A comparative study of the thermal reactivities of some transition metal oxalates in selected atmospheres

摘要: Abstract A comparative investigation has been made of the nonisothermal, solid-state thermal decompositions oxalates six divalent transition metals (cations: manganese, iron, cobalt, nickel, copper and zinc) in alternative flowing atmospheres, inert (N 2 , CO ), reducing (H ) oxidizing (air). Derivative thermogravimetry (DTG) differential scanning calorimetry (DSC) response peak maxima, providing a measure reaction temperatures, have used to determine salt reactivities thus characterize factors that control relative stabilities this set chemically related reactants. Two trends were identified. Trend (1): decomposition temperature (salt stability) increased with rise enthalpy formation metal oxide, MO. It is concluded rupture cation-oxygen (oxalate) bond parameter determines stability salts within set. (2): diminution temperatures from values for reactions inert/reducing atmosphere those an difference between MO other participating oxide (MO 3/2 or 1/2 ). The change cation valence tended promote reaction, most O occurred at lower but magnitude effect varied considerably Observed variations stoichiometric kinetic characteristics conditions are discussed, together mechanisms these solid oxalates. This approach elucidation crystolysis emphasizes value investigations group Previous isothermal studies had each reactants selected here. From these, much learned about form (isothermal) yield–time curves, often interpreted provide information geometry interface development individual rate processes. However, identification controls reactivity, initiation (nucleation) advance (nucleus growth), more difficult less progress towards chemistry. reactivity changes compositions, identified here, offer complementary provided by study single salts. Much recent literature on solids concerned reactants, many results conclusions not presented widest possible perspective. Comparisons systematically here as chemical context steps participate reactions. article advocates use (solid-state chemical)