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(KxNa0.96-xLi0.04)(Nb0.85Ta0.15)O3 lead-free piezoelectric ceramics were produced by conventional solid-state reaction method. The effects of K/Na ratio on the phase transitional behavior, Raman spectrum, microstructure, and dielectric, piezoelectric, and ferroelectric properties of the ceramics have been investigated. The phase structure of the ceramics undergoes a transition from orthorhombic to tetragonal phase with increasing x. A double-degenerate symmetric O–Nb–O stretching vibration v1 and a triply degenerate symmetric O–Nb–O bending vibration v5 are detected as relatively strong scattering in the Raman spectra. The peak shifts of v5 and v1 modes all have a discontinuity with x between 0.42 and 0.46, which may suggest the coexistence of orthorhombic and tetragonal phases in this range. Properly modifying x reduces the sintering temperature, promotes the grain growth behavior, and improves the density of the ceramics. The polymorphic phase transition (at To-t) is shifted to near room temperature by increasing x to 0.44 (K/Na ratio of about 0.85:1), and the coexistence of orthorhombic and tetragonal phases in the ceramics at x=0.44 results in the optimized electrical properties (d33=291 pC/N, kp=0.54, [variant_greek_epsilon]r=1167, tan δ=0.018, To-t=35 °C, TC=351 °C, Pr=27.65 μC/cm2, and Ec=8.63 kV/cm). The results show that the equal K/Na ratio is not an essential condition in obtaining optimized electrical properties in (KxNa0.96-xLi0.04)(Nb0.85Ta0.15)O3 ceramics. [ABSTRACT FROM AUTHOR]

Rare earth element neodymium was adopted to refine grain and in turn increase the volume of grain boundary of Y 2/3 Cu 3 Ti 4 O 12 ceramics, which could strongly increase the resistance of grain boundary. Proper amount of Nd substitution in Y 2/3− x Nd x Cu 3 Ti 4 O 12 ceramics could significantly depress the low-frequency dielectric loss. When the doping level is 0.06 and 0.09, the samples exhibited a relatively low dielectric loss (below 0.050 between 0.3 and 50 kHz) and high dielectric constant above 11000 over a wide frequency range from 40 Hz to 100 kHz. Based on the ɛ′- T plots, dielectric relaxation intensity was substantially weakened by Nd doping so that the temperature stability of dielectric constant was improved obviously. The correlations between low-frequency dielectric loss and the resistance of grain boundary were revealed. After Nd doping, the activation energies for the conduction behavior in grain boundaries were significantly enhanced, and the activation energies for the dielectric relaxation process in grain boundaries were slightly influenced. [ABSTRACT FROM AUTHOR]

Considering the contribution of the mixed valence structure of Ti 3+ and Ti 4+ to the semiconductivity of grain, compositions with the formula of Y 2/3 Cu 3 Ti 4+ x O 12 were designed and prepared. The dielectric bulk responses of Y 2/3 Cu 3 Ti 4+ x O 12 ceramics were explored in detail. Changing Ti stoichiometry gives rise to an increase of the intrinsic permittivity. Y 2/3 Cu 3 Ti 3.925 O 12 ceramic exhibits a higher intrinsic permittivity of ~120 at 60 MHz than that of pure Y 2/3 Cu 3 Ti 4 O 12 ceramics (87 at 60 MHz). Additionally, the activation energies of bulk responses are significantly enhanced by changing Ti stoichiometry, which is closely linked with the increase of Ti 3+ /Ti 4+ . [ABSTRACT FROM AUTHOR]

ZnMnO active layer for resistance random access memory (RRAM) was deposited on p-Si substrate by chemical solution deposition. The bipolar resistive switching behaviours of the Ag/ZnMnO/p-Si capacitor are investigated. The bipolar resistive switching is reproducible and shows high ON/OFF ratio of > 10 and long retention times of > 10 s. The conduction mechanism of the Ag/ZnMnO/p-Si capacitor in the low-resistance state (LRS) is ohmic conduction, whereas that of the device in high-resistance state (HRS) successively undergoes Ohm's law, trap-filled-limited and Child's law conduction procedure at room temperature. [ABSTRACT FROM AUTHOR]

Aluminum-doped zinc oxide (AZO) target was fabricated using AZO nanopowders synthesized by co-precipitation method and then the AZO films with different thicknesses were deposited on glass by d.c. magnetron sputtering at room temperature. AZO target is nodules free and shows homogeneous microstructure, ultra-high density and low resistivity. ZnAlO phase appears in AZO target and disappears in AZO films. All AZO films show c-axis preferred orientation and hexagonal structure. With increasing film thickness from 153 to 1404 nm, the crystallinity was improved and the angle of (002) peak was close to 34.45°. The increase in grain size and surface roughness is due to the increase in film thickness. The decrease of resistivity is ascribed to the increases of carrier concentration and Hall mobility. The lowest resistivity is 9.6 × 10 Ω·cm. The average transmittance of AZO films exceeds 80%, and a sharp fundamental absorption edge with red-shifting is observed in the visible range. The bandgap decreases from 3.26 to 3.02 eV. [ABSTRACT FROM AUTHOR]

Abstract: The effects of growth temperature, coating cycles on the structure, electrical and optical properties of ITO films were investigated, and the stability under high temperature, high temperature & high humidity and alkaline environments was focused. With increasing the growth temperature, the crystalline phase transforms from amorphous to crystalline. The surface morphology shows flat and dense structure. The thickness, sheet resistance and resistivity firstly decrease and then increase, and the optimal sheet resistance and resistivity is 7.6Ω/sq and 1.1×10−4 Ωcm. The average visible transmittance of the ITO films and ITO glass exceeds 85% and 80%. The band gap increases from 3.75eV to 3.95eV. The electrical and optical properties of the ITO films are very stable after eight coating cycles. The growth temperature significantly affects the change rate of sheet resistance under high temperature, high temperature & high humidity and alkaline environments. However, the change rate of sheet resistance is stable and sight for eight coating cycles. [Copyright &y& Elsevier]

