Enhanced dielectric properties of La-doped 0.75BaTiO3-0.25Bi(Mg0.5Ti0.5)O3 ceramics for X9R-MLCC application

Abstract A series of 0.75Ba(1−x)La2x/3TiO3-0.25Bi(Mg0.5Ti0.5)O3 (x = 0–0.2) ceramics have been synthesized by doping La2O3 into 0.75BaTiO3-0.25Bi(Mg0.5Ti0.5)O3 (0.75BT-0.25BMT), and their structure and dielectric properties investigated. Upon characterizing the structural properties, the single-phase perovskite structure is identified for all the samples and the long-range order of 0.75BT-0.25BMT is verified to be further destroyed with the addition of La2O3. Moreover, it is found that the density of 0.75BT-0.25BMT can be improved by doping with La2O3, which also promotes the grain growth. Regarding the dielectric properties, the peak shifting effect induced by La3+ improves the permittivity-temperature stability of 0.75BT-0.25BMT remarkably by strengthening its relaxation behavior. Among all the samples, 0.75Ba0.8La0.4/3TiO3-0.25Bi(Mg0.5Ti0.5)O3 shows the most outstanding permittivity-temperature stability with er = 572 ± 15% (compared with er at 25 °C) over the temperature range −70°C–238 °C at 1 kHz, which is notably better than that of 0.75BT-0.25BMT (−4°C–58 °C) and satisfies the specification of the X9R multilayer ceramic capacitor (MLCC). Our work provides one promising option for selecting an alternative dielectric material in terms of permittivity-temperature stability, which advances the development of the X9R MLCC.