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Hybrid systems represent a new sustainable type of cement combining the properties of ordinary Portland cement and alkali-activated materials. In this study, a hybrid system based on blast furnace slag and Portland clinker was investigated. The economic aspects and appropriate waste management resulted in the usage of technological waste from water glass production (WG-waste) as an alkaline activator. Although the Portland clinker content was very low, the incorporation of this by-product significantly improved the mechanical properties. Nevertheless, the high amount of alkalis in combination with possible reactive aggregates raises concerns about the risk of alkali–silica reaction (ASR). The results obtained from expansion measurement, the uranyl acetate fluorescence method, and microstructure characterization revealed that the undesirable effects of alkali–silica reaction in mortars based on the hydration of hybrid cement are minimal.

In this work, various tunable sized spinel ferrite MnFe2O4 nanoparticles (namely MF20, MF40, MF60 and MF80) with reduced graphene oxide (RGO) were embedded in a polypropylene (PP) matrix. The particle size and structural feature of magnetic filler MnFe2O4 nanoparticles were controlled by sonochemical synthesis time 20 min, 40 min, 60 min and 80 min. As a result, the electromagnetic interference shielding characteristics of developed nanocomposites MF20-RGO-PP, MF40-RGO-PP, MF60-RGO-PP and MF80-RGO-PP were also controlled by tuning of magnetic/dielectric loss. The maximum value of total shielding effectiveness (SET) was 71.3 dB for the MF80-RGO-PP nanocomposite sample with a thickness of 0.5 mm in the frequency range (8.2–12.4 GHz). This lightweight, flexible and thin nanocomposite sheet based on the appropriate size of MnFe2O4 nanoparticles with reduced graphene oxide demonstrates a high-performance advanced nanocomposite for cutting-edge electromagnetic interference shielding application.

This paper investigates the combination of commonly used blast furnace slag (BFS) and quite non-traditional cement kiln by-pass dust (BD) for the preparation of alkali-activated binder. More specifically, the possibilities of alkali-activated slag (AAS) shrinkage compensation and cracking mitigation using BD were studied. For this purpose, mixtures with ratios of BFS/BD ranging from 100/0 to 60/40 were prepared and cured in different environment, namely autogenous conditions, water curing, air curing and their combinations. The results showed that curing regime is a determinative parameter for performance of the mixtures: BD containing specimens showed a certain expansion during the first days of water curing leading to AAS shrinkage compensation, while in absence of water curing increasing dose of BD increased drying shrinkage significantly.

This work tries to evaluatethe amount of surfactant leached from the AAS-based mortars using a very simple surface-tension (ST) measuring technique.Mortars based on AAS with and without2%ofPEGvarying in molecular weight (MW) were prepared. Waterglass with aSiO2-to-Na2O ratio equal to 2.0 was used at a dose corresponding to8%Na2O with respect to the slag weight. Mortarspecimens were prepared and sealed for 24 h, 3 d and 7 d. Then they were demolded and immersed in demineralized water,whose ST was monitored over time. During the early stages (from minutes to a few hours) the ST dropped rapidly, while itremained approximately constant after a few days, which indicates that organic molecules are leached from the AAS specimensvery quickly. It was observed that a relatively small fraction of PEGs can be leached out, which indicates that organic moleculesare rather bound in the matrix, unable to reduce the ST of the pore solution.

Herein, we presented electromagnetic interference shielding characteristics of NiFe2O4 nanoparticlesin-situ thermally-reduced graphene oxide (RGO)polypropylene nanocomposites with the variation of reduced graphene oxide content. The structural, morphological, magnetic, and electromagnetic parameters and mechanical characteristics of fabricated nanocomposites were investigated and studied in detail. The controllable composition of NiFe2O4-RGO-Polypropylene nanocomposites exhibited electromagnetic interference (EMI) shielding effectiveness (SE) with a value of 29.4 dB at a thickness of 2 mm. The enhanced EMI shielding properties of nanocomposites with the increase of RGO content could be assigned to enhanced attenuation ability, high conductivity, dipole and interfacial polarization, eddy current loss, and natural resonance. The fabricated lightweight NiFe2O4-RGO-Polypropylene nanocomposites have potential as a high performance electromagnetic interference shielding nanocomposite.

