Structural and ferroelectric modifications in SrBi2Nb2O9 Aurivillius phase compounds by Nd3+ ion doping

Layered bismuth ferroelectrics such as SrBi₂Nb₂O₉ (SBN) are recognized for their potential in advanced ferroelectric technologies. This study involves enhancing the dielectric characteristics of SBN through Nd³⁺ doping, leading to the development of SrBi_2-xNd_xNb₂O₉. These compound were synthesized across a series of compositions (x = 0.025, 0.05, 0.075, 0.1, 0.125, 0.25, and 0.275) via the molten salt method. X-ray diffraction (XRD) confirmed that all the samples retained an orthorhombic lattice structure in the A2₁am space group. This demonstrated decreased in cell volume and orthorhombicity as Nd³⁺ concentration increased. Scanning electron microscopy (SEM) with particle size distribution histogram revealed a progressive reduction in grain size, forming smaller, plate-like structures with higher levels of Nd³⁺. The alteration in Nd³⁺ concentration significantly lowered the ferroelectric transition temperature (T_c) and dielectric constant, primarily due to the reduced effect of Bi³⁺ ions 6s² lone pairs on structural distortion. The compound with x = 0.275 demonstrated a diffuse ferroelectric transition, marked by an expanded T_c peak, illustrating the profound impact of Nd³⁺ doping on SBN dielectric and ferroelectric properties. This study investigates the effects of Nd³⁺ doping on the structural and dielectric properties of SBN, with implications for its potential use in ferroelectric applications such as FeRAM (Ferroelectric Random Access Memory).