolidone (PVP) as surfactant and PCNS as reinforcement. The influence of PVP treatment and the effectiveness of PCNS on the mechanical properties of Mg-based composites were investigated. The results show that the PCNS can enhance the properties of the Mg matrix. Moreover, the PVP can effectively improve the dispersion of PCNS in the Mg matrix but had a negative influence on the tensile properties of composites. The MgO films with high tensile strength were produced between matrix and reinforcement after removing PVP, which effectively promotes the interface compatibility and improves the properties of the composite. The tensile yield strength and specific strength of PCNS-reinforced Mg matrix composite exhibited 177 MPa and 102.4 × 103 N∙m/kg, respectively, which were 77% and 78% higher than those of the Mg matrix.

[Investigation of synthesis and luminescent properties of the Sr2CeO4: Dy3+].

In the present article, Sr2CeO4:Dy3+ was synthesized with N,N-methylene bisacrylamide (MBAA) as the net agent. The structure, morphology and luminescent properties were also characterized. It is indicated that Sr2CeO4:Dy3+ was single-phased without other phase existing and also had good dispersion The UV-visible absorption spectra suggested that the absorption bands were almost at 480 nm. The excitation spectrum for 270 nm emission has several excitation bands; The emission spectrum of Sr2 CeO4:Dy3+ shows two broad bands at 292 and 338 nm under the 370 nm excitation. The effects of Dy3+ doping concentration on the emission spectrum intensity of Sr2 CeO4:Dy3+ were also studied, the results showed that the ratio of yellow emission to blue emission increases with increasing the D/3+ doping concentration, but with increasing the Dy3+ doping concentration, the emission intensity firstly increased, then decreased, and the maximal emission intensity was at 0.4 mol% Dy3+ concentration.

[Research on synthesis and luminous mechanism of a soluble blue-light luminescence material derived from carbazole].

In the present paper, a kind of blue light-emitting organic small molecule luminescent materials was designed and synthesized, which is composed of carbazole and 8-benzyloxyquinoline functional groups. Alkyl chain can effectively play the role of electron transfer barrier. The synthesis principle was on the basis of the mechanisms of SN1 nucleophilic reaction and SUZUKI coupling reaction mechanisms. It is entitled N-[6-(8-benzylquinoline)-hexyl] carbazole (CzBQ). Its molecular structure was simulated and optimized by Gaussian03. Its chemical structure was identified by measurements of ultraviolet-visible spectra and H1 NMR spectra. It photo physical property was characterized by method of fluorescence spectra. t is indicated that CzBQ was a kind of blue-light luminescence material and its optical band gap is 3.02 eV. Ethanol solution of CzBQ exhibits the maximal emission peak at 410 nm in photoluminescence spectra In the luminescence process of CzBQ, carbazole groups and 8-benzylquinoline groups were separately involved in excitation and light emission. This kind of blue-light luminescence material possesses excellent solubility, It can be dissolved in different solvents such as ethanol and ethyl acetate and dichloromethane. The test results of AFM show that CzBQ was provided with very good film formability. It is expected to be utilized in blue-light organic light-emitting device fabricated by wet method such as spin-coding method and screen printing.

Structural characteristics of nanocrystalline copper after carbon ion implantation.

A gradient structure was produced in a pure copper plate by means of surface mechanical attrition treatment (SMAT). The microstructure of the surface layer was reduced to nanoscale and the grain size increased gradually along the depth of the treated sample. In situ transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) observation was performed on the nanocrystalline copper after implantation of carbon. Carbon atoms first precipitated along the edges of the copper substrate or at the surface, then formed amorphous carbon layers. Subsequently, onion-like fullerenes were formed under electron-beam irradiation. The effects of ion implantation, electron beam irradiation, nanostructure of the substrate and interaction of C and Cu atoms on the formation of the onion-like fullerenes are discussed.

[Molecular structure and luminescent property of bis(2-(4-methyl-2-hydroxyphenyl)benzothiazolate) zinc].

