December 11, 2020: PhD public defense – Matteo Griseri – Development of carbide materials for radioactive ion beam production at high-power ISOL facilities - KULeuven

Name: Matteo Griseri

Date: December 11, 2020

This is an online event streamed from the Kasteel Arenberg auditorium, Leuven.

Development of carbide materials for radioactive ion beam production at high-power ISOL facilities 

The isotope separation on-line (ISOL) technique consists of on-line evaporation, ionization, acceleration, and mass purification of radioisotopes produced in a target material irradiated by an accelerated particle beam. At SCK CEN, the ISOL@MYRRHA project envisages the construction of a high power ISOL facility that will utilize a 600 MeV proton beam of 200 to produce radioactive isotope beams (RIBs) for various applications including nuclear medicine. In this framework, the project aimed at developing novel target materials based on tantalum carbide for the production of radiolanthanides, such as 149,152,155Tb, proposed for novel cancer radio-theragnostics. 
Factors affecting the isotope release performance of ISOL target materials are open and interconnected porosity and the ability to operate at high temperatures (>2000°C) for prolonged periods of time (up to several weeks) without material degradation. This work focused on the production of porous TaCx ceramics via a processing route involving the thermal decomposition of Ta4AlC3 MAX phase precursor, mold casting and sacrificial templating with the addition of large spherical pore formers. 
A campaign of heat treatments in a specifically designed thermal test bench was conducted at SCK CEN in order to prove the stability of the microstructure at an operating temperature of 2200°C for up to 12 h. The obtained materials had an interconnected porous structure with a percentage of the theoretical density in the 35-50% range, with remarkably high stability under operating conditions and without loss of open porous structure.
Moreover, MAX phases with Hf, Nb solid solutions on the M sites were discovered with the following formulas: (TaxHf1-x)4AlC3, (TaxHf1-x)2AlC, (TaxNb1-x)4AlC3 and (TaxNb1-x)2AlC, with x = 0.9, 0.85, 0.8, 0.75; (Ta0.75,Nb0.25)4(Al0.5,Sn0.5)C3 and (Ta0.75,Nb0.25)2(Al0.5,Sn0.5)C. This finding revealed the potential to produce complex carbides with fine-tuned properties by using MAX phases as precursors.
Ultimately, an off-line release experiment was proposed and designed with the aim to be conducted at the ISAC-TRIUMF facility. Such a test will allow to assess the performance of porous TaCx targets in terms of the release of lanthanides.


 

Promotor:
  • Jozef Vleugels (KULeuven)

SCK CEN mentors:
  • Lucia Popescu (SCK CEN)

  • Konstantina Lambrinou (SCK CEN)

Click here for a list of obtained PhD degrees.