Piezoelectric and dielectric properties of Cr-doped PSN-PZN-PZT qua-ternary piezoelectric ceramics

PSN-PZN-PZT + x wt. %Cr2O3, X = 0.0-0-9, were prepared by conventional mixed oxide techniques at sintering temperatures of 1220 degrees C-1300 degrees C for 2 h. The effect of sintering temperature on the microstructure and the piezoelectric properties was investigated by XRD, SEM, and other conventional measurement. The result indicated that with temperature increasing, the valence of Cr ion from Cr5+ or Cr6+ changes into C3+, and the piezoelectric properties turn hard. With increasing Cr2O3 content, the amount of rhombohedral phases increases and the morphotropic boundary phase is correspondingly shifts to rhombohedral phase. A uniform microstructure and excellent comprehensive properties were obtained at 1240 degrees C as the amount of Cr2O3 is 0.5 wt.%.

Effects of Cr_2O_3 doping on the electrical properties and the temperature stabilities of PZT binary piezoelectric ceramics

The ceramics with Pb1.04Zr0.52Ti0.48O3 ＋ z wt.% Cr2O3 were prepared using the traditional technique. 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 （fx） were studied. The results showed that the △fr/fr,25℃ decreased with the addition of 0.2 wt.% - 0.8 wt.% Cr2O3 as compared with the undoped samples. The minimum value （-0.182%） of △fr/fr,25℃ was obtained for z = 0.6 wt.% Cr2O3 samples that sintered at 1260℃. The values of ε^τ33/ε0 = 1650, tanδ = 0.006, d33 = 328 pC/N, Kp = 0.63, Qm = 2300 were obtained when Cr2O3 was 0.6 wt.%, which exhibited more excellent piezoelectric properties than other compositions such as those with z = 0.2 wt.%, 0.4 wt.%, and 0.8 wt.%, but had a similar value as compared with the tmdoped samples. When the Cr2O3 additive increased, the Curie temperature moved toward low temperature and the changes of resonant frequency changed from positive to negative with increasing temperature.

Effects of CeO_2 doping on the structure and properties of PSN-PZN-PMS-PZT piezoelectric ceramics

Quinary system piezoelectric ceramics PSN-PZN-PMS-PZT were prepared by using a two-step method. The effects of CeO2 doping on piezoelectric and dielectric properties of the system were investigated at morphotropic phase boundary （MPB）. The results reveal that the relative dielectric constant ε33^T｜ε0, the Curie temperature To, the piezoelectric constant d33, the mechanical quality factor Qm, and the electromechanical coupling coefficient Kp are changed with the increase of CeO2 content. On the other hand, the effects of CeO2 doping on the dielectric properties of PSN-PZN-PMS-PZT piezoelectric ceramics at high electric field are consistent with the change at weak electric field. The values of dielectric constant and dielectric loss are enhanced with the increasing of electric field.

Effects of Sr^(2+) substitution on the structural, dielectric, and piezoelectric properties of PZT-PMN ceramics

This study described the structural, dielectric, and piezoelectric behavior of Pb1-xSrx[（Zr0.52Ti0.48）0.95（Mn1/3Nb2/3）0.05]O3 ceramics （PSZT-PMN, x=0, 0.025, 0.050, and 0.075）, prepared by a semi-wet route. X-ray diffraction, dielectric, and piezoelectric investigations were carried out to analyze the crystal structure. The relative dielectric constant and dielectric loss were both calculated as the functions of temperature. The room-temperature dielectric constant reaches a maximum for a Sr2＋-modified PZT-PMN ceramic with an x value of 0.050, which corresponds to the morphotropic phase boundary （MPB）. Raman spectroscopy studies also confirm the existence of this MPB for x=0.050. The piezoelectric strain coefficients （d33） value shows a maximum response for this composition. In addition, the phase transition temperature decreases significantly when the Sr2＋concentration increases in the PZT-PMN ceramics.