Bis(2-(4-methyl-2-hydroxyphenyl)benzothiazolate) zinc(Zn(4-MeBTZ)2) was synthesized. Its molecular structure was confirmed by single-crystal x-ray diffraction. Single-crystal data are as follows: space group triclinic, P-1; a = 8.989 9(11) angstroms, b =12.161 7 (15) angstroms, c = 12.871 9 (16) angstroms, alpha = 63.492 (2) degrees, beta = 84.825 (2) degrees, gamma =71.187 (2) degrees. The steric hindrance provided by introduction methyl groups on phenoxide ring prohibited effectively the formation of pentacoordinate complex. There is distinct intermolecular pi-pi interaction between molecules. The dihedral angle between the phenol and benzothiazolate rings of Zn(4-MeBTZ)2 is 2.166 degrees. The HOMO energy, LUMO energy and optical gap are -5.84, -3.46 and 2.37 eV, respectively. The maximum wavelength peak of PL spectra located at 470 nm. The double-layer devices were employed using Zn(4-MeBTZ)2 as emitter and NPB as hole-transport material. The EL spectra split into two peaks located at 501 and 544 nm respectively. The broadened EL spectra were demonstrated to be originated from the exciplexes formed at the interface between NPB and Zn(4-MeBTZ)2.

[A new type of iridium (III) phenylpyrazole complexes: synthesis, photophysical characterization].

New heteroleptic iridium(III) complexes (ppz)2Ir(LX), which consist of two cyclometalated ligands ppz(1-phenylpyrazole) together with an ancillary ligand LX (LX= 2-(2'-hydroxylphenyl)benzothiazole (BTZ), 2-(3'-methyl-2'-hydroxylphenyl) benzothiazole (3-MeBTZ), 2-(4'-methyl-2'-hydroxylphenyl) benzothiazole (4-MeBTZ) and 2-(4'-Trifluoromethyl-2'hydroxylphenyl) benzothiazole (4-tfmBTZ)), were synthesized and characterized. The molecular structures and photophysical properties were characterized and analyzed comparatively. The results show that the four complexes have basically similar UV-Vis absorption spectra, fluorescence excitation and emission spectra. Their maximum emission peaks are located at 583-615 nm, and accompanied by a lower intensity emission band around 400 nm. The weak emissions around 400 nm are ascribed to the radi ation transition of single state excition from ancillary ligand BTZ perturbed by metallic ion, and light emission around long-wave-length to the radiation transition of 3MLCT of Ir(BTZ) fragment. While the triplet state 3 MLCT of Ir(ppz)2 fragment might be quenched at room temperature. For all complexes, the excitations with maximum efficiency are located at 250-310 nm, which indicates that main contributor to light emitting is ligand-centered absorption (1pi-pi*) of ppz and BTZ rather than 3MLCT transitions, and thus provides a striking evidence that there is intersystem crossing from 1pi-pi* state to 3MLCT state in these complexes. Compared with Ir(ppz)3, these complexes not only have stronger phosphorescence at room temperature but also their emission color can be tuned by modifying ancillary ligand.

[Study on the conversion of acrylic C=C double bonds during dark reaction after UV curing using infrared spectroscopy].

Infrared spectroscopy was used to determine 1,648-1,589 cm(-1) characteristic absorption peak area so as to study the conversation of acrylic C=C double bonds after UV curing. The effects of phototinitiators, active diluents and UV curing resins on the conversion of C=C double bonds were also investigated. The results showed that 40%-85% of C=C double bonds were conversed during dark reaction after 45 s UV curing. Dark reaction will be changed gently after 1.75 h, but 95% conversion of C=C double bonds needed more than 24 h. The rates of polymerization and conversation were affected by photoinitiators, the concentration of photoinitiator, oxygen inhibition, and C=C functional groups of active diluents. The rate of polymerization was affected by the C=C functional groups and types of UV curing resins, but conversation was not.

