Sol-gel Combustion Route Research Articles

Exploring dielectric and electrical characteristics in Sr0.5Ba0.5SnxFe12-xO19/CoFe2O4 nanocomposites

This study examined the morphological, structural, electrical, and dielectric characteristics of hard-soft (H-S) Sr0.5Ba0.5SnxFe12-xO19/CoFe2O4 (x ≤ 0.10) ferrite nanocomposites (NCs), created using one-pot sol-gel combustion route. This study systematically investigated the electrical/dielectric features of H-S Sr0.5Ba0.5SnxFe12-xO19/CoFe2O4 NCs where x is within the range of 0.00 ≤ x ≤ 0.10. The examination realizes frequencies that reach 3.0 MHz, conducted within 20 °C–120 °C. A detailed analysis was performed to investigate various conduction mechanisms linked with dielectric constant, dissipation factor, AC/DC conductivity, loss of dielectric capacity, and real/imaginary modulus, which were explored across the entire range of Sn ion substitution ratios. Observations reveal that the conductivity variations adhere to power law dynamics concerning frequency, predominantly influenced by the Sn ion substitution ratios within the NCs. Furthermore, the frequency dependency of the dielectric coefficient across all NCs substantiates the common propagation of dielectric behavior, prominently contingent upon the substitution ratio of "x". Notably, the majority of dielectric parameters observed in H-S Sr0.5Ba0.5SnxFe12-xO19/CoFe2O4 (x ≤ 0.10) NCs are attributable to grain-to-grain boundaries, elucidated by conduction mechanisms similar to those observed in most compositional ferrites, explicable through Koop's model.

Enhancement of Bioactivity, Mechanical and Degradation Properties of the Diopside by Incorporation of Ba2+ Ion via Sol–gel Combustion Route

Enhancement of Bioactivity, Mechanical and Degradation Properties of the Diopside by Incorporation of Ba2+ Ion via Sol–gel Combustion Route

Effect of Cetyl Trimethyl ammonium bromide (CTAB) amount on the Nanoindentation creep behaviour of Sn-cu-Y2O3 nanocomposite Lead-free solder

Sn-Cu-Y2O3 nanocomposite solder is synthesized from a citrate bath by pulse electrodeposition route. Y2O3 powder is synthesized from a sol-gel assisted combustion route. Different techniques such as SEM, XRD, and TEM are used to characterize Y2O3 powder. The particle size of Y2O3 powder is found to be 27 nm. The effect of adding cetyl trimethyl ammonium bromide (CTAB) on the synthesis of Sn-Cu-Y2O3 nanocomposite lead-free solder is studied. The amount of CTAB is varied for a particular amount of Y2O3 powder. It is carried out to find the exact ratio of CTAB for better dispersion of Y2O3 powder in the electrolytic bath. Because the distribution of reinforcement in the matrix which is associated with the dispersion of Y2O3 powder in the electrolyte is as important as the amount of reinforcement in the solder matrix. For the synthesis of nanocomposite solder, the optimum ratio of CTAB to Y2O3 is found to be 1:1. After the synthesis of nanocomposite solder, the influence of Y2O3 powder on the melting temperature of the solder is also studied. Incorporating Y2O3 has little effect on the melting point of the nanocomposite solder. Nanoindentation creep test results showed that the deposit at 0.2 A/cm2 (monolithic solder) has a lower creep resistance than the nanocomposite solders. Additionally, the creep resistance of the nanocomposite with a CTAB to Y2O3 ratio of 1:1 was higher.

Unraveling the effect of Cu doping on the structural and morphological properties and photocatalytic activity of ZrO2

Pristine ZrO2 and doped with different concentrations of Copper (0–7 %) were synthesized using a sol-gel combustion route. Several advanced techniques like XRD, EDX, TEM, XPS, P.L., and UV–vis spectrophotometer have characterized the compositions. The XRD proved that all peaks matched with a tetragonal phase of ZrO2 without any impurities of other phases. An average crystallite size rises from 20 to 55 nm by increasing the concentrations of Copper. The elemental analysis was examined by EDX and confirmed the presence of Cooper, Zirconium, and Oxygen. The red shift was observed due to a decrease in the bandgap (5.5–4.01 eV) with increasing the Cu concentrations. From the analysis of photocatalysis of pure ZrO2 and different concentrations of Cu-doped ZrO2 for M.B., RHB, and mix of them. The increase in doping of Cu led to enhancing the performance of the removing MB from 35 to 80 %, however, the RHB degradation was from 42 to 81 % while the mix of M.B. and RHB reached 85 % with 7 % Cu-doping ZrO2.

