Investigation of the composition-dependent properties of BaTi1−xZrxO3 ceramics prepared by the modified Pechini method (original) (raw)
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Analysis on dipole polarization of BaTiO3-based ferroelectric ceramics by Raman spectroscopy
Journal of the Ceramic Society of Japan, 2010
Analysis of asymmetric Raman line shape disclosed the variation of phonon correlation length in A 1 (3TO) mode, L A1(3TO) , with temperature in the ceramics of BaTiO 3 (BT), Ba 0.6 Sr 0.4 TiO 3 (BST-0.6) and BaZr 0.25 Ti 0.75 O 3 (BZT-0.25), namely normal ferroelectrics, ferroelectrics with diffuse phase transition (DPT ferroelectrics) and relaxor ferroelectrics, respectively. In BT, L A1(3TO) exhibited steep increase at the Curie temperature (T c) on cooling. This is attributed to the formation of the ferroelectric domains at the T c. Both BST-0.6 and BZT-0.25 showed gradual increase in L A1(3TO) on cooling across the dielectric maximum temperature (T m), indicating the continuous increase in the average size of the polar nanoregions (PNRs). Normal ferroelectrics can be distinguished from DPT and relaxor ferroelectrics in this point. L A1(3TO) of BZT-0.25 was longer than that of BST-0.6 near the T m. This suggests the size of PNRs in BZT-0.25 is larger than that in BST-0.6. Huge dipole polarization of BZT-0.25, giving rise to the strong relaxor behavior, could be originated from the contribution of the large PNRs near the T m. DPT ferroelectrics can be also differentiated from relaxor ferroelectrics in terms of the average size of PNRs.
PHASE FORMATION , MICROSTRUCTURE AND FUNCTIONAL PROPERTIES OF SOME BaTi 1-XZrXO 3 CERAMICS
2015
BaTi1-xZrxO3 (0 ≤ x ≤ 0.20) solid solutions were prepared by solid state reaction method. XRD investigations showed the formation of individual BaTiO3ss (solid solution) and BaZrO3ss perovskite phases, from the ceramic samples with higher Zr content (x ≥ 0.10). All the ceramics under investigation were singlephased after sintering at 1500C for 4 hours. Dielectric measurements indicated a maximum of permittivity only for the sample corresponding to undoped BaTiO3. All Zr-doped ceramic samples showed diffuse phase transition. The increase of the solute content induces the decrease of the ferroelectric – paraelectric phase transition temperature. The diffuseness corresponding to the permittivity maxima originates not only in the increase of Zr content, but also in some particular microstructural features.
Dielectric and phase transition of BaTi 0.6 Zr 0.4 O 3 ceramics prepared by a soft chemical route
Applied Physics A-materials Science & Processing, 2008
BaTi0.6Zr0.4O3 (BTZ) ceramic was synthesized by a soft chemical route. X-ray diffraction at room temperature shows that the sample has cubic perovskite structure with space group Pm-3m. Temperature dependent dielectric study of the sample has been investigated in the frequency range from 50 Hz to 1 MHz. The density of the sample was determined using Archimedes’ principle and found to be ∼ 97% of the X-ray density. The average grain size in the pallet was found to be ∼ 1 μm. The dielectric constant peaks at temperature Tm which is dependent on the frequency. The dielectric relaxation rate follows the Vogel–Fulcher relation with activation energy = 0.0185 eV, and freezing temperature = 186 K. All these measurements confirm that BTZ is a relaxor ferroelectric.
