Modified PbTiO3 Ceramics Research Articles

Dielectric and room temperature ferromagnetism in vacuum annealed Bi(Zn0.5Zr0.5)O3 modified PbTiO3 ceramics

Polycrystalline solid solutions of (1-x)PbTiO3-(x)Bi(Zn0.5Zr0.5)O3[x = 0.10, 0.20, 0.30] have been synthesized by using solid state reaction method and followed by air annealing (AA)/ vacuum annealing (VA). All the samples show single phase perovskite structure with tetragonal symmetry (P4mm). Structural parameters are calculated using the Rietveld refinement technique. With the help of Scanning Electron Microscope (SEM), the surface morphology of all the samples is recorded at room temperature. The influence of VA on dielectric parameters such as dielectric constant and tangent loss of the synthesized samples are studied and compared with that of AA samples. These results unfold superior dielectric properties of VA samples as compared to AA samples. Intriguingly, the VA samples exhibit exotic ferromagnetism in non-magnetic PbTiO3–Bi(Zn0.5Zr0.5)O3 samples, transforming these into room temperature magneto-electric multiferroics. Besides, both the ferroelectric and ferromagnetic order parameters were found to increase with the increase in Bi(Zn0.5Zr0.5)O3 doping in PbTiO3. The enhanced physical properties witnessed in VA PbTiO3–Bi(Zn0.5Zr0.5)O3 samples localized hopping of charge carriers confined to the grain.

Dielectric polarization and electrical properties of Modified PbTiO3 Piezoelectric Ceramics for high frequency transducer applications

PbTiO3 ceramics which modified by chiral symmetry material LiYW2O8 for the applications of high frequency transducers or actuators were investigated. The densification test results show that the LiYW2O8 modified PbTiO3 ceramics have good sintering properties at 900 °C. The dipole relaxation of PbTiO3 ceramics occurred at around 107 Hz, the difference of dipole relaxation time between polarized and unpolarized sample shows strong correlation with the piezoelectric constant. The d33, K33, and Np are close related to Tetragonality. The Tetragonality is higher, the value of d33, and K33 are also higher, and the value of Np is lower. The PbTiO3-0.35wt.% LiYW2O8 ceramic shows the relatively good properties of 68 pC/N and 245.4 for d33 and K33, respectively, which can meet the applications of high frequency transducers.

Phase transition and thermal depolarization of double perovskite modified low sintering temperature PbTiO3 piezoelectric ceramics

Phase transition and thermal depolarization of PbTiO3 piezoelectric ceramics with Double Perovskite modified were investigated. With 5mol% Double Perovskite (BFM, BNM, YNM, SNM), the PbTiO3 has a possibility to change the crystal structure to a large extent, and the sintering temperature can be controlled below 960°C. With increasing ionic radius difference between addition and PbTiO3, the crystal structure of modified PbTiO3, measured by synchrotron radiation changed from Tetragonal (P4mm) to Orthorhombic (Pmm2) and became more ordered (from 2×2×1 super cell to 6×2×2 super cell). The ordered Orthorhombic structure PT has higher phase transition temperature (496–540°C) than the Tetragonal PT (481°C). All modified PbTiO3 ceramics show high depolarization temperature. The depolarization temperatures of PT-BFM, PT-BNM, PT-YNM, and PT-SNM are 470°C, 480°C, 495°C, and 505°C, respectively.

XRD Study on D-Values of Modified PbTiO<sub>3</sub> Ceramics during Poling Process

The Calcium modified PbTiO3 ceramics with large piezoelectric anisotropy was poled in consecutive steps. X-ray diffraction (XRD) found that the values of inter-planar spacing, d002 and d200, increased with poling field at initial poling stages. A noticeable drop of the d¬002 and d200 at the coercive field was observed. The residual stresses measured by the  angle tilt method were introduced. The relations of d002-sin2ψ and d¬¬200-sin2ψ at different poling stages were simulated by a mathematic model. The linear terms in the model are related to the macro-stress which may cause an elastic deformation; the exponential term in the model is related to the micro-stress which may cause a plastic deformation by the 90o domain switch. The results show that macro-stress and micro-stress decreased and the decay speed along  angle increased as to the d002 lattice spacing. The residual stresses related to the d200 lattice spacing were almost not changed.