[New highly phosphorescent heteroleptic tris-cyclometalated iridium (III) complexes: synthesis and photophysical characterization].

New heteroleptic tris-cyclometalated iridium(III) complexes (ppy)2 Ir(LX) (ppy==2-phenylpyridine, LX==Sal (salicylic acid), Msal (4-methylsalicylic acid), FSal(4-trifluoro methyl salicylic acid)) was synthesized and characterized. The molecular structure, photophysical properties and thermal stability were tested and analyzed. The results show that the absorption peaks were located around 270, 370, 450 and 484 nm respectively at room temperature. The two former peaks at 270 and 370 nm should belong to 1pi--pi* transition at ppy and transition from salicylic acid ligands to 2-phenylpyridine; The peaks around 450 and 484 nm can be assigned to the charge transfer transition from Ir to ligand (1MLCT and 3MLCT) and 3pi--pi* transition respectively. The PL emission peaks were located at 520, 522, and 510 nm, respectively. The emission of (ppy), Ir(Sal) and (ppy), Ir (MSal) was mainly ascribed to the radiation transition of triple state 3MLCT, while the emission of (ppy)2 Ir(FSal) was mainly from the radiation transition between Sal and ppy, partly from the radiation transition of single state 1MLCT and triple state 3MLCT. The quantum efficiencies of these complexes were 0.37, 0.33 and 0.29 respectively. The thermal decomposition temperature was from 306 to 328 degrees C. (ppy)2 Ir(LX), being a series of efficient phosphorescent materials with good thermal stability, can be used in the organic electroluminescent devices.

[Spectral analysis and band gap of RbVO3].

In the present paper, RbVO3 was prepared by wet chemistry synthesis from hybrid precursor. The structure of RbVO3 was characterized by X-ray diffraction (XRD) pattern and FTIR spectra. Photoluminescent (PL) properties were investigated by UV-Vis absorption spectrum and PL spectrum. In addition, the band gap of RbVO3 was calculated by using the CASTEP code with density-functional theory (DFT) method. The results indicated that RbVO3 could emit intense green-white fluorescence with peak wavelength at 525 nm and the color coordinates was (0.318 0, 0.430 9) under UV excitation at 357 nm. It was demonstrated that the theoretical result of band gap, which is 2.67 eV, agreed well with the experiment.

[Characterization and photoluminescence properties of a blue-light-emitting material].

Tris (2-methyl-8-hydroxyquinoline) aluminum (AlMeq3) was synthesized and purified by vacuum sublimation. The structure of the complex was characterized by 1H NMR, FTIR spectra and elemental analysis techniques. AlMeq3 consists of three 2-methyl-8-hydroxyquinoline ligands and one aluminum atom. Its thermal stability was studied by TG and DSC analysis and the result shows that AlMeq3 is a thermally stable material, with decomposition and crystalline transition temperature being 357 and 158 degrees C, respectively. Energy band structure was investigated by UV-Vis absorption spectra and fluorescence emission spectra. Experimental results show that its UV absorption bands were at about 246 and 390 nm, and the absorption band at about 246 nm can be assigned to pi--pi* of phenyl ring. AlMeq2 displays 8-hydroxyquinoline-oriented photophysical properties. The optical gap of AlMeq3: was about 2.85 eV, as determined by intrinsic absorption band edge of the complex in ethanol solution. Under UV excitation at 365 nm, the complex in ethanol solution emitted intensive blue fluorescence with the maximum emission peak at 479 nm, while the effective energy-transfer from the ligand to the central AlP+ ion occurred in the complex. AlMeq3 with bright blue photoluminescence can be applied as luminescent material in OLEDs.

[Synthesis and spectral properties of polymer of Tis (5, 5'-methylene-bis (8-hydroxy-quinoline) gallium with orange-red light emitting].