Abstract: Ca0.28Ba0.72Nb2O6 (CBN28) ceramics with addition of CeO2 and La2O3, were prepared by the conventional ceramic fabrication technique. XRD results showed that the single tungsten bronze structure of CBN28 was not changed by adding CeO2 or La2O3. SEM results indicated that both CeO2 and La2O3 dopants were effective in inhibiting the grain growth and suppressing the anisotropic growth behavior in tungsten bronze structure. It was also found that both two kinds of dopants had remarkable effects on the dielectric and ferroelectric properties of CBN28 ceramics. Compared with CBN28 ceramics, the dielectric constant around room temperature ε r , dielectric loss tan δ, the degree of diffuseness γ and coercive field E c were all ameliorated when doping proper amount of CeO2 or La2O3. The comprehensive electric performance was obtained in CBN28–0.3wt% CeO2 and CBN28–0.4wt% La2O3 ceramics. Besides, the underlying mechanism for variations of the electrical properties due to different dopants was explained in this work. [Copyright &y& Elsevier]

Y2/3 Cu3 Ti4 O12 ceramics were successfully prepared by the conventional solid-state reaction method. Effects of sintering conditions on microstructure, phase structure, and the dielectric properties of Y2/3 Cu3 Ti4 O12 ceramics were investigated in detail. Y2/3 Cu3 Ti4 O12 ceramics sintered at 1010°C for 25 h exhibited a giant dielectric constant (1.10 × 104) and a relatively low dielectric loss (0.033) around room temperature. The samples showed good temperature stability ( [ABSTRACT FROM AUTHOR]

Abstract: The phase structure, microstructure and dielectric properties of Na0.5Bi0.5−x La x Cu3Ti4O12 (NBLCTO) ceramics were investigated. La3+ substitution had a great influence on the phase structure and dielectric properties. The results showed that the pure phase could be more easily obtained when substituting La3+ for Bi3+. Under the same processing condition (970°C for 7.5h) and measuring condition (10kHz around room temperature), NBLCTO ceramics with x =0.10 possessed the highest permittivity (1.02×104) and lowest dielectric loss (0.022). The obtained NBLCTO ceramics with x =0.10 also had good frequency stability and good temperature stability (−1.87% to +3.27%) from −60°C to 120°C at both 1 and 10kHz. Complex impedance results revealed that the grain resistance R g was 7.18Ωcm and the grain boundary resistance R gb was 1.19×106 Ωcm. [Copyright &y& Elsevier]

Abstract: The addition of BiFeO3 in the ceramics shifts the PPT below room temperature to improve the temperature stability of KNN-based ceramics. The phase structure, microstructure, dielectric, piezoelectric properties and temperature stability of (1− x)[(K0.458Na0.542)0.96Li0.04](Nb0.85Ta0.15)O3–xBiFeO3 piezoelectric ceramics were investigated. The phase structure of these ceramics changed from tetragonal phase to pseudo cubic phase with BiFeO3 additives. The optimal piezoelectric properties were obtained at x =0.004, which were listed as follows: d 33 =261pC/N, tan δ =0.016, K p =0.58, T c =345°C and ɛ r =1116. Especially, the results demonstrated that the PPT of (K0.458Na0.542)0.96Li0.04](Nb0.85Ta0.15)O3 ceramics has been shifted below room temperature successfully by the addition of BiFeO3. The time stability and ageing rate values of the ceramics with x =0.000 were 15% and 7.8%. These values decrease to 4.97% and 6.09% at x =0.004, respectively, showing that the ceramics have better temperature and time stability for the polymorphic phase transition below room temperature. [Copyright &y& Elsevier]

Abstract: The Ca1−x Sr x Cu3Ti4O12 (CSCTO) giant dielectric ceramics were prepared by conventional solid-state method. X-ray diffraction patterns revealed that a small amount of Sr2+ (x<0.2) had no obvious effect on the phase structure of the CSCTO ceramics, while with increasing the Sr2+ content, a second phase of SrTiO3 appeared. Electrical properties of CSCTO ceramics greatly depended on the Sr2+ content. The Ca0.9Sr0.1Cu3Ti4O12 ceramics exhibited a higher permittivity (71,153) and lower dielectric loss (0.022) when measured at 1kHz at room temperature. The ceramics also performed good temperature stability in the temperature range from −50°C to 100°C at 1kHz. By impedance spectroscopy analysis, all compounds were found to be electrically heterogeneous, showing semiconducting grains and insulating grain boundaries. The grain resistance was 1.28Ω and the grain boundary resistance was 1.31×105 Ω. All the results indicated that the Ca0.9Sr0.1Cu3Ti4O12 ceramics were very promising materials with higher permittivity for practical applications. [Copyright &y& Elsevier]

Abstract: The phase structure, microstructure, piezoelectric properties, dielectric characteristic and the ME effect of magnetoelectric Pb[Zr0.23Ti0.36+0.02(Mg1/2W1/2)+0.39(Ni1/3Nb2/3)]O3 (PZT)+xNi0.8Co0.1Cu0.1Fe2O4 (NCCF) composite ceramics were prepared by the conventional solid state reaction method. The structural analysis of both the constituent phases and their composites was carried out by X-ray diffraction, energy dispersive spectrometry and scanning electron microscopy. The results showed cubic spinel structure for ferrite phase and tetragonal perovskite structure for ferroelectric phase. The piezoelectric constant, dielectric constant, Curie temperature, remanent polarization and coercive electric field decreased with increase of ferrite content. The coercive field strength, saturation magnetization and remanent magnetization increased with increasing ferrite content. [Copyright &y& Elsevier]

Abstract: LiSbO3 doped Sr0.53Ba0.47Nb2O6 ceramics were synthesized by conventional mixed-oxide method. The phase structure, microstructure, dielectric and ferroelectric properties of obtained ceramics were investigated. Pure tungsten bronze structure could be obtained in all ceramics and LiSbO3 additive could promote densification and reduce the sintering temperature. The dielectric characteristics showed diffuse phase transition phenomena for all samples, which was proved by linear fitting of the modified Curie–Weiss law with γ value varying between 1.65 and 1.92. With increasing LiSbO3 content, the transition temperature T c decreased gradually to near room temperature. Normal ferroelectric hysteresis loops could be observed in all compositions, but the remnant polarization (P r) and coercive field (E c) all decreased gradually. Besides, the underlying mechanism for variations of the electrical properties caused by LiSbO3 doping was explained in this work. [Copyright &y& Elsevier]

