*Article* **Enhanced Ferroelectric, Dielectric Properties of Fe-Doped PMN-PT Thin Films**

**Chao Feng, Tong Liu, Xinyu Bu and Shifeng Huang \***

Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022, China; mse\_fengc@ujn.edu.cn (C.F.); shandongmems@163.com (T.L.); buxinyu98@163.com (X.B.) **\*** Correspondence: mse\_huangsf@ujn.edu.cn

**Abstract:** Fe-doped 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) thin films were grown in Pt/Ti/SiO2/Si substrate by a chemical solution deposition method. Effects of the annealing temperature and doping concentration on the crystallinity, microstructure, ferroelectric and dielectric properties of thin film were investigated. High (111) preferred orientation and density columnar structure were achieved in the 2% Fe-doped PMN-PT thin film annealed at 650 ◦C. The preferred orientation was transferred to a random orientation as the doping concentration increased. A 2% Fe-doped PMN-PT thin film showed the effectively reduced leakage current density, which was due to the fact that the oxygen vacancies were effectively restricted and a transition of Ti4+ to Ti3+ was prevented. The optimal ferroelectric properties of 2% Fe-doped PMN-PT thin film annealed at 650 ◦C were identified with slim polarization-applied field loops, high saturation polarization (*P*<sup>s</sup> = 78.8 μC/cm2), remanent polarization (*P*<sup>r</sup> = 23.1 μC/cm2) and low coercive voltage (*E*<sup>c</sup> = 100 kV/cm). Moreover, the 2% Fe-doped PMN-PT thin film annealed at 650 ◦C showed an excellent dielectric performance with a high dielectric constant (*ε*<sup>r</sup> ~1300 at 1 kHz).

**Keywords:** PMN-PT thin films; preferred orientation; ferroelectric property; dielectric property
