|Support type:||Scholarships in Brazil - Post-Doctorate|
|Effective date (Start):||September 01, 2018|
|Effective date (End):||August 31, 2021|
|Field of knowledge:||Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials|
|Principal Investigator:||Ana Candida Martins Rodrigues|
|Home Institution:||Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil|
|Associated research grant:||13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass, AP.CEPID|
A nanoparticle (NP) could be defined as a material with a size smaller than 100 nm whose properties differ from their bulk counterparts. Semiconductor NPs show tunable optical properties due to the discretization of the energy levels. Metallic NPs exhibit peculiar absorption features because of the collective oscillation of the electrons on the metal surface (plasmon oscillations). The combination of a metal and a semiconductor in the same nanocrystal is of interest from both fundamental and technological points of view. These hybrid semiconductor-noble metal nanocrystals not only combine the unique properties of the metal and the semiconductor but also generate collective new phenomena based on the intra-particle interactions at the interface. Understanding metal-semiconductor interactions and how they depend on particle size, shape, composition, and the space between the metallic and semiconductor segments is crucial for a variety of applications ranging from photocatalysis, optoelectronics, and photovoltaics to biological labelling and nanomedicine. Semiconductor NPs and semiconductor-metal HNPs are quite promising materials for a widespread application area. Generation of semiconductor-metal HNPs in glass via one-step melt quenching technique has not been reported so far. It has excellent scopes for various photonic applications but not explored yet. Doping of semiconductor NPs in glass has been successfully studied which has given very promising results; visible photoluminescence (PL) has been found which is controlled by the size of the NPs. Significant enhancement in PL intensity takes place with controlled thermal treatment. Doping of metal NPs in glass is also well-known. Significant enhancement was observed in the PL intensity of the RE ions in presence of nanometals in specific concentration. This enhancement grows even further when the glass matrix gets crystallized. Thus, tuneable luminescence properties have been found in nanometal-RE co-doped low-phonon energy glasses and glass-ceramics. If the local field enhancement effect, exhibited by metal NPs, can be utilized to enhance the optical absorption and emission properties of the semiconductor NPs, this plan of doping semiconductor-metal HNPs in glass stands a good chance of success.In view of the above motivations, the prime objectives can be specified as: i) generation of semiconductor (like CdS, CdSe etc.) and semiconductor-metal HNPs (using metals like Ag, Au) into a low phonon glass matrix by different synthesis methods, ii) heat treatment of the glasses to form glass-ceramics and observation of change in optical properties with matrix crystallization, iii) incorporating suitable RE ions in different concentrations into them and study the effect of semiconductor-metal HNPs on PL properties.In order to prepare semiconductor-metal HNPs embedded glass, two methods can be applied: i) a two-step method where semiconductor NPs and semiconductor-metal HNPs can be prepared separately and then can be embedded into a suitable glass matrix, ii) a single-step method, where both semiconductor and semiconductor-metal hybrid nanoparticles can be in situ generated into the glass matrix during the melting process. The expected results include: i) generation of visible PL, which can be applied in the field of high performance optoelectronic devices such as light emitting diodes (LEDs), laser diodes (LDs) etc., ii) nanometal enhanced PL could exhibit up to 10-20 fold enhancement in intensity of the emitted radiation, depending on the size and shape of the metal NPs. This is enormously useful for various photonic applications, iii) the PL intensity can be tuned by heat treatment temperature and duration. This tunable emission can be utilized in various photonic and laser devices, iv) generation of white light emitting diode (WLED) by proper combination of dopants, v) enhanced frequency up and down-conversation, which are very useful in solar cell applications.