Dielectric behaviour of La substituted BPZT ceramics (original) (raw)
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Dielectric behaviour of Pb-substituted BZT ceramics
Bulletin of Materials Science, 2011
Material series with compositional formula Ba 1⋅0-x Pb x Ti 0⋅90 Zr 0⋅10 O 3 (0 ≤ x ≤ 0⋅20, in steps of 0⋅05) were prepared by conventional solid state method. All the samples were subjected to X-ray diffraction (XRD) studies and found to be single phase with perovskite structure. SEM measurements were done in order to collect micro-structural information. Different transition temperatures were found to depend on the Pb content. Tetragonality (c/a) and Curie temperature (T c) increase with increase in lead content x. Dielectric properties were studied as a function of temperature and frequencies.
Structural and dielectric properties of (La, Bi) modified PZT ceramics
Solid State Communications, 2004
Polycrystalline samples of Pb0.9(La 12z Bi z )0.1(Zr0.55Ti0.45)0.975O 3 [referred as PLBZT] (z = 0 : 0 ; 0.3, 0.5 and 0.7) have been synthesized by a high-temperature solid-state reaction technique. X-ray diffraction analysis suggests the formation of singlephase compounds with monoclinic structure. The dielectric studies of the compounds as a function of temperature (room temperature, RT to 350 8C) at frequency (1, 10 and 100 kHz) show that the compounds undergo a phase transition of diffuse type. Diffusivity ðgÞ study of phase transition of these compounds provided its value between 1 and 2, indicating the variation of degree of disordering in the system. Measurement of dc resistivity ðrÞ as a function of temperature (RT to 350 8C) at a constant biasing field suggests the compounds have negative temperature coefficient of resistance.
Structural and ferroelectric properties of lanthanum modified BPZT ceramics
Materials Chemistry and Physics, 2011
Lanthanum modified Ba0.80Pb0.20Ti0.90Zr0.10O3 (BPZT) ceramics with composition Ba0.80−xLax Pb0.20Ti0.90Zr0.10O3; x = 0–0.01 in steps of 0.0025 were prepared by conventional solid state method. All the samples were sintered at 1325 °C after compacting in circular discs. Detailed structural and ferroelectric properties were carried out for sintered specimens. X-ray diffraction analysis for all the sintered specimens shows tetragonal structure with perovskite. Coercive field (Ec) and remanent polarization (Pr) to spontaneous polarization (Ps) ratio (Pr/Ps) was found to decrease with increase in temperature. Pr/Ps ratio was found to decrease with increase in x, except x = 0.0025.
Materials Chemistry and Physics, 2011
A-site deficient rare-earth doped barium zirconate titanate (BZT) ceramics (Ba 1−y Ln 2y/3 )Zr 0.09 Ti 0.91 O 3 (Ln = La, Pr, Nd, Gd) are obtained by a modified solid-state reaction method. Perovskite-like single-phase compounds were confirmed from X-ray diffraction data. Morphological analysis on sintered samples shows that the addition of rare-earth ions inhibits the growth of the grain and remarkably changes the grain morphology. The effect of rare-earth addition to BZT on phase transition and dielectric properties is analyzed. A dramatic fall in the transition temperature occurs when BZT ceramic is doped with rare-earths. Moreover, diffusivity degree of the phase transition increases and a relaxor-type behaviour is induced due to both the increment of the lanthanide content and the increase of the ionic radius of the dopant element. High values of dielectric tunability are obtained for lanthanum doped BZT. A direct relation between transition temperature and tunability is discussed. Conclusively, low permittivity and high tunability materials can be obtained by the adequate substitution of rare-earths into BZT ceramics.
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.
Nanomaterials
Fine-tuning of grain sizes can significantly influence the interaction between different dielectric phenomena, allowing the development of materials with tailored dielectric resistivity. By virtue of various synthesis mechanisms, a pathway to manipulate grain sizes and, consequently, tune the material’s dielectric response is revealed. Understanding these intricate relationships between granulation and dielectric properties can pave the way for designing and optimizing materials for specific applications where tailored dielectric responses are sought. The experimental part involved the fabrication of dense BCT-BZT ceramics with different grain sizes by varying the synthesis (conventional solid-state reaction route and sol-gel) and consolidation methods. Both consolidation methods produced well-crystallized specimens, with Ba0.85Ca0.15O3Ti0.9Zr0.1 (BCTZ) perovskite as the major phase. Conventional sintering resulted in microstructured and submicron-structured BCT-BZT ceramics, with a...
Dielectric response of tungsten modified Ba(Ti0.90Zr0.10)3 ceramics obtained by mixed oxide method
Processing and Application of Ceramics, 2010
The electrical response of Ba(Ti0.90Zr0.10)O3 (BZT) ceramics obtained by the mixed oxide method as a function of tungsten content was investigated. According to X-ray diffraction analysis the single phase BZT1W (1 wt.% W doped BZT) and BZT2W (2 wt.% W doped BZT) ceramics, crystallized in a perovskite structure, were obtained. It is also shown that tungsten substituted ceramics can be sintered at a reduced temperature when compared to the undoped BZT. Electron paramagnetic resonance (EPR) analyses reveals that substitution of Ti4+ by W6+ causes distortion in the crystal structure changing lattice parameter. Substitution of W6+ on B-site of ABO3 perovskite BZT ceramics shifted the phase transition to lower temperatures up to a tungsten content of 2 wt.% leading to a relaxor-like behaviour.
Metal Powder Report, 2003
A binary solid solution of Pb 0.9 (La 1 À y Sb y ) 0.1 (Zr 0.65 Ti 0.35 ) 0.975 O 3 (PLSZT) was synthesized by a high-temperature solidstate reaction method, near the morphotropic phase boundary (MPB). Detailed studies of the dielectric permittivity (e) and loss tangent (tand) of PLSZT ceramics as a function of temperature (30 -400 jC) at 10 kHz suggest that the compounds exhibit a phase transition of diffuse type. The transition temperature (T c ) is found to increase with an increase in Sb concentration. The activation energy (DC and AC) of PLSZT was found to be very small ( < 0.1 eV), which is comparable to other ferroelectric oxides of the family. The decrease of DC resistivity of PLSZT with an increase in temperature suggests a negative temperature coefficient resistance (NTCR) behavior of the compound. D
Ceramics International, 2013
(1 Àx)(Bi 0.4871 Na 0.4871 La 0.0172 TiO 3) Àx(BaZr 0.05 Ti 0.95 O 3) ceramics (abbreviated (1 Àx)BNLT À xBZT) where 0.1r xr 0.3 were fabricated by the combustion technique using glycine as fuel. BNLT and BZT powders were calcined at temperatures of 825 1C for 4 h and 925 1C for 6 h, respectively. After that they were mixed with the different compositions. It was found that the optimum sintering temperature of (1À x)BNLT ÀxBZT ceramic was obtained at 1125 1C for 2 h. This ceramic had the highest density. The structure of the (1 Àx)BNLT ÀxBZT ceramics exhibited the coexistence of tetragonal and rhombohedral phases with xr0.1. The tetragonality increases with the increase of x content. The average grain size, the density and the Curie temperatures decrease with increasing x content. The maximum dielectric constant and the highest P r were at about 4850 and 12.7 mC/cm 2 , respectively, and were obtained by the 0.85BNLT À0.15BZT sample.