Thermal decomposition of bishydrazinocarboxylate iron(II) di-hydrazinate

Abstract

Low temperature (T < 200~ thermal decomposition in air of bishydrazinocarboxylate iron(II) dihydrazinate [Fe(II)(N2H3COO)2(N2H4)2] is known to produce 7-Fe203 in ultrafine form [1][2][3][4]. This decomposition process is known to be exothermal and autocatalytic but details regarding the stepwise mechanism of decomposition is yet unknown although a few attempts have been made with limited success [1,5]. In our present work, we have combined the results from (i) thermal analysis of complex precursor and (ii) characterization of products isolated at intermediate and final stages of decomposition in order to explain the stepwise mechanism of decomposition of Fe(N2H3COO)2(N2H4)2 in air. ExperimentalThermal stability of Fe(N2H3COO)2(N2H4)2 was studied in air as well as in nitrogen atmospheres by simultaneous recording of DTA/TG/DTG curves in NETZSCH STA 409 thermal analyzer. The first thermoanalyfical curves ( Fig. la) were recorded in dynamic air using around 25 mg sample heated at a rate of 10 deg/min. Since we failed to understand clearly the nature of these curves (A) due to overlapping of DTA peaks, other curves (B) (Fig. lb) were recorded with = 50 mg of sample heated at a rate of 5 deg/min. In nitrogen atmosphere, DTA, TG and DTG curves were recorded with = 25 mg of sample heated at a rate of 5 deg/min, only to confirm the autocatalytic decomposition of the complex and will be referred to during the discussion, whenever necessary.