Effect of A Site and Oxygen Vacancies on the Structural and Electronic Properties of Lead-Free KTaNbO Crystal.

The structural and electronic properties of lead-free potassium tantalite niobate KTaNbO (KTN) with A site vacancies $$ V_{\rm{K}}^{0} $$ , $$ V_{\rm{K}}^{1 - } $$ and oxygen vacancies $$ V_{\rm{O}}^{0} $$ , $$ V_{\rm{O}}^{2 + } $$ , were investigated by first-principles calculations, which indicated that A site vacancies $$ V_{\rm{K}}^{0} $$ are likely to form in the KTN compared with $$ V_{\rm{K}}^{1 - } $$ , and oxygen vacancies $$ V_{\rm{O}}^{2 + } $$ are likely to form compared with $$ V_{\rm{O}}^{0} $$ in the KTN according to the investigation of formation energy. The results show that K and O vacancies have significant influence on the atomic interactions of the atoms and the electronic performance of the materials. And Ta atoms are more easily influenced by the K and O vacancies than the Nb atoms from the atomic displacements in KTN with K and O vacancies. The investigation of density of state indicates that the compensation of electrons in KTN with vacancies make the hybridization become stronger among Ta d, Nb d and O p orbitals. Besides, Mulliken population of all the Ta and Nb atoms in KTN with charged vacancies are influenced by complement electrons. The strength of the Nb-O bond is stronger than Ta-O based on the changes of bond lengths and Mulliken population. [ABSTRACT FROM AUTHOR]