Enhanced piezoelectric properties of Nd^(3+) doped nano-lead zirconate titanate piezoelectric ceramics

Nd3+ doped lead zirconate titanate (Pb1-3x/2NdxZr0.52Ti0.48O3, PNZT) nanopowders were prepared through a modified sol-gel method. The effects of Nd3+ doping on the microstructures and properties of PNZT ceramics have been studies. The grain sizes of the perovskite PNZT nanopowders were about 100nm and the lattice distortion of the PNZT increased with the content of Nd3+ up to 9 mol%. The dopant of Nd3+ resulted in the decrease of crystal lattice parameter a and the obvious increase of c and c/a, which effectively improved the sintered densification and activity of the PNZT ceramics. Due to lead vacancies caused by the doping of Nd3+ in the PZT, the piezoelectric constant, electromechanical coupling coefficient and dielectric constant observed were much higher than the monolithic PZT.

Dielectric, piezoelectric, and ferroelectric properties of lanthanum-modified PZTFN ceramics

Specimens of Pb1-1.5xLax（Zr0.53 Ti0.47）1-y-zFeyNb2O3 （x = 0, 0.004, 0.008, 0.012, and 0.016, y = z = 0.01） （PZTFN） ceramics were synthesized by a semi-wet route. In the present study, the effect of La doping was investigated on the structural, microstructural, dielectric, piezoelectric, and ferroelectric properties of the ceramics. The results show that, the tetragonal （space group P4mm） and rhombohedral （space group R3c） phases are observed to coexist in the sample at x = 0.012. Microstructural investigations of all the samples reveal that La doping inhibits grain growth. Doping of La into PZTFN improves the dielectric, ferroelectric, and piezoelectric properties of the ceramics. The hys- teresis loops of all specimens exhibit nonlinear behavior. The dielectric, piezoelectric and ferroelectric properties show a maximum response atx 〉 0.012, which corresponds to the morphotropic phase boundary （MPB）.

Microstructure and electrical properties of Ti-modified (Na_(0.5)K_(0.5))(Ti_xNb_(1-x))O_3 lead-free piezoelectric ceramics

Ti-Modified (Na0.5K0.5)(TixNb1-x)O3 (NKNT) piezoelectric ceramics were fabricated by double-layer buried powder process at 1020°C for 2 h. The microstructures,and piezoelectric and dielectric properties of the lead-free NKNT ceramics were investigated. X-ray diffraction re-sults indicated that Ti4+ had diffused into the (Na0.5K0.5)NbO3 lattices to form a solid solution with a perovskite structure. The introducing of Ti into the (Na0.5K0.5)NbO3 solid solution effectively reduced the sintering temperature and...

Microstructures and Electrical Properties of Bi_(0.5)-(Na_(1-x-y)K_xLi_y)_(0.5)TiO_3 Lead-free Piezoelectric Ceramics

The microstructures and electrical properties of Bi0.5（Na1-x-yKxLiy）0.5TiO3 lead-free piezoelectric ceramics were studied.These ceramics were prepared by conventional ceramic technique.XRD analysis reveals that the ceramics possess almost pure perovskite phase when y≤0.2.The SEM results show that,with more amounts of Li＋,the crystalline grain growing speed is accelerated,and the sintering temperature can effectively be decreased.The measurements of piezoelectric properties indicate that the ceramics with relatively low amount of Li＋ and high amount of K＋ have comparatively large piezoelectricity.The dielectric measurements show that the ceramics have properties like relaxor ferroelectrics and diffuse phase transition（DPT） at Td and Tc,respectively.The results of ferroelectric measurements reveal the system has relatively higher remanent polarization Pr（27.6 μC/cm2） and lower coercive field Ec（37.5 kV/cm）.

Dielectric and piezoelectric properties of(Li,Ce) modified NaBi_5Ti_5O_(18) composite ceramics

Nominal （Li0.5Ce0.5）x（Na0.5Bi0.5）（1-x）Na0.5Bi4.5Ti5O18 composite ceramics were fabricated using conventional solid-state reaction method. The coexistence of bismuth layer-structured phase and perovskite phase was determined in these ceramics using XRD technique. At room temperature, the x=0.11 sample showed the largest piezoelectric constant, d33, of about 26.5 pC/N and the largest electromechanical coupling factor, kt, of about 30%. Even after annealing at 500 ℃, the value of d33 was still about 19 pC/N, in x=0.08-0.11 samples. Moreover these composite ceramics showed low temperature coefficients of dielectric constant and high electrical resistivity in the temperature region of 450-550 ℃. These results indicated that （Li, Ce） modified NaBi5Ti5O18 composite ceramics were promising piezoelectric materials for high-temperature applications.