A ligand 5,5'-methylene-bis(8-hydroxyquinoline)(Hqq) was synthesized by condensation reaction at low temperature and was subsequently coordinated to gallium ions to prepare the polymer of tis(5,5'-methylene-bis(8-hydroxyquinoline) gallium (Gaqq3)n. Both chemical structure and phase structure of the ligand and complexes were characterized by Infrared absorption spectrum and X-ray diffraction (XRD). The thermal stability of the complexes was studied by thermogravimetry (TG). The photo-physical properties of the complexes were investigated by ultraviolet absorption spectrum (UV), fluorescence excitation spectrum and emission spectrum. The result indicated that (Gaqq3)n is a thermally stable material, whose decomposition temperature is 443.6 degrees C. The ultraviolet absorption bands of (Gaqq3)n are in the range of 250-500 nm, with a relatively strong band tail absorption between 500 and 650 nm, which shows that the band-gap defect states exists in the forbidden band. The fluorescence excitation band of (Gaqq3)n is located at 380-456 nm, and (Gaqq3)n. emits orange-red fluorescence with the emission peak at 568 nm, which shows that the fluorescence emission of (Gaqq3), is mainly attributed to the charge transfer transitions from phenol to ring pyridine ring, while the pi-->pi* transition of benzene ring is deactivated by non-radiative transition, and makes no contribution to fluorescence emission. (Gaqq3)n optical band gap is 2.49 eV. Compared with the fluorescence emission peak of Gaq3, the fluorescence intensity of (Gaqq3), decreases, which is attributed to the distortion of the two quinoline rings connected to the methylene, hence leads to the poor rigidity and coplanarity of (Gaqq3)n, thus affects fluorescence emission intensity. Because of the extending of the molecular conjugation system, pi electron of (Gaqq3)n is more delocalized, resulting in the redshift of fluorescence emission peak (Gaqq3)n is expected to be applied in organic light emitting display and organic photovoltaic devices.

[Spectral analysis and photoluminescence properties of Eu-Tb codoped polymer].

In the present paper, Eu0.5 Tb0.5 (TTA)3 Phen was synthesized and Eu0.5 Tb0.5 (TTA)3 Phen/PMMA was prepared by in-situ polymerization. The structure of Eu0.5 Tb0.5 (TTA)3 Phen/PMMA was characterized by FTIR spectra. Microscopic morphology and photoluminescence properties were investigated by SEM photographs and fluorescence spectra. The results indicated that polymer parts were attached with the rare-earth molecular parts in the composite luminescent materials. And Eu0.5 Tb0.5 (TTA)3 Phen/PMMA could emit mostly characteristic fluorescence of europium ion and intense red fluorescence with a peak wavelength at 611.8 nm and a bandwidth of 10.4 nm (Purity: 0.9905) under UV excitation at 365 nm. Its fluorescence intensity was found to be influenced with the content of MMA. It w as demonstrated that Eu0.5 Tb0.5 (TTA)3 Phen/PMMA was an excellent red photoluminescent rare-earth polymer material.

[Studies on a new type structure OELD with interinserting interface].

A new type organic electroluminescent device with interinserting interface was fabricated. The basic structure of the device is ITO/NPB/Alq3/Al. By tailor-made template, the two interinserting interfaces were fabricated with NPB/Alq3 and Alq3/Al, respectively. The charge distribution on the interface and the electric field distribution in the organic layer were changed by introducing interinserting interfaces, thus the electron injection was improved, and the balance of the number of the electrons and holes at the interface was obtained. Therefore, the formation probability of exciton was enhanced and the leakage current was reduced. Compared to the traditional two-layer structure devices, the interinserting structure device has lower turn-on voltage and higher luminous efficiency. The driving-voltage of the interinserting structure OELD decreased while the brightness increased with the increase in the number of the interinsertion. As the current density increased, all the devices with interinserting interface showed high optical-electrical stability. The turn-on voltage of the device e is 3 V, and was made using the three slots template. At the current density of 54 mA x cm(-2), the device e gets its maximum efficiency, which is 34% higher than the traditional structure device a.

[A novel yellow organic light-emitting device].

