Improving piezoelectric properties and temperature stability for KNN‐based ceramics sintered in a reducing atmosphere

Abstract

Lead‐free 0.955K0.5Na0.5Nb1‐zTazO3‐0.045Bi0.5Na0.5ZrO3+0.4%MnO ceramics (abbreviated as KNNTaz‐0.045BNZ+0.4Mn) were prepared by a conventional solid‐state sintering method in a reducing atmosphere (oxygen partial pressure of 1 × 10−10 atm). All ceramics with a pure perovskite structure show the two‐phase coexistence zone composed of rhombohedral and tetragonal phase. Ta5+ ions substitute for Nb5+ ions on the B‐site, which results in a decrease in the R phase fraction in the two‐phase coexistence zone. The R‐T phase transition temperature moves to room temperature due to the substitution of Nb5+ ions by Ta5+ ions. A complex domain structure composed of small nano‐domains (~70 nm) formed inside large submicron domains (~200 nm) exists in KNNTa0.02‐0.045BNZ+0.4Mn ceramics, which can induce a strong dielectric‐diffused behavior and improve the piezoelectric properties. The temperature stability for the reverse piezoelectric constant d33∗ for the KNNTaz‐0.045BNZ+0.4Mn ceramics can be improved at z = 0.02. Excellent piezoelectric properties (d33 = 328 pC/N, and d33∗ = 475 pm/V at Emax = 20 kV/cm) were obtained for the KNNTa0.02‐0.045BNZ+0.4Mn ceramics.

Hybrid Atmosphere Processing of Lead-Free Piezoelectric Sodium Potassium Niobate-Based Ceramics

“…Reducing atmospheres have been investigated in recent years for sintering of KNN-based ceramics [18][19][20][21][22][23]. The reducing atmosphere enables co-firing with inexpensive base metal electrodes [23], and is also shown in some studies to improve densification without lowering dielectric and piezoelectric response [22].…”

Effect of acceptor–donor co‐doping on the microstructure and electrical properties of BiScO3–PbTiO3‐based ceramics

“…Furthermore, a high piezoelectric coefficient originating from the nanodomains was confirmed in the (K,Na)NbO 3 (KNN) ceramics. 37 Hence, similar to the KNN ceramics, the excellent electric properties of the BSPT-LW0.01 ceramics can be attributed to their small domains and increased domain wall density.…”

Elevating electrical properties of (K, Na)NbO3ceramics via cold sintering process and post‐annealing

“…29,30 The physics of resin under pressure is similar to the seepage pr lar approaches have been used also to mod into a mold containing fiber mats. 23,[31][32][33][34][35][36][37][38] T in these cases to determine the resin flow ing times corresponding to different infilt Preceramic polycarbosilane polymers as precursors to make ceramic fibers 10,3 trix. [7][8][9]40,41 The chemical and volume ch pany ceramization of the polymer during documented in several studies.…”

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Owing to excellent electrical properties and high Curie temperature, environmentally friendly lead-free (K, Na) NbO 3 (denoted as KNN hereafter) ceramics were considered as the most expected substitution for lead zirconate titanate (PZT). [1][2][3][4][5] However, it is difficult to fabricate highly dense KNN ceramics with high electrical properties via conventional sintering (CS) due to the volatilization of K 2 O and Na 2 O at high temperature, 6,7 unless the partial pressure of oxygen is used as a dependent variable. Meanwhile, the sintering temperature cannot be reduced to coordinate energy conservation and sustainable development in this way.

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