Smaller Crystallite Size Research Articles

Impact of erbium substitution on structural, dielectric, spectral, and microwave absorption properties of Ba3Co2Fe24O41 Z-type hexa-ferrites for microwave devices applications

A series of erbium-substituted Z-type hexaferrites with composition Ba3Co2ErxFe24-xO41 (0.00≤ x ≤ 0.12, Δx = 0.03) was synthesized via the sol-gel auto combustion technique and sintered at 1200 °C for 5:30 h. XRD analysis confirmed the single phase crystals throughout the samples. Incorporating erbium ions into a Z-type hexagonal lattice showed improved structural parameters. The lattice parameters (a, c) exhibited an increasing trend with the rare earth (Erbium) substitution in the range of 5.884–5.891 nm and 52.561–52.770 nm. Scherrer's equation was used to find crystallite size in 28–30 nm range. Absorption bands of ferrite phase were confirmed by Fourier Transform Infrared Spectroscopy. Dielectric characteristics of synthesized materials were studied through Epsilometer R60 VNA over a frequency 1 MHz to 6 GHz range. Variations in dielectric parameters were observed by substituting erbium ion into a Z-type hexaferrite lattice. The magnitude of the dielectric constant, AC conductivity, tangent loss, and dielectric loss increases at higher frequencies. While, dielectric constant, AC conductivity, loss factor, and tangent loss decrease with Erbium substitution. The high value of Q-factor ∼10232 at 0.87 GHz was observed. The cole-cole plots in impedance analysis confirmed the character of grains and grain boundaries in the conduction mechanism. Minimum reflection loss (RL) was −67 dB for the sample x = 0.06 at 0.2 GHz. At 1.28 GHz frequency, RL = −46 dB was observed for sample x = 0.03. The morphological study (SEM) revealed the hexagonal platelet-type grains with an average grain size of 2.48–2.73 μm. Minimum reflection loss, small crystallite size <50 nm, and high-quality factor suggested that these materials are suitable candidates for microwave absorbers, resonant circuits, multi-layer chip inductors, and high-frequency devices.

Effect of Calcination Conditions on Co3O4 Catalysts in the Total Oxidation of Toluene and Propane

Co3O4 catalysts were prepared via carbonate precipitation and subsequent calcination under specific conditions. The different catalysts were characterized as received using several techniques and tested in the total oxidation of toluene or propane. Calcination at low temperature or under dynamic conditions resulted in Co3O4 catalysts with small crystallite sizes and large surface areas. The performances of the Co3O4 catalysts appeared to be closely related to the low-temperature reducibility. The best catalyst, Co-350D, showed a toluene oxidation rate of 44.5 nmol g−1 s−1 at 200 °C and a propane oxidation rate of 54.0 nmol g−1 s−1 at 150 °C. Meanwhile, Co-350D exhibited excellent cycling stability and decent long-term durability in both reactions.

Chemically Modified TiO2 Photocatalysts as an Alternative Disinfection Approach for Municipal Wastewater Treatment Plant Effluents

