Microstructure and Dielectric Properties of Bi Substituted PLZMST Ceramics

Bismuth (Bi) and lanthanum (La) doped lead manganese antimoine zirconate titanate (PZMST) ceramic powders have been synthesized by high temperature solid-state reaction method. Preliminary X-ray structural analysis of the compounds shows the formation of tetragonal structure. Scanning electron micrographs (SEM) shows a uniform grain distribution and grain size of the order of ~2.28 μm. Detailed dielectric studies of the Pb0.95(La1-z Biz)0.05[(Zr0.6Ti0.4)0.95(Mn1/3Sb2/3)0.05]O3 samples as a function of the temperature (from 25°C to 450°C) at frequency 1 kHz suggest that the compounds undergo a diffuse phase transition. The transition temperature shifts increase with increasing the Bi ratio. Diffusivity (γ) study of phase transition of these compounds provided its value from 1.59 to 1.78 indicating the degree of the disordering in the system.

Synthesis and Dielectric Properties of (0.80 - x)Pb(Cr_1/5,Ni_1/5,Sb_3/5)O₃-xPbTiO₃-0.20PbZrO₃Ferroelectric Ceramics

Perovskite PZT variants were synthesized from stoichiometric oxide ratios of Pb, Zr, Ti, Cr, Ni and Sb. The oxide powders were mixed mechanically and calcinated, and then sintered to form the desired perovskite phase. The detailed structural and ferroelectric properties were carried out for sintered specimens. The results of X-ray diffraction showed that all the ceramics specimens have a perovskite phase. The multi-component ceramic system consists of the (0.80?- x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 (PZT-CNS), with 0.30 ≤ x ≤ 0.42, and the ternary system near the rhombohedral/tetragonal morphotropic phase boundary(MPB) was investigated by X-ray diffraction and dielectric properties. In the present system, the MPB that coexists with the tetragonal and rhombohedral phases is a narrow composition region of x = 0.38 - 0.42. The scanning Electron Microscopy (SEM) showed an increase of the mean grain size when the sintering temperature was increased. A sintered density of 92.93% of the theoretical density was obtained for Ti = 42% after sintering at 1180°C. Ceramics sintered at 1180°C with Ti = 42% achieve excellent dielectric properties, which are as follows εr = 4262.48, and Tc = 340°C.

Effects of Thermal Conditions in the Phase Formation of Undoped and Doped Pb(Zr_1-xTi_x)O₃Solid Solutions

The purpose of this research is to study the effect of thermal conditions such as temperature ramp rate and isothermal times in the phase formation of Pb(Zr1-xTix)O3 solid solutions with composition near the morphotropic phase boundary (MPB) by using the conventional ceramic method. The perovskite phase formation and morphology of undoped Pb(Zr0.52Ti0.48)O3 (abbreviated PZT) and doped new material Pb0.98Gd0.02[(Zr0.52Ti0.48)0.98(Mg1/3Nb2/3)0.01(Ni1/3Sb2/3)0.01]O3 (abbreviated PZT-PGMNNS) specimens calcined between 700°C and 900°C have been examined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) while the thermal evolution of the initial precursor was followed by TG-DTA. So the results of these studies have been discussed.

Investigation on the Microstructure and Electrical Properties of the Compositionally Modified PZT Ceramics Prepared by Mixed-Oxide Method

The structural and electrical properties of Pb[ZrxTi0.95-x(Mo1/3In2/3)0.05]O3 piezoelectric ceramics system with the composition near the morphotropic phase boundary were investigated as a function of the Zr/Ti ratio. Studies were performed on the samples prepared by the conventional method of thermal synthesis of mixed oxides. The materials structure was investigated by X-ray diffractometry to demonstrate the co-existence of the tetragonal and rhombohedral phases. In the present system, the MPB, in which the tetragonal and rhombohedral phases coexist, is in a composition range of 0.47 ≤ x ≤ 0.50. The lattice constants of the a and c axes for the samples were calculated from the XRD patterns. Microstructure of the sintered ceramics was observed by scanning electron microscopy (SEM) of free surfaces specimens. The relative permittivity, dielectric dissipation, piezoelectric coefficient and electromechanical coupling factor reach at maximum value x = 0.49 (εr = 7300.345 (at the Curie temperature), tanδ = 0.002050, d31 = 94.965 PC/N and kp = 0.513 and a Curie temperature of 430°C). These properties are very promising for applications in ultrasonic motors.

The Study of Reaction Sequences for Formation of Solid Solution of Ceramic Material: Pb_1-2XSm_xNd_x[(Zr_0,55Ti_0,45)_1-0.02,0.01(Y_2/3,Mo_1/3),0.01 (Y_2/3,Ni_1/3)]O₃and the Study of These Structures

This work is aimed to synthesize new type ceramic materials: Pb1-2XSmxNdx[(Zr0,55Ti0,45)1-0.02,0.01(Y2/3,Mo1/3),0.01 (Y2/3,Ni1/3)]O3 of structure perovskite in the presence of the doping agents: NiO, Sm2O3, Y2O3, Nd2O3 and MoO3 near the morphotropic phase boundary. These ceramics worked out by solid way, we present the preparation and the different stages of the formation reaction of the solid solution. Then we will detail the different techniques of analysis applied to this compound;we begin by the X-ray diffraction in the following by analysis spectroscopic (FTIR), analysis by scanning electron microscopy (SEM) and finally analysis by spectrometric energy dispersive (EDS). These studies help us to accumulate as much information on these materials.