Abstract: New (1−x)Ba(Y1/2Nb1/2)O3–xPbTiO3 ceramics have been synthesized by conventional mixed-oxide process. Two morphotropic phase boundaries (MPBs) corresponding to the rhombohedral–orthorhombic and orthorhombic–tetragonal phases are observed with increasing PT. The appearance of E(2TO1), E(2TO2), silent, R l and E(4LO) modes indicates the presence of an orthorhombic symmetry. Remarkable variation with two MPBs appears in the whole frequency region, where the rhombohedral modes change into the tetragonal ones in the system. [Copyright &y& Elsevier]

Abstract: Lead-free Sr2K x Na1−x Nb5O15 (0.00≤ x ≤0.20) piezoelectric ceramics were prepared by two-step solid state reaction method. Pure tungsten bronze structure could be obtained in all ceramics and K substitution could accelerate the phase formation at lower temperatures. The lattice constant calculation indicated expansion of the unit cell and reduced distortion of the crystal structure with K substitution due to the bigger ionic size of K+ (1.64Å) compared to that of Na+ (1.39Å). Electrical properties of Sr2K x Na1−x Nb5O15 ceramics greatly depended on the K content. Curie temperature T c shifted downward, whereas the maximum dielectric constant ɛ m and the degree of diffusion phase transition all increased initially and then decreased as K content increased, indicating that proper amount of K substitution with x between 0.05 and 0.10 could enhance the dielectric properties. All the ceramics showed an intermediate relaxor-like behavior between normal and ideal relaxor ferroelectrics according to the modified Curie–Weiss law. With increasing K content, the remnant polarization (P r) decreased gradually and the coercive field (E c) decreased initially and then increased. But normal ferroelectric hysteresis loops could be observed in all compositions. Besides, the underlying mechanism for variations of the electrical properties due to K substitution was explained in this work. [Copyright &y& Elsevier]

Abstract: In this work, we report on the Pb(Mg1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3–Pb(Zr0.52Ti0.48)O3 (PMN–PZN–PZT) ceramics with Ba(W0.5Cu0.5)O3 as the sintering aid that was manufactured in order to develop the low-temperature sintering materials for piezoelectric device applications. The phase transition, microstructure, dielectric, piezoelectric properties, and the temperature stability of the ceramics were investigated. The results showed that the addition of Ba(W0.5Cu0.5)O3 significantly improved the sintering temperature of PMN–PZN–PZT ceramics and could lower the sintering temperature from 1005 to 920°C. Besides, the obtained Ba(W0.5Cu0.5)O3-doped ceramics sintered at 920°C have optimized electrical properties, which are listed as follows: (K p =0.63, Q m =1415 and d 33 =351pC/N), and high depolarization temperature above 320°C. These results indicated that this material was a promising candidate for high-power multilayer piezoelectric device applications. [Copyright &y& Elsevier]

Abstract: Ta5+ doped strontium barium niobate (SBN) ceramics were synthesized by conventional oxide-mixed method. The phase structure, microstructure and dielectric properties of the ceramics with different Ta5+ contents and sintering temperatures were investigated. The X-ray diffraction patterns show that pure tungsten bronze structure can be obtained in all the ceramics. The ceramics with high relative density and a uniform and fine-grained microstructure could be obtained at 1430°C. The grain size of Sr0.53Ba0.47Nb2−x Ta x O6 decreased with increasing the Ta5+ content. The relaxor behavior observed in SBNT ceramics should be attributed to a cationic disorder induced by B-site substitutions, which was proved by linear fitting of the modified Curie–Weiss law. All samples are proved to be relaxor ferroelectric. It is also found that Curie temperature T c and maximum dielectric constant ɛ m both decrease with increasing Ta5+ content. [Copyright &y& Elsevier]

Abstract: In this paper, low temperature sintering of the Bi2(Zn1/3Nb2/3)2O7 (β-BZN) dielectric ceramics was studied with the use of BiFeO3 as a sintering aid. The effects of BiFeO3 contents and the sintering temperature on the phase structure, density and dielectric properties were investigated. The results showed that the sintering temperature could be decreased and the dielectric properties could be retained by the addition of BiFeO3. The structure of BiFeO3 doped β-BZN was still the monoclinic pyrochlore phase. The sintering temperature of BiFeO3 doped β-BZN ceramics was reduced from 1000°C to 920°C. In the case of 0.15 wt.% BiFeO3 addition, the β-BZN ceramics sintered at 920°C exhibited good dielectric properties, which were listed as follows: εr =79 and tan δ =0.00086 at a frequency of 1MHz. The obtained properties make this composition to be a good candidate for the LTCC application. [Copyright &y& Elsevier]

Abstract: Effects of ZnO addition on electrical properties and low-temperature sintering of BiFeO3-modified Pb(Zr,Ti)O3–Pb(Fe2/3W1/3)O3–Pb(Mn1/3Nb2/3)O3 were investigated. The investigations revealed that the sintering temperature can be decreased to 950°C, and the favorable properties were obtained with 0.10wt% ZnO added ceramics. The electrical properties were as follows: d 33 =313pC/N, K p =0.56, tan δ =0.0053, ε r =1407 and T c =295°C, which showed that this system was a promising material for the multilayer devices application. [Copyright &y& Elsevier]

Abstract: The ternary system (1− x − y)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3–yBi0.5Li0.5TiO3 (abbreviated to BNKLT-x/y) was synthesized by conventional oxide-mixed method. The phase structure, microstructure, and dielectric, ferroelectric and piezoelectric properties of the ceramics were investigated. The X-ray diffraction patterns showed that pure perovskite phase with rhombohedral structure can be obtained in all the ceramics. The grain size varied with x and y. The temperature dependence of dielectric constant and dielectric loss revealed there were two phase transitions which were from ferroelectric (tetragonal) to anti-ferroelectric (rhombohedral) and anti-ferroelectric to paraelectric (cubic). Either increasing x or y content can make T m (the temperature at which dielectric constant ɛ r reaches the maximum) increase. With the addition of Bi0.5K0.5TiO3, the remanent polarization P r increased but the coercive field E c decreased. With the addition of Bi0.5Li0.5TiO3, P r increased obviously and E c increased slightly. Due to the stronger ferroelectricity by modifying Bi0.5K0.5TiO3 and Bi0.5Li0.5TiO3, the piezoelectric properties were enhanced at x =0.22 and y =0.10, which were as follows: P r =31.92μC/cm2, E c =32.40kV/cm, ɛ r =1118, tan δ =0.041, d 33 =203 pC/N and K p =0.31. The results show that the BNKLT-x/y ceramics are promising candidates for the lead-free materials. [Copyright &y& Elsevier]

