Dielectric oxide, method for producing same, solid-state electronic device and method for producing said solid-state electronic device

One method for producing a dielectric oxide according to the present invention comprises: a precursor layer formation step wherein a layer of a first mixed precursor solution, which is obtained by mixing a first precursor solution that contains, as solutes, a precursor containing bismuth (Bi) and a precursor containing niobium (Nb) with at least one additive selected from the group consisting of sorbitan fatty acid esters, polyoxyethylene ethers of sorbitan fatty acid esters, polyvinyl polymers and ethylene polymers, is formed by means of a coating method; and a dielectric oxide layer formation step wherein a layer (30x) of a first dielectric oxide which has a crystal phase having a pyrochlore crystal structure and contains a first oxide that is composed of bismuth (Bi) and niobium (Nb) (and which may contain unavoidable impurities) is formed by means of a heating treatment in which the layer of the first mixed precursor solution is heated in an oxygen-containing atmosphere.