Among key issues in municipal wastewater treatment plants (MWTP) is the existence of pathogenic bacteria in the discarded effluents. Conventional disinfectants (ozone, UV irradiation, chlorine) have been insufficient in providing safe water due to the development of undesirable and noxious by-products. TiO2 comprises an attractive alternative to conventional methods because of its versatility and recently explored biocidal efficiency. As a result, within the framework of this study, chemically modified, visible active nanocrystalline TiO2 powders (N-TiO2, N,S-TiO2, and Ag@N-TiO2) were prepared via a low-cost, feasible sol-gel method for the treatment of real municipal wastewater effluents. Wastewater samples were acquired from the outlet of the treatment of Antiparos (Cyclades, Greece) MWTP during the summer period in which a great number of seasonal habitants and tourists usually visit the island, resulting in at least a doubling of the population. All synthesized powders were thoroughly characterized using various morphological and spectroscopic techniques, such as FE-SEM, XRD, micro-Raman, FTIR, DLS, UV-DRS, and XPS. Photocatalytic evaluation experiments were initially conducted towards Rhodamine B degradation under visible light irradiation. Among all studied powders, Ag@N-TiO2 indicated the highest efficiency, reaching total degradation (100%) of RhB within 240 min due to its smaller crystallite size (1.80 nm), enhanced surface area (81 m2g−1), and reduced energy band gap (Eg = 2.79 eV). The effect of the produced powders on the disinfection as assessed in terms of fecal indicator microorganisms (E. coli and total coliforms) inactivation was also examined in a semi-pilot scale-up photocatalytic reactor. Ag@N-TiO2 nanopowder was also found substantially more active for both groups of bacteria, leading to complete inactivation in less than 35 min, probably due to the higher production of H2O2/•OH, as emerged from the photocatalytic mechanism study. In addition, Ag@N-TiO2 nanoparticles demonstrated excellent photocatalytic and disinfection stability even after five subsequent recycling trials (8.34% activity loss and complete inactivation, respectively). The results of the present study demonstrate the feasibility for Ag@N-TiO2 to be utilized as a viable, eco-friendly approach for the photocatalytic pathogenic bacteria inactivation as an alternative disinfection approach for municipal wastewater treatment plant effluents with intense seasonal fluctuations in volume.

Effects of annealing on the structure and microhardness of nanocrystalline Ni–Mn electrodeposits

Nanocrystalline pure nickel and Ni-Mn alloy with 1.2 at% Mn deposits were obtained via pulse current electrodeposition. To understand the effects of annealing on their structure and microhardness, the surface morphology, crystal structure, grain size, microhardness and microstructure of the obtained Ni-Mn and pure Ni deposits were investigated. The results indicated that Ni-Mn alloy exhibited a similar face-centered cubic structure with a strong (111) preferred orientation to that of Ni deposits, but as-deposited Ni–Mn had a smaller crystallite size and substantially higher microhardness compared to as-deposited Ni deposit. During annealing, the crystal grains of Ni deposits grew sharply, resulting in a great decrease in their microhardness, while Ni-Mn deposits showed good thermal stability and annealing induced hardening at 300 °C and 350 °C. Neither precipitate nor clear segregation of Mn was observed on annealed deposits; however, a number of twin boundaries were found. It is suggested that the thermal stability of Ni-Mn was mainly derived from the formation of twin boundaries and the annealing-induced hardening could be ascribed to grain boundary relaxation and annealing twin strengthening.

Titania nanoparticles for photocatalytic degradation of ethanol under simulated solar light.

TiO2 nanoparticles were synthesized by laser pyrolysis from TiCl4 vapor in air in the presence of ethylene as sensitizer at different working pressures (250-850 mbar) with and without further calcination at 450 °C. The obtained powders were analyzed by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and transmission electron microscopy. Also, specific surface area and photoluminescence with optical absorbance were evaluated. By varying the synthesis parameters (especially the working pressure), different TiO2 nanopowders were obtained, whose photodegradation properties were tested compared to a commercial Degussa P25 sample. Two series of samples were obtained. Series "a" includes thermally treated TiO2 nanoparticles (to remove impurities) that have different proportions of the anatase phase (41.12-90.74%) mixed with rutile and small crystallite sizes of 11-22 nm. Series "b" series represents nanoparticles with high purity, which did not require thermal treatment after synthesis (ca. 1 atom % of impurities). These nanoparticles show an increased anatase phase content (77.33-87.42%) and crystallite sizes of 23-45 nm. The TEM images showed that in both series small crystallites form spheroidal nanoparticles with dimensions of 40-80 nm, whose number increases with increasing the working pressure. The photocatalytic properties have been investigated regarding the photodegradation of ethanol vapors in Ar with 0.3% O2 using P25 powder as reference under simulated solar light. During the irradiation H2 gas production has been detected for the samples from series "b", whereas the CO2 evolution was observed for all samples from series "a".