Abstract: Pb(Zr,Ti)O3–Pb(Fe2/3W1/3)O3–Pb(Mn1/3Nb2/3)O3 (PZT–PFW–PMN) quaternary piezoelectric ceramics using CeO2 and excess Pb3O4 as additives were fabricated by the addition of LiSbO3 as a sintering aid. The effects of LiSbO3 contents and sintering temperature on the phase structure, density, dielectric and piezoelectric properties of ceramics were investigated. It was observed that the addition of LiSbO3 not only decreased the sintering temperature from 1200 to 930°C but also optimized the properties. Temperature dependence of dielectric and piezoelectric properties of PZT–PFW–PMN ceramics with LiSbO3 addition were studied at a temperature range from room temperature to 290°C. It was found that the anti-resonant frequencies (f a) decreased with increasing temperature but the trend was reversed for resonant frequency (f r) which was related to the increased domain activities at higher test temperatures. Piezoelectric constant (d 33) was finally found to decrease with increasing temperature. The result showed that 0.10wt.% LiSbO3-modified ceramics sintered at 930°C exhibited favorable properties, which were listed as follows: d 33 =363 pC/N, K p =0.60, Q m =749, ɛ r =1596, T c =286°C, P r =14.84μm/cm−2 and E c =11.06kV/cm, which make this system be a promising material for multilayered piezoelectric actuator and sensor applications. [Copyright &y& Elsevier]

Abstract: Nd2O3 doped 0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3 (abbreviated to BNKT) binary lead-free piezoelectric ceramics were synthesized by the conventional mixed-oxide method. The results show that the BNKT ceramics with 0–0.15wt.% Nd2O3 doping possesses a single perovskite phase with rhombohedral structure. The grain size of BNKT decreased with the addition of Nd2O3 dopant. The temperature dependence of the dielectric constant ɛ r revealed that there were two-phase transitions from ferroelectric to anti-ferroelectric and anti-ferroelectric to paraelectric. A diffuse character was proved by linear fitting of the modified Curie–Weiss law. At room temperature, the specimens containing 0.0125wt.% Nd2O3 with homogeneous microstructure presented excellent electrical properties: the piezoelectric constant d 33 =134pC/N, the electromechanical coupling factor K p =0.27, and the dielectric constant ɛ r =925 (1kHz). [Copyright &y& Elsevier]

Abstract: (0.05− x)Pb(Mg1/3Nb2/3)O3–xPb(Sb1/3Nb2/3)O3–0.10Pb(Ni1/3Nb2/3)O3–0.85Pb(Zr1/2Ti1/2)O3 piezoelectric ceramics (abbreviated as PMN–PSN–PNN–PZT) were synthesized by traditional ceramics process. The effects of Pb(Sb1/3Nb2/3) content (abbreviated as PSN) on density, electrical properties and temperature stability of the ceramics were investigated in detail. The results showed that PMN–PNN–PZT ceramics with 0.015 PSN content sintered at 995°C exhibited the favorable electrical properties and good temperature stability, which were listed as follows: d 33 =538pC/N, k p =0.81, Q m =71, tan δ =0.0095, ɛ r =3902, Δf r/f r20°C =−2.21% and Δk p/k p20°C =3.61%. Meanwhile, the multilayer piezoelectric actuators with 65 piezoelectric layers and a thickness of 25μm for each layer were fabricated using PMN–PSN–PNN–PZT by the tape-casting method and the ceramic/internal electrode co-firing technology. The multilayer piezoelectric actuators sintered at 995°C exhibited larger displacement of 1.46μm at the working voltage of 25V. [Copyright &y& Elsevier]

Abstract: The effect of ZnO addition on the phase structure, microstructure and dielectric and piezoelectric properties of 0.2wt.% MnO2 and 0.6wt.% WO3-doped Pb(Zr0.52Ti0.48)O3–Pb(Mn1/3Sb2/3)O3–Pb(Zn1/3Nb2/3)O3 (PZT–PMS–PZN) ceramics was investigated. X-ray diffraction shows that the phase structure of ceramics is transformed from rhombohedral to tetragonal with the increasing of ZnO addition. The bulk density significantly increases when ZnO is added and then it slightly decreases for ZnO addition above 0.2wt.%. SEM micrographs show the grains of ceramics are uniform and well developed by adding 0.1wt.% ZnO. The Curie temperature (T c) of 270°C is obtained at the 0.1wt.% ZnO addition. Mechanical quality factor (Q m), electromechanical coupling factor (K p) and piezoelectric constant (d 33) increase firstly, and then decrease with the increasing of ZnO addition, while dielectric loss tan δ drops all the time. The Q m, K p, d 33, tan δ and T c of the ceramics show the optimum values of 1899, 0.55, 300 (pC/N), 0.0063 and 270°C, respectively, at the lower sintering temperature of 1120°C and with 0.1wt.% ZnO addition. [Copyright &y& Elsevier]

Abstract: NaNbO3 (NN) particles were synthesized by using conventional mixed-oxide (CMO), molten salt synthesis (MSS) and topochemical micro-crystal conversion methods (TMC), respectively. The effects of preparation methods on the phase structure, morphology and Raman characteristics of the NaNbO3 particles were investigated. The results show that the NN particles prepared by conventional mixed-oxide and molten salt synthesis methods are all of orthorhombic structure in Pbma space group. Furthermore, those particles have equiaxial morphology. The single-crystal NaNbO3 particles synthesized by the topochemical micro-crystal conversion method are of pseudocubic structure. Moreover, they are of plate-like shape with a high aspect ratio and a high (h 00) degree of orientation, which is very promising as template for texturing (K, Na)NbO3 (KNN) based ceramics. Besides, all the spectra lines in the Raman spectra can be attributed to the internal modes of NbO6 octahedron, and they prove that the particles synthesized by the different methods have different structure types. [Copyright &y& Elsevier]