The fabrication of a novel organic yellow-light-emitting device using Rhodamine B as dopant with double quantum-well (DQW) structure was introduced in the present article. The structure and thickness of this device is ITO/CuPc (6 nm) /NPB (20 nm) /Alq3 (3 nm)/Alq3 : Rhodamine B (3 nm) /Alq3 (3 nm) /Al q3 : Rhodamine B(3 nm) /Alq3 (30 nm) /Liq (5 nm)/Al (30 nm). With the detailed investigation of electroluminescence of the novel organic yellow-light-emitting device, the authors found that the doping concentration of Rhodamine B (RhB) had a very big influence on luminance and efficiency of the organic yellow-light-emitting device. When doping concentration of Rhodamine B (RhB) was 1.5 wt%, the organic yellow-light-emitting device was obtained with the maximum current efficiency of 1.526 cd x A(-1) and the maximum luminance of 1 309 cd x m(-2). It can be seen from the EL spectra of the devices that there existed energy transferring from Alq3 to RhB in the organic light-emitting layers. When the doping concentration of RhB increased, lambda(max) of EL spectra redshifted obviously. The phenomenon was attributed to the Stokes effect of quantum wells and self-polarization of RhB dye molecules.

[Characterization and photoluminescence properties of an azomethin-zinc complex].

A Schiff base organic metal complex, Bis(salicylidene)-1,2-phenylenediam-ine Zinc(II) with high purity, was synthesized and purified by vacuum sublimation. Its structure, thermal stability and energy band structure were investigated by element analysis, FTIR spectra, TG-DTA curve, UV-Vis absorption spectra, fluorescece emission spectra and PL spectra. Experimental results showed that the complex is a thermally stable, polycrystalline material, with glass temperature and decomposition temperature being 183 and 449 degrees C, respectively. In its infrared spectrum, a high intensity band was at about 1 385 cm(-1). This band was typical of the conjugated C=N stretching vibration, which shifted to higher frequency in relation to the free ligand of salicylaldehyde with 1,2-phenylenediamine. The new bnd at 529 cm(-1) was assigned to Zn-O stretching vibration. Its UV absorption bands were at about 297 and 406 nm, and its tetrahydrofuran solution emitted intensive blue-green fluorescence at the peak wavelength of 508 nm. The absorption band at about 406 nm can be assigned to the intrinsic absorption of C=N. Its optical gap was about 2.62 eV, which was determined by the intrinsic absorption band edge of the complex in tetrahydrofuran solution. Under UV excitation at 365 nm, the complex in film emitted yellow-green fluorescence with the maximum emission peak at 562 nm and a full-width at half-maximum of 48.5 nm in PL spectra. Finally, yellow organic light-emitting devices using this complex as the emissive layer were fabricated and investigated.

[Luminescence properties of white LED blue light conversion materials].

Using rare earth oxides as raw materials, yttrium aluminum garnets activated by cerium and gadolinium ions were prepared by high energy ball milling and solid-state reaction at 1300 degrees C. The crystal structures of the products were studied by XRD, and the luminescence characteristics of Ce ion and the influence of Gd ion were studied by emission and excitation spectra. The results indicated that the products were yttrium aluminum garnet crystals of cubic system, and they were excited by blue light chips effectively. The emission peak of phosphors could change among 530-560 nm by adjusting the mole density of doping ions. The red shift of emission spectra could be interpreted with the configuration coordination figure. White LEDs were fabricated by phosphor conversion. When electric current is 20 mA, and the working voltage is 3.5 V, the white light LED chromaticity coordinates are x=0.310 and y=0.323, the lumen efficiency is 26.131 m x W(-1), the color rendering index is 81.8, and the color temperature is 6605 K.

[Spectroscopic properties of salicylaldehyde anil zinc and its thin film].

