Magnetic and Electrical Properties of Al3+ Implanted Co–ZnO

Co-doped ZnO ceramic samples sintered at four different temperatures were prepared by solid-state reaction method and implanted by Al ions subsequently. The microstructural, defect, magnetic and electrical properties of the samples were systematically investigated by x-ray diffraction, micro-Raman spectroscope, vibrating sample magnetometer and Hall measurement, respectively. The results show that all the samples exhibit room-temperature ferromagnetism with a saturation magnetization of 0.02–0.03 emu g−1, the value of which is affected by the sintering temperature. The origin of room-temperature ferromagnetism is considered as the formation of Co2+– VO–Co2+ bound magnetic polarons. Even though the implantation of Al3+ slightly reduces the saturation magnetization because of the lattice damage, less VO and larger lattice spacing, however, an appropriate amount of Al3+ implantation and a proper sintering temperature can remarkably improve the electrical properties with the mobility of 200 ∼300 cm2 Vs−1 and the resistivity of 20 ∼40 Ω cm. In general, samples sintered at 1200∘C present more excellent comprehensive performances.