摘要
Different magnetodielectric effects were observed in Bi1-xGdxFeOa ceramics depending on gadolinium content. A positive one was observed in the samples with x ≤ 0.10 at 295 K and 16 K, and a negative one in the sample with x = 0.4 at 16 K. Structure analysis by x-ray diffraction （XRD） reveals that the samples crystallize in the R3c structure （ferroelectrics） for x 〈 0.08 and in the Pbnm structure （paraelectrics） for x ≥ 0.3 at room temperature. Temperaturedependent dielectric response and x-ray diffraction confirm the occurrence of a structural transition in the Pbnm phase at low temperature for the samples with x ≤0.4. While the positive magnetodielectric effects can be attributed to a coupling of magnetic and crystallographic structures of the R3c phase, the observed negative magnetodielectric effect in the Pbnm phase can be associated with a low-temperature modification of the Pbnm structure. The observed dualsigned magnetodielectric effects suggest that the Bi1-xGdxFeO3 oxides are a good prototype for understanding the magnetodielectric coupling mechanism in this kind of materials.
Different magnetodielectric effects were observed in Bi1-xGdxFeOa ceramics depending on gadolinium content. A positive one was observed in the samples with x ≤ 0.10 at 295 K and 16 K, and a negative one in the sample with x = 0.4 at 16 K. Structure analysis by x-ray diffraction （XRD） reveals that the samples crystallize in the R3c structure （ferroelectrics） for x 〈 0.08 and in the Pbnm structure （paraelectrics） for x ≥ 0.3 at room temperature. Temperaturedependent dielectric response and x-ray diffraction confirm the occurrence of a structural transition in the Pbnm phase at low temperature for the samples with x ≤0.4. While the positive magnetodielectric effects can be attributed to a coupling of magnetic and crystallographic structures of the R3c phase, the observed negative magnetodielectric effect in the Pbnm phase can be associated with a low-temperature modification of the Pbnm structure. The observed dualsigned magnetodielectric effects suggest that the Bi1-xGdxFeO3 oxides are a good prototype for understanding the magnetodielectric coupling mechanism in this kind of materials.
基金
Project supported by the National Basic Research Program of China (Grant No. 2007CB925003)
the National Natural Science Foundation of China (Grant No. 50872148)