Abstract: Temperature stability and electrical properties of the piezoelectric material are very important in piezoelectric transformers applications. In this study, it was investigated the temperature stability of PNW–PMN–PZT with CeO2 additives and the variation of Zr/Ti ratio. Meanwhile, effects of CeO2 additives and the variation of Zr/Ti ratio on the microstructure and electrical properties of PNW–PMN–PZT were investigated in detail. The results revealed that the optimized temperature stability of Δf r/f r25°C =0.15%, ΔK p/K p25°C =−0.86% and ΔQ m/Q m25°C =−45.26% could be attained at x =0.1wt.% and Zr/Ti=51/49. Moreover, optimized electrical properties were achieved: K p =0.60, Q m =1405, d 33 =388pC/N, ɛ r =2140 and tan δ =0.0059. The obtained temperature stabilities and electrical properties make this composition a good candidate for high power piezoelectric transformer applications. [Copyright &y& Elsevier]

Abstract: Large platelet NaNbO3 (NN) seed crystals have been successfully synthesized from bismuth layer-structured ferroelectric Bi2.5Na3.5Nb5O18 (BNN) precursor by topochemical microcrystal conversion method. The effects of synthesis parameters, such as salt/oxide ratio, synthesis temperature and Na2CO3/BNN ratio, on the phase structure and morphology of both the BNN precursor and NN particles were investigated. The results show that large platelet BNN precursor with bismuth layer structure was obtained at 1125°C with a salt-to-oxide weight ratio of 1.50:1. Besides, by optimizing the synthesis parameters, anisotropic NN seed crystals with pure perovskite phase were obtained at 975°C with a Na2CO3/BNN molar ratio of 1.50:1. The obtained NN particles are very promising template for texturing (K, Na) NbO3-based ceramics by reactive-template grain growth method. [Copyright &y& Elsevier]

Abstract: For the fabrication as step-down multilayer piezoelectric transformer, piezoelectric properties of Pb(Mg1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3–Pb(Zr0.52Ti0.48)O3 (PMN–PZN–PZT) ceramics were optimized by ZnO–Li2CO3 (ZL) and Pb3O4 content. Effects of the additions on the structure, bulk density and electrical properties of ceramics were investigated. The results revealed that the proper additions of ZL with Pb3O4 content could modify the electrical properties of the PMN–PZN–PZT ceramics. The composition sintered at 995°C with 0. 01wt.% ZL and 0.10wt.% Pb3O4 content showed higher values, which were listed as follows: d 33 =256pC/N, K p =0.60, Q m =1910, ɛ r =1032, tan δ =0.0070 and r =2.09Ω. In addition, the step-down piezoelectric transformers with optimized PMN–PZN–PZT composites were fabricated and the characteristics as the output power and resistance loads were measured. Meanwhile, the step-down piezoelectric transformers sintered at 995°C showed the favorable characteristics with a higher gain G of 0.204 and a lower temperature rise of 6°C when the output power was 5W, and the driving frequency were approximately constant (≈126kHz) when the output power was from 5 to 13W. Moreover, the maximum efficiency (90.2%) was obtained at load resistance of 10Ω. [Copyright &y& Elsevier]

Abstract: Pb(Zr,Ti)O3–Pb(Fe2/3W1/3)O3–Pb(Mn1/3Nb2/3)O3 (PZT–PFW–PMN) ceramics doped with BiFeO3 as sintering aids were manufactured in order to develop the low temperature sintering ceramics for piezoelectric devices, and phase structure, microstructure, dielectric, piezoelectric properties and the temperature stability were investigated. The results show that addition of BiFeO3 significantly improved the sinterability of PZT–PFW–PMN ceramics and could decrease the sintering temperature from 1200 to 1020°C. The 0.20wt.% BiFeO3-added PZT–PFW–PMN ceramics sintered at 1020°C exhibited the favorable piezoelectric and dielectric properties, which were listed as follows: d 33 =309 pC/N, K p =0.59, Q m =1551, tan δ =0.0056, ɛ r =1723, T c =308°C, Δf r/f r25°C =0.331% and ΔK p /K p25°C =−0.564%. The obtained properties make this composition to be a good candidate for high power piezoelectric devices. [Copyright &y& Elsevier]

Abstract: The binary lead-free piezoelectric ceramics with the composition of (1− x)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3 were synthesized by conventional mixed-oxide method. The phase structure transformed from rhombohedral to tetragonal phase in the range of 0.16≤ x ≤0.20. The grain sizes varied with increasing the Bi0.5K0.5TiO3 content. Electrical properties of ceramics are significantly influenced by the Bi0.5K0.5TiO3 content. Two phase transitions at T t (the temperature at which the phase transition from rhombohedral to tetragonal occurs) and T c (the Curie temperature) were observed in all the ceramics. Adding Bi0.5K0.5TiO3 content caused the variations of T t and T c. A diffuse character was proved by the linear fitting of the modified Curie–Weiss law. Besides, the ceramics with homogeneous microstructure and excellent electrical properties were obtained at x =0.18 and sintered at 1170°C. The piezoelectric constant d 33, the electromechanical coupling factor K p and the dielectric constant ɛ r reached 144pC/N, 0.29 and 893, respectively. The dissipation factor tan δ was 0.037. [Copyright &y& Elsevier]

Abstract: Low temperature sintering of Pb(Zr,Ti)O3–Pb(Fe2/3W1/3)O3–Pb(Mn1/3Nb2/3)O3 (PZT–PFW–PMN) quaternary piezoelectric ceramics were studied with the use of YMnO3 as sintering aid. The sintering aid improved the sinterability of PZT–PFW–PMN ceramics due to the effect of YMnO3 liquid phase. The effects of YMnO3 contents and sintering temperature on the phase structure, density, dielectric and piezoelectric properties were investigated. The results show that the sintering temperature can be decreased and the electrical properties can be maintained by the YMnO3 addition. The optimized properties were obtained by doping 0.30wt.% YMnO3 and sintering at 1020°C, which are listed as follows: d 33 =341pC/N, K p =0.57, Q m =1393, tan δ =0.0053, T c =304°C, P r =17.13μC/cm2 and E c =11.15kV/cm, which make this system be a promising material for multilayer piezoelectric actuator and transformer applications. [Copyright &y& Elsevier]

