Lowering of ground state induced by core-shell structure in strontium titanate

Abstract

International audienceA new ground state of textbook compound strontium titanate (SrTiO 3) is obtained by inducing a specific core-shell structure of the particles. Using a combination of high energy synchrotron and neutron diffraction, we demonstrate a lowering of the ferroelastic ground state towards a new antiferrodistortive phase, accompanied with strong shifts of the critical temperature. This new phase is discussed within the Landau theory and compared with the situation in thin films and during pressure experiments. The crucial competition between particle shape anisotropy, surface tension, and shear strain is analyzed. Inducing a specific core-shell structure is therefore an easy way to tailor structural properties and to stabilize new phases that cannot exist in bulk material, just like film deposition on a substrate

Temperature-Dependent Electron–Electron Interaction in Graphene on SrTiO3

“…This will lead to the change of the dielectric property of SrTiO 3 . Indeed, the dielectric constant of SrTiO 3 very close to the surface can be as low as ε ∼ 5 . This implies an effective dielectric constant at the SrTiO 3 surface of ∼3 using the simple standard approximation, ε = (ε vacuum + ε surface )/2, similar to the extracted dielectric constant for graphene on SrTiO 3 from our ARPES data.…”

“…Indeed, the dielectric constant of SrTiO 3 very close to the surface can be as low as ε ∼ 5. 44 This implies an effective dielectric constant at the SrTiO 3 surface of ∼3 using the simple standard approximation, ε = (ε vacuum + ε surface )/2, similar to the extracted dielectric constant for graphene on SrTiO 3 from our ARPES data. Thus, both the interfacial effect between graphene and SrTiO 3 , and the ill-defined surface of SrTiO 3 are attributed to play an important role in the dramatic change of the dielectric property of the SrTiO 3 surface.…”

“…Indeed, the dielectric constant of SrTiO 3 very close to the surface can be as low as ε ∼ 5. 44 This implies an effective dielectric constant at the SrTiO 3 surface of ∼3 using the…”

Specific core-shell approaches and related properties in nanostructured ferroelectric ceramics

“…The broadband dielectric spectroscopy is also very useful to analyze the dielectric relaxation processes in the GHz and THz ranges linked to the defects associated with the giant permittivity behavior [34,35]. Theoretical approaches have been also proposed to reproduce the giant permittivity behavior and to evaluate the potentiality of electrical energy storage and electrocaloric effect in the framework of a core-shell model of nanoceramics [36][37][38].…”