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MgAl2O4:Mn2+ hexagonal nanoplates have been synthesized via a simple two-step method. The nanoplates have uniform hexagonal morphology with an average edge length of 1 mu m and thickness of 30 nm. X-ray diffraction and various microscopic techniques indicate that MgAl2O4:Mn2+ nanoplates are single-crystal with multilayered morphology. The formation mechanism has also been discussed. Photoluminescence (PL) spectrum of the MgAl2O4:Mn2+ nanoplate shows a broad green emission band centered at 568 nm. which is assigned to the T-4(1)-->(6)A(1) transition of Mn2+ ion. The MgAl2O4:Mn2+ nanoplate is a promising candidate for efficient nanoscale optical material. (C) 2008 Elsevier Ltd. All rights reserved.

Powder phosphor yttrium aluminum garnet (YAG), doped with trivalent cerium (Ce 3+ ) is synthesized by sol–gel method. The formation of YAG and YAG:Ce (cerium-doped yttrium aluminum garnet) was investigated by means of X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were also used. The purified crystalline phases of YAG and YAG:Ce were obtained at 1000 °C. The maximum average grain size is about 20–23 nm for undoped samples and 28–34 nm for doped samples. The crystalline YAG:Ce emission shows one peak in the range 480–535 nm with the maximum near 520 nm. Photoluminescence (PL) intensity of 5d → 4f transition of Ce 3+ increased with increasing annealing temperature. With increasing the concentration of Ce 3+ , the photoluminescence peak shifts towards the red region.

In this paper we report on the synthetic investigation of single-crystalline aluminum borate (Al 4 B 2 O 9 ) nanowires in large scale by a direct calcination of a precursor powder made of Na 2 B 4 O 7 ·10H 2 O and Al (NO 3 ) 3 ·9H 2 O at a low temperature of 850 °C. The nanowires, with the diameter of 20–40 nm and the length up to several micrometers, possess smooth surfaces and uniform sizes along the entire wire. The growth mechanism of the nanowires is attributed to a solid–liquid–solid process, which controls the nanowire morphology.