Analysis of the crystal structure and electrical properties of Li-doped (K, Na)NbO3 prepared by solid state reaction

• Main Authors: Agustinawati, Dian, Isnaini, Nur Lailiyah, Suasmoro, S.
• Format: Conference Proceeding
• Language: English
• Subjects: Crystal structure; Curie temperature; Dissipation factor; Electrical properties; Electrical resistivity; Niobates; Niobium oxides; Pellets; Perovskites; Phase transitions; Potassium carbonate; Q factors; Rietveld method; Roasting; Sintering (powder metallurgy); Sodium carbonate; Solid state; Temperature
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/1.4968382

(K0.5Na0.5)NbO3 (KNN) and (K0.5Na0.4Li0.1)NbO3 (KNLN) ceramic were successfully prepared by solid state reaction method. Single phase KNN was obtained from calcined of mixed powders K2CO3, Na2CO3 and Nb2O5 at 700°C/2h and sintered of KNN pellets at 1125°C/4h. Similar with KNN, single phase KNLN was obtained from calcined of mixed powders K2CO3, Na2CO3, Li2CO3 and Nb2O5 at 750°C/2h and sintered of KNLN pellets at 1100°C/2h. The result of XRD pattern of KNN before and after Li-doped were investigated. By using Rietveld refinement method, it was known that the Li-doped makes KNN crystal structure changes from perovskite orthorhombic (a=3.957898Å, b=5.641918Å, c=5.682394Å) to perovskite tetragonal (a=b=3.942611Å, c=4.011262Å). Electrical properties of these material were investigated using impedance analyzer. KNN exhibited two Curie temperature due to its phase transition: orthorhombic-tetragonal at temperature 220°C and tetragonal-cubic at temperature 440°C. However, KNLN only has one Curie temperature due to phase transition from tetragonal to cubic at temperature 510°C. Besides, Li-doped increases the number of KNN dissipation factor, dielectric constant and quality factor value. At 380°C, the KNN show better conductivity than KNLN. Below 130°C, KNLN activation energy was smaller than KNN.