THE LOW TEMPERATURE SINTERING PROPERTIES OF MODIFIED PbTiO3 CERAMICS

ABSTRACT In the study, in order to develop low-temperature-sintering ceramics for multilayer piezoelectric transformer, (Pb0.76Ca0.24 −xSrx)Ti0.96 (Mn1/3Sb2/3)0.04O3 ceramics were fabricated using Na2CO3 and Li2CO3 as sintering aids and their dielectric and piezoelectric properties were investigated with amount of Sr substitution. The modified PbTiO3 ceramics with a composition of (Pb0.76Ca0.24 − xSrx)Ti0.96 (Mn1/3Sb2/3)0.04O3; x = 0 − 0.05 were prepared by conventional mixed-oxide at sintering temperature of 880, 900 and 930°C. At the sintering temperature of 900°C, thickness vibration mode electromechanical coupling factor (Kt) and thickness vibration mode mechanical quality factor (Qmt) of composition ceramics with 1.0mol% Sr substitution showed the optimal value of 0.50 and 1575 respectively, for multilayer piezoelectric transformer application.

Nontrivial behavior of the piezoelectric coefficients of 0–3 composites of the modified PbTiO3 ceramics-polymer type

Piezoelectric properties of the 0–3 connectivity composites comprising spheroidal inclusions of modified PbTiO3 ceramics dispersed in a polymer matrix have been studied. Monotonic and nonmonotonic concentration dependences of the effective piezoelectric coefficients e 3j *, d 3j *, h 3j *, and (j=1, 3) of the composites with elongated ferroelectric ceramic (FC) inclusions are analyzed. The observed nontrivial piezoelectric response of the 0–3 composites of the modified PbTiO3 ceramics-polymer type is determined to a considerable extent by properties of the polymer matrix and by the sign of the e 3j (FC) coefficients (e 3j (FC) >0).

Electrical and Frequency Characteristics of Third-Overtone Vibration-Mode Surface Mount Device High-Frequency Filter Using Modified PbTiO3 Ceramics

In this study, a 3rd-overtone thickness-vibration-mode surface mount device (SMD) filter was manufactured using modified PbTiO3 system ceramics for application as an intermediate frequency (IF) filter with a split electrode and gap size. To investigate the effects of the split electrode and gap size on the filter characteristics of the 3rd-overtone-mode energy-trapped filter, ceramic wafers were fabricated by etching split rectangular electrodes with sizes (b ×d) of b=0.4, 0.6, 0.8 and 1 mm, d=0.3, 0.4, 0.5 and 0.6 mm and gap sizes (c) of the c=0.2, 0.3, 0.4 and 0.6 mm, respectively. Then, SMD ceramic filters were fabricated with the size of 3.7 ×3.1 mm2. SMD ceramic filter with the size of b=0.8 mm, d=0.4 mm and c=0.4 mm showed insertion loss of 2.951 dB, 3 dB bandwidth of 54.7 kHz and 20 dB stop bandwidth of 129.27 kHz. Also, these two filters were cascaded and their bandwidth characteristics were investigated by varying the coupling capacitance to check their applicability as high frequency band-pass filters. The cascaded filter showed a higher stop band, reduction of spurious response and increase of selectivity. With increasing coupling capacitance, insertion loss increased but spurious response decreased. The cascaded filter with a coupling capacitance of 15 pF showed insertion loss of 5.643 dB, 3 dB bandwidth of 55.089 kHz and 20 dB bandwidth of 83.608 kHz.

Electrical and resonant characteristics of modified PbTiO3 ceramics for SMD-type high frequency resonators using 3rd overtone thickness vibration mode

Abstract The micro-structural, electrical and resonant properties of (Pb, La, Nd)(Ti, Mn, Sb)O3 ceramics were investigated as a function of CuO addition and internal electrode weight. The best properties for the resonator application were observed from the 0.25 wt.% CuO added specimen sintered at 1200 °C. Curie temperature and density of the specimen were measured to be 325 °C and 7.72 g/cm3, respectively. Dynamic characteristics of energy-trapped 30 MHz surface mount device (SMD) type resonators using 3rd overtone thickness vibration mode were also investigated as a function of internal electrode weight and CuO addition. Ceramic wafers for resonator were fabricated by evaporating electrode weights of 0.66, 1.765, 2.32, and 3.87×10−4 g/cm2 with silver, respectively. And then, 30 MHz SMD-type ceramic resonators were fabricated with the size of 3.7 mm ×3.1 mm and electrode diameter of 0.77 mm. With increasing electrode weight, resonant resistance was gradually decreased. At the electrode weight of 2.32×10−4 g/cm2, mechanical quality factor (Qmt3) and dynamic range (DR) for the 3rd overtone thickness vibration mode showed the maximum value of 2152 and 49 dB, respectively.

