Dielectric relaxations of LaAlO3 ceramics over broad temperature range

LaAlO3 ceramics were prepared via the solid-state reaction route. The low-frequency dielectric properties were investigated in detail in a broad temperature range from 100 to 1100 K. We found that LaAlO3 shows a flat dielectric plateau independent of frequency and temperature below 500 K. When temperature higher than 500 K, two thermally activated dielectric relaxations were observed with the activation energy of 1.13 eV for the low-temperature relaxation and 1.9 eV for the high-temperature relaxation. Our result indicates that the low-temperature relaxation is related to the bulk effect due to hopping motions of oxygen vacancies and the high-temperature relaxation was associated with the Maxwell–Wagner relaxation due to the interface effect.

Graphical abstractWe analysis the dielectric properties for LaAlO3 at various frequencies over broad temperature range. The result indicates that LaAlO3 shows a flat dielectric plateau independent of frequency and temperature below 500 K. Two thermally activated dielectric relaxations were observed when temperature higher than 500 K. The low-temperature relaxation is related to the bulk effect due to hopping motions of oxygen vacancies and the high-temperature relaxation was associated with the Maxwell–Wagner relaxation due to the interface effect.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► LaAlO3 shows a flat dielectric plateau independent of temperature below 500 K. ► LaAlO3 shows a flat dielectric plateau independent of temperature below 500 K. ► The low relaxation is related to the bulk effect due to oxygen vacancies. ► The high relaxation is ascribed to be the Maxwell–Wagner relaxation.