Intense red (Er3+:F9∕24→I15∕24, Tm3+:G41→F43), green (Er3+:H11∕22, S3∕24→I15∕24), and blue (Tm3+:D21→F43, G41→H63) upconversion emissions were simultaneously generated in the transparent glass ceramics containing Tm3+∕Er3+∕Yb3+:β-YF3 nanocrystals under single 976nm laser excitation. It was demonstrated that Tm3+ behaves as the sensitizer for red luminescence of Er3+ and Er3+ as the quenching center for blue, red, and near-infrared upconversion emissions of Tm3+. Various colors of the luminescence, including perfect and bright white light with CIE-X=0.310 and CIE-Y=0.358, can be easily tuned by adjusting the concentrations of the rare earth ions in the material.
The wet etching of Pb(Zr,Ti)O 3 (PZT) thin films has gained considerable attention in microelectromechanical systems (MEMS) since it is economical and effective compared with dry-etching methods. In this paper, a novel wet-etching process is proposed for PZT thin film patterning using 1BHF:2HCl:4NH 4 Cl:4H 2 O solution as the etchant, where NH 4 Cl is used as an additive to decrease the undercutting of the obtained PZT pattern. According to energy dispersion spectroscopy (EDS) analysis and X-ray diffraction (XRD) patterns, PbClF particles were left as residues on the substrate after etching using 1BHF:2HCl:4NH 4 Cl:4H 2 O solution. Therefore, an additional 2HNO 3 :1H 2 O etching process was applied to convert PbClF to PbCl 2 , which can be dissolved completely in deionized water. This process exhibits a high etching rate (0.016 mm/s) and good selectivity over the photoresist and Pt bottom electrode. Using this technique, PZT patterns with acceptable undercutting (1.5:1) can be obtained.
The liquefaction of biomass is an important technology to converse the biomass into valuable biofuel. The common technologies for liquefaction of biomass are indirect liquefaction and direct liquefaction. The indirect liquefaction refers to the Fischer–Tropsch (F–T) process using the syngas of biomass as the raw material to produce the liquid fuel, including methyl alcohol, ethyl alcohol, and dimethyl ether. The direct liquefaction of biomass refers to the conversion biomass into bio-oil, and the main technologies are hydrolysis fermentation and thermodynamic liquefaction. For thermodynamic liquefaction, it could be divided into fast pyrolysis and hydrothermal liquefaction. In addition, this review provides an overview of the physicochemical properties and common upgrading methods of bio-oil.
Measurements of the linear (Pockels) electro-optical coefficient of wurtzite GaN are reported. The values for the electro-optic coefficients r33 and r31 are 1.91±0.35 and 0.57±0.11 pm/V at 633 nm, respectively, in agreement with extrapolations from measured second-harmonic generation coefficients (χ33(2)=−20±6 pm/V and χ31(2)=10±3 pm/V) suggesting that the dominant contributions are electronic in origin. Measurements were performed using a Mach–Zehnder interferometer with LiNbO3 as a reference material. Piezoelectric effects were also observed.
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