Lead Calcium Titanate Research Articles

Composite materials ferropiezoelectric ceramics-polymer for hydroacoustic receivers

The purpose of this work is to study the processes of interfacial interactions, their influence on the piezoelectric properties in highly elastic composite structures, to establish the patterns that determine the volume-sensitive piezoelectric characteristics of composites and to create effective piezoelectric materials for hydroacoustic receiving devices. In the process of this work, the development of a method for obtaining anisotropic ferropiezoelectric ceramics, the development of methods for the preparation of perfect ceramic powders and composite materials based on thermoplastic fluoropolymers and the study of composite materials based on lead–calcium titanate were carried out. As a result of the study, the dependences of the hydrostatic parameters of the composites on the degree of filling, particle size distribution, piezoelectric anisotropy of the active phase and the elastic properties of the polymer matrix were established. Composite materials were based on ceramics of the PT–CT system and thermoplastic fluoropolymers F-2ME, F-62, F-2N with a degree of filling with a ceramic phase from 30 to 60% vol. The dependences of the hydrostatic piezoelectric moduli [Formula: see text] and [Formula: see text], and the quality factor [Formula: see text] on the degree of filling of the composite for polymers F-62 and F-2ME with different average sizes of ceramic particles are plotted. It has been established that the maximum values [Formula: see text] = 119.1⋅10[Formula: see text]V⋅m/N and the quality factor [Formula: see text] = 6074⋅10[Formula: see text] m2/N are achieved for a polymer with a higher elastic compliance (F-62) at a degree of filling of 60% vol. and the use of granular filler.

Mechanical, surface morphological and multi-objective optimization of tribological properties of V2O5 doped lead calcium titanate borosilicate glass ceramics

In the 55[(PbxCa1−x).OTiO2]-44[2SiO2.B2O3]-1V2O5 system, various experimental studies were performed to obtain the mechanical and tribological properties of synthesized glass ceramics (GCs). The surface morphological study and elemental analysis were carried out using scanning electron microscope (SEM) followed by EDAX. The tribological measurements were also performed; based on Taguchi's L25 orthogonal array, considering different GC compositions, sliding speeds and loads. The signal to noise (S/N) ratio was used to identify the influencing parameters on minimizing wear coefficient (k) and coefficient of friction (COF). To improve the tribological properties, the modeling of output responses was performed using response surface methodology (RSM) that was being used for multi-objective optimization using a Pareto optimality approach i.e. Genetic Algorithm (GA). The experimentally achieved k and COF were compared with the earlier work that carried out by the authors for germanium (Ge) doped GC samples. It is observed that the various mechanical properties (Vickers hardness, 29 GPa, Young's modulus, 1808 MPa, and compressive strength, 221 MPa) improved significantly in comparison to the Ge doped GC samples. The improved mechanical and tribological properties of the synthesized GC can be used as a coating material for the structural alloys and machine tool slides in view of its effective wear and corrosion resistance.

Structural, optical, and nuclear magnetic resonance studies of V2O5-doped lead calcium titanate borosilicate glasses

In this study, the melt-quenching technique was used to synthesize various glass compositions for the system 55[(PbxCa1-x)·OTiO2]-44[2SiO2·B2O3]-1V2O5 (0.0 ≤ x ≤ 0.7). The synthesized glasses were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy, scanning electron microscopy (SEM), and nuclear magnetic resonance spectroscopy (NMR). The experimental density of the glass samples increased from 1.48 to 2.19 g/cm3 as the concentration of lead oxide (PbO) increased. The XRD results agreed well with the SEM observations and they confirmed the amorphous nature of the glasses. The FTIR and Raman analyses indicated the presence of various bonds comprising VOV, PbOB, BOB, SiOSi, BOSi and BOH, which were attributed to different vibrations. The optical band gap values decreased from 2.07 to 1.65 eV as the PbO content increased. 29Si and 11B magic angle spinning solid state NMR spectral analysis suggested that the number of non-bridging oxygens increased within the silicate and borate network as the concentration of PbO increased in the glassy system.

