| dc.description | Lamellar ??-MoO3 crystals were implanted with low fluence of radioactive 111mCd ions at ISOLDE-CERN.
Subsequently, we have probed the interaction of the Cd impurity in the lattice with native point defects, such
as oxygen vacancies, as a function of annealing temperature using the time differential perturbed angular
correlations nanoscopic technique. The experimental data were complemented and interpreted by modeling
different Cd-defect configurations in ??-MoO3 with first-principles density functional theory (DFT). The agreement between experiments and DFT simulations shows that only the interstitial Cd (CdI) prevails in the van
der Waals gap, by inducing a polaron effect. Upon raising the annealing temperature, CdI is able to trap hole
charge carriers resultant from the oxygen vacancies VO. Oxygen vacancies were found to form most commonly
at two-fold coordinated (O2) atoms. According to comparison DFT results with the experimental electric field
gradient values (Vzz and ??) and the calculated formation energies for different defect complexes, the configuration
of CdI with two (O2) vacancies (VO2), located at different planes, is found to be more favorable and stable than
the other defect configurations. The electron-polaron formation around the Cd impurity at an interstitial site is
enhanced by inducing (O2) vacancies with the creation of hole polaron states. | |
