X-ray diffraction, dielectric and Raman spectroscopy studies of Ba1−xNd2x/3(Ti0.9Zr0.1)O3 ceramics (original) (raw)
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Journal of Materials Science: Materials in Electronics
Ferroelectric ceramics (Ba 0.85 Ca 0.15)(Ti 0.9 Zr 0.1-x Sn x)O 3 (x=0.00, 0.02, 0.04, 0.06) were prepared by a sol-gel method. Structural investigation revealed the coexistence of tetragonal (P4mm) and orthorhombic (Pmm2) symmetries at room temperature for the undoped ceramic, while only a tetragonal structure (P4mm) was observed for the doped ceramics. Dielectric measurements indicate a dielectric relaxation process at high temperatures which is essentially related to the hopping of oxygen vacancies. Furthermore, a down shifting of the Curie temperature (T C) with increasing Sn 4+ doping rate has been revealed. The temperature profiles of the Raman spectra unveiled the existence of polar nanoregions (PNRs) above the Curie temperature in all ceramics. The ferroelectric properties were found to be related to the microstructure. Electrocaloric effect was investigated in this system that revealed an electrocaloric responsivity of 0.225 10-6 K m/V for the composition with x = 0.04 Sn doping, where other remarkable physical properties were also observed.
2021
We have studied the effects of Zn and Nb substitutions on dielectric, ferroelectric, and piezoelectric properties of Ba0.87Ca0.13(Ti0.9Zr0.1)(1−x)(Zn1/3Nb2/3)xO3 ceramics. X-ray diffraction (XRD) results display that morphotropic boundary occurs from tetragonal to orthorhombic region for x = 0; 0.005; 0.01 and polymorphic phase transitions from tetragonal to orthorhombic and rhombohedral regions for x = 0.02. The evolution of the Raman spectra demonstrates the introduction of a disorder in this composition, which promotes ferroelectric relaxor behaviors. Ferroelectricity is confirmed by hysteresis investigation. A piezoelectric coefficient of d33 = 205 pC N−1 and a high planar electromechanical coupling factor of kp = 47% are reported for x = 0.1. The ceramics for x = 0.01 also depicts uniform microstructure that contributes to the important electrical properties. These results indicate that this Ba0.87Ca0.13(Ti0.9Zr0.1)(1−x)(Zn1/3Nb2/3)xO3 system with optimal composition is a promi...
Journal of Mountain Research, 2021
Pellet samples of (Ba1-xCaxZr1-yTiy)O3 (x = 0.150, y = 0.90) were prepared using the solid-state reaction method following double sintering. The electrical and optical properties of (Ba1-xCaxZr1-yTiy)O3 (x = 0.150, y = 0.90) ceramics were studied. For Ba0.85Ca0.15Zr0. 1Ti0.9)O3 ferroelectric perovskite ceramics, the dielectric and structural properties were explored. The prepared composition of BCZT ceramics were calcined at 1100 oC. The sintering temperature was 1300 oC. Dielectric properties were observed from room temperature (RT) to 150 oC, at 1 MHz. The powder of the sintered samples has been taken for reflectance measurement at UV-Vis range. From the observed tauc plot, the band-gap is calculated. The measured band- gap is 3.19 eV.
Journal of Electroceramics, 2007
The compositions in the system (Ba 1−x Sr x) (Ti 0.5 Zr 0.5)O 3 with different Sr (x) content, were synthesized through solid oxide reaction route. The phase formation behaviors in the system were investigated by XRD. The room temperature dielectric properties of the compositions were investigated in the frequency range 10 Hz to 13 MHz. The solid solution system Ba 1−x Sr x Ti 0.5 Zr 0.5 O 3 remains as cubic perovskite up to x<0.6 and transforms into the tetragonal structure above x>0.6. Composition with x=0.6 contains a mixture of cubic and tetragonal phases with broadened diffraction pattern. It is observed that the increasing of Sr substitution results in the decreasing of bulk density, average grain size and dielectric constants etc. in the composition system. The AC dielectric conductivity of the ceramics also decreases with the increase in Sr-substitution due to decrease in loss as well as grain size with that substitution.
