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The mechanism of formation of zinc ferrite (ZnFe2O4) from ZnC2O4·1.8H2O–2FeIIC2O4·2H2O and ZnC2O4·1.8H2O–Fe2III(C2O4)3·6H2O mixtures is investigated. By combination of TG and XRPD measurements it has been shown that microcrystalline ZnFe2O4 forms from physical mixtures after prolonged annealing at 1000 °C while nanocrystalline ZnFe2O4 powders are produced by mild annealing (1 h at 500 °C in air) of mechanically activated mixtures. The magnetic properties of ZnFe2O4 powders obtained from physical and from milled mixtures are compared.

Zinc oxide and strontium titanate are among the most interesting materials for oxide electronics due to their semiconducting and dielectric properties respectively. We obtain high electron mobility values in epitaxial ZnO thin films deposited on (110) oriented strontium titanate substrates. Values up to 400 cm 2 /V s are found below 50 K in samples grown by a two step method: firstly a thin ZnO relaxing layer is deposited on the SrTiO 3 (110) substrate at relatively low temperature (550 ∘ C) and then the deposition temperature is raised up to 750 ∘ C for the growth of a second ZnO layer. The realized epitaxial ZnO/SrTiO 3 heterostructures are used to fabricate field effect transistors transparent at visible wavelength. By conventional photolithographic techniques we realize micrometric sized devices in planar side-gate configuration. The transistors have an 80% transmittance, on–off ratios up to 10 6 , and field effect mobilities up to 30 cm 2 /V s.