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Mg/Al layered double hydroxide (LDH) was successfully synthesized at different pHs values. The Mg/AL LDH was well characterized by X-Ray diffraction and Fourier transform infrared analysis. The morphology of the LDH was observed using Scanning electron microscopy with energy dispersive X-ray spectroscopy. The influence of pH values on the morphology of the Mg/Al LDHs were studied. The result showed that the well-synthesized Mg/Al LDHs could be obtained when the pH value was about 10.0 at room temperature.

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We have first studied the crystal and electronic structures, and magnetic property for sodium double tungstate NaFexCr 1-x(WO 4)2 (x =0, 0.50 and 1.0) compounds using the plane wave self-consistent method within the framework of density functional theory (DFT). We show that the ground state of sodium double tungstate compounds is the antiferromagnetic (AFM) state. We emphasize that the AFM coupling on the bc plane is generated by the 90 o superexchange mechanism. While the AFM coupling of the long-range magnetic interaction between the layers along the a - axis is generated by the Na mediated super - superexchange mechanism.