Low-temperature sintering of Li2O-doped BaTiO3 lead-free piezoelectric ceramics

Abstract

Low-temperature sintering of BaTiO 3 ceramics using Li 2 O as sintering aids was investigated with a special influences of Li 2 O content (0-4 mol%) and sintering temperature (1000-1100°C) on crystalline structure and electrical properties. The sinterability of BaTiO 3 ceramics significantly improved by adding Li 2 O, whose densification sintering temperature reduced from 1300°C to 1000°C. XRD pattern indicated that BaTiO 3 -xLi 2 O samples were single phase with a tetragonal symmetry as x00-0.3 mol%, while the samples became an orthorhombic symmetry as x 0 0.5-4 mol%. The densification sintering temperature in which samples showed relative density higher than 90 % decreased with increasing Li 2 O content. A maximum d 33 value (200 pC/N) was obtained for the BaTiO 3 -0.5 mol%Li 2 O sample sintered at 1050°C, which is attributed to a vicinity of the phase transition and the high density. Adding Li 2 O not only reduced the sintering temperature but also obtained the acceptable piezoelectric properties, which will make BaTiO 3 become a kind of promising and practical lead-free piezoelectric ceramics.

Low sintering temperature and high piezoelectric properties of Li-doped (Ba,Ca)(Ti,Zr)O3 lead-free ceramics

“…It may be attributed to the liquid phase sintering mechanism. Li 2 CO 3 has a low melting point of 723°C [24], which can form a liquid phase to lower the sintering temperature, accelerate the grain growth and improve the density. Fig.…”

Phase Transition and Large Electrostrain in Lead‐Free Li‐Doped (Ba, Ca)(Ti, Zr)O3 Ceramics

“…Furthermore, dopants with lower valence (Zn 2+ , Cu 2+ ) can tune the phase boundaries of BCTZ‐based ceramics and contribute to the occurrence of phase transition around room temperature. The Li + ‐containing additives have the similar effect . For example, Ma et al observed that Li 2 O‐doped BT ceramics become densification at low sintering temperature (1050°C vs 1250°C, BT) and keep good piezoelectric properties ( d 33 = 200 pC/CN) by shifting the orthorhombic (O)–tetragonal (T) phase transition to room temperature.…”

“…The Li + ‐containing additives have the similar effect . For example, Ma et al observed that Li 2 O‐doped BT ceramics become densification at low sintering temperature (1050°C vs 1250°C, BT) and keep good piezoelectric properties ( d 33 = 200 pC/CN) by shifting the orthorhombic (O)–tetragonal (T) phase transition to room temperature. Yang et al also reported that LiF‐doped BT ceramics sintered at 1100°C have a high d 33 (270 pC/N), caused by O–T phase coexistence at room temperature.…”

Large electrostrain in low‐temperature sintered NBT‐BT‐0.025FN incipient piezoceramics

“…On the other hand, adding sintering aids is well‐known to be a valid approach to reduce the sintering temperature for piezoceramics . For instance, Li 2 CO 3 was considered as excellent sintering aids to lower firing temperature of the samples without significantly affecting the crystal structure, which destroyed the long‐range order of the lattices and increased the relaxor phases in the ceramics . The effects of Li 2 CO 3 on the sintering temperature and piezoelectric properties for BT were thoroughly investigated by Ma et al and the sintering temperature decreased from 1300°C to 1050°C .…”

“…27,28 The effects of Li 2 CO 3 on the sintering temperature and piezoelectric properties for BT were thoroughly investigated by Ma et al and the sintering temperature decreased from 1300°C to 1050°C. 28 It was also reported that the sintering temperature of NBT-ST ceramics can decrease from 1230°C to 1075°C by using Li 2 CO 3 . Furthermore, another effective oxide, CuO, 29 was reported by Wook et al to form a liquid phase around grain boundary, allowing to sinter NBT-BT-KNN piezoceramics in a lower sintering temperature of 940°C.…”