Controlled Growth of Silica Shell on Ba_0.6Sr_0.4TiO₃ Nanoparticles Used As Precursors of Ferroelectric Composites

Abstract

A method based on a seeded growth process was developed to coat ferroelectric nanoparticles with a dielectric silica shell. This method, applied to size-polydispersed (Ba0.6Sr0.4)TiO3 particles (BST, mean diameter 150 nm), allows the control of the silica shell thickness from 2 to 80 nm with an accuracy of 1−2 nm. The morphology and surface physical chemistry of the core−shell were studied by transmission electron microscopy, photon correlation spectroscopy, and zeta potential measurements. A size-sorting procedure consisting of several cycles of centrifugation was optimized to extract the BST@silica nanoparticles of the required size for dielectric properties tuning. Upon sintering, dielectric measurements showed that the ferroelectric transition was maintained in the dense nanocomposites.

Innovative architectures in ferroelectric multi-materials: Chemistry, interfaces and strain

“…This soft chemistry route, derived from the so-called St€ ober process, ensures a uniform, continuous and homogeneous nanoscale silica coating (from 1 to 100 nm) whatever the size and the shape of the ferroelectric cores. 22 Further functionalization is possible leading to raspberry design generated by electrostatic interactions and consisting of silica coated ferroelectric particles surrounded by an assembly of silica coated magnetic nanoparticles (-Fe 2 O 3 @SiO 2 ). 23 The coating of ferroelectric nanoparticles with a shell of few nanometers of amorphous alumina was performed using the supercritical fluid chemical deposition process (SFCD).…”

“…30 In our pioneer work, silica was initially selected as coating material because it acts as an efficient dielectric loss barrier at the grain scale. 22,17 The seed growth process used for the silica coating, allows an accurate control of the shell thickness ( Fig. 1(a)).…”

Bioconjugation of barium titanate nanocrystals with immunoglobulin G antibody for second harmonic radiation imaging probes

“…Therefore, after the treatment, we have a ''TiO 2 -like'' particle surface. We then placed the treated particles in 10 mM of APTES in ethanol-water-ammonia solution 75/23.5/1.5 v/v/v % at 70 C for 8 h. The organofunctional silanes act as a bridge between organic and inorganic phases by forming a covalent attachment of organic monolayers [34][35][36]. As a result, we have accessible amine groups immobilized on the surface of BaTiO 3 nanocrystals, referring to as amino-BaTiO 3 , for further antibody conjugation.…”

The possibility of giant dielectric materials for multilayer ceramic capacitors

“…8 We then made a composition analysis by ICP-AES (Shimadzu ICPS-8100CL) to make sure that the amount of coated SiO 2 is equal to the amount charged. Coating quality was confirmed by TEM observation (JEOL JEM-2100F).…”

“…8 After dripping tetraethoxysilane (TEOS) in the slurry of BT and stirring, the pH was 7, so we thought that the amount of base that serves a catalyst of hydrolysis reaction of TEOS was not enough. So, we increased the amount of ammonia, a base, to accelerate the hydrolytic reaction of TEOS.…”