Influence of Sb_2O_3 doping on the properties of KBT-NBT-BT lead-free piezoelectric ceramics

0.144（K0.5Bi0.5）TiO3-0.85（Na0.5Bi0.5）TiO3-0.006BaTiO3（KBT-NBT-BT） lead-free piezoelectric ceramics were prepared using a conventional solid state method.The influence of Sb2O3 doping on the crystal phase,surface microstructure and properties of the KBT-NBT-BT lead-free piezoelectric ceramics were investigated using X-ray diffraction（XRD）,scanning electron microscope（SEM） and other analytical methods.The results show that all compositions are of pure perovskite structure solid states.Sb2O3 doping does not influence the microstructure of KBT-NBT-BT lead-free piezoelectric ceramics obviously in the Sb2O3 doping range of 0.1-0.5 wt.%.Sb2O3 functions as a donor when doped small amount,while functions as a acceptor when doped large amount.The piezoelectric strain constant（d33） increases first and then decreases;the dielectric constant（ε33^T/ε0） and the dielectric loss（tanδ） decrease continuously when the amount of Sb2O3 dopant increases.When the doping amount of Sb2O3 is 0.1 wt.%,the KBT-NBT-BT piezoelectric ceramics with good comprehensive properties are obtained,whose d33,ε33^T/ε0 and tanδ are 147 pC/N,1510 and 4.2%,respectively.

Preparation and Piezoelectric Properties of CuO-added(Ag_(0.75)Li_(0.1)Na_(0.1)K_(0.05_)NbO_3 Lead-free Ceramics

CuO-doped（Ag0.75Li0.1Na0.1K0.05）NbO3（ALNKN-xCuO, x = 0.2mol%） lead-free piezoelectric ceramics were prepared by the solid-state reaction method in air atmosphere. The effects of CuO addition on the phase structure, microstructure, and piezoelectric properties of the ceramics were investigated. The experimental results show that the ALNKN ceramics without doping CuO possess rhombohedral phase along with K2NbrO16- type phase and metallic silver phase. For all of the CuO-doped ALNKN ceramics, a pure perovskite structure with the orthorhombic phase was obtained by enclosing the samples in a corundum tube. A homogeneous microstructure with＇the grain size of about 1 ~tm was formed for the ceramics with 0.5mo1% CuO. The grain size increases with increasing amount of CuO. The temperature dependence of dielectric properties indicates that the ferroelectric phase of the ALNKN-xCuO ceramics becomes less stable with the addition of CuO. The ceramics with x = lm01% exhibit relatively good electrical properties along with a high Curie temperature. These results will provide a helpful guidance to preparing other AN-based ceramics by solid-state reaction method in air atmosphere.

Phase Structure, Microstructure and Electrical Properties of K_xNa_((1-x))NbO_3 Piezoelectric Ceramics with Different K/Na Ratio

The K_xNa_((1-x))NbO_3(x=0.45, 0.46, 0.47, 0.48, 0.49, 0.50) lead-free piezoelectric ceramics was fabricated by conventional solid-state sintering method. It was found that the ratio of alkaline metal would affect the microstructure, bulk density, and optimum sintering temperatures of ceramics. Meanwhile, the electrical properties were also influenced by modulating the K/Na ratio, exhibiting corresponding composition-dependent properties. The optimum electrical properties of K_xNa_((1-x))NbO_3 such as piezoelectric constant d_(33) = 115 pC/N, mechanical quality factor Q_m = 20, Curie temperature Tc = 365 ~oC, ε_(33)~T/ε_0= 588.1, dielectric loss tan δ = 0.024, bulk density(ρ) = 3.08 g/cm^3, remnant polarization(P_r) = 8.87 μC/cm^2 and coercive field(Ec) = 13.79 kV/cm were obtained at x = 0.46.

