In this work, La0.1Ag0.9NbO3−δ lead-free ceramic was synthesized by the conventional solid-state method. Rietveld refinement of XRD data revealed that the La0.1Ag0.9NbO3−δ ceramic crystallized in orthorhombic (Pbcm) structure with small impurities of metallic Ag and confirmed by TEM and XPS techniques. HR-TEM image and SAED pattern confirmed the polycrystalline nature of La0.1Ag0.9NbO3−δ ceramic. FTIR spectrum of this ceramic revealed the formation of NbO6 octahedral structure. Raman spectroscopy of this ceramic revealed the suppression of the ferroelectric distortion compared with pure of AgNbO3. The chemical elements, oxygen vacancies (δ), and electronic states of this ceramic were identified by XPS. The La0.1Ag0.9NbO3−δ ceramic displayed the direct and indirect band gap energies of 3.75 and 1.95 eV, respectively. The dielectric constant (εr) of this ceramic showed four dielectric anomalies at 355, 505, 565 and 631 K which are accompanying the phase transitions (M1↔M2, M2↔M3, M3↔O, and O↔T) and confirmed by differential scanning calorimetry (DSC) technique. The P-E loops of this ceramic exhibited weak ferroelectric behavior. Significant improvement of recoverable energy density (Wrec =0.450 J/cm3), and energy storage efficiency (ɳ=29.05%) were achieved at 3 kV/cm for this ceramic.
Almohammedi et al. (Tue,) studied this question.