Hydrothermal synthesis, characterization and formation mechanism of self-assembled mesoporous SrTiO3 spheres assisted with Na2SiO3·9H2O

Abstract

Mesoporous SrTiO 3 spheres were synthesized via the self-assembly of nanocrystallites in the presence of Na 2 SiO 3 $9H 2 O through a hydrothermal process. The as-prepared samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis and nitrogen gas sorption isotherms. The results revealed that the mesoporous spheres consisted of SrTiO 3 nanocrystallites with an amorphous silicate shell and mesopores formed among them. Na 2 SiO 3 $9H 2 O played an important role in the formation of the mesoporous SrTiO 3 spheres. Based on the experimental results a possible formation mechanism of the mesoporous SrTiO 3 spheres was preliminarily proposed.

Influence of Annealing Temperatures on the Structural, Morphological,Crystalline and Optical properties of BaTiO3 and SrTiO3 Nanoparticles

“…Various synthesis routes can be used to synthesize both BaTiO 3 and SrTiO 3 nanoparticles [11]. Synthesis routes such as electrochemical, hydrothermal [12], sol-gel, solvothermal [13], polymeric precursor and solid state bi-modal distribution methods, play a huge role in the purity and crystallinity of the nanoparticles. The rapid advances in nanotechnology, nanomaterials and nanomechanics offer huge potentials in national defense, homeland security, and private industry.…”

Solvothermal synthesis, characterization and formation mechanism of single-crystalline SrTiO3 dense spheres with monoethanolamine as reaction medium solvent

“…[9][10][11][12][13] Since the semiconductor nanocrystals have been found to have superior properties than their bulk counterpart, the current world-wide intense research on nanomaterials was initiated. 14,15 Various simple one-dimensional (1D) nanostructures, such as nanotubes, 16,17 nanorods/ nanowires, 18,19 and nanobelts, 20 as well as some complex highorder architectures, such as three-dimensional (3D) hierarchical dendrites, 21,22 3D porous architectures, 23,24 and mesoporous spheres, [25][26][27] have been successfully realized through a number of approaches. As one kind of eminent microwave dielectric, ferroelectric, and photocatalytic material, the synthesis of SrTiO 3 nanostructures with various morphologies has also attracted great attention.…”

“…Due to calcination at high temperature, severe agglomeration always occurs accompanying the formation of SrTiO 3 perovskite, which strongly attenuates the physical and chemical properties of the obtained SrTiO 3 materials. 28 In order to prevent the severe agglomeration, so far, many wet chemical methods, such as sol-gel, 29 coprecipitation, 30 molten salt method, 31 and hydrothermal reaction route, [25][26][27] have been employed to prepare SrTiO 3 perovskite with controlled physical and chemical characteristics. Among these methods, the hydrothermal technique is an aqueousbased precipitation route, allowing control over the nucleation and crystal growth by tuning the hydrothermal reaction conditions.…”

“…Usually, under the effect of potassium hydroxide (KOH) the hydrothermally synthesized SrTiO 3 crystallizes and grows to cubic particles. 27 However, very low concentration of KOH results in the hydrothermal formation of SrTiO 3 dendrites. 32 By employing amorphous TiO 2 mesospheres as a template, Wang and coworkers have first realized the hydrothermal synthesis of SrTiO 3 mesoporous spheres.…”

“…33 Recently, our group has also successfully synthesized single-crystal-like SrTiO 3 mesoporous spheres by self-assembly of nanocrystallites via a hydrothermal reaction route in the presence of polyvinyl alcohol (PVA) or Na 2 SiO 3 ?9H 2 O. 26,27 In the presence of PVA, the high Sr/Ti molar ratio of 3 : 1 plays an important role in the synthesis of SrTiO 3 mesoporous spheres. High Sr/Ti molar ratio accelerates the nucleation and results in the pouring crystallization of SrTiO 3 nanocrystallites.…”