Structure, photoluminescence and electrical properties of Eu–Nd codoped CaBi4Ti4O15 synthesized by sol–gel method

Eu–Nd codoped CaBi3.75−xEuxNd0.25Ti4O15 (CBENT) powders were synthesized by a simple sol–gel method. Their structures were examined by X-ray diffraction, Raman spectrum, respectively. The coexistence of orthorhombic and tetragonal phase was found when the Eu3+ doping content varied from 0.3 to 0.6. The photoluminescence properties of the CBENT powders show that the intense emission bands centered at around 574, 590 and 612 nm are due to the transitions of 5D0 → 7F0, 5D0 → 7F1 and 5D0 → 7F2 of the Eu3+ ions, respectively. The spectra of the temperature dependence of dielectric constant indicate that the Curie temperature TC gradually decreases from 785 to 765 °C. The peaks of dielectric constant are restrained with increasing Eu3+ doping concentration, suggesting the weakness of the ferroelectricity. Combining the photoluminescence with the ferroelectric property in the CBENT, the optimal Eu3+ doping concentration x is 0.2.