we prepared LaFeO3 with Lanthanum nitrate (La(NO3)3·6H2O),ferric nitrate (Fe(NO3)3·9H2O) with equal molar ratio and citric acid(C6H8O7.H2O). I want to know the possible chemical equation of La2O3, Fe2O3 and La(OH)3 during the process.
Consider 2LaFeO3 to be equimolar La2O3 and Fe2O3 or LaFeO3 = [1/2].[Fe2O3 + La2O3] This preserves the +3 valence states for both La and Fe. We then consider the standard decomposition routes of the nitrates to the oxide (which favor any higher oxidation state in the products). The water of crystallization is irrelevant but easily factored in. As we have X(NO3)3 in both cases, then it's a simple process to get to:
4[X(NO3)3.yH2O] → 2X2O3 + 12NO2 + 3O2 + 4y.H2O
I do not believe that such a decomposition favors any hydroxide production as nitric acid would be (initially) produced in any conceivable reaction mechanism and this will react with the hydroxide producing the nitrate again (which would decompose as above). For example:
La(NO3)3.6H2O → La(OH)3 + 3HNO3 + 3H2O
The citrate as reducing agent (or stabilizer) is irrelevant and could be considered to be fully oxidized to CO2 and water.