Structurally tuned multifunctional characteristics of Nd-substituted lanthanum zirconates

Phase stable Nd-substituted lanthanum zirconates of the form La_2−xNd_xZr₂O₇ (x = 0.0, 0.2, 0.4, 0.6 and 2.0) with tunable structural parameters, were synthesized using a cost effective, wet chemical based sol–gel auto-combustion route. Rietveld’s refined X-ray diffraction patterns confirmed the formation of phase pure cubic pyrochlore structure with space group Fd3m. Data obtained from the refinement revealed that Nd-substitution at La-site reduced the lattice parameters from 10.782 to 10.637 Å and thus caused the shrinkage of the unit cell volume from 1253.452 to 1203.820 Å³. Field emission scanning electron microscopy operated in back scattered electron mode at 5.0 kV confirmed that Nd-substitution promoted the grain growth (77–430 nm) and densification of the prepared ceramics. Ferroelectric analysis showed that pure as well as Nd-substituted samples exhibited leaky ferroelectric loops at room temperature however, maximum value of polarization increased with substitution. Smaller values of coercivity and remanence obtained in the magnetic investigation suggested the superparamagnetic nature of the prepared samples. A profound effect of magnetic field on dielectric properties was also observed from the magnetodielectric study. The probable origin of magnetodielectric effect is discussed on the basis of dielectric study in the presence of magnetic field.