In this work, nickel ferrite (NiFe2O4) nanoparticles were synthesized by dextrin from corn-mediated sol-gel combustion method and were annealed at 600, 800, and 1000 °C. The structural and physical characteristics of prepared nanoparticles were studied in detail. The average crystallite size was 20.6, 34.5, and 68.6 nm for NiFe2O4 nanoparticles annealed at 600 °C (NFD@600), 800 °C (NFD@800), and 1000 °C (NFD@1000), respectively. The electromagnetic interference shielding performance of prepared nanocomposites of NiFe2O4 nanoparticles (NFD@600 or NFD@800 or NFD@1000) in polypropylene (PP) matrix engineered with reduced graphene oxide (rGO) have been investigated; the results indicated that the prepared nanocomposites consisted of smaller-sized nickel ferrite nanoparticles exhibited excellent electromagnetic interference (EMI) shielding characteristics. The total EMI shielding effectiveness (SET) for the prepared nanocomposites have been noticed to be 45.56, 36.43, and 35.71 dB for NFD@600-rGO-PP, NFD@800-rGO-PP, and NFD@1000-rGO-PP nanocomposites, respectively, at the thickness of 2 mm in microwave X-band range (8.2-12.4 GHz). The evaluated values of specific EMI shielding effectiveness (SSE) were 38.81, 32.79, and 31.73 dB·cm3/g, and the absolute EMI shielding effectiveness (SSE/t) values were 388.1, 327.9, and 317.3 dB·cm2/g for NFD@600-rGO-PP, NFD@800-rGO-PP, and NFD@1000-rGO-PP, respectively. The prepared lightweight and flexible sheets can be considered useful nanocomposites against electromagnetic radiation pollution. Copyright © 2019 American Chemical Society.

This paper demonstrates a three-dimensional electromagnetic interference shielding nanocomposite flexible sheet which is consisted of NiFe2O4 spinel ferrite nanoparticles, and carbon source materials such as graphite, graphene oxide and reduced graphene oxide in the elastomer matrix. The prepared nanocomposite exhibited ferromagnetic behavior. The total shielding effectiveness was up to 28.5 dB for the elastomer nanocomposite sheet having filler NiFe2O4 nanoparticles with reduced graphene oxide. The coexistence of electric and magnetic dipoles in the prepared shielding nanocomposite sheet can response highly to electromagnetic waves and consequently high electromagnetic loss. The high value of shielding efficiency is also related to dual interfaces of NiFe2O4 and reduced graphene oxide in the ternary NiFe2O4-Reduced Graphene Oxide-Elastomer nanocomposite. The investigated results indicate that the absorption attenuation is a dominant mechanism for electromagnetic interference shielding. The current study demonstrates a facile strategy to develop advanced lightweight electromagnetic interference shielding nanocomposite flexible sheet. © 2018 Elsevier Ltd