On the structural and electrical properties of modified PbTiO3 ceramics

Ceramics (Pb0·75Ca0·25)[(Ni1/2W1/2) y Ti1−y ]O3 fory = 0 ·05, 0·10, 0·15 and 0·30 have been prepared using high temperature solid state reaction method. X-ray analyses show that these materials are of single-phase perovskite type tetragonal structure. To solve inaccuracy in finding para-ferroelectric phase transition temperatureT c(ε max), we have carried out the analyses of the data using a computer program. The role of Ni and W as modifiers on structural and electrical (dielectric and pyroelectric) properties is discussed in terms of the usefulness of these materials. Results indicate that ceramic Pb0·75Ca0·25Ni0·25W0·025Ti0·95O3 is a good candidate for pyroelectric applications.

Microstructure study of Sm, Mn-modified PbTiO3 piezoelectric ceramics by XRD profile-fitting technique

By using the X-ray diffraction profile-fitting technique, the microstructures of Sm, Mn-modified PbTiO3 piezoelectric ceramic discs, including ferroelectric domain sizes, microstrains, and their variations with the poling strength have been quantitatively investigated. The results manifest that the modified PbTiO3 ceramics contain a high density of domain walls due to the presence of finely-divided coherent domain structures (tens of nanometres in dimension). The poling treament can evidently influence the domain-size distribution, with a more homogeneous microstructure being developed; however, it simultaneously causes high anisotropic microstrains within the structure which, together with the high density of domain walls, is expected to be responsible for the unusual high electromechanical coupling properties possessed by this material.

AN X Ray Diffraction STUDY ON THE ULTRA-HIGH ELECT-ROMECHANICAL ANISOTROPY IN (Pb0.85Sm0.10)(Ti0.98Mn0.02)O3 PIEZOELECTRIC CERAMICS

XRD technique was employed to examine Sm-modified PbTiO3 piezoelectric ceramics with typical ultra-high electromechanical anisotropy. By introducing crystal plane orientation density ρ(hkl) and establishing wall translation model for 90°ferroelectric domain switching, a quantitative analysis and discussion on the domain texture change within the ceramic disks poled at various electric forces has been carried out. The results indicate that 90°domain walls in the modified PbTiO3 ceramics show a strong spatial orientation preference, and little changes in their orientation can result from poling treatment but noticeable wall displacement appears. Another noteworthy result is that the thickness electromechanical coupling coefficient Kt develops with poling field almost at the same pace as the orientation density gain △ρ(002) of the crystal plane (002).

Investigation on switching behaviour of 90° ferroelectric domains in (Pb0.85Sm0.10) (Ti0.98Mn0.02)O3 piezoelectric ceramics of ultra-high electromechanical anisotropy by the X-ray diffraction technique

An investigation on Sm modified PbTiO3 ceramics of typical ultra-high electromechanical anisotropy was carried out by means of X-ray diffraction (XRD) technique. By introduction of crystal plane orientation density ρ(hkl), a good description of switching behaviour of 90° ferroelectric domains within the ceramic discs poled at different electric forces has been achieved. The results indicate that 90° domains show a strong spatial orientation preference so that most of the 90° walls are oriented with their normal vectors enclosing an angle 45° with the specimen surface. After poling treatment few changes occurred in the 90° wall distribution but noticeable domain wall shifts occurred. Another noteworthy result is that the thickness electromechanical coupling coefficient K t develops with poling field almost at the same pace as the orientation density gain Δρ (002) of (002) crystal plane does. The implications of their mutual linkage are outlined.

Effects of Sm2O3 and Gd2O3+ Nd2O3 on Electromechanical Properties of PbTiO3 Ceramics

The electromechanical properties of PbTiO3 ceramics, modified by substitution of Sm or Gd + Nd (same average atomic radius as Sm) for Pb, were studied in the range of 6% to 14% substitution. The modified PbTiO3 ceramics were stable, and the Curie temperature decreased linearly over this composition range. The 10% Sm composition had a large anisotropy in the coupling factor ratio, kt/kp, and a similar, but weaker, effect developed for 12% (1/2 Gd + 1/2 Nd). This indicates that other than average ion size may influence the electromechanical coupling factor ratio.

