Magnetoelectric, dielectric, and magnetic investigations of multiferroic NixCo1-xFe2O4-SryBa1-yNb2O6 composites
Magnetoelectric (NixCo1-xFe2O4)0.3-(SryBa1-yNb2O6)0.7 composites with a 0–3 connectivity and different cation stoichiometries were synthesized via a classical mixed-oxide method. XRD patterns of all ceramics show reflections of the target phases SryBa1-yNb2O6 and NixCo1-xFe2O4. The influence of stoichiometry of the ferrimagnetic and ferroelectric phase on the magnetoelectric behavior was studied on composites with composition of (NixCo1-xFe2O4)0.3-(Sr0.5Ba0.5Nb2O6)0.7 and (NiFe2O4)0.3-(SryB...
Unusual adsorption-induced phase transitions in a pillared-layered copper ethylenediphosphonate with ultrasmall channels
In this work, we thoroughly assess the CO2 adsorption behaviour of a recently reported, pillared-layered CuII ethylenediphosphonate of formula Cu2(H2O)1.7(O3P–C2H4–PO3)1.5H2O (Cu-EtP), that features narrow channel-like pores (diameter o 5 Å). Once the metal coordinated H2O molecules are removed, Cu-EtP features a very high density of open metal sites (0.0188 sites Å-3) and can adsorb a significant amount of CO2 at saturation (2.9 mmol g-1, 6.9 mmol cm-3). Most interesting, it displays a...
Improvement of the magnetoelectric response in NiFe2O4-Sr0.5Ba0.5Nb2O6 composites using LiNbO3 as sintering additive
Magnetoelectric (NiFe2O4)0.3-(Sr0.5Ba0.5Nb2O6)0.7 composites with addition of LiNbO3 as sintering additive were prepared by a classical mixed-oxide method. XRD patterns of ceramics sintered between 1000 and 1200 ◦C show the desired Sr0.5Ba0.5Nb2O6 and NiFe2O4 phases. SEM investigations confirm the 0–3 connectivity of the composite ceramics. The addition of 10 and 20 mol% LiNbO3 improves the densification of the composite ceramics and leads to an increase of the size of the Sr0.5Ba0.5Nb2O6...
Preparation and characterization of Ce-MOF/g-C3N4 composites and evaluation of their photocatalytic performance
https://doi.org/10.1016/j.ceramint.2023.01.063._ In this study, unique hybrid structures were constructed between a Ce-based metal-organic framework (Ce-MOF) and and graphitic carbon nitride (g-C3N4) materials. In addition, the g-C3N4 materials used for these heterostructures were prepared by five different methods, namely the conventional pyrolysis method, chemical exfoliation by a strong acid, activation by an alkaline hydrothermal treatment, melamine-cyanuric acid supramolecular assembly w...
Effect of sintering additives on the densification and dielectric properties of Sr0.5Ba0.5Nb2O6 ceramics synthesized by a soft-chemistry method
https://doi.org/10.1016/j.jssc.2022.123564._ Nano-crystalline Sr0.5Ba0.5Nb2O6 powders with addition of LiNbO3 or LiF as sintering additives were prepared by a soft-chemistry synthesis using polyethylene glycol. Calcination at 600 C results in nanocrystalline powders (dcryst. 30 nm) which were sintered between 1000 and 1300 C to ceramic bodies. By addition of 10 and 20 mol % LiNbO3, the sintering temperature was reduced by about 200 K and the activation energy of the initial stage of sintering...
Fine-grained Magnetoelectric Sr0.5Ba0.5Nb2O6–CoFe2O4 Composites Synthesized by a Straightforward One-pot Method
https://doi.org/10.1016/j.matchemphys.2021.125616._ Magnetoelectric (Sr0.5Ba0.5Nb2O6)1-x(CoFe2O4)x (x = 0.2–0.6) composites were prepared by a one-pot softchemistry synthesis using PEG400. Calcining at 700 ◦C resulted in nanocrystalline composite powders (dcryst. = 24–30 nm) which were sintered between 1050 and 1200 ◦C to ceramic bodies with relative densities up to 98%. SEM investigations confirm the formation of composite ceramics with a 0–3 connectivity and variable grain sizes f...
Investigations of Nano-crystalline Sr0.5Ba0.5Nb2O6 and Bulk Ceramics Synthesized by a Polymerization Method using PEG400
Abstract. J. Eur. Ceram. Soc. 39 (2019) 1156–1163. (DOI: 10.1016/j.jeurceramsoc.2018.11.043). Nano-crystalline Sr0.5Ba0.5Nb2O6 was synthesized by a one-pot method using PEG400 and citric acid. Calcination of the (Sr,Ba,Nb)-gel at 600 °C leads to Sr0.5Ba0.5Nb2O6 with a crystallite size of 24(2) nm and a specific surface area of 38.5(10) m2 g-1. Sintering upto 1325 °C leads to ceramics with globular or irregular-shaped grains and average grain sizes between 1.3 and 2.4 μm, whereas higher ...
