Chemical design of lead-free relaxors with simultaneously high energy density (W rec) and high efficiency (η) for capacitive energy-storage has been a big challenge for advanced electronic systems. The current situation indicates that realizing such superior energy-storage properties requires highly complex chemical components. Herein, we demonstrate that, via local structure design, an ultrahigh W rec of 10.1 J/cm3, concurrent with a high η of 90%, as well as excellent thermal and frequency stabilities can be achieved in a relaxor with a very simple chemical composition. By introducing 6s 2 lone pair stereochemical active Bi into the classical BaTiO3 ferroelectric to generate a mismatch between A- and B-site polar displacements, a relaxor state with strong local polar fluctuations can be formed. Through advanced atomic-resolution displacement mapping and 3D reconstructing the nanoscale structure from neutron/X-ray total scattering, it is revealed that the localized Bi enhances the polar length largely at several perovskite unit cells and disrupts the long-range coherent Ti polar displacements, resulting in a slush-like structure with extremely small size polar clusters and strong local polar fluctuations. This favorable relaxor state exhibits substantially enhanced polarization, and minimized hysteresis at a high breakdown strength. This work offers a feasible avenue to chemically design new relaxors with a simple composition for high-performance capacitive energy-storage.

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In this paper, we systematically study the dopability and magnetic properties of a 3d TM-doped atomic-thick SnTe(001) monolayer based on first-principles calculations. It is found that, for separately distributed TMs in a SnTe(001) monolayer, all of the TMs, except Sc, Cu, and Zn for the substitutional configuration and Ni, Cu, and Zn for the adsorption and interstitial configuration, could induce local magnetic moments. On the other hand, contradictive to the intuition that TM may adsorb on the SnTe(001) slab, substitution is more favorable. Even though the formation energy of Ni adsorbed and interstitial in a SnTe(001) monolayer is comparably low, its local magnetic moment is 0 as a result of the 3d orbitals fully occupied. Considering both the low formation energy and large magnetic moment, Mn is expected to be a prominent choice to introduce magnetism in atomic-thick SnTe in substitutional configuration. Thus, a pristine flat magnetic SnTe monolayer is probable to be obtained.