Room temperature ferromagnetism in combustion synthesized nanocrystalline Co, Al co-doped ZnO

Effect of shallow donors on Curie–Weiss temperature of Co-doped ZnO

“…A given cation in wurtzite ZnO has 12 equivalent nearest cation neighbors. The fraction of Co 2 þ at Zn 2 þ site having no other Co 2 þ neighbors in Zn 1 À x Co x O can be expressed as f¼ (1 À x) 12 if Co 2 þ is supposed to be statistically distributed over the Co-doped ZnO lattice. The statistical probability f decreases with increasing x.…”

“…We guessed that a positive Θ may be related to the presence of more intrinsic shallow donors in Zn 0.97 Co 0.03 O prepared under low temperature. According to only the presence and absence of hysteresis and remanence in magnetization curves, some authors claimed that Al-doping induced ferromagnetic ordering and did not induce ferromagnetic ordering in ZnO:Co, respectively [12][13][14]. But Al as shallow donor has been confirmed consistently.…”

Heterogeneous phase formation in diluted magnetic semiconducting Zn1−x−yCoxAlyO (CAZO) nanoparticles

“…14 The M-H curve exhibits ferromagnetic nature with high remnant magnetization with a small coercive eld and highly magnetized narrow hysteresis loop. 14 The ferromagnetic hysteresis increases with increase of Co concentration in the CAZO. For the 2 at% of Co, the ferromagnetism was very small; it seems almost like paramagnetic as shown in Fig.…”

“…For semiconductors, doping and incorporation of metal elements is a powerful tool to tailor the electrical and optical properties for the construction of many optoelectronic devices. More interestingly, in previous theoretical studies and experimental results have showed that ZnO doped with appropriate transition metals were considered as diluted magnetic semiconductors [11][12][13][14][15] which attracted a lot of interest due to their ferromagnetism at room temperature. Thus, zinc oxides of different morphologies with different dopant combinations are signicant and their applications are growing up.…”

“…[16][17][18][19][20][21][22][23] Among the methods, combustion synthesis has many potential advantages such as low processing cost, energy efficiency, relative simplicity, high production rate, etc. 21,24,25 In our previous study, 14 a combustion synthesis process was developed for the synthesis of Zn 1ÀxÀy Co x Al y O (CAZO) nanoparticles, where only the single phase formation was detected based on fast-scan XRD. Within present paper, we report in-depth analyses of the crystalline phase formation by slow-scan XRD, SAXS/WAXS and SAED prole tting.…”