Abstract: The ceramics with 0.90Pb(Zr0.50Ti0.50)O3–0.07Pb(Mn1/3Nb2/3)O3–0.03Pb(Ni1/2W1/2)O3 were prepared by adding Cr2O3. The effects of Cr2O3 doping on the phase structure, the microstructure and the electrical properties of ceramics were investigated. Meanwhile, the temperature stabilities of the resonant frequency (f r) and the electromechanical coupling factor (K p) were studied. The results showed that the better temperature stability could be obtained at x =0.2wt.% when the calcining temperature was 800°C and the sintering temperature was 1150°C. The parameters were Δf r/f r25°C =−0.17% and ΔK p /K p25°C =−1.39%. Moreover, the optimized electrical properties were also achieved, which were K P =0.54, Q m =1730, d 33 =330pC/N, ɛ r =2078 and tan δ =0.0052. The optimized properties make the ceramics with this composition to be a good candidate for high power piezoelectric transformers applications. [Copyright &y& Elsevier]

Abstract: In this study, three kinds of central driving type piezoelectric transformers, Types A, B and C with different electrode distributing were investigated by using impedance analyses. With the increase of the input electrode area, the resonant resistance of input section decreased and the effective electromechanical coefficient increased. With the decrease of the length of the generator section, the resonant resistance of generator section increased and the effective electromechanical coefficient decreased. The voltage step-up ratio increased with the increase of the ratio of the input and output resonant resistance. The temperature rise of Type A was lower because the impedance matching between the load resistance and the output impedance was achieved. Taking into consideration of the mechanical quality factor (Q m), the output impedance (Z out) and the temperature rise (ΔT) of each transformer, Type A with the input electrode length ratio of 1:1:1 could be selected as the optimum structure to drive the LCD backlight. [Copyright &y& Elsevier]

Abstract: For the fabrication as piezoelectric transformers, the density, microstructure, dielectric and piezoelectric properties of Pb(Mg1/3Nb2/3)O3–Pb(Zn1/3Nb2/3)O3–Pb(Zr0.52Ti0.48)O3 (PMN–PZN–PZT) ceramics as a function of calcining temperature and sintering temperature were investigated. In addition, the piezoelectric transformers with the composition of PMN–PZN–PZT were fabricated and the characteristics with various resistance loads were measured. The results indicated that the optimized properties of ceramics were obtained at calcining temperature of 800°C and sintering temperature of 1020°C, which were listed as follows: d 33 =249pC/N, K p =0.57, Q m =1954, ɛ r =1122 and tan δ =0.0059. Meanwhile, piezoelectric transformers sintered at 1020°C show the favorable characteristics with a higher step-up ratio of 145 and a lower temperature rise of 5°C at 250kΩ. [Copyright &y& Elsevier]

Abstract: (K0.5Na0.5)NbO3 (KNN) and 0.995(K0.5Na0.5)NbO3–0.005AETiO3 (AE=Mg, Ca, Sr, Ba) were successfully prepared by conventional ceramic processing and without the cold-isostatic-pressing (CIP) process. The effects of low AETiO3 (AET) concentration on crystal structure, density, dielectric and piezoelectric properties of the KNN based ceramics were evaluated. The results show that adding MgTiO3(MT) and BaTiO3(BT) to KNN can lead to the appearance of a trace amount of second phase(s), reduced density and deteriorated electrical properties. Adding CaTiO3(CT) and SrTiO3(ST) to KNN can promote densification and optimize electrical properties. Two phase transitions at T t–o ( the temperature at which the phase transition from orthorhombic to tetragonal occurs) and T c (the Curie temperature) were observed in KNN and all KNN–AET ceramics, by using differential scanning calorimetry (DSC) analysis and dielectric characterization. Adding AET to KNN caused the variations of T t–o and T c. [Copyright &y& Elsevier]

Abstract: Anisometric KSr2Nb5O15 (KSN) particles were synthesized by conventional mixed-oxide (CMO) method and molten salt synthesis (MSS) method, respectively. In MSS method, preparation of KSN was carried out in both SrCO3–Nb2O5–K2CO3–KCl system (system I) and SrNb2O6–Nb2O5–KCl system (system II). The results revealed that the single-phase KSN obtained by CMO method was clumped and without obvious acicular morphology, making it difficult to use in texturing processes. In system I, though acicular KSN particles were synthesized by controlling the amount of KCl salt, they were easily contaminated by the presence of blade-like Sr2Nb2O7. In contrast, pure KSN particles with high aspect ratio and uniform size were successfully synthesized by controlling the ratio of SrNb2O6/Nb2O5 in the new system (system II). The obtained KSN particles which are 5–30μm in length and 2–4μm in diameter are ideal templates for fabricating textured ceramics with tungsten bronze structure. Growth mechanisms in MSS method were also proposed in this work. [Copyright &y& Elsevier]

Abstract: The quaternary piezoelectric ceramics of Pb(Zr0.52Ti0.48)O3–Pb(Mn1/3Sb2/3)O3–Pb(Zn1/3Nb2/3)O3 (PZT–PMS–PZN) with different PZN contents were synthesized by molten salt synthesis (MSS). The influence of PZN content on phase structure, microstructure, dielectric and piezoelectric properties was investigated in detail. The results of X-ray diffraction (XRD) show that the phase structure of ceramics transforms from rhombohedral phase to tetragonal phase with the increasing of PZN content. The morphotropic phase boundary (MPB) of composition is located in the range of PZN content from 2 to 7mol%. The grain size of the ceramics gradually decreases with the increasing of PZN content. Dielectric and piezoelectric properties of ceramics are significantly influenced by the PZN content. Ceramics sintered at 1150°C with 5mol% PZN achieve excellent properties, which are as follows: Q m =1381, K p =0.64, d 33 =369pC/N, tan δ =0.0044 and T c =275°C. The PZT–PMS–PZN system is a promising material for high power piezoelectric transformers application. [Copyright &y& Elsevier]

Abstract: Lead-free piezoelectric ceramics with the composition of (K0.5Na0.5)NbO3 (KNN) and 0.995(K0.5Na0.5)NbO3–0.005AETiO3 (AE=Mg, Ca, Sr, Ba) were successfully prepared by conventional ceramic processing. Single perovskite phase with orthorhombic syngony can be obtained in pure KNN, KNN-CT and KNN-ST ceramics. The trace amounts of secondary phase(s) can be detected in KNN-MT and KNN-BT ceramics. Ceramics of KNN-CT and KNN-ST have higher cell parameters and higher densities than those of pure KNN ceramics. Good electrical properties (d 33 =122pC/N, K p =0.38, ɛ r =421, tan δ =0.033 and T C =406°C) can be obtained in pure KNN ceramics. The KNN-CT ceramics have optimized electrical properties, which are d 33 =116pC/N, K p =0.39, ɛ r =411, tan δ =0.024 and T C =397°C. Besides, the P r is 18.8μC/cm2 and the E c is 9.65kV/cm for pure KNN ceramics. By adding AET to KNN, the P r values decrease with increasing the AE ions radii. The air-sintered pure KNN and KNN-CT ceramics are promising lead-free piezoelectric materials for transducer applications. [Copyright &y& Elsevier]