Parametric optimization of dry sliding wear and friction of germanium doped lead calcium titanate borosilicate glass ceramic

In this study, specific wear rate (SWR) and coefficient of friction (COF) of the synthesized samples in 55[(PbxCa1−x)O.TiO2]−44[2SiO2.B2O3]−1Ge with (0 ≤ x ≤ 0.7mol%) system of glass ceramics was optimized using Taguchi method. The ASTM standards were used for preparing the samples for friction and wear tests on a pin-on-disc tribometer. The glass ceramic samples were used as pin materials that slid against a disc made up of EN32 steel. For assessing the tribological properties of the glass ceramics, three control factors, viz. material-compositions with varying fraction of x (x = 0.0, 0.1, 0.3, 0.5 and 0.7mol%), sliding speeds (2.61, 3.14, 3.66, 4.18 and 4.71m/s) and loads (10, 15, 20, 25 and 30N) were considered in an L25 orthogonal array design. The optimum input parameters for the minimum SWR and COF were selected based on signal to noise ratios and main effect plots. Analysis of variance (ANOVA) revealed that the sliding speed and lead oxide content of the material are the most contributing factors on SWR and COF, respectively. The optimization for minimizing the SWR and COF was carried out and confirmed. The surface morphologies of the tested glass ceramic sample were studied using scanning electron microscope (SEM) and the elemental analysis of the samples was done using energy dispersive analysis of X-rays (EDAX). The Vickers hardness at the free surface of the glass ceramic samples increased up to 9.59mol% of lead oxide with the maximum hardness of 23.59GPa. The compressive strength of glass ceramic samples could reach up to 190MPa.

Mechanical and tribological characterization of lead calcium titanate borosilicate glass ceramic doped with ferric oxide

This paper portrays the mechanical and tribological study of the ferric doped glass ceramic sample synthesized in 59[(PbxCa1−x)O.TiO2]-40[2SiO2.B2O3]-1Fe2O3 system for x = 0.1 mole % using melt quenching technique. A pin-on-disc tribometer was used to study the wear and friction properties of the sample at various applied loads and sliding speeds under dry condition. It has been observed that the coefficient of friction decreased with an increase in the applied load and sliding speed. The specific wear rate initially increased and then decreased with an increase in increase in sliding speed. Whereas, the specific wear rate increased with an increase in applied load. Several important parameters such as Vickers hardness, fracture toughness and brittleness index of the sample were measured using Vickers hardness tester. The surface morphology and the types of wear of the worn out surface of the glass ceramic sample was studied using field emission scanning electron microscope (FESEM)

Processing and optical characterization of lead calcium titanate borosilicate glass doped with germanium

In this study, various compositions of lead calcium titanate borosilicate glass doped with a fixed amount of germanium were synthesized using the rapid melt quench technique. The amorphous nature of the synthesized glass was confirmed by X-ray diffraction and scanning electron microscopy analyses. The structural and optical properties were deduced using Raman, Fourier transform infrared (FTIR), and ultraviolet–visible (UV–Vis) spectroscopy. FTIR spectroscopy confirmed the presence of borate groups in triangular and tetrahedral coordination. Infrared and Raman analyses detected the vibrational bonds of GeOGe, BOGe, SiOGe, SiOSi, and PbOGe. The energy band gaps were evaluated for the prepared glass samples based on Tauc plots of the UV–Vis spectra. The calculated values of the optical band gap decreased from 2.91 to 2.85 eV as the PbO content increased from x = 0.0 to x = 0.7. Furthermore, the Urbach energy was studied based on the UV–Vis results to confirm the disordered structure of the glass. The calculated densities of the glass samples (1.5835 g/cm3 to 3.9184 g/cm3) increased as the concentration of PbO increased, whereas they decreased with the molar volume.

Fabrication and optical characterizations of lead calcium titanate borosilicate glasses

Different glass samples were prepared in the system 59[(PbxCa1−x)O·TiO2]-40[2SiO2·B2O3]-1Fe2O3 (0≤x≤0.7) employing a rapid melt-quenching technique. The IR structural and optical properties were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and ultraviolet-visible (UV–VIS) spectroscopy. The amorphous nature of the glass samples were confirmed using XRD and SEM analysis. The Archimedes principle was used to calculate the density of all glass samples. The density increased with decrease in CaO content and the trend of molar volume reciprocal to the density. The band gap energy of the prepared glass samples are in the range of 1.25–2.37eV and decrease with an increase in the concentrations of PbO.