Background: Suitable fluorophores are the core of fluorescence imaging. Among the most exciting, yet controversial, labels are quantum dots (QDs) with their unique optical and chemical properties, but also considerable toxicity. This hinders QDs applicability in living systems. Surface chemistry has a profound impact on biological behavior of QDs. This study describes a two-step synthesis of QDs formed by CdTe core doped with Schiff base ligand for lanthanides [Ln (Yb3+, Tb3+ and Gd3+)] as novel cytocompatible fluorophores. Results: Microwave-assisted synthesis resulted in water-soluble nanocrystals with high colloidal and fluorescence stability with quantum yields of 40.9-58.0%. Despite induction of endocytosis and cytoplasm accumulation of Yb- and TbQDs, surface doping resulted in significant enhancement in cytocompatibility when compared to the un-doped CdTe QDs. Furthermore, only negligible antimigratory properties without triggering formation of reactive oxygen species were found, particularly for TbQDs. Ln-doped QDs did not cause observable hemolysis, adsorbed only a low degree of plasma proteins onto their surface and did not possess significant genotoxicity. To validate the applicability of Ln-doped QDs for in vitro visualization of receptor status of living cells, we performed a site-directed conjugation of antibodies towards immuno-labeling of clinically relevant target-human norepinephrine transporter (hNET), over-expressed in neuroendocrine tumors like neuroblastoma. Immuno-performance of modified TbQDs was successfully tested in distinct types of cells varying in hNET expression and also in neuroblastoma cells with hNET expression up-regulated by vorinostat. Conclusion: For the first time we show that Ln-doping of CdTe QDs can significantly alleviate their cytotoxic effects. The obtained results imply great potential of Ln-doped QDs as cytocompatible and stable fluorophores for various bio-labeling applications.

This paper investigates the possibilities of the use of sodium hydroxide activated blast furnace slag for preparation of filtration barriers. The motivation for this research is searching for cheaper and more eco-friendly alternative to sintering, which is commonly used for filtration membranes preparation. Such an alternative could be alkaline activation, which is able to bind slag particles together. Low amount of activator, low water to slag (w/s) ratio together with pressure compaction was used to obtain microstructure with preserved continuous porosity. To confirm this presumption scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) analyses were carried out.

Alkali-activated matrices are suitable materials for the immobilization of hazardous materials such as heavy metals.. is paper is focused on the comparison of immobilization characteristics of various inorganic composite materials based on blast furnace slag and on the influence of various dosages of the heavy metal Pb on the mechanical properties and fixation ability of prepared matrices. Blast furnace slag (BFS), fly ash, and standard sand were used as raw materials, and sodium water glass was used as an alkaline activator. Pb(NO3)(2) served as a source of heavy metal and was added in various dosages in solid state or as aqueous solution. The immobilization characteristics were determined by leaching tests, and the content of Pb in the eluate was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The microstructure of matrices and distribution of Pb within the matrix were determined by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Increasing the dosage of the heavy metal had negative impacts on the mechanical properties of prepared matrices. The leaching tests confirmed the ability of alkali-activated materials to immobilize heavy metals. With increasing addition of Pb, its content in eluates increased.

Alkali-activated materials, especially when activated by water glass, exhibit substantial drying shrinkage that hinders their broader industrial application. The effect of shrinkage-reducing admixtures (SRA), based on polypropylene glycol, on drying shrinkage of alkali-activated blast furnace slag (BFS) mortars was examined. The determination of SRA efficiency and the influence of potassium alkali activators with varying silicate modulus on drying shrinkage characteristics were studied. It was observed that a high amount of alkalis positively affected the effect of SRA. The higher the amount of alkalis was, the lower was the drying shrinkage. The paper further discusses and underlines the role of the amount of alkali ions on the properties of alkali-activated BFS systems.

The gadolinium (Gd3+) substituted zinc ferrite nanoparticles (ZnFe2−xGdxO4) for Gd3+ (x = 0.00, 0.05, 0.10, 0.20) have been synthesized by honey mediated sol–gel auto-combustion method. The X-ray diffraction study revealed the formation of spinel ferrite crystal structure. The Raman spectroscopy and Fourier transform infrared spectroscopy study well support the XRD results analysis. The field emission scanning electron microscopy micrograph revealed spherical morphology and grain size around 10–30 nm for ZnFe2−xGdxO4 (x = 0.10) nanoparticles. The presence of Zn2+ and Fe3+ oxidation state in synthesized nanoparticles was confirmed by X-ray photoelectron spectroscopy. Magnetic properties of the Gd3+ substituted zinc ferrite nanoparticles were investigated by vibrating sample magnetometer at room temperature. The conversion of magnetic hysteresis curves from ferromagnetic to a paramagnetic with the substitution of Gd3+ in zinc ferrite nanoparticles was observed. Frequency dependent dielectric constant and ac conductivity measurements revealed that Gd3+ substitution improved the value of dielectric constant and ac conductivity of the Gd3+ substituted zinc ferrite nanoparticles. Further, the existence of two semicircles in Cole–Cole plot demonstrated the role of both grains and grain boundaries to conduction process in synthesized Gd3+ ion substituted zinc ferrite nanoparticles. Furthermore, the grain relaxation time (τg), grain boundary relaxation time (τgb), grain resistance (Rg), grain capacitance (Cg), grain boundary resistance (Rgb) and grain boundary capacitance (Cgb) for synthesized ZnFe2−xGdxO4 (x = 0.00, 0.05, 0.10, 0.20) nanoparticles have been calculated using modulus spectroscopy analysis. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

