Structure, photoluminescence and electrical properties of Eu–Nd codoped CaBi 4 Ti 4 O 15 synthesized by sol–gel method

Eu–Nd codoped CaBi 3.75− x Eu x Nd 0.25 Ti 4 O 15 (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 Eu 3+ 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 5 D 0 → 7 F 0 , 5 D 0 → 7 F 1 and 5 D 0 → 7 F 2 of the Eu 3+ ions, respectively. The spectra of the temperature dependence of dielectric constant indicate that the Curie temperature T C gradually decreases from 785 to 765 °C. The peaks of dielectric constant are restrained with increasing Eu 3+ doping concentration, suggesting the weakness of the ferroelectricity. Combining the photoluminescence with the ferroelectric property in the CBENT, the optimal Eu 3+ doping concentration x is 0.2.