A new light emitting material, salicylaldehyde anil zinc (SAZ), was synthesized. It can form high quality nano-scale amorphous thin films on clean glass substrates by vacuum evaporation. Its structure, crystallization, thermal stability, and optical property were investigated by IR spectra, DTA-TG analysis, XRD spectra, UV-Vis spectra, and fluorescence spectra. Its energy band structure was confirmed by cyclic voltammogram and optical absorption band edge. Results show that the SAZ film is a thermally stable material, and can emit intense green fluorescence with a peak wavelength at 508 nm and a full width at half-maximum of 90.2 nm under UV irradiation. Its HOMO energy level is about -5.659 eV, LUMO energy level is about -3.054 eV, optical gap band is about 2.604 eV. The fluorescence decay of stored films under ambient atmosphere is more rapid than that of 8-hydroxyquinoline aluminum films. However, the fluorescence decay of the films under UV irradiation is slower than that of 8-hydroxyquinoline aluminum films.

[Spectral analysis and photoluminescence properties of 1,5-naphthalene diamine derivative].

In the present paper, 1,5-bis[N-(1-naphthyl)-N-phenyl] naphthalene diamine (NPN) with high purity was synthesized by liquid-phase Ullmann reaction, and high quality film of NPN was formed on cleaned glass substrates by vacuum evaporation. Photoluminescence properties were studied by solvent effects on UV-Vis absorption spectra and fluorescence spectra. In addition the structure of energy band of NPN was studied by cyclic voltammetry, UV-Vis absorption spectra, and fluorescence spectra. The results indicate that the fluorescence emitting is attributed to the charge transfer transition from nitrogen to aromatic ring. The molecules of NPN in its film form "J-aggregate". The HOMO energy and optical gap of NPN are -5.74 and 2.79 eV respectively. NPN film could emit intense blue fluorescence with a peak wavelength at 448.6 nm and a bandwidth of 72.6 nm under UV-Vis excitation at 365 nm.

[Preparation and spectral analysis of a new type of blue light-emitting material delta-Alq3].

In the present article, delta-Alq3, a new type of blue light-emitting material, was synthesized and investigated by IR spectra, XRD spectra, UV-Vis absorption spectra, photoluminescence (PL) spectra, and electroluminescence (EL) spectra. The relationship between molecular spatial structure and spectral characteristics was studied by the spectral analysis of delta-Alq3 and alpha-Alq3. Results show that a new phase of Alq3 (delta-Alq3) can be obtained by vacuum heating alpha-Alq3, and the molecular spatial structure of alpha-Alq3 changes during the vacuum heating. The molecular spatial structure of delta-Alq3 lacks symmetry compared to alpha-Alq3. This transformation can reduce the electron cloud density on phenoxide of Alq3 and weaken the intermolecular conjugated interaction between adjacent Alq3 molecules. Hence, the pi--pi* electron transition absorption peak of delta-Alq3 shifts toward short wavelength in UV-Vis absorption spectra, and the maximum emission peak of delta-Alq3 (lamda max = 480 nm) blue-shifts by 35 nm compared with that of alpha-Alq3 (lamda max = 515 nm) in PL spectra. The maximum emission peaks of delta-Alq3 and alpha-Alq3 are all at 520 nm in EL spectra.

[Preparation and characterization of 2(8-hydroxyquinoline)-2( phenol) zirconium thin film].

In this paper, the new emitting material zirconium complex with 8-hydroxyquinoline and phenol (Zr(OPh)2 q2), which can form high quality nano-scale amorphous thin films at glass substrates cleaned by vacuum evaporation, was synthesized. Its crystallization, thermal stability, the structure of energy band and PL mechanism were investigated respectively by FTIR spectra, DTA-TG analysis, SEM, XRD spectra, UV-Vis absorption spectra and fluorescence spectra. Results show that the Zr(OPh)2 q2 is a thermally stable material, whose melting point is 381.2 degrees C, decomposition temperature is 467.1 degrees C, whose film can emits intense yellow-green fluorescence with peak wavelength at 525 nm and a full width at half-maximum of 107.6 nm under UV excitation (390 nm), powder has intense yellow fluorescence, therefore it may be a excellent electroluminescent material.