Journal of the American Ceramic Society, Vol.103, No.10, 5502-5514, 2020
Ion beam irradiation of ABO(4) compounds with the fergusonite, monazite, scheelite, and zircon structures
The effects of irradiation on CaWO4, SrWO4, BaWO4, YVO4, LaVO4, YNbO4, and LaNbO(4)were investigated on thin crystals using 1.0 MeV Kr ions at 50-1000 K. All of the ABO(4)compounds can be amorphized with calculated damage cross sections (sigma(a) = 1/F-c0) in the range of similar to 0.30-1.09 x 10(-14)cm(2)ion(-1)at zero Kelvin. The analysis of fluence-temperature data returned critical temperatures for amorphization (T-c) of 311 +/- 1, 358 +/- 90, 325 +/- 19, 415 +/- 17, 541 +/- 6, 636 +/- 26, and 1012 +/- 1 K, respectively, for the compounds listed above. Compared with previous in situ irradiation of ABO(4)orthophosphate samples using 0.8 MeV Kr ions, theT(c)values of LaVO(4)and YVO(4)are higher than those of LaPO(4)and YPO(4)by 82 K and 124 K, respectively. TheT(c)values of the three scheelite structures, CaWO4, SrWO4, and BaWO4, indicate that they are the most radiation tolerant compounds under these conditions. The A-B cation anti-site energies,E-fAB, determined by DFT range from 2.48 to 10.58 eV and are highly correlated with the A-B cation ionic radius ratio,r(A)/r(B), but are not correlated withT(c)across the different structure types, suggesting that the formation and migration energies of Frenkel defects play a more important role in damage recovery in these compounds. We also discuss the role of cation and anion charge/iconicity as determined by DFT. ABO(4)compounds with the zircon structure and B = P or V have a distinct advantage over those with B = Si as the damaged regions do not appear to be significantly affected by polymerization of (PO4)(3-)or (VO4)(3-)groups which might stabilize the amorphous fraction and ultimately lead to phase separation as observed in zircon (ZrSiO4).