Structural and ferroelectric properties of lanthanum modified BPZT ceramics (original) (raw)
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Integrated Ferroelectrics, 2018
The influence of sintering conditions on phase formation, density, microstructure and electrical properties of BCZT ceramics wer investigated. The BCZT (Ba 0.85 Ca 0.075 Zr 0.1 Ti 0.9 O 3) ceramics were fabricated by a mixed oxide synthetic route of BaCO 3 , CaCO 3 , ZrO 2 and TiO 2 precursors and then sintered at 1250, 1300 and 1350°C for 2 and 4 hrs. Phase formation, densification, microstructure surfaces, dielectric properties, ferroelectric and piezoelectric properties were analyzed by using X-ray diffraction (XRD), Archimedes method, Scanning Electron Microscopy (SEM), LCR Meter, P-E hysteresis and d 33 meter, respectively. In processes of sintering, the results show that BCZT structures are perovskite with pseudocubic phase. Sintering condition at 1300°C for 4 hrs exhibits optimum density, grain size and higher electrical properties: density 5.62 g/cm 3 (∼98% of theoretical density), average grain size = 2.19 ± 0.87 µm, dielectric constant (ε r) = 2840, dielectric loss (tan δ) = 0.10, remanent polarization (P r) = 5.84 µC/cm 2 and d 33 = 167 pC/N.
Structure–property relations of ferroelectric Pb(Zr0.52Ti0.48)O3–(Bi3.25La0.75)Ti3O12 ceramics
Current Applied Physics, 2008
Ceramics with formula (1 À x)Pb(Zr 0.52 Ti 0.48 )O 3 -x(Bi 3.25 La 0.75 )Ti 3 O 12 (when x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) were prepared by a solid-state mixed-oxide method and sintered at 1150°C for 4 h. All samples had densities at least 95% of theoretical values. Phase analysis using X-ray diffraction indicated the existence of BLT -as well as PZT -based solid solutions with corresponding lattice distortion. Scanning electron micrographs of ceramic surfaces showed a plate-like structure in BLT-rich phase while the typical grain structure was observed for PZT-rich phase. Ferroelectric measurements of these samples showed that addition of small amounts of BLT into PZT increased coercive field and remanent polarization to about 18 kV/cm and 12.5 lC/cm 2 , respectively. Further increasing the amount of BLT in PZT degraded the ferroelectric properties of the ceramics. This behavior was in agreement with their microstructures and dielectric properties.
Dielectric behaviour of La substituted BPZT ceramics
Physica B-condensed Matter, 2009
Here, we report dielectric behaviour of lanthanum substituted Ba0.80Pb0.20Ti0.90Zr0.10O3 (BPZT) ceramics. The material series with compositional formula Ba0.80−xLaxPb0.20Ti0.90Zr0.10O3 (BLPZT) with x varying from 0 to 0.01 in the steps of 0.0025 was chosen for investigations. The material was synthesized by solid state reaction method. Reacted powder compacted in form of circular discs were sintered at 1325 °C. All the samples were subjected to X-ray diffraction (XRD) analysis and found to be single phase. Dielectric behaviour was studied as a function of frequency and temperature and Curie temperature (Tc) was determined. Tc was found to decrease with increasing x. The details are discussed and presented in this paper.
Relaxor ferroelectric behavior of La substituted BPZT ceramics
Ceramics International, 2010
Barium titanate (BT) based compounds have been of great importance in the fabrication of multilayer ceramic capacitors. Several substitutions are used to tailor its structural, electrical and ferroelectric properties. Substituent like zirconium (Zr) for titanium results in decrease in non-centrosymmetric tetragonal to centrosymmetric cubic phase transition temperature (Curie temperature). Whereas substituent like lead (Pb) for barium results in the increase in the Curie temperature. Here we are reporting effect of lanthanum (La) substitution on the properties of Zr and Pb co-substituted BT. The system Ba0.80−xLaxPb0.20Ti0.90Zr0.10O3 with x = 0 and 0.01 was selected for study of structural and dielectric properties. Samples were prepared using solid state ceramic route. X-ray diffraction studies (XRD) were used to confirm single phase structure. Dielectric properties were studied as a function of frequency and temperature. Composition with x = 0.01 was found to show relaxor behavior.
Journal of Materials Science: Materials in Electronics, 2020
This article describes preparation of Barium (Zirconium) Titnate (BaZr 0.2 Ti 0.8 O 3) ceramics by the sol-gel technique and its structural, dielectric, ferroelectric, and piezoelectric properties investigated with sintering temperature variation. The phase and microstructure analysis of the sintered ceramics was carried out by X-ray diffraction method (XRD) and scanning electron microscopy (SEM), respectively. XRD analysis revealed structural transformation from cubic to tetragonal phase with increase in sintering temperature. Dielectric properties have been measured with variation of frequency up to 1 MHz and with temperature up to 200°C. The BZT ceramics exhibit diffuse phase transition with normal ferroelectric behavior. Hysteresis loop measurements disclosed that BZT ceramics have good ferroelectric nature with saturation at higher applied electric fields. Leakage current density show negative temperature coefficient resistance (NTCR) behavior. The highest value (261 pC/N) of piezoelectric coefficient (d 33) has been obtained for BZT ceramic sintered at 1400°C and revealed that ceramics have great potentials for electronic industry based on sensor technology.