Abstract: Lead-free piezoelectric ceramics with the composition of (1− x)(K0.5Na0.5)NbO3–xLiSbO3 [(1− x)KNN–xLS] have been synthesized by conventional solid-state sintering process and without cold isostatic pressing (CIP). A morphotropic phase boundary (MPB) between orthorhombic and pseudocubic phases was found in the composition range of 0.06≤ x <0.10. Analogous to Pb(Zr, Ti)O3, the density, dielectric and piezoelectric properties were enhanced for the composition near the MPB. The 0.94KNN–0.06LS ceramics show excellent electrical properties, which are as follows: ρ =4.44g/cm3, ɛ r =708 (10kHz), tan δ =0.037 (10kHz), d 33 =171pC/N, k p =0.38 and T c =365°C. Dielectric study revealed that the dielectric relaxor behavior was induced by increasing LS content. In addition, 0.94KNN–0.06LS ceramics also exhibited relatively good ferroelectric properties with remanent polarization (P r) of 18.9μC/cm2 and coercive field (E c) of 9.38kV/cm. The results show that KNN–LS ceramics have the potential to be one of the leading lead-free piezoelectric materials for electromechanical transducers applications in the future. [Copyright &y& Elsevier]

Abstract: The ceramics were prepared successfully by Pb3O4 and WO3 additions to 0.90Pb(Zr,Ti)O3–0.03Pb(Fe2/3W1/3)O3–0.07Pb(Mn1/3Nb2/3)O3 (0.90PZT–0.03PFW–0.07PMN). Effects of the additions on the structure, bulk density and electrical properties of ceramics were investigated. The results revealed that the proper additions of WO3 with 2.0wt.% Pb3O4 excess could form liquid phase that promoted the densification of the ceramics. The fracture mode changed from transgranular to intergranular as increasing WO3 with 2.0wt.% Pb3O4 excess. The piezoelectric and dielectric properties were also promoted by excess of Pb3O4 and WO3 additions. The optimized electrical properties were obtained at excess of 2.0wt.% Pb3O4 and 0.15wt.% WO3. The parameters were as follows: d 33 =351pC/N, K p =0.64, Q m =1882, ɛ r =1798, tan δ =0.0052, P r =19.94μC/cm2 and E c =11.98kV/cm, which shows high K p, Q m, d 33 and low tan δ can be obtained simultaneously by adding WO3 addition to Pb3O4 modified PZT–PFW–PMN system. [Copyright &y& Elsevier]

Abstract: The ceramics were prepared successfully by the addition of WO3 to the Mn-modified Pb(Zr0.52Ti0.48)O3–Pb(Mn1/3Sb2/3)O3–Pb(Zn1/3Nb2/3)O3 (PZT–PMS–PZN) for high power piezoelectric transformers application. XRD analysis indicated that the ceramics were mainly composed of a tetragonal phase in the range of 0–1.0wt.% WO3 addition. The grain size of the ceramics significantly decreased from 10.0 to 2.9μm by addition of WO3. Moreover, the addition of WO3 promoted densification of the ceramics and increased mechanical quality factor (Q m), planar coupling factor (K p) and piezoelectric constant (d 33) kept high values, whereas, dielectric loss (tan δ) was low. Δf (=f a − f r) slightly changed when WO3 addition was above 0.5wt.%. The ceramics with 0.6wt.% WO3 addition, sintered at 1150°C showed the optimized piezoelectric and dielectric properties with Q m of 1852, K p of 0.58, d 33 of 243pC/N and tan δ of 0.0050. The ceramics are promising candidates for high power piezoelectric transformers application. [Copyright &y& Elsevier]

Abstract: Piezoelectric powders and ceramics with the composition of Pb0.95Sr0.05(Zr0.52Ti0.48)O3–Pb(Zn1/3Nb2/3)O3–Pb(Mn1/3Sb2/3)O3 (PZT–PZN–PMS) were prepared by molten salt synthesis (MSS) and conventional mixed-oxide (CMO) methods, respectively. The influence of synthesis process on the properties of powders and ceramics were investigated in detail. The results show that the MSS method significantly improved the sinterability of PZT–PZN–PMS ceramics, resulting in an improvement of dielectric and piezoelectric properties compared to the CMO method. The optimum values of MSS samples are as follows: ɛ r =1773; tan δ =0.0040; T c =280°C; d 33 =455pC/N; k p =0.70; Q m =888; E c =10.3kV/cm; and P r =28.2μC/cm2, at calcination of 800°C and sintering of 1120°C temperature. [Copyright &y& Elsevier]

Abstract: A new piezoelectric material, Pb(Zr,Ti)O3–Pb(Fe2/3W1/3)O3–Pb(Mn1/3Nb2/3)O3 (PZT–PFW–PMN) ceramics, was prepared by conventional mixed-oxide method. Effects of Pb(Fe2/3W1/3)O3 (PFW) content on phase structure, microstructure, dielectric and piezoelectric properties of PZT–PFW–PMN ceramics were studied. It indicates that substitution of Pb(Fe2/3W1/3)O3 is effective on forming the solid solution and inhibiting the formation of pyrochlore phase. The proper addition of Pb(Fe2/3W1/3)O3 can promote the grain growth of the ceramics and make the ceramics have a high density. The dielectric and piezoelectric properties are also enhanced by adding Pb(Fe2/3W1/3)O3 into PZT–PMN. The 0.90PZT–0.03PFW–0.07PMN ceramics exhibit optimized properties. The dielectric and piezoelectric properties of this composition are as follows: d 33 =358 pC/N, K p =0.63, Q m =1655, tanδ =0.0053, ɛ r =1745 and T c =273 °C, which show that this system is a new promising material for high power piezoelectric transformers application. [Copyright &y& Elsevier]

