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Dense potassium niobate ceramics, K(1+x)NbO3(KN-10000x, x = 0–0.001), were fabricated using KHCO3powder as a starting material to improve their reproducibility, and the densification flow were also discussed in this paper. The KN-7.2 ceramics all had high density ratios exceeding 96% and resistivities of above 1012Ω˙cm. The relative density ratios of all the KN-7.2 ceramics were similar, showing the excellent reproducibility obtained using KHCO3powder as a starting material. The electromechanical coupling factor k15and piezoelectric strain constant d15of the KN-7.2 ceramics were 0.46 and 153 pC/N, respectively. [ABSTRACT FROM PUBLISHER]

Bismuth potassium titanate, (Bi1/2K1/2)TiO3(BKT), ceramics were fabricated using smaller-particle-size TiO2(∼0.1 μm) as a starting material for the improvement of BKT ceramic densification. The BKT ceramics were prepared by a conventional ceramic fabrication process without any additives or special techniques, such as hot-pressing methods. The BKT ceramics prepared using TiO2(∼0.1 μm) powder had high density ratios of at least 95%. In addition, they had good electrical properties equal to or greater than the BKT ceramics prepared by other manufacturing methods. [ABSTRACT FROM PUBLISHER]

The phase transition temperatures and piezoelectric properties of (Bi0.5Na0.5)TiO3 (BNT) ceramics and single crystal were investigated. This study revealed that the high conductivity of BNT ceramics is attributed to the Bi vaporization during sinterint. The highest depolarization temperature Td of 187°C was obtained for the stoichiometric BNT ceramics, and Td tends to decrease as the composition deviates from stoichiometric BNT. Td of BNT single crystal was 158°C because of Na poor composition. BNT ceramics was easy to pole fully when the Bi/Na ratio is more than 1.0. The electromechanical coupling factor k33 and piezoelectric properties d33 of fully poled stoichiometric BNT ceramics were 0.459 and 72.9 pC/N, respectively. [ABSTRACT FROM AUTHOR]

The phase transition temperatures and the dielectric, ferroelectric, and piezoelectric properties of bismuth perovskite lead-free ferroelectric ceramics such as (Bi1/2Na1/2) TiO3 (BNT)- and (Bi1/2K1/2)TiO3 (BKT)-based solid solutions have been reviewed. According to the results obtained by our group, these ceramics can be considered as superior lead-free piezoelectric materials for reducing environmental damage. Perovskite-type ceramics appear to be suitable for actuator and high-power applications that require a large piezoelectric constant d33 and a high Curie temperature TC or a high depolarization temperature Td (>200°C). In this paper, we summarize the relationship between phase transition temperatures and piezoelectric properties. In the case of the BNT-based solid solutions, the highest piezoelectric properties were obtained at the morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases. However, d33 and Td were shown to have a tradeoff relationship. Considering the high Td and high d33, the tetragonal side of the MPB composition is suitable for piezoelectric actuator application. Meanwhile, the Qm values on the rhombohedral side of the MPB composition were better than those on the tetragonal side, and excellent high-power characteristics were obtained for Mn-doped BNT-(Bi1/2Li1/2)TiO3-BKT ternary systems with rhombohedral symmetry. BKT ceramic were prepared by the hot-pressing (HP) method, and their ferroelectric and piezoelectric properties were clarified. BKT ceramics doped with a small amount of Bi have a relatively high remanent polarization of Pr = 27.6 μC/cm2 and high piezoelectric properties (k33 = 0.40 and d33 = 101 pC/N). In addition, it was clarified that BKT ceramics have a high Td of approximately 300°C. The solid solution (1-x)BKT-xBaTiO3(BKT-BT100x) exhibited a high Td of approximately 300°V at x > 0.4. [ABSTRACT FROM AUTHOR]

Abstract: The phase transition temperature and piezoelectric properties of x(Bi1/2Na1/2)TiO3–y(Bi1/2Li1/2)TiO3–z(Bi1/2K1/2)TiO3 [x + y + z =1] (abbreviated as BNLKT100y–100z) ceramics were investigated. BNLKT100y–100z ceramics were prepared by conventional ceramic fabrication. The depolarization temperature T d was determined by the temperature dependence of the dielectric and piezoelectric properties. This study focuses on the effect of Li1+ and K1+ ions on T d and the piezoelectric properties of BNT ceramics. BNLKT100y–100z (y =0–0.08) has a morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases at z =0.18–0.20, and high piezoelectric properties were obtained at the MPB composition. The piezoelectric constant d 33 increased with increasing y; however, T d decreased above y =0.06. The d 33 and T d values of BNLKT4-20 and BNLKT8-20 were 176pC/N and 171°C, and 190pC/N and 115°C, respectively. [Copyright &y& Elsevier]

