Composition and temperature dependence of structure and piezoelectricity in (1−x)(K1−yNay)NbO3‐x(Bi1/2Na1/2)ZrO3 lead‐free ceramics. Issue 2 (11th October 2016)

• Record Type: Journal Article
• Authors: Wang, Dawei; Hussain, Fayaz; Khesro, Amir; Feteira, Antonio; Tian, Ye; Zhao, Quanliang; Reaney, Ian M.
• Is Part Of: Journal of the American Ceramic Society. Volume 100:Issue 2(2017)
• Page Start: 627
• Page End: 637
• Publication Date: 2016-10-11
• Subjects: lead‐free ceramics -- piezoelectric materials/properties -- potassium‐sodium niobate/KNN; Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.14589
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract: Lead‐free piezoceramics with the composition (1−x)(K1− y Nay )NbO3 ‐x(Bi1/2 Na1/2 )ZrO3 (KNyN‐xBNZ) were prepared using a conventional solid‐state route. X‐ray diffraction, Raman spectroscopy, and dielectric measurements as a function of temperature indicated the coexistence of rhombohedral (R) and tetragonal (T) phase, typical of a morphotropic phase boundary (MPB) as the BNZ concentration increased and by adjusting the K/Na ratio. High remnant polarization ( P r =24 μC/cm 2 ), piezoelectric coefficient ( d 33 =320 pC/N), effective piezocoefficient ({d_{33}^*}=420 pm/V), coupling coefficient ( k p =48%), and high strain ( S =0.168%) were obtained at room temperature, but significant deterioration of P r, {d_{33}^*}, and k p were observed by increasing from room temperature to 160°C (17.5 μC/cm 2, 338 pm/V, and 32%, respectively) associated with a transition to a purely T phase. Despite these compositions showing promise for room‐temperature applications, the deterioration in properties as a function of increasing temperature poses challenges for device design and remains to be resolved.