Phase structure and electrical properties of strontium modified (Na_0.48–xK_0.48–xLi_0.04Sr_x)Nb_0.89Ta_0.05Sb_0.06O₃ ceramics

Abstract

(Na0.48–x K0.48–x Li0.04Srx)Nb0.89Ta0.05Sb0.06O3 (abbreviated as NKLSrx NST) lead‐free ceramics are fabricated by conventional solid state reaction. The material with perovskite structure contains both tetragonal and orthorhombic phases at room temperature when x ≤ 0.02, and it changes into cubic phase gradually as x increases. A second phase KSr2Nb5O15 begins to appear at x = 0.03 and becomes obvious with increasing Sr content. Dielectric studies show that the Sr2+ modification lowers the Curie temperature and induces the diffuseness of cubic–tetragonal phase transition. The addition of Sr2+ improves the density and piezoelectric properties of NKLNST. The ceramic modified with 0.008 mol SrO shows the optimum piezoelectric properties (d33 = 278 pC/N, kp = 0.504, tan δ = 0.025). Degradation of kp is found after the first thermal cycling due to the tetragonal–orthorhombic phase transition near room temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Enhancement of the photoluminescence modulation ratio in highly transparent KNN-based ceramics for optical information storage

“…The environmentally friendly lead-free K 0.5 Na 0.5 NbO 3 (KNN) is a classical ferroelectric material with good piezoelectric, dielectric, and ferroelectric properties and high Curie temperature. 4–8 Generally, vacancy defects would appear in KNN during high-temperature ceramic sintering due to the easy volatilization of K and Na elements, making KNN naturally a photochromic material. 9–12…”

Electric Properties of SrTiO3Modified (Na0.48K0.48Li0.04)Nb0.89Ta0.05Sb0.06O3Lead-Free Ceramics

“…13 However, the (Li, Ta, and Sb) modified NKN compositions have the critical problem: a high loss tangent of 4% at room temperature. [14][15][16] Nevertheless, many researchers have reported that SrTiO 3 (ST) dopants can improve the piezoelectric properties and reduce the loss tangent for NKN ceramics. 17,18 Accordingly, we predict that ST dopants can also reduce the loss tangent for (Na 0.48 K 0.48 Li 0.04 )Nb 0.89 Ta 0.05 Sb 0.06 O 3 ceramics.…”