Modified phase transition and electrical properties of [Li_(0.05)(Na_(0.535)K_(0.48))_(0.95)]- (Nb_(0.94)Sb_(0.06))O_3 lead-free piezoelectric ceramic by sintering temperature

Li/Sb-doped (Na,K)NbO3 with a nominal composition of [Li0.05(Na0.535K0.48)0.95](Nb0.94Sb0.06)O3 ceramic was synthesized by normal sintering. The phase structure, microstructure, and electrical properties were investigated with a special emphasis on the influence of the sintering temperature. A polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry was observed when the sintering temperature was raised from 1040 to 1050 ℃, whereby the piezoelectric coefficient d33 and the electromechanical coupling coefficient kp reached the peak values of 245 pC·N-1 and 41.2%, respectively. The PPT induced by varying the sintering temperature is due to the different volatilization extents of alkali metals and appears to a lower sintering temperature with increasing Li content. The trace modifying of alkali metal content is more effective than doping B site element to enhance the d33 value.

Effect of KNbO_3 content on the crystal structure and electrical properties of(1-x)PbZr_(0.54)Ti_(0.46)O_3-xKNbO_3 piezoelectric ceramics

（1 - x）PbZr0.54Tio.4603-xKNbO3 （0 〈 x 〈 25mo1%） （abbreviated as PZT-xKN） piezoelectric ceramics were successfully fabricated by a traditional sintering technique at 1225℃ for 30 min. The influence of KNbO3 content on the crystal structure and electrical properties of the PZT-xKN piezoelectric ceramics was studied. Samples with 0 〈 x 0.20 show a pure peroskite structure, indicating that ul KNbOdiffused ito the crystal lattice of PZT to form a single solid solution in this compositional range. A second Pb3Nb4013 phase is observed in the PZT-0.25KN sample, showing that the maximum solid solubility of KNbO3 in PZT matrix ceramic is less than 25mo1%. Compared with pure PZT piezoelectric ceramics, samples containing KNbO3 have smaller crystal grains. PZT-0.15KN exhibits excellent piezoelectric properties with d33 ： 209 pC/N.

Intermediate Temperature Sintering of La-Modified Ph(Zn_(1/3)Nb_(2/3))O_3-PbZrO_3-PbTiO_3 Piezoelectric Ceramics

in order to realize the co-firing with Ag/Pd electrodes in multilayer devices, Pb(Zn1/3Nb2/3)(1-x-y) ZrxTiyO3(0.25<x<0.35, 0.25<y<0.35) piezoelectric ceramics thereafter designated PZN-PZT) modified by La2O3 has been prepared by conventional technique with sintering temperature from 1100 degreesC to 1140 degreesC. X-ray diffraction patterns demonstrated that pure perovskite phase was obtained. Secondary electron image (SEI) showed that crystalline grains in ceramics were well grown. d(33) of manufactured sample was as high as 560 x 10(-12)C/N. k(p) was about 0.61 and tg delta about 30 x 10(-3). The existence of liquid phase examined by electron diffraction in PZN-PZT sample is beneficial to sintering of the ceramic.

Effects of Excess Barium on the Structure and Electrical Properties of(Ba,Ca)TiO_3 Piezoelectric Ceramics with High Mechanical Quality Factors

Manganese-doped Ba（0.925）Ca（0.075）TiO3 lead-free piezoelectric ceramics（abbreviated as BCT）with high mechanical quality factor were synthesized by conventional solid-state reaction method.The effects of excess Ba on the crystal structure,microstructure,and electrical properties of the ceramics were systematically investigated.X-ray diffraction and Raman spectra revealed that Ca^2＋ions were pushed from Ba sites to Ti sites of BCT when 1.5 mol%extra Ba^2＋ions were added after sintering.The grain size of the ceramics was decreased by adding extra Ba^2＋ions.The mechanical quality factor and resistivity of the ceramics decreased dramatically when the excess Ba was more than 1.5 mol%.High piezoelectric coefficients（d（33）=150-190 pC/N）and high mechanical quality factors（Qm=1 000-1 200）were obtained in the ceramics when the excess of Ba was between 0.5 mol%and 1 mol%.These results indicated that the properties of BCT ceramics could be tailored by adjusting the content of Ba.