Defence Science Journal, 2013
Lead zirconate titanate (PZT) based ceramics attracted the technologists and researchers for sensor and actuator applications because of the excellent piezoelectric properties 1,2. Mechanical quality factor (Q m), dielectric loss factor (tan δ), dielectric constant (T K 3), piezoelectric charge coefficient (d 33), piezoelectric voltage coefficient (g 33) are the important parameters which decide the suitability of the material for particular application. Materials with high Q m and low tan δ are suitable for ultrasonic and high frequency applications. Materials with higher T K 3 and d 33 are suitable for actuator applications like vibration and noise control, benders, optical positioning etc. 3,4. Materials with higher g 33 are useful for sensor applications 5. Particularly, materials with higher d 33 , g 33 and higher figure of merit (d 33 x g 33) are suitable for power harvesting applications since they offers higher power output 6-9. Incorporating the suitable dopant and optimising the process parameters, desired properties can be obtained. Sintering parameters viz. atmosphere, temperature, time and heating rate have significant effect on microstructure and thus on electromechanical properties of the final product 10,11. Dense microstructure with optimum grain size formed during sintering results in better dielectric and piezoelectric properties 12. In our earlier studies,effect of Zr/Ti ratio 13 and lanthanum concentration 14 on power harvesting properties of ferroelectric composition Pb(Ni 1/3 Sb 2/3)-(ZrTi)O 3 were investigated. In the present study, ferroelectric composition Pb 0.98 La 0.02 (NiSb) 0.05 [(Z r 0.52 Ti 0.48) 0.995 ] 0.95 O 3 14 was investigated for the effect of sintering time on the microstructure and electromechanical properties viz. Qm, kp, T K 3 d 33 , g 33 and figure of merit. Study was also aimed towards analysing the suitability of this composition for power harvesting applications and its comparison with PZT type 5A. 2. EXPERIMENTAL Lanthanum doped Pb(Ni 1/3 Sb 2/3)-(ZrTi)O 3 ferroelectric composition Pb 0.98 La 0.02 (NiSb) 0.05 [(Zr 0.52 Ti 0.48) 0.995 ] 0.95 O 3 [La-PNS-PZT] was synthesised by mixed oxide route using the oxides of elements.Raw material powders NiO (97%, Acros), Sb 2 O 5 (99%, Loba Chemie), PbO (99.5%,Waldies Ltd., Kolkata), ZrO 2 (99.37%, Loba Chemie) and TiO 2 (98.5%, Travancore Titanium Products) were wet milled in pure water medium for 24 hours. Calcination was performed at 1060 °C followed by wet milling. Phase formation of the calcined powder was analysed from slow scanned X-ray diffraction pattern recorded from 42° to 58° by X-Ray diffractometer (Make-PANalytical, Model-X'pert pro). Powder was granuled using polyvinyl alcohol as a binder. Discs of diameter 29 mm and 1.7 mm thickness were compacted using double ended die punch machine (Make-GMT) by maintaining green density near to 4.8 g/cc. Samples were sintered in lead rich environment at 1270 °C for 20 min, 40 min, 60 min, 80 min and 100 min. They were lapped to 1.2 mm thickness and electroded with silver paste, followed by poling. Microstructure of polished and chemically etched samples was studied using optical microscope. Capacitance (C at 1 kHz), resonance frequency (f r), anti
In the present work, a 'soft-doped' PZT ceramic system with a near MPB Zr/Ti ratio of about 54/46, is characterized when simultaneously modified with Lanthanum (La) and Niobium (Nb) at the same doping level, x = 0.4, 1.0 and 1.4 mol%. X-rays diffraction patterns showed the rombohedral/tetragonal perovskite phase coexistence as reported for Zr/Ti ratios near the Morphotropic Phase Boundary (MPB). Scanning Electron Microscopy (SEM) showed a decrease of the mean grain size when increasing the doping level. On the other hand, permittivity and AC conductivity were analysed in the ferro-and paraelectric phases. Samples showed a lower Curie temperature for higher doping levels as well as normal ferroelec-tric/paraelectric transitions. The piezoelectric response of thin polarized cylinder-shaped samples was measured for a near-saturation poling field. The behaviour of some electromechanical parameters and possible applications for these materials are also discussed herein.
Transactions of the Indian Ceramic Society, 2019
The structural, ferroelectric, piezoelectric and dielectric properties of lead-free 0.45Ba 0.92 Ca 0.08 TiO 3-0.55BaTi 0.96 Zr 0.04 O 3 (BCT8-BZT4) ceramics synthesized by conventional solid state reaction method have been reported. Structural analyses by X-ray diffraction (XRD) and Raman spectroscopic measurements indicate that the BCT8-BZT4 ceramics possesses both tetragonal (space group P4mm) and orthorhombic (space group Amm2) crystal structures at room temperature. Dense microstructure with 5-7 m grain size has been observed from scanning electron micrographs. Ferroelectric nature of BCT8-BZT4 has been confirmed from the polarization-electric field (P-E) hysteresis loop measurements. For BCT8-BZT4, the values of maximum polarization (P max =17.24 C/cm 2), remnant polarization (P r =6.36 C/cm 2), coercive electric field (E c =3.66 kV/cm) and direct piezoelectric coefficient (d 33~2 20 pC/N) have been observed to be comparable with those of lead based piezoelectric ceramics. The BCT8-BZT4 ceramics shows usual dielectric dispersion with dielectric constant ~1210 above 100 kHz frequency at room temperature. The observed properties show that the BCT8-BZT4 ceramics is suitable for ferroelectric memory, piezoelectric sensor, capacitor, etc applications. Thus, it has been predicted that BCT8-BZT4 may be a potential candidate for replacing lead-based piezoelectric ceramics.