Microstructure and piezoelectric properties of (Na0.5K0.5)NbO3 lead-free piezoelectric ceramics with V2O5 addition

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 2009-11, Vol.56 (11), p.2337-2342
• Main Authors: Seo, I.-T., Park, H.-Y., Dung, N.V., Choi, M.-K., Nahm, S., Lee, H.-G., Choi, B.-H.
• Format: Article
• Language: English
• Subjects: Business; Ceramics; Ceramics - chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Environmentally friendly manufacturing techniques; Equipment Design; Equipment Failure Analysis; Exact sciences and technology; Materials processing; Materials science and technology; Materials Testing; Micro-Electrical-Mechanical Systems - instrumentation; Microstructure; Physics; Piezoelectricity and electromechanical effects; Power engineering and energy; Research and development; Scanning electron microscopy; Transducers; Vanadium Compounds - chemistry; Vibration; X-ray diffraction
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2009.1321

Various amounts of Nb 2 O 5 in the (Na 0.5 K 0.5 ) NbO 3 (NKN) ceramic were replaced by V 2 O 5 to decrease its sintering temperature to below 950°C. A small V 2 O 5 content resulted in a dense microstructure with an increased grain size for the specimen sintered at 900°C due to the presence of a liquid phase. When V 2 O 5 was added to the NKN ceramics, their orthorhombic-to-tetragonal transition temperature increased from 178°C to around 200°C. However, their Curie temperature decreased from 402°C to around 330°C. The k p , ε3 T / ε0 , and Q m values increased with V 2 O 5 addition, probably due to the increased density and poling state, which was identified by the phase angle. The specimen with x = 0.05, sintered at 900°C for 8 h, exhibited the following piezoelectric properties: k p = 0.32, ε3 T / ε0 = 245, d 33 = 120 (pC/N), and Q m = 232.