Thermal behaviour of urea nitrate

The thermal decomposition under argon of the boracites M₃B₇O₁₃X (M=divalent metal ion, X=halogen ion or OH^?) has been studied by thermogravimetry (TG) and differential thermal analysis (DTA) for the compositions MgCl, MgOH, CrC1, CrBr, CrI, MnCl, MnBr, MnI, FeCl, FeBr, FeI, CoCl, CoBr, CoI, NiCl, NiBr, NiI, CuCl, CuBr, ZnCl, ZnBr, ZnI, CdCl, CdBr and CdI. The lithium boracites Li₄B ₇O₁₂X, with XCl and Br, have also been studied. The stability of the boracites systematically decreases in the order MCI>MBr>MI. The most stable boracite is CrCl (1% weight loss at 1242°C) and the least stable one studied here is MgOH (1% weight loss at 717°C).