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Relationship between electrical conductivity and MoO3 content of Bi3.25La0.75(Ti1-xMox)3O12 ceramics. The measurement was done at frequencies of 1, 50, and 100 kHz.
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In this work, the fabrication and investigation of substituting higher-valence Mo6+ for Ti4+ ion on the B-site of La3+-doped Bi4Ti3O12 [BLT] structure to form Bi3.25La0.75(Ti1-x
Mo
x
)3O12 [BLTM] (when x = 0, 0.01, 0.03, 0.05 0.07, 0.09, and 0.10) ceramics were carried out. X-ray diffraction patterns of BLTM ceramics indicated an orthorhombic struc...
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0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 (PMNT) ceramics were fabricated by using their powders synthesized through a sol–gel process. Excess Pb(CH3COO)2·3H2O (0, 2, 5, 10 or 15 mol%) was added to the starting materials to study the effect of excess Pb on the microstructures, ferroelectric
and dielectric properties of the PMNT ceramics. All the X-ray diffra...
Iron-containing ferroelectrics tend to exhibit large dielectric loss accompanied by strong frequency dispersion of the dielectric properties, which is considered to correlate with the partial reduction of Fe3+ to Fe2+ ions during sintering. After sintering in an O2 atmosphere, MnO2 and Li2CO3 dopings exhibit superior behavior in decreasing the diel...
La/Mn codoped BaTiO 3 ceramics with various La 2 O 3 content, ranging from 0.3 to 1.0 at% La, were investigated regarding their microstructure and dielectric properties. The content of MnO 2 was kept constant at 0.01 at% Mn in all samples. La/Mn codoped and undoped BaTiO 3 were obtained by a modified Pechini method and sintered in air at 1300 0 C f...
Improving the energy storage density of dielectrics without sacrificing charge-discharge energy storage efficiency and reliability is crucial to the performance improvement of modern electrical and electronic systems, but traditional methods of doping high-dielectric ceramics cannot achieve high energy storage densities without sacrificing reliabil...
Citations
... On the other hand, many researchers have co-doped the (Ti-site) with different pairs of ions such as (Fe 3+ /Co 3+ ), (Fe 3+ /Nb 5+ ), (Nb 5+ /Ta 5+ ) and (W 6+ /Cr 3+ ) to improve multiferroic properties and magnetoelectric coupling [19][20][21][22][23][24]. According to the literature, the synthesis of BIT aurivillius was done by different preparation methods: sol-gel method [25,26], Pucheni method [27,28] and solid state reaction [29][30][31][32]. ...
Abstract: The effect of 8% of (Ni2+, Ta5+) content and the route of synthesis (i.e., conventional solid state reaction « CSS
» and molten salt method « MS ») on micro-structural, morphological and dielectric properties of BIT ceramics have been
investigated. X-ray diffraction (XRD) analysis revealed that the (Ni,Ta)- modified BIT ceramics have a pure orthorhombic
three-layer Aurivillius type structure. Phase purity is obtained at 950°C by CSS reaction and by the MS method at 850°C.
SEM/ EDX results confirms that the samples have a relatively dense pure, with micro-grains plate-like, structure typical
for Aurivillius layered structures but strongly influenced by the crystallite size of both methods. The dielectric constant and
the tangent loss of 8%-BNTT have been found to be decreasing by shifting the curie temperature to a high temperature,
when we change the reaction from CSS to MS.
(1-x)Bi0.5Na0.5TiO3-x(Bi3.25La0.75)Ti3O12; (1-x)BNT-xBLT ceramics with x = 0–0.20 wt.% were prepared by solid-state reaction method. The Bi0.5Na0.5TiO3 (BNT) and (Bi3.25La0.75)Ti3O12 (BLT) powders were calcined separately. The BNT powder was calcined at 850 °C for 2 h. and BLT powder at 750 °C for 4 h. The (1-x)BNT-xBLT samples were sintered between 1050 °C and 1200 °C for 4 h. All samples exhibit almost a pure perovskite phase with coexistence of rhombohedral and orthorhombic phases. The average grain size decreased with increased in x(BLT) contents. The maximum density and relative density of about 5.87 ± 0.11 g/cm³ and 97.2% were obtained for the composition of 0.97BNT–0.03BLT. The temperature at maximum permittivity (Tm) tended to increase from 324 °C to 341 °C with increase in x(BLT) contents. The results revealed that the fatigue behavior was improved in the sample of 0.97BNT–0.03BLT, where a slight decrease in remanent polarization with low degradation of ferroelectric properties was observed after electrical fatigue.
The wide band gap of complex oxides is one of the major obstacles limiting their use in photovoltaic cells. To tune the band gap of complex oxides, this study examined the effects of chemical/oxygen vacancy doping on Bi4Ti3O12 based oxides synthesized using a solid reaction method. The structural, optical and electrical properties of the synthesized powers were determined by x-ray diffraction, scanning electron microscopy, ultraviolet-visible spectroscopy, and resistant measurements. Both types of doping, chemical doping and oxygen doping, could affect the tunability of the band gap. On the other hand, the decrease in band gap from oxygen vacancy doping was much more significant in the chemical doped sample than in the sample without chemical doping. Two stage doping, which combined chemical and oxygen vacancy doping, of La doped bismuth titanate reduced the band gap of La doped bismuth titanate from 2.75eV to 1.2eV without breaking symmetry.
Studies of the photoelectric properties of complex oxides have recently focused on materials with a narrow band gap because the wide band gap of complex oxides is one of the major obstacles limiting their use in photovoltaic cells. To tune the band gap of complex oxides, this study examined the effects of cobalt and iron doping on lanthanum-modified Bi4Ti3O12-based oxides (BLT) synthesized using a solid reaction method. The structural, optical and electrical properties of the synthesized powers were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible spectroscopy. Doping with both atoms affected the tunability of the band gap dramatically without breaking symmetry. On the other hand, the transition region in the band gap from the iron-doped sample was much sharper than that from the cobalt-doped sample. Control of the band gap chemical doping can be applied to other complex oxides materials and provides a new tool for manipulating oxide optoelectronics.
The wide band gap of complex oxides is one of the major obstacles limiting their use in optoelectronic devices. To control the band gap of wide complex oxides, cobalt-doped lanthanum-modified bismuth titanates powders (Co-BLT) were synthesized using a solid-state reaction at various calcination temperatures. The structural and optical properties were analyzed by X-ray diffraction (XRD) and ultraviolet-visible (UV-vis) absorption spectroscopy. XRD confirmed that the samples calcined at 700 °C crystallized in an orthorhombic structure without breaking symmetry, while the samples calcined under 600 °C formed the α-Bi2O3 phase and the samples calcined at high temperatures (800, 900 °C) formed a Bi-based secondary phase. UV-vis absorption spectroscopy showed that the optical band gap decreased gradually from 2.82 eV to 1.56 eV with increasing calcination temperature from 300 to 900 °C. The optimal calcination temperature to reduce the optical band gap was 700 °C. Tuning of the band gap using different calcination temperatures might be applicable to other complex oxides materials for use in emerging oxide optoelectronic devices.