Modified lead titanate thin films for pyroelectric infrared detectors on gold electrodes

Pyroelectric infrared detectors provide the advantage of both a wide spectral response and dynamic range, which also has enabled systems to be developed with reduced size, weight and power consumption. This paper demonstrates the deposition of lead zirconium titanate (PZT) and lead calcium titanate (PCT) thin films for uncooled pyroelectric detectors with the utilization of gold electrodes. The modified lead titanate thin films were deposited by pulsed laser deposition on gold electrodes. The PZT and PCT thins films deposited and annealed at temperatures of 650°C and 550°C respectively demonstrated the best pyroelectric performance in this work. The thin films displayed a pyroelectric effect that increased with temperature. Poling of the thin films was carried out for a fixed time periods and fixed dc bias voltages at elevated temperature in order to increase the pyroelectric coefficient by establishing a spontaneous polarization of the thin films. Poling caused the pyroelectric current to increase one order of magnitude.

High pyroelectric coefficient modified lead titanate thin films deposition using gold electrode

Reported is the deposition and characterisation of lead zirconium titanate (PbZr0.4Ti0.6O3) (PZT) and lead calcium titanate (Pb0.7Ca0.3Ti03) (PCT) deposited on a gold electrode with a gold top electrode to form a capacitor structure. Pulsed laser deposition was utilised to deposit the thin films. The thin films were characterised for their dielectric constant and loss tangent variation with temperature as well as the pyroelectric coefficient. The thin films were poled to improve the pyroelectric effect. The highest pyroelectric coefficient was found to be 280 µC/m2 K for PZT film and 400 µC/m2 K for the PCT film after poling.

Ferroelectric Properties of Laser Ablated Sm Modified PCT Thin Films

Crystallized thin films of samarium modified lead calcium titanate ceramics with composition; Pb0.66Sm0.08Ca0.24Mn0.02Ti0.98O3 were deposited under different annealing and laser energy conditions. Thin films deposited at these conditions show a surface roughness, coercive field and remnant polarization in the range of 1.9–6.0 nm, 120–220 kV/cm and 4–11.5 μC/cm2, respectively. I-V and C-V measurements were also performed in order to study the electrical behaviour of the films.

Characterization of PCT 76/24 Ceramics Synthesized by Modified Chemical Route

Lead calcium titanate with 24% Ca (PCT 76/24) was synthesized by modified chemical route. X-ray diffraction study showed the development of single perovskite phase with tetragonal structure at 600°C calcination temperature. Effect of sintering temperature on structure, morphology and dielectric properties were studied. At room temperature (RT), high value of ϵr ∼ 442 and low tanδ ∼ 0.20 are observed for PCT 76/24 ceramic sample sintered at 1000 °C. Low calcination temperature and uniform microstructure obtained reflect the usefulness of modified chemical route.

Microstructure and electron properties of Sm modified lead calcium titanate ceramics

Abstract Lead calcium titanate ceramics modified by partial substitution of rare earths for lead, particularly, (Pb, Sm, Ca)(Ti, Mn)O 3 ceramics, were explored for their structural, dielectric and piezoelectric properties. These modified ceramics with a composition of Pb 0.76−3 x /2 Sm x Ca 0.24 Ti 0.98 Mn 0.02 O 3 ( x = 0 − 0.08) were prepared by solid state reaction route. The XRD study showed single-phase formation with tetragonal structure. Lattice anisotropy ( c / a ) was found to decrease from 1.057 to 1.023 with increase in Sm substitution from 0 to 8 mol%, respectively. Microstructural study revealed the average grain size between 1.2 and 2.2 μm. The relative density was found to increase from 95% to 98.4% with increase in samarium substitution from 0 to 8 mol%, respectively. Detailed dilatometric study was performed in order to study the shrinkage behaviour during the sintering schedule. The maximum shrinkage was found to occur between 900 °C and 1100 °C. The dielectric constant ( ɛ ′) and loss (tan δ ) for all the compositions were investigated over a wide frequency (100 Hz to 1 MHz) and temperature (25–450 °C) range. The room temperature (25 °C) dielectric constant was found to increase from 130 (at 10 kHz) for pure lead calcium titanate sample to 380 (at 10 kHz) for 8 mol% samarium substituted sample and also showed a decreasing trend with increase in the frequency for all the substitutions (0–8 mol% Sm). Curie temperature, T C (determined from the plot of ɛ ′ vs. temperature) and tan δ were found to decrease with increasing samarium content. The Curie temperature was found to decrease from 348 °C to 192 °C for 0–8 mol% Sm substitutions, respectively. Piezoelectric coefficients were also measured at room temperature. Electromechanical anisotropy ( k t / k p ) was observed to increase from 11.7 (0 mol% Sm) to 27 (8 mol% Sm). Piezoelectric anisotropy ( d 33 / d 31 ) was also observed to increase from 22.5 for un-substituted sample to 28 for the sample substituted with 8 mol% samarium. The experimental results successfully showed that samarium substitution not only reduces the lattice anisotropy but also helps in improving piezoelectric properties.