Journal of Electroceramics, 2008
The phase formation behavior and room temperature dielectric properties of bulk perovskite solid solution composition (Ba 0.5 Sr 0.5)(Ti 1−x Zr x)O 3 have been investigated. The samples with different Zr-content were prepared through solid state reaction. The XRD investigation showed that Zr +4 is systematically dissolved in Ba 0.5 Sr 0.5 TiO 3 lattice up to about 60 atm.% substitution, having cubic Pm3m structure. Eighty atom percent Zr substituted composition showed to contain a cubic phase similar to that of x=0.6 composition and a tetragonal (I4/mcm) phase. That is the solid solution breaks around at 80 atm.% Zr substitutions. Ba 0.5 Sr 0.5 ZrO 3 was having orthorhombic Imma structure. Decrease in grain sizes were observed with increase in Zr content. The permittivity of the ceramics decreased with the increase in Zr substitution. The frequency dependency of dielectric loss in the frequency range 10 Hz to 10 MHz, were improved with Zr substitution in the ceramics. The room temperature ac and dc conductivity also decreased significantly with the increase in Zr-content.
Journal of Physics and Chemistry of Solids, 2011
a b s t r a c t Na 1 À x Li x NbO 3 ceramics with composition 0.05 r x r 0.30 were prepared by solid-state reaction method and sintered in the temperature range 1100-1150 1C. These ceramics were characterised by X-ray diffraction as well as dielectric permittivity measurements and Raman spectroscopy. Dielectric properties of ceramics belonging to the whole composition domain were investigated in a broad range of temperatures from 300 to 750 K and frequencies from 0.1 to 200 kHz. The Rietveld refinement powder X-ray diffraction analysis showed that these ceramics have a single phase of perovskite structure with orthorhombic symmetry for x r0.15 and two phases coexistence of rhombohedral and orthorhombic above x ¼ 0.20. The evolution of the permittivity as a function of temperature and frequency showed that these ceramics Na 1 À x Li x NbO 3 with composition 0.05 r x r 0.15 present the classical ferroelectric character and the phase transition temperature T C increases as x content increases. The polarisation state was checked by pyroelectric and piezoelectric measurements. For x ¼ 0.05, the piezoelectric coefficient d 31 is of 2pC/N. The evolution of the Raman spectra was studied as a function of temperatures and compositions. The results of the Raman spectroscopy study confirm our dielectric measurements, and they indicate clearly the transition from the polar ferroelectric phase to the non-polar paraelectric one.
physica status solidi (a), 2006
New ferroelectric ceramics of ABO3 perovskite type were synthesized in the Ba1–x (Sm0.5Na0.5)x TiO3 system by solid state reaction technique. The effect of the replacement of barium by samarium and sodium in the A cationic site on structural and physical properties was investigated. These compounds crystallize with tetragonal or cubic symmetry. The material is classical ferroelectric for 0 ≤ x ≤ 0.1 and 0.5 ≤ x ≤ 0.6, and present a relaxor behavior for 0.2 ≤ x ≤ 0.4. The dielectric behavior depends upon the cationic disorder in the A site and the cell size. Small rate substitution allows a ferroelectric‐paraelectric transition. For higher rate of substitution the possible random position of the Sm–Na cations brings to a relaxor sate and when the substitution rate x becomes higher than 0.5, the material comes back to a ferroelectric state due to the reduced cell size. Some of these new compositions are of interest for applications due to their physical properties and environmentally ...
Structural and dielectric studies of relaxor ferroelectric Ba1−xLax(1−y)/2Euxy/2Nax/2TiO3 ceramics
Journal of Alloys and Compounds, 2006
Structural and dielectric properties of Ba 1−x La x(1−y)/2 Eu xy/2 Na x/2 TiO 3 (0 ≤ x ≤ 0.5) have been investigated. Ceramic samples were elaborated by the classical solid-state routine, they crystallize in the tetragonal distorted perovskite structure for 0 ≤ x ≤ 0.1 and in cubic for 0.1 ≤ x ≤ 0.5. Dielectric measurements showed that the compounds exhibit an evolution from a classical ferroelectric to a relaxor ferroelectric with rising substitution rate x. T C or T m and ε r decrease when x increases. This study is in the field of preparation of lead-free relaxor ceramics, which have a great importance for the environment.
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.