The phase-transition temperatures and piezoelectric properties of ∞(Bi1/2Na1/2)TiO3-y(Bi1/2Li1/2) TiO3-z(Bi1/2K1/2)TiO3 [∞ + y + z = 1] (abbreviated as BNLKT100y-100z) ceramics were investigated. These ceramics were prepared using a conventional ceramic fabrication process. The phase-transition temperatures such as depolarization temperatures Td, rhombohedral- tetragonal phase transition temperature TR-T, and dielectric-maximum temperature Tm were determined using electrical measurements such as dielectric and piezo- electric properties. The X-ray powder diffraction patterns of BNLKT100y-100z show the morphotropic phase boundary (MPB) between rhombohedral and tetragonal at approximately z = 0.20, and the piezoelectric properties show the maximum at the MPB. The electromechanical coupling factor k33, piezoelectric constant d33 and Td of BNLKT4- 20 and BNLKT8-20 were 0.603, 176 pC/N, and 171°C, and 0.590, 190 pC/N, and 115°C, respectively. In addition, the relationship between d33 and Td of tetragonal side and rhombohedral side for BNLKT4-100z and BNLKT8-100z were presented. Considering both high Td and high d33, the tetragonal side of BNLKT4-100z is thought to be the superior composition. The d33 and Td of BNLKT4-28 were 135 pC/N and 218°C, respectively. Moreover, this study revealed that the variation of Td is related to the variation of lattice distortion such as rhombohedrality 90-α and tetragonality c/a. [ABSTRACT FROM AUTHOR]

Potassium niobate, KNbO3 (KN), ceramics were prepared by the modified conventional ceramic fabrication process to characterize their piezoelectric properties. KN single crystal has high electromechanical coupling factor k33 = 0.66. On the other hand, the difficulty in obtaining dense and nondeliquescent KN ceramics by conventional methods limits our knowledge of the piezoelectricity of this ceramic. The KN ceramics showed the piezoelectric properties such as the electromechanical coupling factor k33, the piezoelectric constant, d33, and the mechanical quality factor, Qm, were 0.49, 91.7 pC/N and 325, respectively. This sample was poled at a DC electric field of 5 kV/mm at 150°C. [ABSTRACT FROM AUTHOR]

Bi3 - xNdxTiTaO9 (B(3-x)NxTT) (0 ≤ x ≤ 0.5) and Bi2.5NdyTiTaO3 - δ (B2.5NyTT) (0 ≤ y ≤ 0.5) ceramics were fabricated by the conventional firing method using Nd(OH)3 and constituent phase, crystal structure and ferroelectric property was investigated. B(3-x)NxTT had single phase of BLSF (m = 2), however not only BLSF (m = 2) phase but also pyrochlore phase was confirmed for the B2.5NyTT. The remanent polarization, Pr, value which was 10 μ C/cm2 with x = 0 decreased down to 6 μ C/cm2 with x = 0.5, and the value of coercive field, Ec, which was 100 kV/cm with x = 0 increased up to 163 kV/cm with x = 0.5. Squareness of hysteresis loops was almost the same in the B(3-x)NxTT. On the other hand, in the case of B2.5NyTT, the Pr value which was 6 μ C/cm2 with y = 0.5 increased up to 13 μ C/cm2 with y = 0.35 though pyrochlore content increased. Furthermore, the squareness of the hysteresis loops with y = 0.35 was better than that of hysteresis loops with y = 0.5. The Ec value was the almost the same. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y : z = 2: 1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280°C and 262°C were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79) and MPB composition O.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88), with depolarization temperatures of 224° C and 162° C, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (~40 µC/cm²) was larger than that of BNBK79 (~29 µ/cm²). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed. [ABSTRACT FROM AUTHOR]