Effect of doped Mn on piezoelectric properties of (Na_(0.5)Bi_(0.5))_ (0.92)Ba_(0.08)TiO_3 lead-free ceramics

Piezoelectric ceramics (Na0.5Bi0.5) （0.92）Ba0.08TiO3 +x%MnCO3（BNBT-Mn, x=0CD*21.6, mass fraction） were synthesized by conventional solid state reaction. The results show that when the addition of MnCO3 is 0CD*2 1.4%, BNBT-Mn ceramics exhibit a single-phase perovskite structure. With the increase of content of MnCO3, piezoelectric constant and electromechanical coupling factor increase rapidly when x is lower than 0.3. Then they both decrease when x is in the range of 0.3 and 1.6. When x=0.3, piezoelectric constant and electromechanical coupling factor reach the maximum value of 160pC/N and 58.5% respectively, which can improve the temperature stability of BNBT-Mn.

Effect of Lead Contents on the Properties of PMSZT Piezoelectric Ceramics

The effects of Pb content on crystallographic phase, microstructure, electric-properties of PMSZT piezoelectric ceramics were studied. The crystallographic phase and microstructure of the ceramics were examined by using X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The experimental result shows that the samples consist of a mixture of tetragonal and rhombohedral phases in the range of lead contents x=0.95-1.06, grains grow up homogeneously and the minimum value of Curie temperature was obtained with x-=1.02. With Pb content x〈l.02 or x〉1.02, the Curie temperature moves towards a high temperature. A well-situated electric-properties of ET33/E0 （1660）, d33 （344pC/N）, Kp （0.684）, Qm （2350）,tan 3（0.0030） were obtained when lead content x=1.02.

Enhanced piezoelectric properties in low-temperature sintering PZN-PZT ceramics by adjusting Zr/Ti ratio

Pb_(0.96)Sr_(0.04)(Zr,Ti)_(0.7)(Zn_(1/3)Nb_(2/3))_(0.3)O_(3)(PZN-PZT)piezoceramics with various Zr/Ti ratios and Li_(2)CO_(3)sintering aid were sintered at 900°C by the solid-state reaction route.The samples with different Zr/Ti ratios were compared according to microstructure,phase structure,piezoelectricity,ferroelectricity,and dielectric relaxation.The Zr/Ti ratio in the PZN-PZT ceramics greatly affects the electrical properties.The Zr/Ti ratio affects the proportion between the rhombohedral and tetragonal phases and also affects the grain size.The PZN-PZT ceramics with the Zr/Ti ratio of 53:47 have the largest grain size and have optimized piezoelectric prop-erties(k_(p)=0.58,d_(33)=540 pC/N,and T_(C)=250°C).The larger the grain size,the lesser the grain boundary,the easier the domain wall motion,and the better the piezoelectric properties.The PZT ceramic with Zr/Ti ratio of 53:47 locates the morphotropic phase boundary(MPB)region which is one of the key factors for the high piezoelectric properties of the PZT.

Effect of poling condition on piezoelectric properties of (K_(0.5)Na_(0.5))NbO_3 ceramics

The lead-free piezoelectric ceramics (K0.5Na0.5)NbO3 (abbreviated as KNN) with the relative density of 97.6% were synthesized by press-less sintering owing to the careful control of processing conditions. The phase structure of KNN ceramics was analyzed. The results show that the pure perovskite phase with orthorhombic symmetry is in all ceramics specimens. The effect of poling conditions on the piezoelectric properties of KNN ceramics was investigated. The results show that the piezoelectric constant d33 and electromechanical coupling factor kp increase with poling field, poling temperature and poling time increasing, then decrease because of electric broken. Take into account of poling conditions and piezoelectric properties of pure KNN ceramics, the optimum poling conditions for pure KNN ceramics are poling field of 4 kV/mm, poling temperature of 140℃and poling time of 20-25 min.