Synthesis of hydroxyapatite via sol–gel combustion route: A comparative analysis of single and mixed fuels

Hydroxyapatite (HAp) is a highly biocompatible mineral source for bone and soft tissue repair, owing to its similarities to native bone. Researchers have adopted combustion synthesis by using various fuels for the synthesis of hydroxyapatite. This study sheds new light on the effects of glycine and succinic acid as single fuels as well as a mixed fuels for hydroxyapatite synthesis. A marked observation from the comparative analysis was that mixed fuels with an optimum ratio resulted in the formation of hydroxyapatite in a single phase with an average crystallite size of 21–23 nm. However, single fuels, such as glycine and succinic acid, produce hydroxyapatite with larger crystallite sizes of 25–28 nm and 38–41 nm. Additionally, the use of mixed fuels facilitated the product formation at a lower temperature of 500 °C, whereas single fuels produced hydroxyapatite at an elevated temperature of 900 °C.

Activated charcoal modified BaFe12O19 powder: a recyclable magnetic adsorbent for removal of methyl blue dye from aqueous solutions

ABSTRACT Use of sophisticated adsorbent materials to clean harmful dye-contaminated water is rapidly gaining popularity. Among different adsorbent, magnetic ferrites based adsorbent are gaining much attention because of their easy recyclability. In this current work, activated charcoal (AC) modified magnetic BaFe12O19 (BaM) ferrite-based novel adsorbent (BaM-AC) powder was synthesised through a sol-gel combustion route. As a model dye pollutant, methyl blue (MB) was used to estimate the adsorption efficiency of BaM-AC adsorbent. X-ray diffraction (XRD) was utilised to analyse pure BaM and BaM-AC powder phases. Fourier transform infrared spectroscopy (FTIR), Brunauer, Emmett and Teller (BET), vibrating sample magnetometer (VSM) and field emission scanning electron microscope (FESEM) were also used for the characterisation of prepared adsorbents. The surface area of BaM-AC powder determined by BET was 5.93 m2 g−1. The BaM-AC adsorbent has a saturation magnetisation (Ms) of 56.8 emu g−1 and a coercive field (Hc) of 5176 Oe. Microstructural analysis showed the porous morphology of the material. In-depth studies with BaM-AC powder investigated how pH, adsorbent dose, adsorption period, MB dye concentration, and effect of temperature affected MB dye adsorption. Conferring to the outcomes of the MB-adsorption experiment, the equilibrium was reached after around 45 minutes. Pseudo-second-order kinetics and the Sips isotherm model govern the adsorption process. BaM-AC powder exhibited a good recyclability up to five-regeneration cycle. These outcomes suggest that the composite material has the potential to serve as an effective adsorbent for dye-containing wastewater treatment.

Mössbauer and Structure-Magnetic Properties Analysis of AyB1-yCxFe2-xO4 (C=Ho,Gd,Al) Ferrite Nanoparticles Optimized by Doping.

AyB1-yCxFe2-xO4 (C=Ho,Gd,Al) ferrite powders have been synthesized by the sol-gel combustion route. The X-ray diffraction of the CoHoxFe2-xO4 (x = 0~0.08) results indicated the compositions of single-phase cubic ferrites. The saturation magnetisation of CoHoxFe2-xO4 decreased by the Ho3+ ions, and the coercivity increased initially and then decreased with the increase of the calcination temperature. The Mössbauer spectra indicated that CoHoxFe2-xO4 displays a ferrimagnetic behaviour with two normal split Zeeman sextets. The magnetic hyperfine field tends to decrease by Ho3+ substitution owing to the decrease of the A-B super-exchange by the paramagnetic rare earth Ho3+ ions. The value of the quadrupole shift was very small in the CoHoxFe2-xO4 specimens, indicating that the symmetry of the electric field around the nucleus is good in the cobalt ferrites. The absorption area of the Mössbauer spectra changed with increasing Ho3+ substitution, indicating that the substitution influences the fraction of iron ions at tetrahedral A and octahedral B sites. The X-ray diffraction of Mg0.5Zn0.5CxFe2-xO4(C=Gd,Al) results confirmed the compositions of single-phase cubic ferrites. The variation of the average crystalline size and lattice constant are related to the doping of gadolinium ions and aluminum ions. With increasing gadolinium ions and aluminum ions, the coercivity increased and the saturation magnetization underwent a significant change. The saturation magnetization of AlMg0.5Zn0.5FeO4 ferrite reached a minimum value (MS= 1.94 mu/g). The sample exhibited ferrimagnetic and paramagnetic character with the replacement with Gd3+ ions, that sample exhibited paramagnetic character with the replacement with Al3+ ions, and the isomer shift values indicated that iron is in the form of Fe3+ ions.

