Phase transition and piezoelectric properties of (1−x)(K0.42Na0.58)(Nb0.96Sb0.04)O3–x(Bi0.5Na0.5)0.90Mg0.10ZrO3 lead-free ceramics

Co-Doping Effect of BiGaO3 and (Bi,Na,K,Li)ZrO3 on Multi-Phase Structure and Piezoelectric Properties of (K,Na)NbO3 Lead-Free Ceramics

“…The origin of this sudden decrease in grain size is attributed to the effects of the solubility limits of low-melting-point Bi 3+ ion or BiMO 3 dopant in KNN and aggregation at grain boundaries. The grain size behavior observed in this work, including a dramatic decrease in grain size, was consistent with those reported in previous studies [23][24][25][26][27]. The only notable difference was that the BG doping induced more compositional sensitivity (i.e., 0.001 mole fraction level) to the grain structure evolution, which is likely owing to the effects of the super-tetragonal structure of BG [17].…”

“…Those behaviors were commonly observed for two BNKLZ compositions. For the KNN-based ceramics doped with Bi-containing perovskite oxides, it has been generally shown that the grain size dramatically decreased owing to a slight increase (usually by about 0.01 mole fraction) of the amount of dopants at certain doping levels [23][24][25][26][27]. The origin of this sudden decrease in grain size is attributed to the effects of the solubility limits of low-melting-point Bi 3+ ion or BiMO 3 dopant in KNN and aggregation at grain boundaries.…”

Potassium–Sodium Niobate Lead-Free Piezoelectric Materials: Past, Present, and Future of Phase Boundaries

“…However, recent advances indicate that there is a limited improvement in the d 33 values for KNN materials with O–T or R–O phase boundaries, − ,− which is also inferior to most PZT ceramics or even textured KNN . As a result, the formation of R–T boundaries that are similar to PZT may become necessary to further enhance the piezoelectric activity of KNN, because the easy rotations of polarization axes can be induced in compositions near such a phase boundary. ,,,,− In addition, we recently confirmed this assumption in potassium–sodium niobate piezoceramics by experimental methods, − and a larger d 33 value has been attained by constructing R–T phase boundaries. − If the R–T phase boundary of KNN is expected to form, it is necessary to concurrently move their T R–O and T O–T values close to room temperature by choosing two or more additives, − ,− such as Ta and Sb and Bi 0.5 (Na 0.82 K 0.18 ) 0.5 ZrO 3 , Sb and Bi 0.5 (Na 0.82 K 0.18 ) 0.5 ZrO 3 , BaZrO 3 and Bi 0.5 Na 0.5 TiO 3 , Sb and BaZrO 3 , Sb and LiTaO 3 and BaZrO 3 , LiSbO 3 and BaZrO 3 ,…”

“…−123 °C) , and provides a poor d 33 . Recently, additives have been used to increase the T R–O values of KNN, including Sb 5+ , ,, Ta 5+ , AZrO 3 (A = Ba 2+ , Sr 2+ , Ca 2+ ), , BiScO 3 , etc. ,,,− For example, the T R–O value of (K 0.48 Na 0.52 )­(Nb,Sb)­O 3 can be tuned to near room temperature by refining the Sb content (see Figure ); thereby an improved d 33 (∼230 pC/N) was demonstrated due to the coexistence of R–O ferroelectric mixed phases . In addition, it was found that doping with Ta 5+ could decrease both T C and T O–T and increase T R–O of KNN, similar to Sb 5+ . , However, the T R–O value of Ta-doped KNN ceramic could not reach room temperature in the investigated composition ranges (see Figure a), showing that the R–O phase boundary is difficult to induce by chemical modification.…”

Transparency of K0.5N0.5NbO3–Sr(Mg1/3Nb2/3)O3 lead-free ceramics modulated by relaxor behavior and grain size

“…The similar results are also obtained in (K 0.5 Na 0.5 )NbO 3 -(Ba 0.5 Sr 0.5 )TiO 3 relaxor ceramics 32. In addition, the dramatic decrease in grain size also cause the ceramics with x  0.04 possess the broadened and suppressed dielectric peaks 33. Fig.…”