Sol–gel derived (Li, Ta, Sb) modified sodium potassium niobate ceramics: Processing and piezoelectric properties

• Published in: Journal of alloys and compounds Vol. 509; no. 3; pp. 936 - 941
• Main Authors: Wang, Hongqiang, Zuo, Ruzhong, Fu, Jian, Liu, Yi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 21.01.2011; Elsevier
• Subjects: Ceramics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Cross-disciplinary physics: materials science; rheology; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Ferroelectrics; Growth from solid phases (including multiphase diffusion and recrystallization); Materials science; Materials synthesis; materials processing; Methods of crystal growth; physics of crystal growth; Nanostructure; Perovskite structure; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Piezoelectricity; Piezoelectricity and electromechanical effects; Potassium niobates; Sodium; Sol gel process; Sol–gel; Tantalum oxides; Piezoelectricity; Ceramics; Ferroelectrics; Sol–gel; Particle size; Material processing; Sodium niobates; Piezoelectric properties; XRD; Fourier-transformed infrared spectrometry; Sol-gel process; Differential scanning calorimetry; Alkoxides; Densification; Grain growth; Phase transformations; Thermal decomposition; Citrates; Sol-gel; Crystallization; Transmission electron microscopy; Ferroelectric materials; Sintering; Morphology; X ray diffractometry; Microstructure; Xerogel; Chelates
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.09.134

▶ A novel soft-chemical processing to prepare nano-scaled NKN based powders with complex compositions. ▶ Sol–gel derived NKN based lead-free piezoelectric ceramics with excellent piezoelectric properties as indicated in Table 1. Nano-scaled lead-free perovskite powders (50–100 nm) with a composition of (Na 0.52K 0.4425)(Nb 0.8825Sb 0.08)O 3-0.0375LiTaO 3 (NKNS-3.75LT) have been synthesized via a modified low-cost citrate sol–gel route, in which Nb 2O 5 and Ta 2O 5 were transformed into stable and soluble chelate complexes to replace costly metal alkoxides. The thermal decomposition process and structural transformation behavior of the as-prepared xerogel was investigated by means of thermo-gravitometry and differential scanning calorimetry, X-ray diffractometry and Fourier-transform infrared spectrometry. The results indicated that the ideal crystallization of the NKNS-3.75LT powder with a single perovskite structure occurs at 500–600 °C, significantly lower than that for a conventional mixed-oxide route. Transmission electron microscopy observation showed that the crystalline powder has particle sizes in the range of 30–100 nm and exhibits polyhedron-like morphology, probably resulting in a specific grain growth behavior upon densification. The sol–gel derived NKNS-3.75LT ceramics sintered at 1090 °C exhibit excellent piezoelectric properties of d 33 ∼418 pC/N and k p ∼0.54 for NKN based random ceramics.