Papers by Keyword: La Substitution

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Authors: Xia Zeng, Wen Xiu Cheng, Ping Sun Qiu, Xi Yun He
Abstract: Highly transparent lead lanthanum zirconate titanate (Pb1−xLax)(Zr0.65Ti0.35)1-x/4O3 (x=0.096-0.1) electro-optic ceramics were prepared by the hot pressing method. The ceramics exhibited transparency as high as 67% at 632.8nm (close to the theoretical value). The effects of lanthanum substitution on the phase structure, microstructure, dielectric, ferroelectric, optical and electro-optic properties of PLZT were examined systematically. The XRD results indicated that all the compositions were single perovskite phases, and La substitution decreased the lattice constant and unit-cell volume. The dielectric results showed that the Tmax and εmax decreased with La content increasing. The hysteresis loops showed that the La content reduced saturate polarization (Ps), remnant polarization (Pr) and coercive field (Ec). Moreover, the half-wave voltage and EO coefficient R was enhanced and reduced respectively with increasing La.
Authors: Abolghasem Ataie, S. Moslemi
Abstract: La substituted barium hexaferrite Ba1-yFe12LayO19 with 0≤ y ≤0.5 was synthesized by chemical co-precipitation method using aqueous solutions of metallic chlorides at ambient temperature. NaOH was used as a precipitant. The co-precipitated products were annealed at 900 and 1000°C. The effects of La addition on the phase composition, morphology and thermal behavior of samples were studied using XRD, SEM and DTA/TGA, respectively. XRD results indicated that barium hexaferrite forms together with some intermediate phases in samples annealed at 900°C and the amount of intermediate phases decreased significantly by increasing annealing temperature to 1000°C. XRD results also showed that in sample annealed at 1000°C, the crystallite size of magnetic phase decreases from 98 to 64 nm by increasing the amount of La. Thermal analysis (DTA/TGA) implies that formation temperature of barium hexaferrite is increased with addition of La.
Authors: Zhi Dong Han, Li Min Dong, Ze Wu, Xian You Zhang
Abstract: The paper aims at synthesizing La substituted BaM hexaferrites (BaLa0.5Fe11.5O19) in the presence of SiO2 nano-particles by sol-gel method. Effects of SiO2 nano-particles on the structure and particle size of hexaferrites are investigated by XRD and SEM. Magnetic properties of BaFe12O19, BaLa0.5Fe11.5O19 and BaLa0.5Fe11.5xO19/SiO2 are compared by vibrating sample magnetometer (VSM). The XRD patterns of BaLa0.5Fe11.5O19/SiO2 calcined at 1000°C manifest that all the species have hexagonal crystal structure and no diffraction peaks of SiO2 are found. Compared with BaLa0.5Fe11.5O19 powders, those synthesized in the presence of SiO2 nanoparticles present in smaller powder size, as proved by SEM. The results of VSM reveal that BaLa0.5Fe11.5O19 possesses much higher saturation magnetization than BaFe12O19. BaLa0.5Fe11.5xO19/SiO2 also shows higher saturation magnetization than BaFe12O19, but lower than BaLa0.5Fe11.5O19 because of addition of nano-SiO2.
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