In this article, Co1−xZnxFe2O4 (x = 0.0 and 0.5) disc-shaped pellets were formed by hot-press sintering of nanoparticles at temperature 925 °C for 10 min in vacuum atmosphere under 30 MPa mechanical pressure. X-ray diffraction study confirmed the formation of spinel cubic ferrite structure of hot-press sintered spinel ferrite Co1−xZnxFe2O4 (x = 0.0 and 0.5) samples. The scanning electron microscopy image indicated that the growth and densification of smaller ferrite nanoparticles were higher than larger ferrite nanoparticles. Magnetic properties of sintered samples were investigated by the superconducting quantum interface device (SQUID) magnetometer at room temperature. The hot press sintered Co1−xZnxFe2O4 (x = 0.0 and 0.5) pellet samples exhibited magnetic properties dependent on the grain size of spinel ferrite particles. The maximum saturation magnetization 82.47 emu/g was obtained for Co0.5Zn0.5Fe2O4 hot press sintered sample of ball-milled ferrite particles. Further, the impact of grain size and density of sample on hardness, dielectric property and ac conductivity of hot-press sintered samples was investigated. In addition, the longitudinal wave velocity (Vl), transverse wave velocity (Vt), mean elastic wave velocity (Vm), bulk modulus (B), rigidity modulus (G), Young's modulus (E), Poisson ratio (σ) and Debye temperature (θD) were calculated. The elastic moduli of hot press sintered ferrite samples were corrected to zero porosity using Hosselman and Fulrath model. © 2017 Elsevier B.V.

Cement kiln by-pass dust (CKD) is a fine-grained by-product of Portland clinker manufacturing. Its chemical composition is not suitable for returning back into feedstock and, therefore, it has to be discharged. Such an increasing waste production contributes to the high environmental impact of the cement industry. A possible solution for the ecological processing of CKD is its incorporation into alkali-activated blast furnace slag binders. Thanks to high alkaline content, CKD serves as an effective accelerator for latent hydraulic substances which positively affect their mechanical properties. It was found out that CKD in combination with sodium carbonate creates sodium hydroxide in situ which together with sodium water glass content increases the dissolution of blast furnace slag particles and subsequently binder phase formation resulting in better flexural and compressive strength development compared to the sample without it. At the same time, the addition of CKD compensates the autogenous shrinkage of alkali-activated materials reducing the risk of material cracking. On the other hand, this type of inorganic admixture accelerates the hydration process causing rapid loss of workability.

