Processing and properties of high-purity micro-lamellate (NH4)2RuCl6 particles

(NH4)2RuCl6 is an important precursor in the synthesis of Ru powder with high-purity requirement. In this study, high-purity (>99.999 wt%) micro-sized (NH4)2RuCl6 pieces were synthesized by distillation and precipitation from crude Ru powder. Then, the thermal decomposition behavior of the (NH4)2RuCl6 pieces was investigated. The decomposition process included two stages. First, (NH4)2RuCl6 was decomposed from 255.0°C to 314.0°C, with the endothermic peak located at 309.4°C. At this stage, HCl and NH3 were released, while the dense micro-pieces were transformed to loosened micro-pieces due to the thermal decomposition. Then, the solid phase [(NH3)4Ru3Cl12] kept decomposing from 314.0°C to 352.7°C, HCl and N2 were released, and agglomerated Ru particles were achieved. Thermogravimetric analysis-differential thermal analysis-mass spectrum coupling (TG-DTA-MS) was used to monitor the thermal decomposition process and identify the released gaseous phases, respectively. The solid phases in different stages were characterized by high-temperature X-ray diffraction (HTXRD). A good understanding of the processing and thermal decomposition of (NH4)2RuCl6 is crucial in the creation of Ru products.