Effects of ZSM-5 Morphology and Fe Promoter for Dimethyl Ether Conversion to Gasoline-Range Hydrocarbons

The synthesis of gasoline-range hydrocarbons by gas-phase dimethyl ether (DME) conversion was investigated on various ZSM-5 zeolites with different morphologies and Fe contents. The different morphologies of ZSM-5 significantly altered the distributions of the acidic sites, which showed different selectivities to gasoline-range hydrocarbons. Nanostructured ZSM-5 (N-ZSM-5) revealed the highest C5+ selectivity of 41.7% with an aromatics selectivity of 23.6% at ~100% DME conversion. The superior catalytic activity of N-ZSM-5 was attributed to the largest strong Brønsted acidic sites and smaller crystallite sizes, which were beneficial for the faster removal rate of heavy hydrocarbons due to its shorter diffusion pathlength compared to conventional ZSM-5 (C-ZSM-5). In addition, 10 wt% Fe-impregnated N-ZSM-5 revealed an enhanced C5+ selectivity of 60.6% with a smaller C1–C4 selectivity of 21.9%, which were attributed to the adjusted acidic sites by suppressing the cracking reactions of the surface intermediates, which are responsible for the selective formation of smaller light hydrocarbons. However, the excess amount of Fe on N-ZSM-5 showed a lower DME conversion of 83.5% with a lower C5+ selectivity of 38.5% due to the blockages of the active acidic sites. Nanostructured N-ZSM-5 possessing a larger amount of strong Brønsted acid sites with 10 wt% Fe modification clearly showed a higher formation rate of gasoline-range hydrocarbons due to an enhanced secondary oligomerization of surface intermediates to form heavier aromatic hydrocarbons.

The effect of milling time, and sintering temperature and time on the microstructure-property relationship of aluminium-matrix hybrid composites

The present study investigates the effect of milling time, and sintering temperature and time on the microstructure and properties of aluminium matrix hybrid composites (AMHCs). The AMHCs containing aluminium nitride (AlN) and yttrium tungstate (Y2W3O12) have been fabricated by powder metallurgy route. The powder mixtures were subjected to milling for different times, i.e., 0.5, 2, 4, 6, 8, 10, 12 & 14 h followed by compaction and sintering in a temperature range of 550–650 °C for different times, e.g., 1, 1.5 and 2 h. The smallest crystallite size along with the homogeneous distribution of reinforcements is observed at 10 h of milling time. The microstructure and corresponding properties, i.e., relative density, hardness and compressive strength are influenced by milling time, sintering temperature and sintering time. The optimised processing parameters for getting the maximum values of relative density, hardness, and compressive strength of the AMHCs are found to be 10 h of milling time, 600 °C of sintering temperature, and 1 h of sintering time.

Titania/reduced graphene oxide nanocomposites (TiO2/rGO) as an efficient photocatalyst for the effective degradation of brilliant green in aqueous media: effect of peroxymonosulfate and operational parameters.

This study is focused on synthesis of highly efficient Titania/reduced Graphene Oxide (TiO2/rGO) nanocomposites by means of simple hydrothermal technique. The TiO2/rGO were synthesized in different ratios of 0.5, 1.0, 2.0, and 3% by varying the concentration of rGO while the concentration of TiO2 was kept constant and the obtained samples were designated as TrG0.5, TrG1, TrG2, and TrG3 respectively. Different characterization techniques (SEM, TEM, HRTEM, XRD, EDX, TGA, UV-DRS, PL, EIS, and BET) showed high crystallinity, small crystallite size (18.4 nm), high thermal stability, high purity, low band gap energy (Eg = 3.12 eV), and high surface area (65.989 m2/g) for the as-synthesized TiO2/rGO nanocomposite. The efficiencies of TiO2/rGO were determined in terms of brilliant green (BG) dye degradation in aqueous media under UV light. The results revealed that 2% TiO2/rGO (TrG2) showed high efficiency for BG degradation with the kapp of 0.023 min-1 compared to TiO2 alone (kapp of 0.006 min-1). The rate of BG degradation was further synergised by the addition of peroxymonosulfate (PMS) to the system. The degradation of BG was improved to 99.4% by the incorporation of PMS in aqueous media compared to TrG2 alone. Furthermore, the degradation of BG was also examined in various media (neutral, acidic, and basic). The results revealed that by increasing pH of the medium from 3.85 to 8.2 the degradation of BG was enhanced from 99.4 to 99.9% with the corresponding kapp of 0.0602 min-1. Moreover, the photocatalytic degradation of BG followed the pseudo-first-order kinetics. Radical scavenging experiments showed that ●OH and SO4●- were the main species responsible for the degradation of BG under UV light. Besides, for determining the efficiency of as-synthesized TrG2/PMS system, the degradation of BG was also performed in various water types (distilled water, tape water, synthetic wastewater, and industrial wastewater). The degradation products (DPs) of BG and their corresponding pathways were proposed, accordingly.

