Dielectric characteristics and phase structure of lead-free Bi0.5(Na1−x−yKxAgy)0.5TiO3 piezoelectric ceramics

TiO 3 nanopowders synthesized by an oxalate precursor route, 0.2-wt %-CuO-doped ceramics can be sintered at a low temperature of 880 C. The shrinkage rate is 16.5%, the relative density D r is 98%, the relative dielectric constant " T 33 =" 0 (1 kHz) is 705, the loss tan (1 kHz) is 2.50%, the electromechanical coupling factor k p is 13.6%, and the piezoelectric charge coefficient d 33 is 105 pC/N.

Section: Introductionmentioning

confidence: 99%

Low-Temperature Sintering of (Bi,Na)_0.83Ba_0.17TiO₃–0.2 wt % CuO Piezoelectric Ceramics from Nanopowders

Karaki

Adachi

2011

“…2) To improve the piezoelectric properties, a number of BNT-based solid solutions have been intensively studied. [3][4][5][6][7][8][9][10] Among these systems, (Bi 0:5 Na 0:5 ) 1Àx Ba x TiO 3 (BNT-BT100x) system has frequently been reported. However, most studies have focused on the morphotropic phase boundary composition with a low depolarization temperature T d % 100 C. 11) When x is about 0.20, T d is high, about 200 C. 12,13) We also investigated BNT-BT100x ceramics, focusing on the relationship between composition and T d .…”

Section: Introductionmentioning

confidence: 99%

Effect of CuO Doping on (Bi,Na)_0.83Ba_0.17TiO₃ Piezoelectric Ceramics

Karaki

Adachi

2010

(Bi0.5Na0.5)0.83Ba0.17TiO3–x wt % CuO ceramics were prepared by a conventional ceramics fabrication method. The effects of CuO doping on densification, microstructure, and electrical properties are presented. The 0.2 wt % CuO-doped sample sintered at 1060 °C for 2 h exhibits good properties: a shrinkage rate of 16.5%, a relative density of 97%, a relative dielectric constant ε 33 T /ε 0 of 555 and a dielectric loss of 2.10% at 1 kHz, an electromechanical coupling factor k p of 18.0%, a piezoelectric charge coefficient d 33 of 148 pC/N, a frequency constant N p of 3096 Hz·m, a mechanical quality factor Q m of 52, a depolarization temperature T d of 218 °C, and a temperature corresponding to the maximum dielectric constant T m of 249 °C.

“…Thus, many investigations have been carried out to improve the electrical properties by modifying BNT with (Bi,K)TiO 3 (BKT), [1][2][3][4][5] BaTiO 3 (BT), [6][7][8][9] SrTiO 3 , 10) BiFeO 3 , 11) (Bi,La)TiO 3 , 12) (Bi,Li)TiO 3 , 5) BKT-BT, [13][14][15][16][17][18] BKT-(Bi,Li)TiO 3 , [19][20][21][22] BT-(Bi,Li)TiO 3 , 23,24) BT-Ba(Zr,Ti)O 3 , 25,26) BT-(Bi,La)TiO 3 , 27) BKT-(Bi,Li)TiO 3 -BT, 28) BKT-(Bi,Li)TiO 3 -Ba(Zr,Ti)O 3 , 29) and BKT-(Bi,Ag)TiO 3 . 30,31) Most recently, the optimum composition search around a morphotropic phase boundary (MPB) that provides excellent piezoelectric properties has been intensively investigated for multicomponent BNT-based solid solutions. 10,17,18,21,24) In addition, it is known that BNT exhibits an anomaly in dielectric properties as a result of a low-temperature phase transition from the ferroelectric phase to the antiferroelectric phase at about 200 C (known as depolarization temperature) except the phase transition from the rhombohedral phase to the tetragonal phase at 300 C. Hiruma and coworkers 5,16,22) have investigated the behavior and more accurate measurement of the phase transition temperatures of BNT-based solid solutions, and determined their temperatures and MPB compositions.…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported 5,10) that a very large field-induced nonlinear strain that is attributable to the electric fieldinduced phase transition was obtained in the BNT-ST and BNT-BKT-BT systems. It is noted 30,31) that Ag þ ion substitution for Na þ or K þ of A-sites in BNKT improved the piezoelectric properties, and Ag þ -doped BNKT exhibited a relaxor behavior.…”

Section: Introductionmentioning

confidence: 99%

Piezoelectric and Dielectric Properties of (Bi,Na,K,Ag)TiO₃–BaTiO₃Lead-Free Piezoelectric Ceramics

Isikawa

Akiyama

Hayashi

2009

Lead-free (1 À y )(Bi 0:5 Na 0:49Àx K x Ag 0:01 )TiO 3 -yBaTiO 3 (x ¼ 0 to 0.1, y ¼ 0 to 0.04) [abbreviated as BNKAT-BT-100x/100y] piezoelectric ceramics were fabricated using various amounts of K and Ba substitutions, and their piezoelectric and dielectric properties were investigated. The crystal structure significantly changed with the amount of K substitution. The BNKAT-BT-5/2 specimens exhibited a pseudocubic structure, while the BNKAT-BT-10/2 specimens exhibited a tetragonal structure and provided a larger electrostrain constant (d 33 Ã ) than BNKAT-BT-0/2 specimens, which exhibited a rhombohedral structure. The addition of La 2 O 3 /MnO to BNKAT-BT specimens affected the crystal structure and electrical properties. La 2 O 3 /MnO-added BNKAT-BT-10/100y (0:02 5 y 5 0:03) specimens with a pseudocubic structure exhibited P-E hysteresis loops different from those that are characteristic of ferroelectric, and provided a peculiar field-induced strain without the residual strain in the butterfly curve and a very large strain constant (d 33 Ã ) of 415 pm/V. This may be associated with the field-forced phase transition from the paraelectric phase to the ferroelectric phase.