Ferroelectric properties and microstructure of doped PbTiO3ceramics

Abstract Modified PbTiO3 ceramics are new materials with applications in ultrasonic transducers. PbTiO3 ceramics modified with Nd3+, Zn2+, Mn4+ and Nb5+ have been prepared and characterized by X-rays. The effect of different sintering times on dielectric properties and the average grain size are reported in this paper. The dielectric constant was found to increase with sintering time. Introduction of niobium decreases the transition temperature Tc . The average grain diameter increases with sintering time. The addition of small amount of dopants control the grain growth with average grain size ranging from 1.26 μm to 3.42 μm.

Investigation of pyroelectric characteristics of modified PbTiO3ceramics for improved IR detector performance

Abstract The detailed physical and ferroelectric-related properties of the modified PbTiO3 ceramics, namely (Pb0.74Ca0.18La0.06Bi0.02)Ti0.98O3 and (Pb0.92La0.06Bi0.02)Ti0.98O3, were investigated; and the results were then discussed in terms of the usefulness of these materials for use in IR detectors. It was found that the Ca-modified PbTiO3 has a relatively high dielectric constant, high pyroelectric coefficient and favorable thermal and mechanical characteristics. These oxide ceramics have proved to have reproducible properties and are economic to fabricate. The calculated figures of merit, based on the measured properties, were compared with other PbTiO3 materials and the widely used LiTaO3 single crystal. The results indicate that the Ca-modified PbTiO3 ceramic is a promising material for both transverse mode and pyroelectric/CCD arrays.

Piezoelectric Anisotropy in Lead Titanate System Ceramics

Pizoelectric anisotropy of PbTiO3 ceramics were experimentally investigated and discussed. The correlation between piezoelectric anisotropy and elastic constants were obtained in (Pb, (Bi, Na))((Fe, Nb)Ti)O3 ceramics. (Pb, Ca)((Co, W)Ti)O3 ceramics with kt=0.54 and kp∼0 was expanded and contracted in a transverse direction by application of a dc electric field in spite of the disappearance of the resonance of radial mode vibration, and the magnitude of displacement was equivalent to that of other modified PbTiO3 ceramics. It was estimated that the disappearance of radial mode vibration for (Pb, Ca)((Co, W)Ti)O3 ceramics was caused by a frequency dependence of transverse displacement.

Electrical Properties and Microstructure of Ca Modified PbTiO3 Ceramics

The (Pb1-x, Cax)TiO3, (x=0.12 to 0.5) ceramics were sintered, and the relationship between dielectric, piezoelectric properties and microstructure were classified as a function of Ca content. There existed no phase boundaries over the range of Ca content of 0.12 to 0.5 mol. However, the ratio of kt and kp was drastically changed as a function of Ca content. These changes were related with the appearance of 90° domains and superlattice.

Laser Micromachining of a Modified PbTiO3 Ceramics in KOH Water Solution

The Ar+ laser-enhanced chemical etching of a modified PbTiO3 ceramics is studied. It is shown that 10 mol/lKOH water solution is the best etchant for the ceramics, giving excellent appearances and edge definitions for hole and slot machining. The depth etch rate is as high as 150 µm/s for the hole machining in the first one second irradiation at 1 W output at 514.5 nm wavelength. It is postulated the main etching mechanism is not direct melting, dissolving or vaporizing of the ceramics but removing of the ceramic grains one after another.

Strain effects on surface acoustic wave velocities in modified PbTiO3 ceramics

The effect of substrate strains upon surface acoustic wave (SAW) velocities were determined for piezoelectric PbTiO3 ceramics that were modified by adding Nd2O3, In2O3, and MnO2. SAW velocity variations were measured against uniaxial bending strain in the direction of propagation. It was found that the relationship between fractional SAW velocity change and uniaxial strain reveals strong nonlinearity, which contrasts with the case for single-crystal substrates. The present ceramics were also found to have an anomalously large SAW velocity strain coefficient (∼10) at a highly strained condition (∼8×10−5).

Tuning fork resonator using modified PbTiO3 ceramics

Tuning fork resonators with very low temperature coefficients of resonance frequency were fabricated using modified PbTiO3 ceramics. The chemical formula of these ceramics is (Pb1−(3/2)x+(1/2)z Ndx) (Ti1−y−z) Mny Inz) 03. The temperature coefficient can be reduced to −2×10−6/°C at room temperature and zero at 0 °C with the composition x=0.11, y=0.02, and z=0.09. The resonance frequency of the resonators is about 30 kHz and the quality factor is 1100 at the composition. These resonators have potential for low-frequency applications such as oscillators for watches.