Photocatalytic activity of solvothermally synthesized rutile TiO2 nanorods for the removal of water contaminants

The TiO2 nanorods are synthesized via a solvothermal route by varying reaction temperatures. The XRD analysis reveals that the synthesized TiO2 nanorods grown with rutile phase with a 14 to 26 nm average crystallite size. The FESEM and HRTEM analysis confirmed the rod-like shape of the synthesized TiO2 nanoparticles, which grew in the same direction. In addition, the EDS analysis revealed the titanium-oxygen elemental ratio is equal to 1:2, confirming the stoichiometry of the grown sample. The UV–vis analysis of TiO2 nanorods shows a red shift in the band gap with a rising temperature. The TiO2 nanorods synthesized at 180 °C (T2) achieves methyl orange and rhodamine B degradation up to 90 and 97% within 50 and 60 min, respectively, under 125 W mercury light irradiation. Since the T2 sample has a high surface area, small crystallite size and a narrow band gap, it significantly affects the photodegradation of methyl orange and rhodamine B dye.

Enhanced wear and corrosion resistances of Al coated Mg alloy using high pressure cold sprayed commercially pure-zirconium coating

Commercially pure (CP) Zr coating with high microhardness (387 ± 26 HV0.025) was produced on CP-Al coated Mg alloy by a high pressure cold spray (HPCS) system. Substantial densification of Al layers, beneath deposited Zr coating, was observed because of shot-peening influence by Zr particles. The electrochemical impedance spectroscopy after 24 h of immersion in 3.5 wt% NaCl electrolyte revealed highest charge transfer resistance (Rct), polarization resistance (Rpol), and corrosion resistance (|Z|f=0.01Hz) for the Zr/Al coated Mg alloy. Also, wear rate for the Zr/Al coating was lowest which could be attributed to its higher hardness caused by smaller crystallite size and higher dislocation density.

Effect of thermal treatment conditions on the stability of MOF-derived Ni/CeO2 catalyst for dry reforming of methane

The synthesis of a novel nanostructured Ni/CeO2 catalysts derived from bimetallic Ni-Ce metal organic framework template is carried out in this work. Different thermal treatment conditions under N2 or H2 or CO2 atmosphere is implemented for the removal of the organic template. Also, further thermal pre-treatment under CO2 environment was performed on the catalysts, and 5 catalysts were prepared and investigated for DRM reaction. The most stable and active catalyst was achieved from a single-step thermal treatment under nitrogen, presenting CO2 and CH4 conversion of 83% and 70%, respectively and H2/CO ratio of 0.98 after 24 h on stream with no decline in activity. A stability test of 120 h on stream further showed no decline in catalyst activity. The high stability of the catalyst was attributed to its high surface area of 245 m2/g and dispersion, smaller crystallite size, higher metallic nickel and Ce3+ content, stronger metal-support interaction, and better structural morphology.