Synthesis and Piezoelectric Properties of Pb_0.98Sm_0.02[(Zr_y,Ti_1–y)_0.98(Fe_1/2³⁺,Nb_1/2⁵⁺)_0.02]O₃Ceramics

The structural and electrical properties of Pb0.98Sm0.02[(Zry,Ti1–y)0.98( Fe1/23+,Nb1/25+)0.02]O3 ceramics system with the composition near the morphotropic phase boundary were investigated as a function of the Zr/Ti ratio by X-ray diffraction (XRD). Studies were performed on the samples prepared by solid state reaction for y = 0.47, 0.49, 051, 0.53, 0.55 and 0.57. Combined with piezoelectric properties results, it was consistently shown that an MPB exists between y = 0.51 and y = 0.55 in this system. When y 0.55, the rhombohedral phase dominates. Lattice parameters of the tetragonal phase and rhombohedral phase were found to vary with chemical composition. The average particle size ranged from 17.18 to 26.05 nm. The dielectric (ε = 1076), tan δ = 0.013 and piezoelectric properties (d31 = 122 pC/N, kp = 0.631 and Qm = 462) obtained were maximum at y = 0.55 which could be suitable for possible electromechanical and energy harvesting applications.

The Study of a New Ceramic PZT Material Pb_1-0.04Sm_0.02Nd_0.02[(Zr_0.55,Ti_0.45)_1-2x,x(Y_2/3,Mo</sub>1/3</sub>), x(Y_2/3,Ni_1/3)]O₃with SEM and X-Ray Diffraction

The PZT is modified by the introduction of doping agents in A-sites and/or B-sites of perovskite structure [1]. The principal role of dopants is generally improving the properties of these materials for their adaptation to specific applications, which is the purpose of this study. Our choice fell on the mixed oxide: acceptor and donor. Five compositions with varying dopants percentage were prepared by the conventional method of thermal synthesis of mixed-oxides. Pb1-0.04Sm0.02Nd0.02[(Zr0.55,Ti0.45)1-2x,x(Y2/3,Mo1/3),x(Y2/3,Ni1/3)]O3 such that (x = 0.01, 0.03, 0.05, 0.07 and 0.1), are studied. All the samples were being sintered at a temperature ranging from 1100°C to 1180°C after being compacted in circular discs. The detailed structure was carried out for sintered specimens. The results of X-ray diffraction showed that all the ceramics specimens have a perovskite phase. The phase structure of Pb1-0.04Sm0.02Nd0.02[(Zr0.55,Ti0.45)1-2x, x(Y2/3,Mo1/3),x(Y2/3,Ni1/3)]O3 ceramics was transformed from the tetragonal to the rhombohedral, with an increase in the ratio of Zr/Ti in system. The scanning Electron Microscopy (SEM) showed an increase of the mean grain size when the sintering temperature was increased. The lattice parameter measurements showed that tetragonal and rhombohedral unit cells of the phases depend on the sintering temperature.

The Structure and the Electrical Properties of Pb_0.95La_0.05[Zr_xTi_(0.95–x)(Mo_1/3,In_2/3)_0.05]_0.9875O₃Ferroelectric Ceramics

The structural, the dielectric, and the piezoelectric properties of new ferroelectric Pb0.95La0.05[ZrxTi(0.95–x)(Mo1/3,In2/3)0.05]0.9875O3(0.46 ≤ x ≤ 0.55) ceramics have been investigated. All the samples were being sintered at a temperature ranging from 1000 to 1180℃ after being compacted in circular discs. The detailed structural and ferroelectric properties were carried out for sintered specimens. The results of X-ray diffraction showed that all the ceramics specimens have a perovskite phase. The phase structure of Pb0.95La0.05[ZrxTi(0.95–x)(Mo1/3,In2/3)0.05]0.9875O3 ceramics was transformed from the tetragonal to the rhombohedral, with an increase in the ratio of Zr/Ti in system. In the present system the MPB that coexists with the tetragonal and rhombohedral phases is a narrow composition region of x = 0.50 – 0.51. The scanning Electron Microscopy (SEM) showed an increase of the mean grain size when the sintering temperature was increased. The dielectric constant ε and the coupling factor Kp reached the maximum values, while the mechanical quality factor Qm and the loss tangent reached the lowest values when x = 0.50. For the composition where x = 0.50, these properties include ε = 5414 (at the Curie temperature), tangδ = 0.039, Kp = 0.67, Qm = 20 and a Curie temperature of 335℃.