Silica‐coated ferroelectric particles are promising building blocks for functional bulk composites such as dielectric resonators, supercapacitors, or multiferroics. The ferroelectric/silica interface was fully investigated by means of high‐temperature in situ X‐ray diffraction, high‐resolution scanning electron microscopy, and X‐ray photoelectron spectroscopy. Mechanisms occurring at the interface were visualized using high‐resolution postmortem and in situ transmission electron microscopy performed at different temperatures. On the light of this interface investigation, we have used advanced sintering processes such as spark plasma sintering and microwave sintering to obtain nanostructured composite ceramics and to evaluate their dielectric properties.

A study of bulk second harmonic generation (SHG) response of lithium niobium silicate glass‐ceramics is presented. The observed macroscopic SHG signals have an isotropic 3D nature. To interpret this particular nonlinear optical response, a multiscale approach is used in which clear correlations between structure and optical response are characterized from the sub‐micrometer to the millimeter scale. In particular, it is inferred that the radial distribution of the LiNbO3 crystallites in spherulite domains is at the origin of the isotropic bulk second order optical property. It is suggested that spherulitic crystallization in glass‐ceramic is a challenging method to elaborate isotropic nonlinear optical properties in inorganic materials.