Effects of Different Ni-Fe/Ni Foam Catalysts on In Situ Preparation of CNTs@Ni Foam Electrode Materials and H2 during Steam Reforming of Pyrrole

New catalysts of Ni–Fe loading Ni foam (Ni–Fe/NF) were used in catalytic reforming of pyrrole for the co-production of H2 and CNTs@Ni foam electrode materials. Ni–Fe/NF with different Fe/Ni ratios (0.5, 1, 2, and 3) and Ni/NF and Fe/NF catalysts were tested. The Ni–Fe alloy was formed on Ni–Fe/NF and remarkably promoted pyrrole conversion and H2 yield. They showed a trend of first increasing and then decreasing with the increase of the Fe/Ni ratio, and the N1F2/NF (Fe/Ni ratio is 2) reached the maximum. The H2 yield over N1F2/NF was 20 times larger than that over Ni/NF and Fe/NF. The high amount of Fe–Ni alloy with a small crystallite size boosted the catalytic activity of Ni–Fe/NF. After the reforming reaction, large amounts of CNTs were observed on the surface of Ni foam’s skeleton network. The structures of CNTs@Ni foam were prepared and promoted by the Ni–Fe alloy. It proved that the CNTs on Ni–Fe/NF catalysts follow the tip-growth and vapor–liquid–solid (VLS) mechanisms. The Ni–Fe alloy contributed to the formation of liquid carbide and carbon intermediates, thus promoting the CNTs’ growth. Compared with the pristine Ni foam, the prepared CNTs@Ni foam materials showed excellent electrochemical performance and had promising application potential in supercapacitors. The spent N1F1/NF (Fe/Ni ratio is 1) showed the best charging and discharging capacity.

MOCVD growth of gadolinium oxide layers on tubes

In the paper, non-porous and smooth gadolinium oxide layers were synthesized on the inner surfaces of quartz glass tubes using MOCVD (Metalorganic Chemical Vapour Deposition) in the temperature range of 580–800 °C.Commercial Gd(tmhd)3 (Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)gadolinium(III), 99% (99.9%-Gd)) was a basic reactant. Pure argon (99.999%) was used as a carrier gas. Air was applied to eliminate the carbon. It also was a carrier gas. The magnitude of the extended Grx/Rex2 criterion did not exceed the value of 0.01. Other synthesis conditions were established in such a way that this condition was maintained. The evaporation temperature of Gd(tmhd)3 varied in the range of 170–270 °C.The influence of the synthesis conditions on microstructure, structure and transparency of the deposited layers was investigated. Oval-shaped Gd2O3 aggregates and fine crystallites were formed regardless of the synthesis conditions. The conducted research also shows that the lower deposition temperature and the higher evaporation temperature of reactant, causes smaller crystallite sizes and smaller their number.

A Visible-Light-Enhanced Heterogeneous Photo Degradation of Tetracycline by a Nano-LaFeO3 Catalyst with the Assistance of Persulfate.

Perovskites with nano-flexible texture structures and excellent catalytic properties have attracted considerable attention for persulfate activation in addressing the organic pollutants in water. In this study, highly crystalline nano-sized LaFeO3 was synthesized by a non-aqueous benzyl alcohol (BA) route. Under optimal conditions, an 83.9% tetracycline (TC) degradation and 54.3% mineralization were achieved at 120 min by using a coupled persulfate/photocatalytic process. Especially compared to LaFeO3-CA (synthesized by a citric acid complexation route), the pseudo-first-order reaction rate constant increased by 1.8 times. We attribute this good degradation performance to the highly specific surface area and small crystallite size of the obtained materials. In this study, we also investigated the effects of some key reaction parameters. Then, the catalyst stability and toxicity tests were also discussed. The surface sulfate radicals were identified as the major reactive species during the oxidation process. This study provided a new insight into nano-constructing a novel perovskite catalyst for the removal of tetracycline in water.

