Organically capped Ag nano-powder (~50 nm)
Desired morphology and particles size of the powder can be achieved by using suitable reducing agent at the time of preparation as also the suitable reaction condition. Use of high boiling solvents as reducing agent may restrict the movement for particles in situ thus increasing the crystallinity to desired level during preparation, Compounds with long carbon chain, are well known surfactants for preparation of surface capped nanoparticles of metals and semiconductors. Use of such selected high density liquids leads formation of nano-sized silver powder with high crystallinity that are suitable for electronics
Capped Ag nano-powder of large particle diameter (~100 nm)
Partially capped Ag nano-powder has been developed at 100 gm level by using double reduction method. Initially silver salt of tricarboxylic acid is made which is then further treated with a mild reducing agent to see a slow precipitation of dark gray powder. The analysis of this powder revealed the particle diameter to be about 100-150 nm and the powder has similar surface area as compared to un-capped but the major advantage of such powder is that it is easily re-dispersed in water and alcohols. Thus this can be utilized well in formulation of thick film pastes. The SEM indicated that the powder has agglomerated spherical morphology and the melting temperature has reduced from 961 C to 800 C. Our results based on absorption spectroscopy re-dispersed powder show that the colloidal solution thus obtained is stable for several months and the absorption band at 410 nm indicated the particles diameter to be about less than 20 nm.
Nano-sized re-dispersible silver powder (less than 50 nm)
The Shiny silver powder was characterized by XRD, SEM, EDAX, TEM, formation of silver metallic particles peaks was confirmed by XRD pattern. UV absorption spectrum of silver nanoparticle in toluene showed a plasmon resonance at 410 nm. TEM shows the particle size less than 50 nm. SEM shows the spherical morphology.
Submicron sized un-capped silver nanopowder (~300 nm)
XRD confirm the FCC structure of the silver powder. SEM shows the morphology of the particle to be spherical and highly agglomerated which is due to the absence of surfactant or capping agent. Such particles are directly useful in thick-film paste technology.
SPECIFICATION C-MET SPECIFICATIONS
CRYSTAL STRUCTURE FCC
AVERAGE PARTICLE SIZE 100NM
BULK DENSITY 10.49 GM/CM3
SURFACE AREA 2–10 m2 /g
VOLUME PER GM 0.5-0.8 GM /CM3
RE-DISPERSIBILITY IN WATER ~25%
MELTING POINT ~800°C
Nano-sized un-capped Ag-Pd Nano-Powder
XRD, SEM, EDAX and TEM was used to characterize the shiny black powder. Formation of Ag-Pd co-powder was confirmed by XRD pattern. It showed all the hkl planes confirming the face centered cubic lattice of Ag-Pd co-powder. TEM showed the particle size to be less than 50 nm. SEM showed that the co-powder has spherical morphology with fine distribution of particles. The firing of this co-powder resulted in discoloration of the powder from black to ray indicating that an alloy of the Ag-Pd is perhaps possible at about 500 °C firing. The XRD of the fired co-powder indicated a slight shift in 2theta (about 0.20 degrees). Such low temperature firing may be very useful for thick paste for applications in electronics technology.
Nano-sized Ag and gold particle for Photonics (OPTICAL WAVEGUIDES)
Nano-particles of silver and gild have been drafted in polymers via aqueous and organic medium to make transparent films that would have applications in photonics. These have been tuned in their optical properties and the composite films show excellent waveguide properties. These nano-particle composites tailored in suitable polymers and can be used as optical waveguide materials.
Quantum dots of semiconductor in various matrices
Quantum dots of CdS, CdSe, PbSe and InP have been prepared and have been successfully drafted in polymers via organic medium with light emission properties. The dots in polymers leads to transparent films that would have applications in display devices and photonics. These have been tuned in their optical properties thus different particles and surfaces leads to different light emissions.
Nano-sized Ruthenium Oxide for Supercapacitor
Nano-particles of Ruthenium oxide have been developed at 100 gm level by solution chemistry method and have been tested at user agency such as VSSSC. The developed material is useful for super capacitor applications. The following specifications are generated for the finished product. Similarly, the submicron to nano-size powder of calcium, strontium and bismuth ruthanates have been developed by solution routes.
SPECIFICATION C-MET SPECIFICATIONS
AVERAGE PARTICLE SIZE< 100 NMBULK DENSITY10.49 GM/CM3PORE DIAMETER40 ASURFACE AREA200 m2 /gVOLUME PER GM0.2 GM /CM3WATER CONTENT~10%