Influence of Zr on Structure and Dielectric Behavior of BaTiO3 Ceramics
Indian Journal of Science and Technology, 2015
Barium zirconium titanate ceramics, BaTi 1-x Zr x O 3 (x = 0-15 at % with a step of 2.5%) (BTZ x), were obtained by a sol-gel method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples by scanning electron microscopy shows that the addition of zirconium ions affects the growth of the grain and remarkably changes the grain morphology. The effect of zirconium addition to BT on dielectric properties is analyzed. Increasing Zr content in the BaTiO 3-based compositions caused a decrease in the Curie temperature (T c) and the permittivity increases. The Curie-Weiss law is well followed for the pure sample, but it is less respected in the case of BTZ 10 and the variation of the Curie Weiss constant as a function of frequency is similar to the variation of the dielectric constant. On the other hand, the application of the modified Uchino law, to the BTZ x materials, shows that the diffusion factor increases from 1.06 to 1.78 with increasing x from 0 to 0.15, implying a composition-induced diffuse transition.
Influence of Zr on Structure and Dielectric Behavior of BaTiO3 Ceramics
Indian Journal of Science and Technology, 2015
Barium zirconium titanate ceramics, BaTi 1-x Zr x O 3 (x = 0-15 at % with a step of 2.5%) (BTZ x ), were obtained by a sol-gel method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples by scanning electron microscopy shows that the addition of zirconium ions affects the growth of the grain and remarkably changes the grain morphology. The effect of zirconium addition to BT on dielectric properties is analyzed. Increasing Zr content in the BaTiO 3 -based compositions caused a decrease in the Curie temperature (T c ) and the permittivity increases. The Curie-Weiss law is well followed for the pure sample, but it is less respected in the case of BTZ 10 and the variation of the Curie Weiss constant as a function of frequency is similar to the variation of the dielectric constant. On the other hand, the application of the modified Uchino law, to the BTZ x materials, shows that the diffusion factor increases from 1.06 to 1.78 with increasing x from 0 to 0.15, implying a composition-induced diffuse transition.
Journal of Applied Physics, 2017
Low-lead (1-x)BT-xPZN (x ¼ 0, 0.025, 0.05, 0.075, 0.10, 0.125, and 0.15) ceramics were successfully synthesized by the spark-plasma-sintering method for the first time. Their phase transition behavior as well as structural, thermal, optical, and electrical properties was investigated. These materials exhibit the structure of perovskite-type solid solutions and undergo a sequence of phase transitions, typical of pure BaTiO 3 (BT). The dielectric test results revealed that with the increase in the PbZn 1/3 Nb 2/3 O 3 (PZN) content, the frequency dispersion of electric permittivity increases, whilst the dielectric/ferroelectric properties tend to deteriorate, which is characteristic of relaxor-type behavior. Therefore, it is reasonable to suppose that these ceramics progressively lack long-range ordering. These effects are due to the competition between lone-pair electrons' induced changes in the A-O band upon Pb 2þ addition and ionic size differences. In general, the transition temperatures observed by dielectric analyses are in good agreement with those obtained from X-ray diffraction and differential scanning calorimetry measurements. The BT-PZN system may help to understand why relaxor behavior appears in perovskite-based materials. It appears that these materials can become a good starting point for the development of new low-lead electronic ceramics.
Journal of Electronic Materials, 2017
BaTi 0.9 Zr 0.1 O 3 (BZT), Ba 1Àx Ln 2x/3 h x/3 Ti 0.9 Zr 0.1 O 3 (with x = 0.5% mol and Ln = Er) (BZT-Er) and Ba 1Àx Ln 2x/3 h x/3 Ti 0.9 Zr 0.1 O 3 (with x = 0.5% mol and Ln = Pr) (BZT-Pr) were prepared via the conventional solid-state reaction method. X-ray diffraction showed that all these ceramics were in the single perovskite phase at room temperature (RT). The temperature dependence of dielectric behavior was investigated in the temperature range 25-225°C and exhibited a classical ferroelectric behavior. A slight decrease of the Curie temperature (T C) with Pr 3+ and Er 3+ substitution was observed in addition to an increase in the maximum dielectric permittivity (e 0 r max) of about 40% for the BZT-Er. At RT, the ferroelectric and piezoelectric coefficients were decreased for BZT-Pr, but were maintained for BZT-Er with a piezoelectric coefficient (d 33) of 185 pC/N, a planar electromechanical coupling factor of 30%, and a remanent polarization of 11.6 lC/cm 2. The Raman bands as a function of temperature confirmed the paraelectric-ferroelectric phase transition of all those ceramics. The photoluminescence spectra showed that strong red (615 nm and 645 nm) and bright green (523 nm and 545 nm) emission bands were obtained, under excitation by laser at 488 nm at RT, for BZT-Pr and BZT-Er, respectively. These multifunctional materials showed a significant technological promise in coupling device applications.
