matrix
(rus. матрица (для матричной изоляции))
—
condensed (solid or liquid) medium in which isolated active particles (atoms, molecules, ions, nanoparticles, etc.) are placed to prevent interaction between them and with the environment.
Description
The general requirements of the matrix material include:
-chemical inertness to the isolated objects and, in case of nanoreactors to the reagents and reaction intermediates;
-sufficient rigidity of the solid body or viscosity of the liquid to prevent coagulation of the particles;
-low intensity of diffusion mass transfer of material particles through the matrix at stabilisation temperatures.
Depending on the nature of isolated particles different materials can be used as a matrix. Thus, low-temperature matrix isolation techniques widely use solid inert gases, whose important advantage is their transparency over a wide range of wavelengths that enables the study of the isolated objects with IR and UV spectroscopy.
The specifics of using matrices as nanoreactors, which is a particular case of matrices, are discussed in corresponding sections. Matrices can be used to prevent secondary recrystallisation and particle growth in heat treatment of nanomaterials. A simple but effective way to isolate nano-objects in this case is intensive mechanical mixing of nanopowders with an excess amount of an inert, thermally stable and sufficiently soluble salt, which after heat treatment can be easily removed by dissolving. Many liquids, up to liquid nitrogen, have proved to be very effective for isolating nanoparticles of various materials in their production using laser ablation in a liquid medium.
-chemical inertness to the isolated objects and, in case of nanoreactors to the reagents and reaction intermediates;
-sufficient rigidity of the solid body or viscosity of the liquid to prevent coagulation of the particles;
-low intensity of diffusion mass transfer of material particles through the matrix at stabilisation temperatures.
Depending on the nature of isolated particles different materials can be used as a matrix. Thus, low-temperature matrix isolation techniques widely use solid inert gases, whose important advantage is their transparency over a wide range of wavelengths that enables the study of the isolated objects with IR and UV spectroscopy.
The specifics of using matrices as nanoreactors, which is a particular case of matrices, are discussed in corresponding sections. Matrices can be used to prevent secondary recrystallisation and particle growth in heat treatment of nanomaterials. A simple but effective way to isolate nano-objects in this case is intensive mechanical mixing of nanopowders with an excess amount of an inert, thermally stable and sufficiently soluble salt, which after heat treatment can be easily removed by dissolving. Many liquids, up to liquid nitrogen, have proved to be very effective for isolating nanoparticles of various materials in their production using laser ablation in a liquid medium.
Author
- Shlyakhtin Oleg A.
Sources
- Chemical nanoreactors // NeoTechProduct (in Russian). — www.neotechproduct.ru/nanochemistry (reference date 12.12.2011).
- Tsuzuki T. et al. Mechanochemical synthesis of gadolinium oxide nanoparticles // Nanostruct. Mater. 1999. V. 11. P. 125–131.
- Sajti Cs. L. et al. Femtosecond laser synthesized nanohybrid materials for bioapplications // Appl. Surf. Sci. 2007. V. 253. P. 8111–8114.