To screen suitable solvents for anthracene crystallization, the solubilities of anthracene and metastable zone width were determined in four different solvents, N,N-dimethyl formamide (DMF), xylene, tetrachloroethylene, and diethylene glycol dimethyl ether from 30 to 80 8C at atmospheric pressure using a self-made crystallizer. The cooling modes, solvents, and the effects of carbazole on the solvent crystallization process of anthracene were also investigated. The composition of mother liquors and solid products were measured by gas chromatography; the solids were analyzed by scanning electron microscope, X-ray diffractometer, differential scanning calorimetry, granulometer, and fluorescence spectrometer. The results showed that a uniform anthracene crystal was obtained when using DMF under the forced circulation cooling mode. Solid solution of anthracene and carbazole was initially detected in solvent crystallization. The existence of carbazole in solution has an obvious effect on the crystal morphology of anthracene, to some extent, is beneficial to the crystal growth of anthracene.The solvent cooling crystallization of anthracene with carbazole as the impurity was investigated with DMF as the solvent. Here, the adding ratios of carbazole varied from 1 to 30 Figure 3. Metastable zone of anthracene in DMF, TCE, xylene, and DGDE.Figure 9. Fluorescence spectrum of crystals of anthracene, carbazole, mechanical mixture, and cocrystals with the excitation wavelength of 356 nm.
Al-doped ZnO (AZO) thin films (~100nm) with low electrical resistivity and high transparency have been prepared by atomic layer deposition on glass and Si(111) substrates at 200 °C with different doping sequence. The films were systematically analyzed using X-ray diffraction, scanning electron microscope (SEM), UV-vis spectroscopy and Hall measurement. XRD patterns showed that all the films were well crystallized with hexagonal wurtzite structure with preferred orientation along (100) plane. The resisitivity of films deposited with doping sequence of DEZ/TMA/H2O was lower than that with other doping sequences. Results from SEM showed a worm-like shape and similar grain sizes of AZO films. Optical transparency of AZO films was measured to be >90% for wavelengths of 400-1000 nm.
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