Electronic Conductivity of A-Site-Deficient and n-/p-Modified Strontium Titanate Nanoparticles Synthesized Using the Supercritical Solvothermal Method

Using a one-step supercritical continuous solvothermal synthesis process, we succeeded in synthesizing several A-site-deficient (∼15%) and modified A- and/or B-site strontium titanate nanoparticles, starting with acetylacetonate and alkoxide precursors as the cation source. Our primary achievement was the assessment of the setup versatility and of the acetylacetonate chemistry for producing a broad range of modifications on both A- and/or B-site ABO₃ perovskite materials. Phase-pure SrTiO₃ nanoparticles featuring different atomic modifications with rare-earth elements, such as yttrium and neodymium, and transition metals, such as niobium and iron, were synthesized and characterized to evaluate their microstructure. The impact of n- and p-type modifications on the lattice structure was elucidated, and dense pellets were processed to investigate the materials' electronic conductivity. We show that modification of the perovskite structure elements can efficiently tune the electronic properties. Indeed, the electronic conductivity is increased by up to 1000 times (up to 1 S cm⁻¹ at 1000 K) compared to that of conventional strontium titanate in such newly synthesized materials through the supercritical solvothermal method.