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Magneto-Electric Properties of Sodium Potassium Lithium Niobate-Ni/Co Ferrite Nanocomposites
Published in Abu Zahrim Yaser, Poonam Khullar, A. K. Haghi, Green Materials and Environmental Chemistry, 2021
Normal sintering method is adopted in our work to prepare (Na0.5 K0.5)0.94 Li0.06 NbO3 − Ni/Co Fe2O4 nanocomposites (NCs). Sintering has greater design flexibility and controllability on grain growth and other physical parameters [17]. In order to fabricate magneto-electric 0–3 composites, physical mixing of individual phases has been done followed by high-temperature sintering. The ferrite nanoparticles (NPs) are synthesized by wet chemical or co-precipitation route. For this, aqueous solutions of 0.4 molar ferric chloride and 0.2 molar metal Ni/Co chloride solutions are mixed and stirred well in an alkaline pH. In order to reduce agglomeration, two or three drops of a surfactant, oleic acid, are added and allowed to mix in a temperature of about 90°C. The precipitate obtained is washed well with deionized water and acetone to remove unreacted salts, extra-base, and surfactant. The calcination was carried out at 600°C for 10 hours [21]. Bulk piezoelectric phase is prepared by conventional solid-state reaction route. Stoichiometric ratios of Na2CO3, K2CO3, Li2CO3, Nb2O5 are mixed using mortar and pestle in ethanol medium and the powder so obtained is calcined at 850°C for 10 hours to get the piezoelectric phase [22].
Transition Metal-Oxide-Based Electrodes for Na/Li Ion Batteries
Published in Vijay B. Pawade, Paresh H. Salame, Bharat A. Bhanvase, Multifunctional Nanostructured Metal Oxides for Energy Harvesting and Storage Devices, 2020
NaxCoO2 was also synthesized in nanocrystalline form by D’Arienzo et al.47 utilizing the hydrothermal synthesis route and solid-state reaction route. They first synthesized Co3O4 using the hydrothermal route, which was then the solid state reacted with either NaOH or Na2CO3. Both the products gave the same P2-Na0.71CoO2 phase, but morphology was drastically different. The material obtained from reacting Na2Co3 had narrow particle length and 2D platelet-like morphology; however, the product obtained from NaOH displayed large microcrystals, which were irregular in shape and had broad particle size distribution. The 2D microplatelets of Na0.71CoO2exhibited superior behavior amongst them, with stable discharge specific capacity of 120, 105, and 80 mAh/g at 5, 20, and 40 mA/g, respectively, in the potential range of 2.0–3.9 V.
Powder Synthesis by Chemical Methods
Published in Mohamed N. Rahaman, Ceramic Processing, 2017
Complex oxides are oxides such as titanates, ferrites, and aluminates that contain more than one type of metal in the chemical formula. Earlier, we outlined the drawbacks of the solid-state reaction route for the production of fine, stoichiometric, high-purity powders. Some of those difficulties can be alleviated by the use of coprecipitation from a solution of mixed alkoxides, mixed salts, or a combination of salts and alkoxides. A common problem in coprecipitation is that the different reactants in the solution often have different hydrolysis rates, resulting in segregation of the precipitated material. Suitable conditions must therefore be found to achieve homogeneous precipitation. As an example, consider the preparation of MgAl2O4 powders [34]. Both Mg and Al are precipitated as hydroxides, but the conditions for their precipitation are quite different. Al(OH)3 is precipitated under slightly acidic or basic conditions (pH = 6.5–7.5), is soluble in the presence of excess ammonia, but is only slightly soluble in the presence of NH4Cl. Mg(OH)2 is completely precipitated only in strongly basic solutions such as NaOH solution. In this case, an intimate mixture of Al(OH)3 and Mg–Al double hydroxide, 2Mg(OH)2·Al(OH)3, is produced when a solution of MgCl2 and AlCl3 is added to a stirred excess solution of NH4OH kept at a pH of 9.5–10. Calcination of the precipitated mixture above ~400°C yields stoichiometric MgAl2O4 powder with high purity and fine particle size.
