Further EPR study of paramagnetic Cr3+ centers in KTiOPO4

Careful reanalysis of EPR spectra of Cr3+ ions in KTiOPO4 has been carried out in order to resolve the weaker lines not considered in our previous study. Two additional centers denoted as C and D have now been identified and the respective spin Hamiltonian parameters have been determined. The reanalysis of the results for the centers A and B identified previously and those for the new centers C and D indicates that the centers A and C originate from Cr3+ ions at Ti(2) sites, whereas the centers B and D originate from Cr3+ ions at Ti(1) sites. Sixteen magnetically inequivalent Cr3+ sites are assigned to two crystallographically different titanium sites: Ti(1) and Ti(2). Possible charge compensation models for the two different centers arising from Cr3+ ions at each of the two Ti sites are also suggested.