SBA-15, an acronym for Santa Barbara Amorphous-15, is a silica-based ordered

mesoporous material A mesoporous material (or super nanoporous ) is a nanoporous material containing pores with diameters between 2 and 50 nm, according to IUPAC nomenclature. For comparison, IUPAC defines microporous material as a material having pores smal ...

that was first synthesized by researchers at the university of California Santa Barbra in 1998. This material proved important for scientists in various fields such as material sciences, drug delivery, catalysis, fuel cells and many other due to its desirable properties and ease of production.

Synthesis procedure

The procedure is a typical Liquid-Crystal templating that consists of three steps: Gel-SBA-15

# Solution preparation — Pluronic P123 is dissolved in an acidic solution of water at specific molar ratios and the silica precursor typically

TEOS Teos () or Teo was an ancient Greek city on the coast of Ionia, on a peninsula between Chytrium and Myonnesus. It was founded by Minyans from Orchomenus, Ionians and Boeotians, but the date of its foundation is unknown. Teos was one of the t ...

or TMOS (sometimes EGMS) is added and mixed in for some time. # Hydrothermal treatment — The solution is sealed in a container and subjected to a temperature T1 for about 24 hours and then a higher temp T2 for 48 hours. # Washing and calcination — The gel obtained from the previous step is washed with water and ethanol under centrifuging, and finally calcinated at about 550 °C for 6 hours.

Structure

The interest in SBA-15 comes from the fact that its mostly

mesoporous A mesoporous material (or super nanoporous ) is a nanoporous material containing pores with diameters between 2 and 50 nm, according to IUPAC nomenclature. For comparison, IUPAC defines microporous material as a material having pores smalle ...

– meaning the pores are in the range of 2 nm to 50 nm according to the IUPAC definition and the fact that these pores have a well defined structure that is cylindrical shape in hexagonal ordering with their relatively thick pore walls which gives thermal stability. The

sorption Sorption is a physical and chemical process by which one substance becomes attached to another. Specific cases of sorption are treated in the following articles: ; Absorption: "the incorporation of a substance in one state into another of a d ...

isotherms of these materials, demonstrate typical hysteric behavior, which is still under discussion for its causes.

TEM

The

transmission electron microscopy Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a g ...

of the sample shows the cylindrical pores but also highlights the fact that the pores of this material exhibit geometric deformations.

SAXS

The small-angle X-ray scattering pattern shows typical

Bragg peak The Bragg peak is a pronounced peak on the Bragg curve which plots the energy loss of ionizing radiation during its travel through matter. For protons, α-rays, and other ion rays, the peak occurs immediately before the particles come to rest. ...

s to the hexagonal structure of the material. The peak positions, is directly related to the

lattice parameter A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has ...

q_ = \frac \sqrt

where h and k are the

miller indices Miller indices form a notation system in crystallography for lattice planes in crystal (Bravais) lattices. In particular, a family of lattice planes of a given (direct) Bravais lattice is determined by three integers ''h'', ''k'', and ''� ...

. SBA-15-TEM.jpg, TEM of a typical SBA-15 sample SBA-15-structure.png, Demonstration of the hexagonal structure of SBA-15. SBA-15-Small_angle_x-ray_scattering.jpg, Small angle x-ray scattering pattern of a SBA-15 sample(data from Haidar et al.) Isotherm_SBA-15.png, Typical isotherm SBA-15 sample, data from Haidar et al.

References

{{reflist Materials science Chemical substances