The particle size effect of Yb_0.8R_0.2MnO₃ (R is Sm, Nd, and Eu) on some physical properties

YbMnO₃ as a rare earth manganite class of perovskite materials displayed a wide range of applications and interests for scientists. This hexagonal perovskite showed a simultaneous ferromagnetism, ferroelectricity, and ferroelasticity properties, which is considered multiferroic materials. This unique magnetic property may lead to use them in spintronic and magnetic storage media. YbMnO₃ and Yb_0.8R_0.2MnO₃ are prepared with different particle sizes to study the effect of its difference in particle size on the electrical properties and Raman scattering. All samples are prepared using co-precipitation method from the initial pure chlorides of ytterbium, samarium, europium, and manganese to be reacted with pure sodium hydroxide taking into consideration the suitable molar ratio. The EDS spectra confirmed the existence of each element in the proposed compounds according to the suggested structure. The hexagonal crystal system of space group P6₃cm (185) is found for all samples. From the experimental Raman measurements, the observed lines in spectra of Yb_0.8Nd_0.2MnO₃ are found at 102, 131, 212, 460, 631, and 685 cm⁻¹, and lines in spectra of Yb_0.8Sm_0.2MnO₃ are found at 101, 137, 217, 462, 630, and 687 cm⁻¹, which correspond to E₂, A₁, E₂, A₁, E₁, and A₁, respectively. The obtained materials showed semiconducting behavior with different activation energy gap (E_a of the undoped ytterbium manganite, E_a = 0.255 eV, increased because of doping to be 414 and 447 eV for Nd- and Sm-doped samples, respectively). The complex impedance measurements are strongly related to the microstructure of polycrystalline materials and depend on the grain size. Our electrical properties enhance the hopping mechanism of charge carrier’s transfer in the under investigation samples. The significant difference in activation energy between pure and doped ytterbium manganites were found because of the remarkable difference in the crystalline size. The crystalline size observed for pure ytterbium manganite is 67 nm to be increased with doping.