Comparison of piezoelectricity in Ta 5+ and La 3+ substituted lead calcium titanate ceramics

This paper reports the experimental investigations on the effect of La 3+ and Ta 5+ substitution on the structural characteristics and dielectric and piezoelectric properties of lead calcium titanate (PCT) ceramic. The PCT samples with A-site and B-site substitution having the composition formula Pb 0.76− x /2La x Ca 0.24(Ti 0.98Mn 0.02) 1− x /2O 3 and Pb 0.76Ca 0.24Mn 0.02Ti 0.98−5 x /4Ta x O 3, x=0 and 0.02, respectively , were prepared using conventional solid-state reaction method. Phase formation and structural analysis were studied using X-ray diffraction and scanning electron microscopy, respectively. Dielectric constant ( ε′) and loss tangent (tan δ) as a function of frequency were measured at room temperature as well as elevated temperature. Both ε′ and tan δ decreased with increase in frequency at room temperature. Curie temperature decreased with La and Ta doping in PCT ceramics due to a decrease in the tetragonality of PCT ceramics. Piezoelectric charge coefficients ( d 33, d 31) increased with La 3+ substitution due to reorientation of the grains and decreased with Ta 5+ substitution because of the increase in porosity. Figure of merit d h g h increased and decreased with La and Ta substitution, respectively. A good ferroelectric behaviour is obtained for La substitution, while no hysteresis is obtained for Ta substitution.

Pressure-induced electrical and structural anomalies in Pb1−xCaxTiO3 thin films grown at various oxygen pressures by chemical solution route

Lead calcium titanate (Pb1−xCaxTiO3 or PCT) thin films have been thermally treated under different oxygen pressures, 10, 40 and 80 bar, by using the so-called chemical solution deposition method. The structural, morphological, dielectric and ferroelectric properties were characterized by x-ray diffraction, FT-infrared and Raman spectroscopy, atomic force microscopy and polarization–electric-field hysteresis loop measurements. By annealing at a controlled pressure of around 10 and 40 bar, well-crystallized PCT thin films were successfully prepared. For the sample submitted to 80 bar, the x-ray diffraction, Fourier transformed-infrared and Raman data indicated deviation from the tetragonal symmetry. The most interesting feature in the Raman spectra is the occurrence of intense vibrational modes at frequencies of around 747 and 820 cm−1, whose presence depends strongly on the amount of the pyrochlore phase. In addition, the Raman spectrum indicates the presence of symmetry-breaking disorder, which would be expected for an amorphous (disorder) and mixed pyrochlore–perovskite phase. During the high-pressure annealing process, the crystallinity and the grain size of the annealed film decreased. This process effectively suppressed both the dielectric and ferroelectric behaviour. Ferroelectric hysteresis loop measurements performed on these PCT films exhibited a clear decrease in the remanent polarization with increasing oxygen pressure.

Comparison of Ca-doped and La-doped PT films for pyroelectric sensors

A comparison of pyroelectric and electrical properties of sol gel derived lead calcium titanate PCT with 20%, 24% and 28% Ca and lead lanthanum titanate PLT with 4%, 8% and 12% La thin films has been made. Investigations have been made on the structure, surface morphology, dielectric and electrical properties of the thin films. XRD patterns show that the films annealed at 650 °C exhibit tetragonal structure with perovskite phase. AFM images are characterized by slight surface roughness with a uniform densely packed structure. Dielectric, pyroelectric and electrical studies carried out on these films have been compared. The pyroelectric figures of merit have also been calculated. These studies show that PCT with 24% Ca is the most suitable for pyroelectric sensors.

Sintering Behaviour of Samarium Modified Lead Calcium Titanate Ceramics

Modified Lead Calcium Titanate (PCT) compositions with representative formula, Pb 0.76−x Sm x Ca 0.24 Ti 0.98 Mn 0.02 O 3 (x = 0–0.1 in steps of 0.02) were prepared by conventional dry ceramic method. Effects of samarium substitution on physical, structural properties and thermal behaviour of PCT ceramics are reported here. All the samples were subjected to XRD analysis and were found to have single phase with tetragonal structure up to 8 mol% Sm substitution. The variations of density and tetragonality have been studied with samarium content. Microstructural analysis shows the uniform grain growth with increasing Sm concentration. Dilatometric study has been done to predict sintering schedule of the green samples.