Au/ZnO Nanocomposites Prepared by Laser Ablation for Enhancement of Antibacterial Activity and Cytotoxic Properties against Cancer Cells

This study presents a comprehensive look into the potential therapeutic, antibacterial, and anticancer properties of a nanocomposite (NC) of gold (Au) and zinc oxide (ZnO). In this study, we analyzed the adherence between Au nanoparticles (NPs) and ZnO NPs. X-ray diffraction analysis showed high crystallinity and small crystallite sizes of Au NPs and ZnO NPs, while transmission electron microscopy showed spherical NPs. Furthermore, histogram analysis showed that the average particle size of Au NPs is 27 nm, while that of ZnO NPs is 35 nm. The adherence of ZnO NPs on the surface of Au NPs increased their combined particle size to 51 nm and revealed a high-population core-shell structure. The activity of Au/ZnO NCs against Escherichia coli was more potent when compared to that of elemental Au and ZnO NPs alone. The cytotoxic effects of Au NPs, ZnO NPs, and Au/ZnO NCs against human breast cancer cells (AMG13) and human esophageal adenocarcinoma cancer cells (SK-GT4) were investigated in this study. We found that AMG13 is more sensitive than SK-GT4 to the activity of Au/ZnO NCs. The cytotoxicity of Au/ZnO NCs against AMG13 was 89%, while that against SK-GT4 was 85%. Less cytotoxic effects were recorded against normal cells (MCF7) when compared with those of cancer cells. Based on these findings, the synthesized Au/ZnO NCs could be used as a promising strategy for biomedical applications.

Mn-Cr mixed oxide adsorbents with high SO2 resistance for elemental mercury removal from coal-fired flue gas

A series of Mn-Cr mixed oxide adsorbents were obtained using co-precipitation method. Then, an investigation was conducted into the effects of Mn/Cr molar ratio, reaction temperature, calcination temperature, initial mercury concentration and flue gas constituents on the outcome of elemental mercury removal. Specifically, the MnCr1:3 with an optimal Mn/Cr molar ratio performed best in the efficiency of mercury removal (>95.4%) in a wide temperature range (100–250 °C). The physicochemical properties and the mechanism were characterized by N2 adsorption–desorption, SEM, XRD, NH3-TPD, H2-TPR, XPS and Hg-TPD in combination. According to the research results, mercury removal was facilitated by MnCr1:3 due to its larger surface area, smaller crystallite sizes, higher acidity and redox properties. Sulfur dioxide promoted elemental mercury capture for MnCr1:3 when different concentrations of SO2 existed in the flue gas. The relative activity over MnCr1:3 approached 100% after five regeneration cycles. Due to the combined effect of manganese and chromium, there was an increase in the concentration of high valence metal elements and surface adsorbed oxygen. MnCr1:3 had the highest content of Cr6+ and adsorbed oxygen species, for which they played a vital role in the outcome of mercury removal.

The study of CO2 reforming of methane over Ce/Sm-promoted NiCaAl catalysts

In this work, we synthesized Ce and Sm-promoted NiCaAl layered catalysts via co-precipitation and freeze-drying strategies for alleviating some problems, such as coke deposition and agglomeration of active sites, in dry reforming of methane. Employing such promoters leads to rising O2 vacancies on the catalyst's surface, resulting from adsorbing CO2 gas under the reaction. X-ray diffraction (XRD) analysis confirmed the formation of a hydrotalcite network. High-resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM) images also indicated a wealth of nanocatalysts, well distributed on the surface and within a porous scaffold structure. The temperature-programmed reduction (H2-TPR) proved that cerium (H2 consumption = 1.2 mmol.g-1) could weaken the interactions between nickel and Ca/Al, leading to better reducibility than samarium (H2 consumption = 1.35 mmol.g-1). Moreover, the temperature-programmed deposition (CO2-TPD) showed the Ce-promoted catalyst possesses more basic sites (0.41 mmol.g-1) on its surface than the Sm-enhanced one (0.25 mmol.g-1). Consequently, the Ce-enhanced catalyst with a smaller crystallite size (8.9 nm), higher dispersion of Ni (10.8%), better reducibility, and more basic sites, which caused the highest methane conversion (82%), and H2/CO ratio (0.9) at 700 °C without any coke deposition after 5 h of time on stream.

