Three-dimensional phase coarsening at various volume fractions is simulated by employing multiparticle diffusion methods. The dynamic process of phase coarsening is visualized through a three-dimensional movie. The present study also characterizes interparticle spacings in polydispersed particle systems and clarifies the controversial mathematical expressions for interparticle spacings used in the literature for 30 years. Consequently, this study reveals spatial, temporal, and nearest-neighbor correlations in polydispersed particle systems. A new three-dimensional movie of a Voronoi network demonstrating these correlations is provided. Our simulation and experiments show that growth rates of individual particles deviate from those of the mean-field theory, which is caused by their differing local environments. Multiplicative noise provides a good basis to describe the stochastic nature of fluctuations during phase coarsening.

No abstract

We report a new strategy to directly attach Au nanoparticles onto YAG:Ce(3+) phosphor via a chemical preparation method, which yields efficient and quality conversion of blue to yellow light in the presence of a low amount of phosphor. Photoluminescent intensity and quantum yield of YAG:Ce(3+) phosphor are significantly enhanced after Au nanoparticle modification, which can be attributed to the strongly enhanced local surface electromagnetic field of Au nanoparticles on the phosphor particle surface. The CIE color coordinates shifted from the blue light (0.23, 0.23) to the white light region (0.30, 0.33) with a CCT value of 6601 K and a good white light CRI value of 78, which indicates that Au nanoparticles greatly improve the conversion efficiency of low amounts of YAG:Ce(3+) in WLEDs.

No abstract

The thermophotovoltaic cells which convert the low temperature (below 500 K) infrared radiation into electricity are of significance due to their potential applications in many fields. In this work, narrow bandgap Bi 2 Te 3 /Sb 2 Te 3 thin film thermophotovoltaic cells were fabricated, and the formation mechanism of Bi 2 Te 3 /Sb 2 Te 3 p-n heterojunctions was investigated. At room temperature, the heterojunctions are formed through the diffusion of electrons and holes along the same direction from n-type Bi 2 Te 3 thin films to p-type Sb 2 Te 3 thin films rather than conventional bi-directional diffusion. Because the strong intrinsic excitation generates a large number of intrinsic carriers which weaken the built-in electric field of the heterojunctions, their I-V curves become similar to straight lines. It is also demonstrated that Bi 2 Te 3 /Sb 2 Te 3 thermophotovoltaic cells can output electrical power under the infrared radiation from a low temperature heat source. Although the open-circuit voltage and the short-circuit current of the cells are low, this work provides a possible way to utilize the low temperature radiation.