Investigation of the crystal structures and electronic features for trivalent praseodymium doped KY(WO4)2 crystal: a theoretical study

Potassium yttrium tungstate (KY(WO 4 ) 2 ) doped with rare-earth ions exhibits efficient continuous laser activities in the near-infrared spectrum, suggesting its great potential as the new-generation of laser crystals. In this work, we report the structural evolution of KY(WO 4 ) 2 doped with Pr 3+ using the CALYPSO structure search method in combination with first-principles calculations. A novel structure of KY(WO 4 ) 2 :Pr crystal with P 2 space group is identified for the first time. The impurity Pr 3+ ion can naturally occupy the Y 3+ site in the host crystal. The doping concentration of Pr 3+ for the system is equal to 12.5%. The electronic features of the KY(WO 4 ) 2 :Pr is calculated by LDA + U method. The results show a gap of 3.106 eV in the electronic band structure, which implies that the KY(WO 4 ) 2 :Pr possesses a semiconductor character. The analysis of the partial density of states demonstrates that the introducing of impurity Pr 3+ ion into KY(WO 4 ) 2 leads to a transformation of the electronic states. Based on the electron localization functions and Bader charge analyses, the ionic bonding character of Pr–O in KY(WO 4 ) 2 :Pr structure are clarified. The absorption coefficient spectra of the KY(WO 4 ) 2 :Pr indicate a blue shift toward higher energies. These results could not only enrich the fundamental understanding on the structural evolution of rare-earth doped KY(WO 4 ) 2 , but also provide information for designing the new laser materials.