In this work, CuFe2O4 nanoparticles were synthesized by natural source of glucose and fructose (i.e., honey)—mediated sol–gel auto-combustion method. Grain size, cation distribution and crystal phase were further tuned through annealing at higher temperature 500, 700, 900 and 1100 °C. The structural investigation was performed using powder X-ray Diffraction, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and X-ray Photoelectron Spectroscopy. X-ray diffraction study confirmed the phase transformation from cubic to tetragonal as a function of annealing temperature. Magnetic properties were investigated by using vibrating sample magnetometer under an applied magnetic field of 10 kOe at room temperature. The highest value of saturation magnetization (Ms) was 26 emu/g for ferrite nanoparticles annealed at 1100 °C, whereas the lowest value was 11 emu/g for annealed at 700 °C. The highest and lowest coercivity (Hc) was 1389 and 65 Oe for ferrite nanoparticles annealed at 900 and 1100 °C, respectively. Detailed study of modulus and impedance spectroscopy revealed the contribution of grain and grain boundary on electrical transport mechanism and relaxation process. Further, dependence of relaxation time, resistance and capacitance at grain and grain boundary on grain size, cation distribution and annealing temperature was noticed. The asymmetry of peak in imaginary part of modulus spectra indicates that the relaxation process is non-Debye type. At lower frequency, ac conductivity is frequency independent, whereas, at high frequency, it follows an apparent power law, σ(ω) α ωs. Dielectric parameters (real and imaginary part, dielectric loss) with variation of frequency (1 Hz to 10 MHz) are investigated and dependence with frequency and annealing temperature is observed. © 2017, Springer Science+Business Media New York.

In this work, we have studied the influence of La3+ substitution on structural, magnetic, dielectric, electrical and modulus spectroscopic characteristics of cobalt ferrite nanoparticles synthesized by starch-assisted sol–gel combustion method. The powder X-ray diffraction analysis confirms the formation of single-phase CoFe2−xLaxO4 (x = 0.00, 0.05, 0.10, 0.15, 0.20) spinel ferrite nanoparticles. Raman spectroscopy study also reveals the formation of single phase spinel ferrite crystal structure. The morphological feature of synthesized ferrite nanoparticle was observed by scanning electron microscopy that demonstrate formation of spherical nanoparticles with grain size 10–50 nm. The presence of constituent’s, i.e., Co, Fe and La were authenticated by energy dispersive X-ray analysis. The magnetic parameters are measured by employing vibrating sample magnetometer. The saturation magnetization decreases with La3+ substitution, whereas coercivity shows anomalous behaviour. Cation redistribution in spinel ferrite nanoparticles are confirmed by X-ray photoelectron spectroscopy. The variation of dielectric constant (ϵ′, ϵʺ), loss tangent (tanδ), ac conductivity (σ), electric modulus (M′, Mʺ) and impedance (Z′, Zʺ) as a function of La3+ ion concentration and frequency has been investigated. The dielectric constant and ac conductivity increases with increase of La3+ substitution, whereas dielectric loss tangent exhibits anomalous behaviour. The modulus spectra reveal two semicircles associated with grain and grain boundary effects. The cole–cole plots in modulus formalism show that the electrical characteristics contribute from both the grains and grain boundaries. Modulus spectra suggest that the distribution of relaxation times and conduction mechanism are influenced by La3+ ion substitution in cobalt ferrite nanoparticles. © 2017, Springer Science+Business Media New York.

In this work CoFe2O4 spinel ferrite nanoparticles were synthesized by honey mediated sol-gel combustion method and further annealed at higher temperature 500 °C, 700 °C, 900 °C and 1100 °C. The synthesized spinel ferrite nanoparticles is investigated by x-ray diffraction, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), field emission scanning electron microscopy, x-ray photoelectron spectroscopy and vibrating sample magnetometer. The x-ray diffraction study reveals face-centered cubic spinel cobalt ferrite crystal phase formation. The crystallite size and lattice parameter are increased with annealing temperature. Raman and Fourier transform infrared spectra also confirm spinel ferrite crystal structure of synthesized nanoparticles. The existence of cation at octahedral and tetrahedral site in cobalt ferrite nanoparticles is confirmed by x-ray photoelectron spectroscopy. Magnetic measurement shows increased saturation magnetization 74.4 emu g-1at higher annealing temperature 1100 °C, high coercivity 1347.3 Oe at lower annealing temperature 500 °C, and high remanent magnetization 32.3 emu g-1at 900 °C annealing temperature. The magnetic properties of synthesized ferrite nanoparticles can be tuned by adjusting sizes through annealing temperature. Furthermore, the dielectric constant and ac conductivity shows variation with frequency (1-107Hz), grain size and cation redistribution. The modulus spectroscopy study reveals the role of bulk grain and grain boundary towards the resistance and capacitance. The cole-cole plots in modulus formalism also well support the electrical response of nanoparticles originated from both grain and grain boundaries. The dielectric, electrical, magnetic, impedance and modulus spectroscopic characteristics of synthesized CoFe2O4spinel ferrite nanoparticles demonstrate the applicability of these nanoparticles for magnetic recording, memory devices and

