Perovskite Phase
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Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5065
Author(s):  
Artyom Plyushch ◽  
Nerijus Mačiulis ◽  
Aliaksei Sokal ◽  
Robertas Grigalaitis ◽  
Jan Macutkevič ◽  
...  

Composite materials with 83 wt.% of the 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 distributed in phosphate-bonded ceramics were prepared at three different pressures. A phosphate matrix comprises a mixture of an aluminum phosphate binder and melted periclase, MgO. All samples demonstrate a homogeneous distribution of the ferroelectric perovskite phase and are thermally stable up to 900 K. At higher temperatures, the pyrochlore cubic phase forms. It has been found that the density of the composites non-monotonously depends on the pressure. The dielectric permittivity and losses substantially increase with the density of the samples. The fabricated composites demonstrate diffused ferroelectric–paraelectric transition and prominent piezoelectric properties.


Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4376
Author(s):  
Songtao Yang ◽  
Weidong Tang ◽  
Xiangxin Xue

Low-grade vanadiferous titanomagnetite ore (LVTM) is as an important mineral resource for sintering ore manufacturing. Furthermore, TiO2 has a significant effect on the sintering process of iron ore fines. The effects of TiO2 on the metallurgical properties, microstructure, and mineral composition of LVTM sinter were investigated by sintering pot tests, X-ray diffraction (XRD), scanning electron microscopy (SEM), and mineral phase microanalysis. The results were as follows: as the TiO2 content increased from 1.75% to 4.55%, the flame front speed and productivity decreased, while the reduction degradation index (RDI) and softening properties deteriorated. In addition, the tumbler index (TI) values reached a maximum at TiO2 = 1.75%. In addition, with increasing TiO2 content, an increase in the magnetite and perovskite phase, and a decrease in calcium ferrite and hematite were found with an increase in TiO2 content. Thus, the lower the TiO2 content, the better the quality of the sinter.


2021 ◽  
Author(s):  
jie jiang ◽  
Lei Liu ◽  
Kuo Ouyang ◽  
Zhouyu Chen ◽  
Shengtao Mo ◽  
...  

Abstract With its excellent ferroelectric properties such as large dielectric constant and large remanent polarization, PZT thin films are extensively used in micro-sensors and other devices. In this study, the sol-gel process was used to fabricate Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1−x)O3 seed islands. The experimental consequences demonstrate that all the Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1−x)O3 seeds show pure perovskite phase with no other impurity phases, and the electrical properties of Pb(Zr0.52Ti0.48)O3 thin films modified by Pb(ZrxTi1−x)O3 seed islands with different Zr/Ti ratios are improved, such as remanent polarization increased, dielectric properties increased, coercive electric field decreased, leakage current density decreased, etc. In particular, the electrical properties of the Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1−x)O3 seed islands are the most optimal when the x is 0.52. This paper provides a new technique for optimizing the electrical properties of PZT thin films, which is of great significance for breaking through the bottleneck of the development of ferroelectric memory.


Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 900
Author(s):  
Ting-Kai Lin ◽  
Huang-Wei Chang ◽  
Wan-Chi Chou ◽  
Chang-Ren Wang ◽  
Da-Hua Wei ◽  
...  

In this work, we adopted pulsed laser deposition (PLD) with a Nd:YAG laser to develop Bi1−xGdxFeO3 (BGFO) films on glass substrates. The phase composition, microstructure, ferroelectric, magnetic, and nanomechanical properties of BGFO films are studied. BGFO films with x = 0.00–0.15 were confirmed to mainly consist of the perovskite phase. The structure is transformed from rhombohedral for x = 0.00 to pseudo-cubic for x = 0.05–0.10, and an additional phase, orthorhombic, is coexisted for x = 0.15. With increasing Gd content, the microstructure and surface morphology analysis shows a gradual decrease in crystallite size and surface roughness. The hardness of 5.9–8.3 GPa, measured by nanoindentor, is mainly dominated by crystallized structure and grain size. Good ferroelectric properties are found for BGFO films with x =0.00–0.15, where the largest remanent polarization (2Pr) of 133.5 µC/cm2 is achieved for x = 0.10, related to low leakage and high BGFO(110) texture. The improved magnetic properties with the significant enhancement of saturation magnetization from 4.9 emu/cm3 for x = 0 to 23.9 emu/cm3 for x = 0.15 by Gd substitution is found and related to large magnetic moment of Gd3+ and suppressed spiral spin structure of G-type antiferromagnetism. Furthermore, we also discuss the mechanisms of leakage behavior as well as nanomechanical characterizations as a function of the Gd content.


2021 ◽  
pp. 2150018
Author(s):  
Abdul Manan ◽  
Maqbool Ur Rehman ◽  
Atta Ullah ◽  
Arbab Safeer Ahmad ◽  
Yaseen Iqbal ◽  
...  

Ceramics-based capacitors with excellent energy storage characteristics, fast charging/discharge rate, and high efficiency have received significant attention. In this work, Na[Formula: see text]Bi[Formula: see text]NbO3(NBN) ceramics were processed through solid-state sintering route. The investigated ceramics were crystallized in a single perovskite phase. Dense microstructure, with small average grain size ([Formula: see text]0.92 [Formula: see text]m) is obtained for the investigated ceramics. A high dielectric constant >1000 accompanied by a low dielectric loss was achieved for these ceramics at ambient temperature. A recoverable energy density [Formula: see text]0.92 J/cm3and ultra-high efficiency of 96.33% at 138 kV/cm were obtained at room temperature. Furthermore, a lower discharging time of 0.14 [Formula: see text]s was also achieved. This material is a suitable candidate for power pulsed applications.