Proceedings of the Estonian Academy of Sciences, 2017
A (1-x)BaTiO 3-xPb(Zn 1/3 Nb 2/3)O 3 ((1-x)BT-xPZN) system with a low content of PZN (x = 0, 0.025, and 0.05) was prepared by the spark plasma sintering process. X-ray diffraction analysis exhibited that the obtained specimens possessed the perovskite structure with tetragonal symmetry and underwent a sequence of phase transformations characteristic of pure BT. The microstructure study showed a dense structure in good agreement with that of above 95% relative density determined by the Archimedes method. Dielectric measurements revealed that the maximum of electric permittivity was broadened and shifted after the PZN doping of BT. The Raman spectra were similar for all samples in agreement with the X-ray data. It was shown that the PZN doping of BT caused a worsening of ferroelectric properties. The obtained results are discussed in terms of an increased degree of crystal structure disorder, which creates local elastic and electric fields. The investigated ceramics are considered to be a good starting point for low-lead electronic materials.
Influence of ZrO_2 Addition on the Structure and Dielectric Properties of BaTiO_3 Ceramics
Acta Physica Polonica A, 2017
Ba(Ti1−xZrx)O3 (x = 0 ÷ 0.3) ceramics were prepared by the standard solid state reaction method and were sintered at 1450 • C for 4 h. The structural and dielectric properties of the samples were studied. The phases formed in the ZrO2 doped BaTiO3 were tetragonal and of cubic symmetry. Increase in ZrO2 content in the BaTiO3 caused to increase of the lattice parameter and crystallite size of the perovskite structure. The evolution of the Raman spectra was studied for various compositions and the spectroscopic signature of the corresponding phase was determined. The scanning electron microscope was used to investigate the microstructure and surface morphology of the sintered samples. Scanning electron microscope observations revealed enhanced microstructural uniformity and retarded grain growth with increase of ZrO2 content. Dielectric characteristics of ZrO2 doped barium titanate were studied using a Hioki 3532-50 LCR meter in the frequency range of 1 kHz-1 MHz. It is found that the dielectric constant (εr) increases while the dielectric loss (tan δ) decreases with increase in zirconium oxide content (x < 0.3).
Bulletin of Materials Science
We prepared a lead-free ceramic (Ba 0.85 Ca 0.15)(Ti 1−x Zr x)O 3 (BCTZ) using the conventional mixed oxide technique. The samples were prepared by an ordinary mixing and sintering technique. In this study we investigated how small amounts of Zr 4+ can affect the crystal structure and microstructure as well as dielectric and piezoelectric properties of BaTiO 3. X-ray diffraction analysis results indicate that no secondary phase is formed in any of the BCTZ powders for 0 ≤ x ≤ 0.1, suggesting that Zr 4+ diffuses into BaTiO 3 lattices to form a solid solution. Scanning electron microscopy micrographs revealed that the average grain size gradually increased with Zr 4+ content from 9.5 μm for x = 0.02 to 13.5 μm for x = 0.1; Curie temperature decreased due to the small tetragonality caused by Zr 4+ addition. Owing to the polymorphic phase transition from orthorhombic to tetragonal phase around room temperature, it was found that the composition x = 0.09 showed improved electrical properties and reached preferred values of d 33 = 148 pC N −1 and K p = 27%.