The structural, dielectric, and magnetic properties of Al3+ doped Sm3Fe5O12 ceramics

The polycrystalline ceramics of Sm3Fe5-xAlxO12 (x=0, 0.5, 1, and 2) are prepared by the sol-gel method. The structure, dielectric, and magnetic properties are studied. The X-ray diffraction patterns indicate that the prepared samples crystallize in garnet phase. All of the samples exhibit relatively high-dielectric permittivity in the low-frequency range. With the increase of Al3+ content, the dielectric permittivity and the temperature and frequency stabilities at low frequency simultaneously decrease, which suggest the important role of Fe3+ for the dielectric property. Two sets of dielectric relaxation are observed in the available temperature from 300 to 700K. With the increase of Al3+ concentration, the high-frequency relaxation peaks that originate from the carriers hopping between Fe2+ and Fe3+ shift toward the direction of low frequency, and the low-frequency relaxation processes that arise from the doubly ionized oxygen vacancies spread to high frequency. By measuring the hysteresis loops and the magnetization-temperature curves, it indicates that the magnetization is decreased and the magnetic property transforms from ferrimagnetism to paramagnetism with increasing the value of x at room temperature. [GRAPHICS] . Large permittivity and ferrimagnetic property are observed in Sm3Fe5O12 and they are decreased via Al3+ doping, reflecting the crucial role of Fe3+ for the high performance. HighlightsSm(3)Fe(5-x)Al(x)O(12) (x=0, 0.5, 1, and 2) are fabricated via sol-gel method.The dielectric relaxation processes are influenced by the content of iron ions.Two magnetic anomalies are detected at low temperature.