Structural, dielectric and piezoelectric characterization of BFN-modified PZT-based (MPB) ceramics
Published in Phase Transitions, 2023
Kahoul Fares, Benseghir Sabrina, Hamzioui Louanes, Guemache Abderrezak, Aillerie Michel, Boutarfaia Ahmed
The BFN–PZT piezoceramics were fabricated via the solid-state reaction route. The starting powders were reagent grade Bi2O3 (99.9%), Fe2O3 (99.6%), Nb2O5 (99.5%), PbO (99%), ZrO2 (99%), and TiO2 (99%). According to the stoichiometric ratios of the formula xBi(Fe1/3Nb2/3)O3–(1-x)Pb(Zr0.50Ti0.50)O3 (x = 0, 0.0025, 0.005, 0.0075 and 0.01), the powders were weighed and an excess of 2 wt% PbO was added to all compositions to compensate for the partial evaporation of PbO at the high temperatures required for sintering. After weighing, the raw powders were mixed by ball milling in ethanol for 24 h. The mixed powders were dried and then calcined at 900°C for 3 h with a heating rate of 5°C/min. The calcined clinker was ground to powders with a mortar and then the powders were ball milled again for 24 h. The 5% polyvinyl alcohol (PVA) solution was added to the calcined powders. The discs with a diameter of 10 mm and a thickness of 1 mm were pressed under the uniaxial pressure of 100 MPa. The green pellets were burnt out at 550°C for 2 h to remove the PVA binder and then sintered at 1100°C for 3 h in a sealed alumina crucible. The silver paste was screen-printed on the surfaces of the sintered pellets and then fired at 750°C for 10 min. The samples with silver electrodes were poled in silicone oil at 120°C for 45 min under a DC voltage of 40 kV/cm.
Synthesis and characterizations of ‘Ca’-doped Ba(FeNb)0.5O3 for device application
Published in Phase Transitions, 2022
Rimpi Chakravarty, Nabasmita Saikia, R. K. Parida, B. N. Parida
The Ba0.96Ca0.04(FeNb)0.5O3 perovskite was prepared using solid-state reaction route. This synthesis technique was chosen as it is simple, cost-effective and has reliable reaction efficiency. The raw materials BaCO3, CaCO3, Fe2O3 and Nb2O5 (purchased from M/s LOBA Chemie.Pvt. Ltd. India) in their proper stochiometic ratio were weighted out in accordance to the following relation: These raw materials were mixed in an agate mortar and ground using a pestle for an hour. It was followed by wet (methanol) grinding for another two hours for better homogeneity. The powder sample was calcined in a high-temperature muffle furnace by placing it in an alumina crucible. Using the repeated firing technique, calcination temperature was finally obtained to be 1250°C. The calcined powder mixed with PVA (acts as a binding agent) was pelletized to form a circular disc of diameter 10 mm and thickness 1 mm by exerting 4 × 104 N/m2 pressure through a hydraulic press. Finally, the pellet was sintered at 1300°C for four hours.
Pyroelectric energy harvesting and ferroelectric properties of Pb x Sr1- x TiO3 ceramics
Published in Journal of Asian Ceramic Societies, 2020
Zhen-Xun Tang, Peng-Zu Ge, Xin-Gui Tang, Qiu-Xiang Liu, Yan-Ping Jiang
In summary, PST ceramics were synthesized successfully by solid-state reaction route. XRD patterns demonstrated that the samples show coexistence of the tetragonal and cubic phases. Phase transition behavior of PST ceramics is investigated by temperature-dependent dielectric permittivity εr measurements. The result showed that Pb2+ doping increased the FE to PE phase transition temperature (PST30 (12°C), PST35 (50°C) and PST40 (98°C)). The temperature-dependent P-E measurements were implemented to study the FE performance of PST ceramics. Slim P-E hysteresis loops were obtained in all samples. The phase transition from FE to PE phase was also observed in P-E measurements. In addition, the pyroelectric energy harvesting performance of PST ceramics was evaluated based on the Olsen cycle. PST35 ceramic (ND = 283 kJ/m3 at ∆T = 70°C, EL = 2.5 kV and EH = 40 kV) was suggested to be most potential for pyroelectric energy harvesting application near RT among all samples.