Phase transition temperatures of (1-x)(Bi1/2Na1/2)TiO3 - x (Bi1/2K1/2)TiO3 (BNKTx) and (1-x)(Bi1/2Na1/2) TiO3 - xBaTiO3 (BNBTx) ceramics were investigated by using electrical measurements such as dielectric and piezoelectric properties. We discussed how to determine the depolarization temperature, Td, and rhombohedral-tetragonal phase transition, TR-T, for (Bi1/2Na1/2) TiO3 (BNT)-based solid solutions, and the Td TR-T and the temperature that dielectric constant become maximum Tm, for BNKTx and BNBTx were clarified in this study. [ABSTRACT FROM AUTHOR]

There is an ongoing need to develop new technologies to enable further down-scaling of layer thicknesses in multilayer ceramic devices, for example, in multilayer capacitors (MLC). Microcontact printing of chemical solutions of both the dielectric and electrode layers was explored as an economical means of preparing patterned thin films for MLC without requiring photolithography. For this purpose, methanol/acetic acid-based BaTiO3 solutions were spun onto polydimethylsiloxane stamps, printed onto substrates, pyrolyzed, and crystallized. LaNiO3 was used as a prototype electrode that could also be microcontact printed. The line edge roughness produced this way was on the order of a tenth of a micrometer, which should enable very small margins. The printed layer thickness was also very uniform. Microcontact printed capacitors with a single dielectric layer were fabricated and found to have dielectric constants >800 with loss tangents <2%. Alignment between subsequent layers is readily achieved. Multilayer dielectric/electrode stacks could be fabricated without cracking or delaminations. Consequently, microcontact printing appears to be a viable potential means of preparing MLC with layer thicknesses in the range of ≤0.2 μm. [ABSTRACT FROM AUTHOR]

Piezoelectric properties of Sr 2 Bi 4 Ti 5 O 18 (SBT)–Ca 2 Bi 4 Ti 5 O 18 (CBT) solid solution, that is, Sr 2(1- x ) Ca 2 x Bi 4 Ti 5 O 18 [SCBT- x ] (0 ≤ x ≤ 1) with m = 5, were investigated. Effects of grain orientation in SCBT system on their piezoelectric properties are also studied using the hot-forging (HF) method. On the ordinarily fired (OF) samples without orientation, electromechanical coupling factor, k 33, and piezoelectric constant, d 33 , of the MnCO 3 (0.4 wt%) doped SCBT-0 were 0.15 and 26 pC/N, respectively. On the other hand, the HF-SCBT-0 showed relatively high k 33 and d 33 values of 0.29 and 51 pC/N, respectively. Temperature coefficient of the resonance frequency, TC -f r , in the (33) mode of SCBT-0 (OF) and HF-SCBT-0 were –89.2 ppm/°C and –63.0 ppm/°C, respectively. [ABSTRACT FROM AUTHOR]

Multiple myeloma is a hematolymphoid malignancy, and patients with this disorder are frequently complicated by infection. An 80-year-old woman with multiple myeloma was complicated by bacterial meningitis, and was admitted to our hospital in August 2007. She initially received ceftriaxone, but culture of cerebrospinal fluid detected Listeria monocytogenes. Ampicillin was administered, but headache and pyrexia persisted for 2 weeks, and on cerebrospinal fluid examination, the proliferation of polymorphonuclear leukocytes had not resolved. After medication with meropenem was started, the clinical symptoms completely disappeared, and the abnormalities on cerebrospinal fluid examination resolved. The patient ultimately received meropenem for 27 days, resulting in a cure. In conclusion, meropenem is useful to treat bacterial meningitis caused by L. monocytogenes. This agent is indicated when ampicillin shows inadequate effect or if the patient has an allergy to ampicillin. [ABSTRACT FROM AUTHOR]

A solid-solution system, (1-x)(Bi1/2Na1/2)TiO3–xBa(Al1/2Sb1/2)O3 (BNT-BAS100x), was fabricated by a conventional ceramic fabrication process. The morphotropic phase boundary (MPB) between rhombohedral and pseudocubic phases of BNT-BAS100x was clarified to be at approximately x=0.045, and the highest normalized strain d33* of 532 pm/V was obtained at this composition. This study also revealed that the MPB composition of a BNT-based solid solution shifts to a BNT-rich composition as the tolerance factor t of the end member increases, and t of the MPB composition is always approximately 0.983. This indicates that the MPB position can be predicted from t values of the end members. [ABSTRACT FROM AUTHOR]