2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Negin Mohammadi ◽  
Zahra Khakpour ◽  
Amir Maghsoudipour ◽  
Aida Faeghinia

The perovskite Lanthanum Strontium Cobalt Ferrite (LSCF) is investigated as the cathode material used in intermediate-temperature solid oxide fuel cells (IT-SOFCs). In the present study, La0.6−xDyxSr0.4Co0.2Fe0.8O3−δ (x = 0, 0.3, 0.6) was synthesized through the coprecipitation method. The obtained precipitate was calcined at 500, 700, 900, and 1000°С. Phase characterization of the synthesized LSCF and LDySCF powder before and after heat treatment at 700°С was carried out by X-ray diffraction (XRD) analysis. XRD patterns revealed that the perovskite phase was obtained at 700°С in all calcined samples. Chemical bond study to investigate the synthesis process was conducted using the Fourier transform infrared spectroscopy technique. Thermal analysis of DTA and TG has been utilized to investigate how the calcination temperature affects the perovskite phase formation. According to the STA results, the perovskite phase formation started at 551°С and completed at 700°С. The density values of synthesized powders were 6.10, 6.11, and 6.37 g·cm−3for the undoped and doped samples calcined at 700°С. Powder morphology was studied by field emission scanning electron microscopy (FE-SEM). The micrographs showed the spherical-shaped particles with the average particle size of 24–131 nm.


Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3674
Author(s):  
Mélanie François ◽  
Maria Paola Carpanese ◽  
Olivier Heintz ◽  
Victoire Lescure ◽  
Davide Clematis ◽  
...  

A complete cell consisting of NiO-Ce0.8Sm0.2O3−δ//Ce0.8Sm0.2O3−δ//(La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ elaborated by a co-tape casting and co-sintering process and tested in operating fuel cell conditions exhibited a strong degradation in performance over time. Study of the cathode–electrolyte interface after cell testing showed, on one hand, the diffusion of lanthanum from (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ into Sm-doped ceria leading to a La- and Sm-doped ceria phase. On the other hand, Ce and Sm diffused into the perovskite phase of the cathode. The grain boundaries appear to be the preferred pathways of the cation diffusion. Furthermore, a strontium enrichment was clearly observed both in the (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ layer and at the interface with electrolyte. X-ray photoelectron spectroscopy (XPS) indicates that this Sr-rich phase corresponded to SrCO3. These different phenomena led to a chemical degradation of materials and interfaces, explaining the decrease in electrochemical performance.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hong Zhang ◽  
Felix Thomas Eickemeyer ◽  
Zhiwen Zhou ◽  
Marko Mladenović ◽  
Farzaneh Jahanbakhshi ◽  
...  

AbstractFormamidinium lead iodide perovskites are promising light-harvesting materials, yet stabilizing them under operating conditions without compromising optimal optoelectronic properties remains challenging. We report a multimodal host–guest complexation strategy to overcome this challenge using a crown ether, dibenzo-21-crown-7, which acts as a vehicle that assembles at the interface and delivers Cs+ ions into the interior while modulating the material. This provides a local gradient of doping at the nanoscale that assists in photoinduced charge separation while passivating surface and bulk defects, stabilizing the perovskite phase through a synergistic effect of the host, guest, and host–guest complex. The resulting solar cells show power conversion efficiencies exceeding 24% and enhanced operational stability, maintaining over 95% of their performance without encapsulation for 500 h under continuous operation. Moreover, the host contributes to binding lead ions, reducing their environmental impact. This supramolecular strategy illustrates the broad implications of host–guest chemistry in photovoltaics.


2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Lewis R. Blackburn ◽  
Rachel Crawford ◽  
Samuel A. Walling ◽  
Laura J. Gardner ◽  
Max R. Cole ◽  
...  

AbstractA fraction of the UK Pu inventory may be immobilised in a zirconolite ceramic matrix prior to disposal. Two zirconolite compositions, targeting CaZr0.80Ce0.20Ti2O7 and CaZr0.80U0.20Ti2O7, were fabricated by hot isostatic pressing, alongside a reformulated composition, nominally Ca0.80Zr0.90Ce0.30Ti1.60Al0.40O7, with an excess of Ti and Zr added to preclude the formation of an accessory perovskite phase. Materials were subjected to accelerated leaching in a variety of acidic and alkaline media at 90 °C, over a cumulative period of 14 d. The greatest Ce release was measured from CaZr0.80Ce0.20Ti2.00O7 exposed to 1 M H2SO4, for which 14.7 ± 0.2% of the original Ce inventory was released from the wasteform into solution. The extent of Ce leaching into the solution was correlated with the quantity of perovskite present in the wasteform, and associated with the incorporation and preferential dissolution of Ce3+. CaZr0.80U0.20Ti2.00O7 exhibited improved leach resistance relative to CaZr0.80Ce0.20Ti2.00O7, attributed to the decreased proportion of accessory perovskite, with 7.1 ± 0.1% U released to in 8 M HNO3 after 7 d. The Ca0.80Zr0.90Ce0.30Ti1.60Al0.40O7 composition, with no accessory perovskite phase, presented significantly improved leaching characteristics, with < 0.4%Ce released in both 8 M HNO3 and 1 M H2SO4. These data demonstrate the need for careful compositional design for zirconolite wasteforms with regard to accessory phase formation and surrogate choice.


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