Two step synthesis and enhanced microwave absorption properties of polycrystalline BaTiO3 coated Ni nanocomposites

The core-shell Ni@BaTiO3 nanocomposites were synthesized by a facile two-step approach. The synthetic parameters on the microstructure and morphology as well as microwave absorption properties of Ni@BaTiO3 nanocomposites were investigated. High resolution transmission electron microscopy studies reveal that as-prepared Ni@BaTiO3 nanocomposites consist of the Ni nanoparticles core and poly-crystalline BaTiO3 shell. The BaTiO3 coated Ni nanocomposites absorbent present significantly enhanced microwave absorption compared with the as-prepared pristine Ni nanoparticles. The optimal reflection loss (RL) of Ni@BaTiO3-parrafin composites are -42.3 dB at 10.6 GHz with an absorbent thickness of 1.88 mm and the absorption bandwidth of those below -10 dB is 6.75 GHz only with absorbent thicknesses of 1.7-2.5 mm. The RL values below -20 dB can be obtained in frequency range of 2.98 -12.21 GHz for Ni@BaTiO3-parrafin composites but 7.96-14.09 GHz for Ni-paraffin composites, corresponding to absorbent layer thickness of 1.7-5.5 mm. Moreover the RL values of Ni@BaTiO3 nano-composites absorbent exceeding 10 dB are about 1.4-3 times of those of the Ni nanoparticles absorbent at absorbent thicknesses of 1.7-5.5 mm. Furthermore, the minimum RL of Ni@BaTiO3-parrafin composite shifts to the lower frequency, compared with that of Ni-parrafin composite. These results show that microwave absorption ability of the Ni@BaTiO3 nanocomposites is superior to Ni nanoparticles and the core-shell type Ni@BaTiO3 nanocomposites are great potential microwave absorbents for practical applications. (C) 2016 Elsevier B.V. All rights reserved.