The structure, magnetic and dielectric properties of Al doping in CaBaCo4O7.

A series of the polar magnets CaBaCo 4- x Al x O 7 (x = 0, 0.15, 0.3, 0.4, 0.5) were synthesized by the Al element doping strategy. Their structure, magnetism, dielectric and magnetodielectric properties were characterized and analyzed. XRD patterns show that the prepared polycrystalline samples (x ≤ 0.5) feature good crystallinity and a small amount of secondary phase can be detected. The magnetic transition temperature (T C) decreases from 60 K to 30 K when the x value increases from 0 to 1.0, due to the diluted effect of Al3+ to the magnetic interaction. The Al3+ doping also results in an antiferromagnetic transition above T C Correspondingly, the dielectric peak around the magnetic transition moves to lower temperature gradually (x ≥ 0.15). Al3+ doping could well suppress the short-range magnetic order. It causes a new dielectric peak near 70 K, suggesting that the magnetism has a great influence on the dielectric property. With increasing doping concentration, the dielectric peak around the magnetic transition temperature merges with the new dielectric peak near 70 K. Finally, only a broad peak was observed. [ABSTRACT FROM AUTHOR]