Significant drying shrinkage is one of the main limitations for the wider utilization of alkali-activated slag (AAS). Few previous works revealed that it is possible to reduce AAS drying shrinkage by the use of shrinkage-reducing admixtures (SRAs). However, these studies were mainly focused on SRA based on polypropylene glycol, while as it is shown in this paper, the behavior of SRA based on 2-methyl-2,4-pentanediol can be significantly different. While 0.25% and 0.50% had only a minor effect on the AAS properties, 1.0% of this SRA reduced the drying shrinkage of waterglass-activated slag mortar by more than 80%, but it greatly reduced early strengths simultaneously. This feature was further studied by isothermal calorimetry, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). Calorimetric experiments showed that 1% of SRA modified the second peak of the pre-induction period and delayed the maximum of the main hydration peak by several days, which corresponds well with observed strength development as well as with the MIP and SEM results. These observations proved the certain incompatibility of SRA with the studied AAS system, because the drying shrinkage reduction was induced by the strong retardation of hydration, resulting in a coarsening of the pore structure rather than the proper function of the SRA.

In recent years, the utilization of different non-traditional cements and composites has been increasing. Alkali-activated cementitious materials, especially those based on the alkali activation of blast furnace slag, have considerable potential for utilization in the building industry. However, alkali-slag cements exhibit very rapid setting times, which are too short in some circumstances, and these materials cannot be used for some applications. Therefore, it is necessary to find a suitable retarding admixture. It was shown that the sodium phosphate additive has a strong effect on the heat evolution during alkali activation and effectively retards the hydration reaction of alkali-activated blast furnace slag. The aim of the work is the suggestion of a reaction mechanism of retardation mainly based on Raman and Xray photoelectron spectroscopy.

Impact of crystal phase evolution on structural and magnetic properties of copper ferrite nanoparticles is studied and reported. The copper ferrite nanoparticles were synthesized by starch-assisted sol-gel auto-combustion method and further annealed at 200, 500, 800, and 1100°C. The X-ray diffraction study indicated phase evolution from cubic to tetragonal with increase of annealing temperature. Raman spectroscopy and Fourier transform infrared spectroscopy study revealed the impact of phase transformation and cation redistribution in copper ferrite nanoparticles with increase of annealing temperature. X-ray photoelectron study revealed the cation migration with annealing temperature, which is responsible for structural phase evolution. The field emission-scanning electron microscopy (FE-SEM) study revealed that the ferrite nanoparticles at a lower annealing temperature (200, 500, and 800°C) were agglomerated spherical and elongated particles in the grain size range 10–100 nm. However, at a higher annealing temperature (1100°C), it was hexagonal plate-like particles in the grain size range 50–200 nm. The increase in saturation magnetization (Ms) from 11.60 emu/g (200°C) to 25.48 emu/g (1100°C) with grain growth and crystal phase evolution (i.e., increase of c/a ratio and cation redistribution in CuFe2O4 mixed spinel ferrite) was noticed. In addition, a crystal phase evolution from cubic to tetragonal and a grain growth as a function of annealing temperature both cause also an increase in coercivity (Hc) value from 132.56 Oe (200 °C) to 1442.50 Oe (800 °C) Furthermore, the decrease of coercivity (Hc) value from 1442.50 Oe (800°C) to 218.06 Oe (1100°C) with increase of annealing temperature was due to the “pinning” effect of domain wall at the grain boundary. © 2015, Springer Science+Business Media New York.

