NMR Studies of Li-doped wide band SnO2 nanoparticles
EMSL Project ID
27691
Abstract
The development of electrical and electronic devices with nanometric dimensions is a great challenge for technological applications. Knowledge of micro structural properties of nanostructureed doped semiconductor oxides plays a fundamental role in the understanding and development of new electronic devices especially sensors properties.. The basic mechanism of sensing in such materials is due to conductivity changes occurring upon exposure to analyte. For traditional n-type SnOx materials, oxidizing or reducing species affect the surface depletion length (i.e. concentration of mobile charge carriers) reducing effective cross-sectional area for charge transport. Recently we reported discovery of p-type SnOx nanoparticles using Li as dopant which has allowed fabrication of new class of sensors based on p-n junctions (diode sensors). Our preliminary studies indicate that it may have great applications to study morphology and dynamics of lithium doping in tin oxide. This is because both static (chemical shift and quadrupolar tensors) and dynamic properties (temperature dependent line shapes, and spin lattice relaxation rates) of Li nucleus can yield wealth of information about the nanoscopic segregation and electron nuclear interactions. Specifically we have found that quadrupolar Li NMR line-shapes are indicative of two electronically distinct sites. Furthermore the spin lattice relaxation rates for one of these components is an orders or magnitude faster that are expected from modulation of quadrupolar/dipolar interactions, thereby raising the possibility of strong electron-nuclear interaction. We wish to quantify the spin relaxation rates and line shapes as function of temperature at the PNNL NMR facility.
Project Details
Project type
Limited Scope
Start Date
2008-02-28
End Date
2008-04-23
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Chaparadza A, and SB Rananavare. 2010. "Towards P-Type Conductivity in SnO2 Nanocrystals through Li Doping." Nanotechnology 21(3):035708. doi:10.1088/0957-4484/21/3/035708