Effects of Mn Additive on Dielectric and Piezoelectric Properties of (Na_0.5K_0.5)NbO₃–BaZrO₃–(Bi_0.5K_0.5)TiO₃Ternary System

Abstract

High-density perovskite titanate zirconate-modified potassium niobate solid solutions 0.92(Na0.5K0.5)NbO3–xBaZrO3–(0.08-x)(Bi0.5K0.5)TiO3 (BBK) and Mn-added BBK have been prepared by the solid-state reaction method. The phase diagram summarized from the dielectric measurement reveals that there exists a tetragonal–rhombohedral morphotropic phase boundary (MPB) for both solid solutions. The piezoelectric properties show enhanced behavior at around the tetragonal–rhombohedral MPB. Mn addition could increase Q m as well as k p and d 33. The behavior is attributed to oxygen vacancy formation and grain size growth, respectively.

Further Enhancing Piezoelectric Properties by Adding MnO2 in AgSbO3‐Modified (Li,K,Na)(Nb,Ta)O3 Lead‐Free Piezoceramics

“…4(a). 24,25,31,32 Both the softening and hardening effects of the MnO 2 occur simultaneously, which also are revealed in the other KNNbased ceramics by other literatures. The remnant polarization (P r ) and coercive field (E c ) dependence of MnO 2 contents are summarized in Fig.…”

“…All these compositions show typical well-saturated ferroelectric hysteresis P-E loops, as shown in Fig. 2,12,16,19,24,25 The enhancement of piezoelectric properties is also considered to benefit from the increase in grain size. In addition, more rectangular P-E loops were observed in the Mn-modified samples, especially for the sample with x = 0.5.…”

“…In addition, more rectangular P-E loops were observed in the Mn-modified samples, especially for the sample with x = 0.5. [22][23][24][25][30][31][32] Mn cation is considered to be incorporated into the B-site of the lattice in KNN single crystal, but cation deficiency in KNN-based ceramics is more complicated specially for the complex composition, the alkali evaporation, and the multivalence (Mn 2+ : 91 pm, Mn 3+ : 70 pm, and Mn 4+ : 54 pm) of Mn ions during the formation of solid solutions. 4(b).…”

“…10 With the purpose to make a balance between maintaining good piezoelectric property and enhancing thermal stability, the PPT effect though phase manipulation should be retained because it is accepted as an indispensable way for piezoelectric property enhancement in KNN-based ceramics. [1][2][3]5,7,18,19,[21][22][23][24][25] However, the enhancement merely dependent on PPT effect could lead to the high sensitivity to temperature fluctuation in KNN-based ceramics. The drawbacks might be partially counteracted by further enhancement of the piezoelectric property via some other mechanisms.…”

“…The drawbacks might be partially counteracted by further enhancement of the piezoelectric property via some other mechanisms. [27][28][29] Besides, MnO 2 is deemed as one of the most intriguing additives in KNN-based ceramics because both "softening" or "hardening" characteristics of MnO 2 are simultaneously observed, which conduce to the increases in piezoelectric constant d 33 , relative permittivity e r , planar electromechanical coupling factor k p , and mechanical quality factor Q m , as well as the decrease in loss tangent tan d. [22][23][24][25][30][31][32] It has been found that a gentle decrease in T O-T and piezoelectric property enhancement could be achieved by the addition of AgSbO 3 . 26 On the basis of the following literature results, incorporating MnO 2 into a compositionally optimized KNN-based ceramics with adjusted PPT should be studied as a solution.…”