Abstract: Piezoelectric powders and ceramics with a composition of Pb0.95Sr0.05 (Zr0.52Ti0.48) O3–Pb(Mg1/3Nb2/3)O3–Pb(Mn1/3Sb2/3)O3 (PZT–PMN–PMS) were prepared by the molten salt synthesis (MSS) method. It was found that the MSS method significantly improved the sinterability of PZT–PMN–PMS ceramics, resulting in a reduction of sintering temperature by about 100 °C compared to the conventional mixed-oxide (CMO) method. The optimum values of d 33, K p, Q m and tanδ were 244 pC/N, 0.53, 1034 and 0.0090, respectively, at calcination of 800 °C and sintering of 1050 °C. [Copyright &y& Elsevier]

The multilayer ferroelectric/ferrite composites were prepared and their interaction, camber development, and interface microstructure were investigated. The results show that no chemical reaction between the ferroelectrics and ferrite materials existed. The camber is because of a mismatch shrinkage of the composites and were observed at the temperature range from 800°C to 900°C. A simple model was established to describe camber. The investigation of camber development showed that the camber developed firstly toward ferrite and then toward ferroelectrics, finally the composites become flat at 950°C. The multilayer ferroelectric/ferrite composites can be cofired at 950°C and the interface is continuous with no delamination and cracks. [ABSTRACT FROM AUTHOR]

Transparent lead-free piezoelectric ceramics, crucial for multifunctional applications in cutting-edge industries, grapple with the dual challenge of achieving superior piezoelectricity and high transmittance, a delicate balance influenced by phase structure and grain size. In this work, we present a breakthrough in 0.9Bi 0 · 5 Na 0 · 5 TiO 3 -0.1Bi 0 · 5 Li 0 · 5 TiO 3 (BNLT90) ceramic, outperforming other reported BNT-based transparent ceramics. BNLT90 showcases exceptional transmittance (T = 80.4% at 2000 nm) and robust piezoelectricity (d 33 ∼110 pC/N, k p ∼ 20.6%). Li+ incorporation induces the coexistence of rhombohedral and pseudo-cubic phases, creating local lattice distortion and enhancing piezoelectric properties. Simultaneously, Bi 0 · 5 Li 0 · 5 TiO 3 (BLT) modification enhances relative density and reduces grain size, contributing to high transparency. Our results highlight A-site Li doping as a potent strategy for stabilizing the non-ergodic relaxor phase in BNT-based ceramics, offering insights for the precision development of piezoelectric transparent ceramics by regulating grain size and phase structure. [ABSTRACT FROM AUTHOR]

High-performance lead-free dielectric ceramics are key to energy storage ceramic capacitors. In this work, an effective strategy was adopted to improve the dielectric energy storage properties (ESP) of Bi 0.5 Na 0.5 TiO 3 based ceramics using CeO 2 doping. The introduction of Ce4+ refines the grain size and improves the dielectric temperature stability of the (1- x)Bi 0.4 Na 0.4 Ca 0.2 TiO 3 - x CeO 2 ceramics. However, Ce4+ is susceptible to reductive valence changes at high temperatures, forming defects that deteriorate the breakdown electric field strength (E b). To address this issue, Ce4+ valence transitions were successfully inhibited by sintering ceramics in an oxygen atmosphere. Remarkably, the E b value increases from 160 kV cm−1 for x = 0 wt% to 220 kV cm−1 for x = 0.8 wt%, and the total energy storage density increases from 1.38 J cm−3 to 2.99 J cm−3, as well as realizing a high energy storage efficiency (η ∼ 81 %). This study offers a framework for optimizing the performance of BNT-based energy storage ceramics and elucidating the precise link between valence variations and ESP. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis of multifunctional ceramics, represented as Sr 2- x Sm x Ag 0.2 Na 0.8 Nb 5- x Ti x O 15 , through the solid-state reaction method. Smaller ions in both A and B sites were co-substituted, resulting in a notable relaxation behavior, which was analyzed to determine the contributing factors for underlying structural mechanisms. Introducing Sm3+ and Ti4+ not only transformed the structure from Im 2 a to Bbm 2 symmetry and then eventually to paraelectric P 4/ mbm phase, but also induced the evolution of incommensurate structure and the formation of nano-domains to modulate relaxation behavior. Notably, the enhanced energy storage properties (W rec ∼ 3.38 J/cm3, η ∼ 84.5 %) and desirable red-orange emission performance (λ em = 610 nm) were obtained for Sr 1.7 Sm 0.3 Ag 0.2 Na 0.8 Nb 4.7 Ti 0.3 O 15 ceramics. Moreover, the multifunctional ceramics exhibited high power and current densities (P D ∼ 116.38 MW/cm3, C D ∼ 1026.43 A/cm2) together with a prolonged decay life (745 μs). Therefore, the proposed materials may be suitable for potential applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Abstract: The Ba0.5Sr0.5TiO3 (BST) thin film with the thickness of 400 nm deposited from powder target is prepared by the radio-frequency magnetron sputtering technique. The deposition rate of BST film is estimated to be 45 nm/min, which is very fast for ferroelectric materials. The dielectric properties of the as-prepared BST thin film are demonstrated. High dielectric tunability up to 42.7% and low dielectric loss small to 0.01 are achieved at a low applied voltage of 5 V. The results demonstrate that the RF magnetron sputtering from powder target is a versatile, novel technique for the deposition of high-quality ferroelectric thin films. [Copyright &y& Elsevier]

Lead-free (K0.46-x/2Na0.54-x/2Lix)(Nb0.76Ta0.20Sb0.04)O3 piezoelectric ceramics were prepared by the conventional solid state sintering method without cold-isostatic pressing process. The x-ray diffraction and Raman scattering results show that the phase structure of the ceramics undergoes a transition from pseudocubic to tetragonal phase with increasing x from 0 to 0.10. Significantly enhanced electrical properties (d33=259 pC/N, kp=0.42, [variant_greek_epsilon]r=1653, and tan δ=0.027) were obtained in the ceramics with x=0.04 near the morphotropic phase boundary, and only the tetragonal-cubic phase transition was observed above the room temperature in the [variant_greek_epsilon]r-T curve. The temperature stability of the ceramics with x=0.04 was also investigated. [ABSTRACT FROM AUTHOR]