Advanced Materials Research Vols. 55-57

Abstract: The objective of the present paper is to give an insight of the fundamental properties strongly depended on the crystallizing phase, grain size, thickness, including stoichiometry of material. The subject of this work is the lead zirconate titanate [Pb(Zr,Ti)O3, PZT] with its composition located at the morphotropic phase boundary (MPB) that were prepared by a solid state method [1] and a conventional sol-gel technique [2,3]. The samples prepared by the first methods are in a bulk form while the latter the multilayer. The physical property and the dielectric and piezoelectric properties of the PZT samples have been discussed comparatively when the sample size decreasing from the bulk to the thin-film scale.

Abstract: he solid solution between the normal ferroelectric Pb(Zr1/2Ti1/2)O3 (PZT) and relaxor ferroelectric Pb(Co1/3Nb2/3)O3 (PCoN) was synthesized by the solid state reaction method. Sintered PZT-PCoN ceramics were annealed at temperatures ranging from 850 to 1,100°C for 4 h. X-ray diffraction patterns revealed changes of crystalline structure after annealing, which could be correlated to the accompanied changes in dielectric properties. Furthermore, significant improvements in the dielectric responses were observed in this system. After annealing, a huge increase of up to 200% occurred in the dielectric constants, especially near the temperature of maximum dielectric constant.

Abstract: Phase evolution and physical properties of (1-x)BZT–xBFN ceramic system were investigated to find the optimum condition for electronic applications. (1-x)BZT–xBFN powders were prepared by solid state reaction technique varying x from 0.2 to 0.8 and various sintering temperatures from 1350 °C to 1450 °C. Phase formation was investigated by X-ray diffraction technique. The XRD analysis demonstrated that with increasing BFN content in (1−x)BZT–xBFN, the structural change occurred from the tetragonal to the cubic phase at room temperature. Changes in the physical and mechanical properties were then related to this structural transformation depending on the BFN content.

Abstract: In present work, lead zirconate titanate (PZT) ceramics, having the composition near morphotropic phase boundary were prepared by conventional mixed oxide method. The sintering process was performed at various sintering temperatures ranging from 1100 to 1300 oC. Relationships between phase and sintering temperature, and phase and structure were reported. An increase sintering temperature affected the increase in grain size. The grain growth rate was found to have a linear fit with the phenomenological kinetic grain growth equation. Tetragonal relative fraction increased with increasing sintering temperature. In addition, dielectric constant at dielectric peak increased with increasing grain size which consistent with the trend of tetragonality.

Abstract: A microwave (MW) plasma reactor for the synthesis of polythiophene (PTh) thin films as well as in situ doping during polymerization process has been designed and assembled. Plasma polymerization parameters were studied. A good MW power was found to be in the range of 150-250W. PTh films were characterized by various spectrophotometric methods. IR analyses showed absorption frequencies of important functional groups. PTh films exhibited UV-Vis spectra indicative of increased conjugative systems as the MW power increased although at 300 and 380W partial fragmentation was evident. Surface analysis by SEM revealed a uniformly deposited film morphology. EDS results were also suggestive of partial fragmentation of the films at high MW powers. Preliminary conductive measurements revealed that the undoped films exhibit higher conductivity (3 to 9×10-5 s.cm-1) than PTh typically prepared from electrochemical methods.

Abstract: Zinc titanate (ZnTiO3) powder was prepared by the coprecipitation oxalate method. Zinc nitrate and titanium (IV) isopropoxide were used as the starting materials with the mole ratio of Zn:Ti was 1:1. Oxalic acid and ammonium hydroxide were added into the mixed solution. Precipitated powder was obtained after the final pH of solution was 5. The fined powder was washed with deionized water, filtered, dried at 100 oC for 2h, and followed by the calcination at 500, 700 and 900 oC for 2h. The phase of ZnTiO3 powder was studied by X-ray diffraction (XRD). The morphology was characterized by scanning electron microscopy (SEM). Hexagonal and cubic phase of ZnTiO3 powder were obtained after calcination at 900 oC. The particle size of ZnTiO3 powder was in the range of 0.1-0.5 µm with irregular in shape and agglomerated. The chemical

Abstract: Boron oxide doped barium stannate titanate ceramics were prepared by a solid-state reaction method. Properties of the ceramics were investigated. The experimental results showed that most properties of the ceramics depend on the sintering temperature. The higher relative permittivity of 13887 with tan 0.034 at 34 °C was observed for the samples sintered at 1350 C. Piezoelectric coefficient (d33) of the samples was found to be in the range of 90 - 115 pC/N. However, the optimum d33 coefficient was observed for the sample sintered at 1250 C.

Abstract: (1-x)(Bi0.5Na0.5TiO3)-xBa(Ti0.95Zr0.05)O3 ceramics were prepared by the mixed oxide technique and their dielectric, piezoelectric and ferroelectric properties determined in detail in the range x = 0.06 to 0.09. At x = 0.07 the maximum relative permittivity of 1338 and piezoelectric constant of 167 pC/N were obtained. It was concluded that 0.93(Bi0.5Na0.5TiO3)-0.07Ba(Ti0.95Zr0.05)O3 is the morphotropic phase boundary region for this system.

Abstract: Niobium doped PZT (PZTN) powder was prepared by a triol-sol-gel method from a mixture of lead (II) acetate trihydrate, 1,1,1-tris (hydroxymethyl), acetylacetone, titanium (IV) isopropoxide, zirconium (IV) propoxide and niobium (V) ethoxide and calcined at temperature ranging from 300-600oC for 2 h and 600oC for 4 h with a heating/cooling rate of 5oC/min. Thermal characteristics of the PZTN powders were studied using thermogravimetric/differential thermal analyses (TG/DTA). Phase formation in the powder was determined using X-ray diffraction analysis (XRD). Morphology of the PZTN powder was investigated by a scanning electron microscopy (SEM) and transmission electron microscopy (TEM). High purity perovskite structure of PZTN powder with a rhombohedral structure and a crystallite size 38 nm was obtained at the temperature of 600oC for 4 h dwell time. Well separated particles with uniform particle size distribution within 10-50 nm were also observed by TEM.

Abstract: Barium titanate (BaTiO3) was synthesized by the oxalate method with the starting precursors as barium chloride and potassium titanium oxalate with mole ratio of 1:1. Precipitate was obtained after adding oxalic acid until the pH of the final solution was 4. The precipitate was milled and calcined at 700 oC for 2h. Mn-doped barium titanate (BaMnTiO3) was prepared by the impregnation method. Barium titanate calcined at 700 oC was mixed with 2 and 4 mole % of Mn from manganese chloride. The mixed powder was calcined at temperatures of 800 oC and 900 oC for 2h. The phase of BaMnTiO3 was studied by X-ray diffraction (XRD). Hexagonal structure of Ba(Mn0.33Ti0.67)O2.84 was obtained after calcination at 900 oC for 2h with 2 and 4 mole % of Mn. The morphology and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The particle size of Ba(Mn0.33Ti0.67)O2.84 powder was in the range of 50-60 nm with irregular in shape. The elemental composition of barium, manganese, titanium and oxygen showed the characteristic X-ray energy values.