Insights into the interface of NiCo2O4 spinel /LaCoO3 perovskite nano-composite for CO and soot oxidation

In the quest for the development of thermally stable, highly active and low-cost catalysts for use in catalyzed diesel particulate filter, nano-composites are new areas of research. Therefore, we reported the easy synthesis of spinel NiCo2O4/perovskite LaCoO3 nano-composite, and its individual oxides NiCo2O4 and LaCoO3 for comparison. The detailed insights into the physio-chemical characteristics of formed NiCo2O4/ LaCoO3 nano-composite were done based on various characterization analysis such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR), N2 physiosorption, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The characterization analysis of NiCo2O4/LaCoO3 revealed the successful formation of a chemical interface possessing strong interfacial interaction, resulting in desirable physicochemical characteristics such as small crystallite size, abundant mesoporosity, high specific surface area and activation of surface lattice oxygen. Owing to the desirable characteristics, the activity results over NiCo2O4/LaCoO3 nano-composite showed the excellent CO oxidation performance and high soot oxidation activity, recyclability and thermal stability. This work mainly attempts to emphasize the effectiveness of the facile, inexpensive and conventionally used precipitation method for the successful formation of highly efficient nano-composites.

Physical Properties Modification of Co-Precipitated CoLa&lt;sub&gt;0.1&lt;/sub&gt;Fe&lt;sub&gt;1.9&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Nanoparticle with Different Fe&lt;sup&gt;3+&lt;/sup&gt; Raw Material

Lanthanum-substituted cobalt ferrite nanoparticles (CoLa0.1Fe1.9O4) with different Fe3+ cation sources i.e., using standard chemical lab (sample A) and a Bengawan Solo River fine sediment (sample B), were synthesized using the co-precipitation method. FTIR analysis showed that the absorption of the two nanoparticles sample appeared at a peak of v1=586.39 cm-1, whereas the v2 appear at 461.97/cm and 435.93/cm respectively. It is suggested that the La3+ cation has succeeded in replacing the original structure of the cobalt ferrite. X-ray diffraction analysis showed that nanoparticles produce using a standard chemical lab (sample A) have smaller crystallite sizes, D=18.16 nm than the natural source of fine sediment (sample B), D=24.56 nm, respectively. Furthermore, the VSM results showed that the magnitude coercive field of Hc = 3100 Oe and Hc = 100 Oe for samples A and B, respectively. Meanwhile, the obtained saturated magnetization Ms of 15.55 emu/g for sample A and the Ms is 58.40 emu/g for sample B. This result informs that if a hard magnetic material is desired then the use of lab raw materials is more promising, while if soft magnetic is desired then a natural source of fine sediment is more appropriate to use.

Mesoporous ZnCr2O4 Nanocatalyst with High Specific Surface Area for Facile Synthesis of Flavonoid Derivatives

ZnCr2O4 nanoparticles with a high specific surface area have been fabricated using a hydrothermal synthetic process and were used as an effective catalyst to synthesize flavonoid derivatives. The textural and structural properties of the spinel were studied by X-ray diffraction (XRD), Field Emission scanning electron microscope (FE-SEM), nitrogen sorption techniques, and Fourier transform infrared spectroscopy (FT-IR). XRD confirmed the formation of cubic Zinc Chromite spinel with a small crystallite size of 5.04 nm. While Transmission Electron Microscopy (TEM) illustrated the particle size of ∼8, 10, and 16 nm. Textural analysis by N2 sorption revealed a mesoporous system with a high specific surface of 215 m2/g for ZnCr2O4. Moreover, all desired flavonoids were obtained in high yields under solvent-free conditions with the aid of the ZnCr2O4 catalyst. Structures of all flavonoid derivatives were confirmed by 1H-NMR, 13C-NMR, FT-IR, and their melting points.