Preparation And Related Properties Of La-Doped Bismuth Ferrite And Bi_0.9La_0.1FeO₃ Matrix Composites

With the rapid development of modern technology,great changes have taken place in people’s lives,but it is accompanied by the depletion of non renewable energy on earth and the increasingly serious electromagnetic interference in our daily life.Therefore,it is an urgent problem for scientists to develop new green energy storage devices and effective electromagnetic wave absorbing materials.Bismuth ferrite is a multiferroic material with excellent magnetic and electrical properties.It has been proved to have important performance contributions in many areas,such as microwave absorption,photocatalysis,gas sensing and energy storage.In this paper,Bi_1-xLa_xFeO₃ particles with different La contents（0.1≤x≤0.4）are synthesized and 3D flower-like Bi_0.9La_0.1FeO₃ microspheres are prepared taking blocky Bi_0.9La_0.1FeO₃ as precursors.Furthermore,we prepares Bi_0.9La_0.1FeO₃/PANI composites and porous Bi_0.9La_0.1FeO₃/rGO composites.The electromagnetic（EM）wave absorption properties and electrochemical performances of all the samples have been investigated and the main research results of this paper are as following:（1）Bi_1-xLa_xFeO₃ particles with different La contents（0.1≤x≤0.4）are synthesized by a molten salt method.It can be seen that the optimal EM wave absorption performance is obtained when the value of x is 0.1,in which the maximal value of reflection loss is-24.74 dB at 15.92 GHz and the matching thickness is 2.4 mm.Meanwhile,the Bi_0.7La_0.3FeO₃ particles exhibit excellent electrochemical property and the maximum specific capacitance is 194.63 F g^-1with the scan rate of 2 mV s^-1.When the Bi_0.7La_0.3FeO₃ electrode exhibits a good capacitance retention of 82.82%after 2000 cycles.（2）Three-dimensional flower-like Bi_0.9La_0.1FeO₃ microspheres with different etching times are prepared by a one-step etching method taking blocky Bi_0.9La_0.1FeO₃ as precursors.When the ecthing time is 60 min,sample p BLFO-60 has the largest specific surface area,75.09 m² g^-1,which corresponds to the optimal EM wave absorption and electrochemical performances.The maximal RL value is-57.9 dB at 6.9 GHz when the sample thickness is 2.9 mm,meanwhile,the effective bandwidth is 2.7 GHz.The maximum specific capacitance is 561.48 F g^-1 with the scan rate of 2 mV s^-1 and the capacitance retention after 1500 cycles is 86.67%.（3）Bi_0.9La_0.1FeO₃/PANI composites with different mass ratios are synthesized by in-situ polymerization.Bi_0.9La_0.1FeO₃/PANI composite with the mass ratio of 1:1 exhibits the best EM wave absorption and electrochemical properties.The maximal RL value can reach-47.7 dB at 15.08 GHz when the thickness is 2.59 mm and the effective bandwidth is 5.12 GHz.The optimal specific capacitance can reach 455 F g^-1 with a scan rate of 2 mV s^-1 and the capacitance retention after 1500 cycles is 85.8%.Compared to pure PANI,Bi_0.9La_0.1FeO₃/PANI electrode has a higher specific capacitance of 536.9 F/g.（4）Porous Bi_0.9La_0.1FeO₃/rGO composites with different rGO contents are prepared via a one-step etching method.The results show that the optimal EM wave absorption and electrochemical performances are obtained when the rGO contents are 30 and 45 mg.S-30 exhibits the maximal reflection loss value of-69.97 dB at 15.04 GHz with a thickness of only 1.91 mm and the effective bandwidth is 5.2 GHz.Similarly,S-45 shows an excellent EM wave absorption performance,in which the maximal RL is-58.19 d B with a thinner thickness of1.58 mm.The largest specific capacitance is 644.51 F g^-1 with S-45 electrode when the scan rate is 2 mV s^-1.Meanwhile,S-30 electrodes show a good specific capacitance of 85.94%with 1500 cycles.