Preparation and Characterization of Nano-sized Magnesium Ferrite Powders by a Starch-gel Process and Corresponding Ceramics
Abstract: J. Mater. Sci. 48 (2013) 6509–6518. (DOI: 10.1007/s10853-013-7447-x).The synthesis and characterization of nano-sized MgFe2O4 by a starch-gel method is described herein. A phase-pure nano-sized MgFe2O4 powder (1a) was obtained after calcining a (MgFe)-starch gel at 550 °C. The powder has a specific surface area of 60.6 m2/g and a crystallite size of 9 nm. TEM investigations reveal particles in the range of 7 to 15 nm. The activation energy of the crystallite growth process w...
BaGeO3 as Sintering Additive for BaTiO3-MgFe2O4 Composite Ceramics.
Abstract: RSC Adv. 5 (2015) 71491 (Open Access, DOI: 10.1039/c5ra12312g).BaTiO3-MgFe2O4 composites (30 wt.% MgFe2O4) with a small addition of BaGeO3 as a sintering additive were synthesized by a one-pot Pechini-like sol-gel process. Nano-crystalline composite powders with a crystallite size of about 10 nm were obtained after reaction at 700 °C for 1 h. Magnetic investigations suggest that the nano-powder is in its superparamagnetic state at room temperature. The addition of BaGeO3 leads to a...
Thermoanalytical, Optical, and Magnetic Investigations on Nanocrystalline Li0.5Fe2.5O4 and Resulting Ceramics Prepared by a Starch-based Soft-chemistry Synthesis.
Abstract. J. Solid State Chem. 287 (2020) 121380. (DOI: 10.1016/j.jssc.2020.121380). Nanocrystalline Li0.5Fe2.5O4 was prepared by a starch-based soft-chemistry synthesis. Calcining of the (LiFe)-gel between 350 and 1000 °C results in Li0.5Fe2.5O4 powders with crystallite sizes from 13 to 141 nm and specific surface areas between 35 and 7.1 m2 g-1. XRD investigations reveal the formation of ordered Li0.5Fe2.5O4. Sintering between 1050 and 1250 °C leads to ceramics with relative densities of ...
Magnetic and Optical Investigations on LaFeO3 Powders with Different Particle Sizes and Corresponding Ceramics
Abstract. Solid State Ionics 249–250 (2013) 1–5. (DOI: 10.1016/j.ssi.2013.07.001). The optical and magnetic properties of nano-LaFeO3 powders prepared by a starch assisted soft-chemistry synthesis and corresponding ceramics have been investigated. Magnetic measurements on LaFeO3 powders with crystallite sizes of 37−166 nm showpronounced magnetization hysteresis loops. Measurements at 300 K reveal that the coercivity (Hc) of 19−32 kOe depends on the crystallite size, whereas the low re...
Synthesis and Characterization of Nano-LaFeO3 Powders by a Softchemistry Method and Corresponding Ceramics
Abstract. Solid State Ionics 231 (2013) 43–48. (DOI: 10.1016/j.ssi.2012.10.017). The preparation of a nano-sized LaFeO3 powder by a soft-chemistry method using starch as complexing agent is described herein. Phase evolution and development of the specific surface area during the decomposition process of (LaFe)-gels were monitored up to1000 °C. A phase-pure nano-sized LaFeO3 powder with a high specific surface area of 25.7 m2/g and a crystallite size of 37 nm was obtained after calcining at...
Crystallite Growth, Phase Transition, Magnetic Properties, and Sintering Behaviour of Nano-CuFe2O4 Powders Prepared by a Combustion-like Process
Abstract. J. Solid State Chem. 213 (2014) 57–64. (DOI: 10.1016/j.jssc.2014.02.010). The synthesis of nano-crystalline CuFe2O4 powders by a combustion-like process is described herein. Phase formation and evolution of the crystallite size during the decomposition process of a (CuFe2)-precursor gel were monitored up to 1000 °C. Phase-purenano-sized CuFe2O4 powders were obtained after reaction at 750 °C for 2 h resulting in a crystallite size of 36 nm, which increases to 96 nm after calcinin...
Synthesis, Phase Evolution and Properties of Phase-pure Nanocrystalline BiFeO3 Prepared by a Starch-based Combustion Method
Abstract. J. Alloys Compd. 590 (2014) 324–330. (DOI: 10.1016/j.jallcom.2013.12.120). The preparation of phase-pure nano-sized BiFeO3 by a combustion-like method using starch as complexing agent is described herein. Phase evolution and development of the crystallite size during the synthesis were monitored depending on the heat treatment and the composition of the (BiFe)-gels. Phase-pure BiFeO3 was obtained at a low heating rate and calcination temperatures between 500 and 600 °C. Above...
Investigations on Bi25FeO40 Powders Synthesized by Hydrothermal and Combustion-like Processes
Abstract. J. Solid State Chem. 217 (2014) 50–56. (DOI: 10.1016/j.jssc.2014.05.006). The syntheses of phase−pure and stoichiometric iron sillenite (Bi25FeO40) powders by a hydrothermal (at ambient pressure) and a combustion−like process are described. Phase−pure samples were obtained in the hydrothermal reaction at 100 °C (1), whereas thecombustion−like process leads to pure Bi25FeO40 after calcination at 750 °C for 2 h (2a). The activation energy of the crystallite growth process ...
