Upconversion nanocrystals NCs of NaYF4:Yb,Ln Ln=Er and Tm in cubic and hexagonal phases were synthesized in oleic acid OA and/or trioctylphosphine TOP with octadecene ODE via a thermolysis method. Only cubic-phase NCs were obtained in OA/ODE and TOP/ODE solvents; on the other hand, the hexagonal-phase NCs resulted in OA/TOP/ODE. The phase transition from cubic to hexagonal was induced by a liga...

The first example of polytypism in the I-II-V semiconductors has been demonstrated with the synthesis of cubic LiZnSb by a low-temperature solution-phase method. This phase exhibits a unique coloring pattern that is novel for this class of compounds. The choice of site configuration has a considerable impact on the band structure of these materials, which in turn affects the transport propertie...

The bulky form factor of traditional optical sensors limits their utility for certain applications. Flat multiplex imaging-sensor architectures face the light-gathering challenges inherent with small collection apertures. We examine a wavefront-coding approach wherein a cubic phase mask is used to increase the aperture sizes of multiplex imaging systems while maintaining the distance from the l...

The phases of ceria–zirconia nanoparticles observed in air are studied as a function of particle size and composition by X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The emergence of two tetragonal phases t00 and t monotonically moves toward higher zirconia concentrations with decreasing particle size. A smaller particle size increases the solubility of zirconia ...

An Rb2CoSi5O12 leucite analogue has been synthesized. ambient temperature X-ray powder diffraction study shows that this the Pbca orthorhombic structure of Cs2CdSi5O12. A high on a to Pa3¯ cubic phase transition at 457 K. The unit cell volume initially decreases with increasing passing through transition.