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Gallium zinc oxynitride powder and its nanocrystals were obtained by nitridation of a ZnGa 2 O 4 precursor under NH 3 flow. The nitrided powder had the chemical composition of (Ga 0.75 Zn 0.23 □ 0.02)(N 0.71 O 0.29), where □ indicates a vacancy, and showed improved crystallinity with a decrease in cationic vacancies compared to that for pristine gallium oxynitride without zinc. Gallium zinc oxynitride nanocrystals with rod-like morphology were obtained by nitridation of the oxide precursor on a NiO pellet. The nanorod crystals were several hundred nanometers wide and several micrometers long. The nanorods had a sawtooth appearance with triangular grains aligned along the length direction of the rods. The nanocrystals with a chemical composition of Ga/Zn = 0.80/0.20 exhibited a broad cathodoluminescence emission at 2.1 eV, similar to the powder products.

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Element blocks, which are composed of various elements, have been widely studied due to their potential application in electric, optical, magnetic and biological fields. Element blocks can be used as functional materials without any further modifications, but it is also possible to polymerize them to prepare element block polymer materials, which are expected to be a series of new functional materials. Magnetite is one of the well-known magnetic oxides, and magnetite nanoparticles are known to exhibit superparamagnetism. In this review, we focus on surface-modified magnetite nanoparticles which can be considered as element blocks. Surface modification of magnetite nanoparticles has been achieved by using silane coupling agents, phosphorus coupling agents, carboxylic acids or alkyl amines based on according to purpose and application to improve their dispersibility and biocompatibility. And magnetite nanoparticles with grafted polymers are potentially useful to the fabrication of magnetite-based medical and biomedical materials. These element blocks prepared from magnetite nanoparticles via surface modification can be applicable to various applications including drug delivery system, hyperthermia and separation of biological matters or heavy metal ions. Examples are demonstrated for typical applications.