Preparation and Characterization of Large-Sized ADM Monocrystals

Non-agglomerated ammonium dimolybdate (ADM) monocrystals with large diameter and high dispersion has been prepared through reaction-evaporation-crystallization (REC) process using ammonium tetramolybdate and ammonia solution as reactants. The as-prepared ADM monocrystals were systematically characterized by x-ray powder diffraction, transmission-reflection optical microscope, Fourier transform infrared spectroscopy and TG-DSC thermal analysis. It is shown that the as-prepared ADM samples are disperse monocrystals with well grain distribution and geometric shape, which can well meet the quality requirements for the subsequent production of molybdenum powders.

Synthesis and Characterization of Rodlike Ammonium Tetrathiomolybdate and its Thermal Decomposition Mechanism

Rodlike ammonium tetrathiomolybdate has been synthesized via ultrasonic assistance using monocrystal ammonium dimolybdate and ammonium sulfide as raw materials. The phase compositions, purity of as-synthesized products were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), laser Raman spectroscopy(LRS). The thermal decomposition mechanism of ammonium tetrathiomolybdate was deduced by thermoanalysis. It is shown that brownish-red rhombic ammonium tetrathiomolybdate crystal with high purity could be obtained at 60°C for 1h under relatively mild conditions.