Synthesis of Substituted Barium Ferrites and Hexaferrites and Their Electrochemical Characterization

Magnetic nanoparticle has been an attractive area of research in view of their unique physical and chemical properties. [1] In the field of electrochemistry, particularly electroanalysis, they are extensively used as functional materials due to their high surface area, mass transport, catalytic effect, and control over the local environment. Barium based ferrites have emerged as attractive materials of interest due to their interesting physical, chemical, magnetic and electrical properties. [2] Hexaferrite and ferrites such as barium ferrite are very important group of magnetic oxides and these are used in different technologies including sensors because of their specific properties such as low cost, corrosion resistance chemical stability and large magneto crystalline anisotropy. [3] However, the investigation of the effect by various other elements on the structure of hexaferrite and ferrite particles and its electrochemical properties remains the subject of popular research. In this work, mixed metallic oxides hexaferrite and ferrite were synthesized by sol–gel combustion route using glycerin as an adjuvant. [4] Their structure was confirmed by means of X-ray powder diffraction. Scanning electron microscopy were used to investigate the morphology of the sample and the vibrations of the functional groups were determined by Raman and IR-ATR spectroscopy. The electrochemical behavior of substituted hexaferrite and ferrite were determined by cyclic voltammetry using an Ag/AgCl electrode, platinum wire and a glass carbon electrode (GCE), as reference electrode, counter electrode and working electrode, respectively. The GCE was modified with mixed metal oxides obtained to analyze their electrochemical behavior.Bibliographic Xueli X, Wei S 2019 Materials Technology, 1-5Kefeni, K.K.; Msagati, T.A.; Mamba, B.B. 2017, Sci. Eng. B. 215, 37–55Valenzuela R, Magnetic Ceramics, Chemistry of Solid State Materials 4 serie. Cambridge (Great Britain): Cambridge University Press, 1994, p. 50Sandra F. Basante-Delgado, Dalliver González-Vidal, Jimmy A. MoralesMorales, William A. Aperador-Chaparro, Jairo A. Gómez-Cuaspud, 2020 Phys.: Conf. Ser. 1541 012013

Electrochemical Characterization in Neutral Electrolyte of Mixed Metal Oxide

The mixed metal oxides, have been used in different environmental and chemical applications in view of their physical and chemical properties. In the field of electrochemistry, particularly electroanalysis, they are extensively used as functional materials due to their high surface area, mass transport, catalytic effect, and control over the local environment. [1] Mixed metal oxides providing a material with different physicochemical and morphological properties, such as, greater surface area, high dispersion, thermal stability, acid/base properties, making its application in various fields of chemistry, mainly as catalysts in various organic reactions. [2]In this work, mixed metal oxides of CuO-Fe2O3 and CoFe2O4 ferrite were synthesized by sol–gel combustion route using glycerin as an adjuvant. [3-4] The mixed metal oxides CuO-Fe2O3 and CoFe2O4 ferrites structure was confirmed by means of X-ray powder diffraction. Scanning electron microscopy were used to investigate the morphology of the sample and the vibrations of the functional groups were determined by Raman and IR-ATR spectroscopy. [3-4]The electrochemical behavior of mixed metal oxides CuO-Fe2O3 and CoFe2O4 ferrite were determined by cyclic voltammetry using an Ag/AgCl electrode, platinum wire and a glass carbon electrode (GCE), as reference electrode, counter electrode and working electrode, respectively. It was used a solution of KNO3 (0,1 mol L-1) as electrolytic medium. The GCE was modified with mixed metal oxides obtained to analyze their electrochemical behavior.Bibliographic Kefeni, K.K.; Msagati, T.A.; Mamba, B.B. 2017, Sci. Eng. B. 215, 37–55Veisi, S.S.; Yousefi, M.; Amini, M.M.; Shakeri, A.R.; Bagherzadeh, M. 2019, Alloy. Compd. 773, 1187–1194Basante-Delgado, S.F.; González-Vidal, D.; Morales-Morales, J.A.; Aperador-Chaparro, W.A.; Gómez-Cuaspud, J.A. 2020 Phys. Conf. Ser. 1541, 012013Granja-Banguera CP, Silgado-Cortázar DG, Morales-Morales JA. 2022, Molecules. 2022, 27, 1550.