Nd3+ doped cobalt ferrite nanoparticles have been synthesized by starch-assisted sol-gel auto-combustion method. The significant role played by Nd3+ added to cobalt ferrite in changing cation distribution and further in influencing structural and magnetic properties, was explored and reported. The crystal structure formation and crystallite size were studied from X-ray diffraction studies. The microstructural features were investigated by field emission scanning electron microscopy and transmission electron microscopy that demonstrates the nanocrystalline grain formation with spherical morphology. An infrared spectroscopy study shows the presence of two absorption bands related to tetrahedral and octahedral group complexes within the spinel ferrite lattice system. The change in Raman modes in synthesized ferrite system were observed with Nd3+ substitution, particle size and cation redistribution. The impact of Nd3+ on cation distribution of Co2+ and Fe3+ at octahedral and tetrahedral sites in spinel ferrite cobalt ferrite nanoparticles was investigated by X-ray photoelectron spectroscopy. Room temperature magnetization measurements showed that the saturation magnetization and coercivity increase with addition of Nd3+ substitution in cobalt ferrite. © 2015 Elsevier B.V. All rights reserved.

The fixation of heavy metals (Ba, Cu, Pb) in an alkali-activated matrix was investigated. The matrix consisted of fly ash and blast furnace slag (BFS). The mixture of NaOH and Na-silicate was used as alkaline activator. Three analytical techniques were used to describe the fixation of heavy metals—X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), and X-ray powder diffraction (XRD). All heavy metals formed insoluble salts after alkaline activation. Ba was fixed as BaSO4, and only this product was crystalline. EDS mapping showed that Ba was cumulated in some regions and formed clusters. Pb was present in the form of Pb(OH)2 and was dispersed throughout the matrix on the edges of BFS grains. Cu was fixed as Cu(OH)2 and also was cumulated in some regions and formed clusters. Cu was present in two different chemical states; apart from Cu(OH)2, a Cu–O bond was also identified.

Dysprosium-substituted cobalt ferrite nanoparticles with composition of CoFe2−xDyxO4 (x = 0 − 0.1 in a step of 0.025) were synthesized by starch-assisted sol–gel auto-combustion method. The effect of Dy3+ cation substitution on structural and magnetic properties of cobalt ferrite nanoparticles was investigated. Powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, infrared spectroscopy (IR), X-ray photoelectron spectroscopy and vibrating sample magnetometer (VSM) were employed to characterize the physical properties of these ferrite nanoparticles. XRD pattern reveals the formation of cubic spinel ferrite with the signature of DyFeO3 phases for x ≥ 0.05. An infrared spectroscopy study shows the presence of two absorption bands in the frequency range around 560 cm−1 (ν1) and around 380 cm−1 (ν2), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. FE-SEM analysis indicated the formation of nanosized particles (5 −15 nm) with spherical morphology. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples at room temperature. It was observed that rare earth ion dopant, crystallite size and foreign phase DyFeO3 affect the magnetic properties of cobalt ferrite nanoparticles. © 2015, Springer Science+Business Media New York.

In this article, cobalt ferrite nanoparticles were synthesized using a starch-assisted sol-gel auto-combustion route. The significant role played by further annealing temperatures of 300, 500, 700, 900 and 1100 A degrees C on particle size and magnetic properties of ferrite nanoparticles was explored and reported. The prepared nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, using a vibrating sample magnetometer. The X-ray diffraction patterns demonstrated singlephase formation of CoFe2O4 spinel ferrite nanoparticles at different annealing temperatures. The FESEM analysis indicated a change of particle size and morphology at higher annealing temperature. The change in Raman modes and infrared absorption bands was observed with change of particle size and cation distribution. The highest value of coercivity (1091.2 Oe) and the saturation magnetization (54.76 erg g(-1)) were obtained at annealing temperatures of 900 and 1100 A degrees C, respectively. X-ray photoelectron spectroscopy revealed the presence of Co2+ and Fe3+ at octahedral and tetrahedral sites in CoFe2O4 nanoparticles. Further, the cation redistribution with change of particle size was confirmed by X-ray photoelectron spectroscopy.