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Colloidal semiconductor nanocrystals (NCs) such as leadbased quantum dots (QDs) have generated intense interest as important active materials in various applications including photovoltaic (PV) devices. 1À4 Schottky-type solar cells based on PbSe or PbS binary nanocrystals have been explored. For the PbSe and PbS NCs with similar bandgap, it was documented that PbSe-based Schottky-type solar cells usually exhibited relatively

High color purity red phosphors of Ca 1À3/2x Eu x TiO 3 and Ca 1À2x Eu x Li x TiO 3 (0 < x 0.3) are synthesized via a solidstate reaction method. The red emission photoluminescence intensity and color purity are enhanced by the incorporation of Li + into CaTiO 3 :Eu 3+ . The Li + doping increases the emission probability from 5 D 0 state, increases photoluminescence intensity by 1.6 times, increases color purity to 92.1%, and shortens the decay time. With increasing Eu 3+ and Li + content, the color coordinates approach the ideal red chromaticity values, coming closer than commercial Y 2 O 2 S:Eu 3+ red phosphor.

Spatial distributions of persistent magnetic field trapped by sintered and melt-textured ceramic-type high-temperature superconductor (HTS) samples have been studied. The trapped field can be reproduced by a model of the current consisting of two components: (i) a surface current Js and (ii) a uniform volume current Jv. This Js + Jv model gives a satisfactory account of the spatial distribution of the magnetic field trapped by different types of HTS samples. The magnetic moment can be calculated, based on the Js + Jv model, and the result agrees well with that measured by standard vibrating sample magnetometer (VSM). As a consequence, Jc predicted by VSM methods agrees with Jc predicted from the Js + Jv model. The field mapping method described is also useful to reveal the granular structure of large HTS samples and regions of weak links.

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