Guohong Zhou

Luminescence characteristics of the Ce 3+ -doped garnets: the case of Gd-admixed Y 3 Al 5 O 12 transparent ceramics

The Ce-doped (Gd, Y)3Al5O12 transparent ceramics with Gd3+ content of 0 to 80 mol% were fabricated using a solid-state sintering method under vacuum. Their phase compositions and structure parameters were checked by X-ray diffraction (XRD). Optical and luminescence characteristics were investigated and thoroughly discussed by transmittance, absorption spectra and luminescence examination. The Gd3+ ions were found of great importance to the band structure of crystal and energy state of Ce3+ in the garnet ceramics. Balanced Gd3+ admixture into the YAG lattice provided excellent color coordinates and CRI for the phosphor for warm white light illumination. This study provides an efficient approach to tailor the luminescence of the garnet phosphors.

HIP and pressureless sintering of transparent alumina shaped by magnetic field assisted slip casting

Alumina green bodies were shaped by slip casting under a strong magnetic field. Alumina ceramics were obtained by hot isostatic pressing (HIP) at 1275°C and pressureless sintering at above 1700°C, respectively. HIP-sintered alumina, with in-line transmittance of 52% at 600nm and 82% at 2μm, showed a sub-micrometer grain microstructure and a slight grain orientation. However, XRD results demonstrated the grains of pressureless sintered alumina sintered at >1700°C oriented along c-axis, and texture microstructure was observed by SEM. It indicated that magnetic field assisted slip casting produced “seeds” of grain orientation, and orientation degree that could achieve depended on the sintering temperature.

Gel-tape-casting of aluminum nitride ceramics

Aluminum nitride ceramic sheets were formed for the first time by a novel and simple method, namely gel-tape-casting process, where only two additives were used to prepare the slurries. PIBM (a water-soluble copolymer of isobutylene and maleic anhydride) acted as both dispersant and gelling agent, and PEG (polyethylene glycol) acted as plasticizer. Combining the advantages of gel-casting and tape-casting processes, flexible and uniform green tapes were obtained. The rheological properties of AlN slurries were studied to optimize the PIBM content and solids loading. After drying and debinding, the green sheets were sintered at 1840 °C in N2 atmosphere. Homogeneous microstructure with average grain size of about 7 μm was observed in the final AlN ceramics. Thermal conductivity of the AlN ceramics was 161 W/(m·K).

Room and Elevated Temperature Mechanical Properties of Hot-Pressed Uni-Cf/SiO2 Composite

Unidirectional carbon fiber reinforced fused silica (uni-Cf/SiO2) composite was prepared by slurry infiltration and hot-pressing. The room and elevated temperatures flexural properties were investigated and the fracture features of the composite were observed. This composite exhibited non-catastrophic failure at room and elevated temperatures. The oxidation of carbon fiber at elevated temperatures was the main reason for the degradation of flexural strength and elastic modulus. The flexural strength tested at 1200 was 376MPa and exhibited anomalously higher than that at 1000 (277MPa), which was attributed to the viscous flow of fused silica matrix and therefore the occurrence of microcracking in the matrix was deferred. And it was inferred that the brittle to plastic transition temperature (Tb-p) of uni-Cf/SiO2 composite corresponded to a certain temperature around 1200°C.

Sensitive detection of free bilirubin in blood serum using β-diketone modified europium-doped yttrium oxide nanosheets as a luminescent sensor

Free bilirubin, when present in excess in the human body, can cause a multitude of diseases and disorders and even be fatal; hence, detecting it is of paramount importance. Herein, we report a luminescence quenching-based non-enzymatic method for the convenient, reliable, and rapid detection of free bilirubin in blood serum samples using sensing films (nanosheets/PS, nanosheets-tta/PS, and nanosheets-dbt/PS) as luminescent sensors. The luminescence intensity of the sensing films is linearly related to the free bilirubin concentration. Nanosheets-tta/PS demonstrated excellent sensing properties for the sensitive and reliable detection of free bilirubin in the range of 0.0–60.0 μM with a correlation coefficient of 0.9915, as compared to nanosheets/PS or nanosheets-dbt/PS. The limit of detection for the determination of free bilirubin was 41 nM. This method can be used to design a sensor-based test spot as a medical detection device for the visual detection of free bilirubin.

Bi/Bi 2 O 3 sensor for quantitation of dissolved oxygen in molten salts

To quantify the oxygen content in molten salts, we examined the performance of an yttria-stabilized zirconia solid electrolyte oxygen sensor with a Bi/Bi2O3 reference electrode, focusing on its output accuracy. When the above sensor was tested in a flow of gas with known oxygen partial pressure,

ZrO2-doped Y2O3 transparent ceramics via slip casting and vacuum sintering

p_{O_2}

Fabrication of transparent Y2O3 ceramics via aqueous gelcasting

pO2, a linear relationship between