Advanced Materials Research Vols. 55-57

Abstract: The piezoelectric ceramics of Pb(ZrxTi1−x)O3 – Pb(Zn1/3Nb2/3)O3 – Pb(Mn1/3Nb2/3)O3; PZT-PZN-PMN with Zr/Ti ratios of 48/52, 50/50 and 52/48 were fabricated in order to investigate the effect of compositional modifications on the ferroelectric properties of PZT-PZN-PMN ceramics. The phase structure of ceramics sintered at 1,150°C was analyzed. Results show that the pure perovskite phase was in all ceramic specimens, and the phase structure of PZT-PZN-PMN piezoelectric ceramics transformed from tetragonal to rhombohedral, with the Zr/Ti ratios increased in the system. The PZT-PZN-PMN ceramics with a Zr/Ti ratio of 50/50 exhibited the most promising properties including high remanent polarization and low coercive field of 25.95 µC cm−2 and 12.5 kV cm−1, respectively. Furthermore, the transition temperature decreased when the Zr/Ti ratio increased in the system.

Abstract: The compositions of Pb(Zr0.52Ti0.48)O3 doped with 1-6 mole% Nb content were prepared by a conventional mixed oxide technique. It was found that the phase formed depended on the dopant concentration. At lower concentration, the dominate phase was the tetragonal. With increasing Nb content the rhombohedral phase tended to increase. Furthermore, the Curie temperature (Tc) and dielectric constant decreased with increasing Nb concentration and the dielectric maximum peaks were broadened with more rhombohedral phase presence, causing the diffused ferroelectric-paraelectric phase transition. The impedance of the samples decreased with increasing temperature and it was also observed that the impedance increased with increasing Nb concentration.

Abstract: Zirconium-doped bismuth sodium titanate ceramics were prepared using the conventional processing method. X-ray diffraction analysis indicated the materials were single phase with a systematic shift due to increased unit cell size. The measured densities and grain size of the ceramic samples were found to range from 5.79-6.03 g/cm3 and 0.5-1.6 µm, respectively. The dielectric constant as a function of temperature became broader as Zr content increased. The piezoelectric constant was found to decrease with increasing Zr. Within the range of the solid solutions investigated, the materials seem to be promising for high temperature applications where stable dielectric constant is required.

Abstract: The structural and physical properties of(1−x)BaTiO3 –xBaFe0.5Nb0.5O3 ceramics system were investigated as a function of the BaFe0.5Nb0.5O3 content by X-ray diffraction (XRD) and dielectric measurement technique. Studies were performed on the samples prepared by solid state reaction for x = 0, 0.2, 0.4 and 0.6. The XRD analysis demonstrated that with increasing BFN content in (1−x)BT–xBFN, the structural change occurred from the tetragonal to the cubic phase at room temperature. Changes in the morphology were then related to these structural depending on the BFN content.

Abstract: In this research, 0-3 composites between non-lead based piezoceramic and polymer were fabricated using the suction technique. Bismuth sodium titanate (Bi0.5Na0.5TiO3:BNT) which prepared from conventional mixed oxide method was used as active phase whereas epoxy resin was used as matrix phase. The 50% volumetric fraction of BNT/epoxy resin can obtain from suction technique. The physical and piezoelectric properties of composites samples were examined. It can be found that density of composite samples were about 1.78 g/cm3. Moreover, the piezoelectric coefficient (d33) of sample was 13 pC/N. Furthermore, the microstructure of composites was determined using SEM technique.

Abstract: Zirconium titanate (ZrTiO4): ZT powders were prepared by solid-state mixed oxide method. The mixed powder was calcined at various temperatures for 3 h ranging from 1100 to 1400 oC with a heating rate of 5 oC/min. X-ray diffraction analysis of the powders was performed using a diffractometer with Cu Ka. Pyrochlore phase was observed for calcinations below 1300 oC. In general, the strongest reflections apparent in patterns could be matched with a JCPDS file number 74-1504. The optimum calcination temperature for the formation of ZrTiO4 phase was found to be about 1300 oC for 3 h with heating rate of 5 oC/min. The microstructures of calcined powders were examined using scanning electron microscope (SEM). The particle size of powder increased with increasing calcination temperature. The ZT ceramics sintered at 1450, 1500, 1550 and 1600 oC for 4 h with heating rate of 5 oC/min, were checked for phase formation by X-ray diffraction. The density of sintered samples was measured by Archimedes method. The microstructures of sintered samples were examined using scanning electron microscope (SEM). The average grain sizes were checked by linear interception method. It was found that, the samples sintered at 1450 and 1500 oC gave rise to high purity ZT ceramics and the peaks matched well with ZrTiO4 phase in a JCPDS file number 74-1504. Unknown phases were found in ZT ceramics sintered at 1550 and 1600 oC. The value of density was in the range of 4.32 - 4.92 g/cm3 or 84.26 - 96.12 % of the ZT theoretical density. The densification of ZT ceramics decreased with increasing sintering temperature. The ZT ceramics sintered at 1450 and 1500 oC showed the average grain size of 8.55 and 12.55 µm, respectively. At sintering temperature 1550 and 1600 oC, morphology of grains changed to plate like crystals of second phases.

Abstract: In this work, barium zirconate titanate (Ba(Zr0.07Ti0.93)O3) ferroelectric ceramics doped with B2O3 were prepared by the conventional mixed-oxide method. The properties of the ceramics as a function of sintering temperature were investigated. Various technique such as X-ray diffraction (XRD) technique, scanning electron microscopy, dielectric permittivity spectroscopy and ferroelectric property measurement were used to obtain characteristic of the ceramics. The optimum density was observed for 1250 oC sintered sample. An increase in sintering temperature produced a decrease in dielectric constant. However, ferroelectric behavior was improved in 1275 oC sintered sample. The results were discussed in term of microstructure and crystallinity of the ceramics.

Abstract: Lithium niobate powder (LiNbO3) were synthesized by citrate gel method using LiNO3, Nb2O5, citric acid and HF as starting materials. LiNO3 was dissolved in distilled water that activated into LiOH. Nb2O5 was dissolved in minimum amount of HF at 370C for 20 h. that activated into NbF5. Then citric acid, LiOH, and NbF5 were mixed in stoichiometric ratio. On heating at 1000C for 3-4 h. a yellowish gel is formed. Lithium niobate powders were obtained after calcination at 550-7000C. The effect of calcination temperature at various temperatures ranging from 5500C to 7000C were investigated. The phase and chemical composition of the synthesized powders were characterized by using XRD, SEM, TEM, FTIR and EDX. We found that the lithium niobate crystallize phase formed when the calcination temperature at 6500C with average particle size of around 100 nm .

Abstract: Barium titanate, BaTiO3 is a significant material for electronic components. It was known that Sr2+ substitution on Ba ion can strongly modify ferroelectric properties of BaTiO3 but the structural change has not been fully understood. An X-ray absorption spectroscopy at the Ti K-edge (4966 eV) and the Ba LIII-edge (5247 eV) was employed to investigate the structure of Ba1-xSrxTiO3 (BSTO) with 0

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