Spectrally resolved microprobe cathodoluminescence of intergrowth Bi₅ˍₓLaₓTiNbWO₁₅ ferroelectrics

Abstract

Spectrally resolved cathodoluminescence measurements of Bi₅ˍₓLaₓTiNbWO₁₅(x=0–1.50) ceramics at room temperature showed three distinct luminescence bands located at about 380, 502, and 660nm, respectively, which were tentatively assigned to F+ center, oxygen vacancy-related defect and octahedron structure-related luminescence center, respectively. These assignments could be made in light of electron irradiation experiments with different exposure times. Bands related to oxygen vacancies were clearly enhanced by lanthanum doping, indicating that charge compensation occurred by the substitution of Bi for La3+ in perovskitelike structured intergrowth ferroelectrics. We observed that, for contents of La³⁺ x>0.75, La³⁺ ions entered the [Bi₂O₂]²⁺ layer according to a doping mechanism which is briefly discussed in this letter. Show more