A stoichiometric nitrate to citrate ratio was maintained in the redox mixture as per the propellant chemistry concept such that the sum of oxidising (nitrates) and reducing (fuel) valencies is zero [14].
Ammonia solution (25%) was added drop-by-drop to the precursor solution under stirring at room temperature and the pH was adjusted to 4.
The solution was heated up to 250 C on a hot plate under continuous stirring till it gets thickened and then transferred to a preheated furnace maintained at 600 C where combustion took place within couple of minutes.
The combusted powders were ground to fine powders and then calcined at 1000 C for complete phase formation.
The calcined powders were ball milled for 4 h to break the agglomerates and were consolidated in a 12mmdie using a cold isostatic press with 1 wt% polyvinyl alcohol (PVA) at a pressure of 750 MPa.
Dense sintered pellets were obtained by sintering the green compacts at 1450 C for 4 h in a muffle furnace.
A sacrificial layer of the same powder was used to cover the pellets during sintering to avoid BaO evaporation.
Density of the sintered compacts was determined by dimensional analysis to avoid any unwanted reaction with water in Archimedes’s principle.