Synthesis of nanosized and microporous zinc aluminate spinel by microwave assisted hydrothermal method (microwave–hydrothermal synthesis of ZnAl2O4)

Microwave assisted hydrothermal method, where the advantages of both microwave and hydrothermal method are being made use of, is proposed for preparing nanosized (mean particle size 2.4 nm with a narrow size distribution) zinc aluminate ZnAl2O4 with a spinel structure of interesting properties including high specific surface area (220 m2/g), microporosity and narrow pore size distribution. The precursors for microwave–hydrothermal synthesis were aluminium hydroxy nitrate having the empirical formula Al2(OH)6−x(NO3)x, wherein x was equal or close to 1, and hydrated zinc acetate. The proposed synthesis, in contrast to other methods, is very rapid and does not require a high temperature heating to obtain the spinel phase. The samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED), scanning electron microscopy (SEM) with EDS analysis, differential thermal analysis-thermal gravimetric (DTA-TG), and textural analysis (surface area and porosity). The potential application of such obtained ZnAl2O4 as convenient material for the preparation of thermal stable thin films coatings on different planar substrates is also reported.

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