Separation of 47Ti and 49Ti Solid-State NMR Lineshapes from crystalline and glassy materials by static QCPMG experiments
EMSL Project ID
3356
Abstract
The structural importance of Titanium in e.g. minerals and glasses has initiated a wide range of projects exploring Ti by NMR. Unfortunately, the two NMR active nuclei, 47Ti and 49Ti, have almost the same Larmor frequency even at 21.1 T, are low-gamma nuclei and are generally characterized by a large quadrupolar coupling constant that results in spectra of the central transition that are more than 100 kHz wide. Presently, a method that takes advantage of the difference in spin (5/2 and 7/2, respectively) for the two nuclei will be used to separate the lineshapes originating from the two isotopes. While this may not be important when only one Ti site is present it is going to be crucial when the lineshapes from two or more sites are to be deconvolved. Our primary interest is in the observation of distributions of sites in amorphous or partially amorphous (metamict) materials where broad contributions to spectra from each Ti isotope make spectral interpretation difficult. The present technique is a modified version of the static QCPMG experiment and the initial results obtained in collaboration with Andrew S. Lipton at EMSL provided partial separation of the two NMR active isotopes in the two TiO2 polymorphs anatase and rutile. These results are promising for this technique as a local probe to characterise radiation induced amorphisation in titanite based ceramics proposed as hosts for nuclear waste. Therefore the two titanosilicates termed NTS2 (Na2O*TiO2*2SiO2) and KTS2 (K2O*TiO2*2SiO2) are going to be analysed by this method in both the glassy and crystalline state in order to characterise the differences between the two titanosilicates and to detect the differences in the Ti environment in the two states.
Project Details
Project type
Capability Research
Start Date
2003-09-01
End Date
2004-04-07
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members