Fabrication and Electrical Properties of Textured Sr_0.53Ba_0.47Nb₂O₆ Ceramics by Templated Grain Growth

Abstract

Textured Sr 0.53 Ba 0.47 Nb 2 O 6 ceramics with a relative density of >95% were fabricated using templated grain growth (TGG). Acicular KSr 2 Nb 5 O 15 template particles synthesized via a molten salt process were aligned by tape casting in a mixture of solid-state-synthesized SrNb 2 O 6 and BaNb 2 O 6 powders. The resulting ceramics possessed strong fiber texture along the polar axis ([001]) of the strontium barium niobate. Samples with 15.4 wt% templates attained a textured fraction of 0.82 after sintering at a temperature of 1450°C for 4 h. These materials showed peak dielectric constants of 7550 at 1 kHz, remanent polarizations of 13.2 C/cm 2 , saturation polarizations of 21 C/cm 2 (60%-85% of the single-crystal value), piezoelectric strain coefficients of 78 pC/N (70%-85% of the single-crystal value), and room-temperature pyroelectric coefficients of 2.9 ؋ 10 ؊2 C⅐(cm 2 ⅐°C) ؊1 (52% of the single-crystal value). These results show that TGG is a viable option for accessing single-crystal properties in polycrystalline ceramics.

Piezoelectric properties of lead-free (Na0.5Bi0.5)TiO3–(Na0.5K0.5)NbO3–BaTiO3 ceramics

“…As is well known, lead zirconate titanate [Pb(Zr, Ti)O 3 ; PZT] ceramics play a dominant role in existing piezoelectric applications because of their excellent piezoelectric properties. It is believed that the high piezoelectric response of this system is related to the morphotropic phase boundary (MPB) between the rhombohedral and tetragonal phases.…”

“…On the other hand, sodium bismuth titanate [(Na 0.5 Bi 0.5 )TiO 3 ; NBT] ceramics are perovskite-type ferroelectrics with good potential to replace PZT piezoelectric ceramics due to their strong ferroelectricity. NBT has a relatively large remanent polarization (P r ≈ 38 C/ cm 2 ) at room temperature and a relatively high Curie temperature (T C ‫ס‬ 320°C).…”

“…1,2 However, waste products containing Pb often cause a crucial environmental problem for underground water. Therefore, the development of lead-free piezoelectric materials, such as tungsten bronze type materials, [3][4][5] bismuth (Bi) layer-structured materials, 6,7 and perovskite type materials, [8][9][10][11][12][13][14][15][16][17][18][19][20] has been widely studied. Among the various lead-free materials, Bi layerstructured materials have stable temperature properties and high Q m values 6,7 and are thus regarded as one of the best lead-free piezoelectric materials.…”

“…Sintering behavior and microstructural evolution Figure 4 shows the change in the sintered density of the (0.98-x)NBT-xNKN-0.02BT ceramics as a function of the NKN content. When the NKN content was increased from 0 to 98 mol%, the bulk density gradually decreased from 5.89 to 4.33 g/cm 3 . Because the theoretical density of NBT (5.997 g/cm 3 ) is higher than that of NKN (4.51 g/cm 3 ), the decrease of the bulk density with increasing NKN content is understandable.…”

“…When the NKN content was increased from 0 to 98 mol%, the bulk density gradually decreased from 5.89 to 4.33 g/cm 3 . Because the theoretical density of NBT (5.997 g/cm 3 ) is higher than that of NKN (4.51 g/cm 3 ), the decrease of the bulk density with increasing NKN content is understandable. The relative densities were in the range of 94% to 98% of the theoretical densities.…”