Structural and electrical properties of lanthanum-substituted lead titanate ceramics

The effect of lanthanum substitution on the structural, dielectric and piezoelectric properties of lead calcium titanate (PCT) ceramics is studied. Samples with compositional formula Pb0.76− x La x Ca0.24Ti0.98Mn0.02O3 (PLCT) (x = 0–0.08, in steps of 0.02) were prepared by the conventional dry ceramic technique. Phase and structural analysis was carried out using XRD and SEM respectively. X-ray analysis confirmed the formation of single-phase compound with tetragonal crystal structure. Dielectric properties were studied in detail as a function of frequency and temperature. The Curie temperature (T C) and tetragonality (c/a) was found to decrease with increase in lanthanum content. The Curie temperature was also confirmed from the thermal-expansion behaviour of the sintered samples. Piezoelectric coefficients (d 33, d 31, g 33, g 31, g h, d h, k t and k p) were measured at room temperature. From this study it is found that La3+ substitution helps in the improvement of electro-mechanical anisotropy.

Improved piezoelectric properties via mechano-chemical activation in modified PCT ceramics

High-density samarium modified lead calcium titanate ceramics were successfully prepared by using a novel mechano-chemical activation technique, which skips the calcinations steps at an intermediate temperature that is always required in the normal conventional technique. Better densification could be achieved by activation process. XRD study showed single-phase formation with tetragonal structure and microstructural study revealed almost uniform grain size of 1.4μm. Dielectric study demonstrated sharp peak in dielectric versus temperature plots and slightly low value of the Tc as compared to that observed for samples prepared by conventional technique. The mechanical alloying technique rendered drastic improvement in piezoelectric properties. The ratio of electromechanical anisotropy (kt/kp) was obtained to be ∼62 as compared to 52 in the case of samples by conventional process. Comparison in the structural and electrical properties is discussed in detail for conventional versus mechano-chemical alloying process.

Dielectric and piezoelectric properties of microwave processed Sm substituted PCT ceramics

The effect of samarium substitution on the structural, dielectric and piezoelectric properties of lead calcium titanate ceramics was investigated. Dense ceramics with nominal composition Pb0.76−3x/2SmxCa0.24Ti0.98Mn0.02O3 (x = 0–0.08) were fabricated by a novel, simple, energy and time efficient, and environment friendly microwave sintering process. The samples were sintered at 1100°C for 30 min. All the compositions show single phase with tetragonal structure. Tetragonality decreases and relative density increases with increase in samarium substitution. The variation of the dielectric constant with temperature shows a ferroelectric phase transition and the transition temperature decreases with increase in the amount of samarium. Diffusivity increases with samarium substitution. All the compositions show well-defined ferroelectric behaviour. The electromechanical thickness coupling coefficient (kt) and piezoelectric longitudinal coefficient (d33) showed an increasing trend whereas the electromechanical planar coupling coefficient (kp) and the magnitude of the piezoelectric transverse longitudinal coefficient (d31) showed a decreasing trend with increase in samarium substitution level, which in turn results in an increase in electromechanical anisotropy.

Crystallisation of Pb 1− xCa xTiO 3 ferroelectric thin films as a function of the Ca 2+ content

Lead calcium titanate (Pb 1− x Ca x TiO 3) thin films with x from 0 to 0.50 were prepared by chemical solution deposition. Crystallinity of the films was studied as a function of calcium content and processing temperature. These studies were carried out on films deposited onto oxidised (1 0 0) Si substrates by means of X-ray diffraction. The analysis seems to indicate that the grain size of the films decreases as Ca 2+ content increases, which was confirmed from the scanning force microscopy images of the films. X-ray data reveal that kinetics of grain growth in films with Ca 2+ contents over 40 at% is very slow. Increase of calcium also produces a decrease in tetragonality of the perovskite films. Besides, it was observed that reflections of the perovskite appear at higher temperature in the films with larger Ca 2+ contents. Brillouin spectroscopy was used to follow the evolution of the elastic properties of the films with temperature. This study shows an elastic instability at temperatures between 475 °C and 500 °C that can be associated to complete film crystallisation. Dielectric and ferroelectric properties were measured on films deposited onto platinised silicon substrates and crystallised at 650 °C. The films with 50 at% of Ca 2+ still have ferroelectric properties, showing diffuse ferro-paraelectric transitions and slim ferroelectric hysteresis loops.