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A series of Mn 2+ -doped zinc germinate ZGO:xMn 2+ (x = 0-0.05) nanorods was synthesized successfully using a hydrothermal method. XRD revealed that crystal phases of the ZGO:xMn 2+ were rhombohedral and in the R-3 space group. The Williamson-Hall equation was also used to explain the strain, nanocrystalline size, and stacking fault. Green LEDs were successfully fabricated by coating ZGO:Mn 2+ nanorods onto UV-LED chips. For high color purity, CIE of the fabricated green LEDs were (0.2404, 0.5428), which made this material a promising candidate for fabrication of UV-based green LEDs.

This paper reports the first attempt to synthesize un-doped spherical Zn 2 GeO 4 stoichiometry and Mn 2+ doped Zn 2 GeO 4 nanoparticles to achieve a controlled luminescence, particularly, by changing Zn:Ge ratio and Mn 2+ concentration during the hydrothermal process. The morphology of the un-doped Zn 2 GeO 4 nanoparticle was depended on the Zn:Ge ratio that was observed to have a nanorod structure to spherelike morphology; however, the morphology of Mn 2+ doped Zn 2 GeO 4 was not changed as the use of Mn 2+ as a dopant. The un-doped Zn 2 GeO 4 showed a broad emission at ³510 nm and its intensities were functioned of Zn:Ge ratio. On the other hand, the Mn 2+ doped Zn 2 GeO 4 showed emission peaks at ³532 nm and they can be attributed to the 4 T 1 ¼ 6 A 1 transition in Mn 2+ ions doped in Zn 2 GeO 4 . These results suggest the effectiveness use of Zn:Ge ratio and Mn 2+ doped Zn 2 GeO 4 in tuning the luminescence of Zn 2 GeO 4 nanoparticles, which are of potential applications as phosphors in wide range of engineered fields, in particular optoelectronics.

The preparation and characteristic of nanorod‐like Zn2GeO4 doped with Eu3+ or zinc germanate (ZGO):xEu3+ (x = 0 ÷ 0.05), which was synthesized using the hydrothermal method, are described. The influence of Eu3+‐doping ions on the structure and the optical properties of ZGO was also investigated. According to the photoluminescence spectra, ZGO:xEu3+ nanophosphors gave a red emission due to the 5D0→7F2 emission of Eu3+ ions. In accordance with Judd–Ofelt theory, the intensity parameters for f–f transitions from the emission and absorption spectrum were determined. At the 5D0 excited state of Eu3+, total spontaneous emission probabilities (AR), lifetimes (τR), branching ratios (βR), and quantum efficiency (η) were calculated. The ZGO:xEu3+ (x = 0.02, 0.03, 0.04) phosphor showed the branch ratio β (5D0→7F2) > 60%, indicating that the phosphors prepared here have a promising potential as laser light. The sample with a concentration of 0.04Eu3+ achieved the highest quantum efficiency of 84%, suggesting that it has potential light‐emitting diode applications.

Polycyclic Aromatic Hydrocarbons (PAHs) in aircraft soot are capable to distribute in the gas phase and particulate phase in chemical transformations in the atmosphere. The desorption of PAHs from the soot surface is a preliminary step in the study of the reactivity of particulate PAHs. The desorption kinetics of PAHs are measured from soot samples to determine desorption rate constants for different PAHs as a function of temperature and the binding energies between PAHs and soot. The kinetics of degradation of particulate PAHs were studied in the flow reactor. The soot samples previously deposited on a Pyrex tube are introduced into the reactor along its axis and the concentrations of PAHs adsorbed on soot are determined by the High-Performance Liquid Chromatography (HPLC) as a function of the desorption time. The results show a correlation between the size of PAHs and the thermodynamics of desorption: with the PAHs have the same number of carbon atoms, their energies of desorption are very similar and increase with this number. The activation energies EA and the number of carbon atoms in PAHs have a linear correlation. It is consistent with the additivity of the laws Van der Waals. The similarity between the activation energies of desorption of PAHs and the corresponding sublimation enthalpies is consistent with the similarity between the graphitic structure of soot and the structure of PAHs.