Structural spectral, dielectric, and magnetic properties of Mg substituted Ba3CoFe24O41 Z-type hexaferrites

The Ba3Co2-xMgxFe24O41 hexaferrites were prepared by the sol–gel combustion route. The materials were annealed at 1350 °C and displayed the single-phase characteristics. X-ray density (Dx) decreases owing to increasing Mg-concentration. Crystallite size was calculated with the help of Debye Scherrer's formula and found within the 17–18 nm range. Fourier transform infrared spectroscopy was used to determine the specific absorption peaks of hexagonal ferrites. It was executed in the region of 420–700 cm−1—the occupancy of Mg2+ ions at the octahedral site at delayed alternation of Fe3+ ions. As a result, the dielectric permittivity decreased. The grain boundary contribution was clearly seen in synthesized ferrites' cole plots. The cole – cole plots show a single semi-circle which reveals that grain boundaries play a significant role in the conduction process. Magnetic measurement indicated the ferrimagnetic behavior of all samples.

Modulation of electric and magnetic ordering in GdFeO3 orthoferrites system by Ce-doping

In the present attempt, orthoferrites system GdFeO3 (GFO) is modified by partially substituting Gd by Ce and its influence on structure, electric and magnetic orderings of GFO are systematically explored. The doped-GFO systems with various compositions Gd1-xCexFeO3 (GCFO; x = 0 ≤ x ≤ 0.1 with 0.02 interval) are developed by using sol-gel combustion route. The Rietveld refinements of the XRD data confirm orthorhombic phase with Pbnm space group of all compositions. The substitutional effect of Gd by Ce in GFO is found to reduce Dielectric constant and to enhance dissipation factor. Both these effect is associated with change in hybridization between O-2p states and Fe-3d due to change in Fe–O bond length by dopant effect. The dielectric relaxation are revealed using impedance loss spectra and electric modulus formalism in the frequency range 1 Hz to 1 MHz and in the temperature rage 200–450 °C and relaxation time is found to decrease with doping level and temperature. The net resistivity of GFO is reduced with increase in conductivity by around two orders by Ce-doping. The frequency dependence of conductivity follows the power law. The activation energy for dielectric relaxation in GCFO is varying between 0.3 and 0.5 eV at grain boundaries; while 0.25–0.4 eV on grain, indicate the conduction mechanism on grain boundaries is attributed by oxygen vacancies defect and grains by polaron hopping. The magnetization study displays doping of Ce modifies the M-H hysteresis loop and gives canted antiferromagnetic behavior in GFO. The remnant magnetization and coercivity is suddenly jumped by two order in GCFO system. The significant enhancement in electric and magnetic orderings is achieved by Ce addition in GFO.

Antibacterial wollastonite supported excellent proliferation and osteogenic differentiation of human bone marrow derived mesenchymal stromal cells

Biocompatibility and bacterial infections are the primary concerns associated with the current bone graft substitutes. The application of wollastonite-based scaffolds for bone tissue engineering becomes a novel subject of interest. In the present study, a single phasic wollastonite scaffold was synthesised using citric acid-based sol–gel combustion route. Its physicochemical characteristics, antibacterial properties as well as its biocompatibility and osteogenic induction effect on human bone marrow derived stromal cells (hBMSCs) are yet to be explored. The TGA/DTA, XRD and SEM/EDX confirmed the characteristics of wollastonite. The antibacterial test indicated wollastonite inhibition of 47.81% and 45.54% for gram-positive, Staphylococcus aureus and Staphylococcus epidermidis and 47.04% and 46.07% for gram-negative, Escherichia coli and Pseudomonas aeruginosa bacterial strains, respectively. The SEM micrographs demonstrated an excellent attachment of hBMSCs on wollastonite and comparable to commercial hydroxyapatite (cHA) scaffold. The alamar blue cell proliferation assay confirmed 1.7- and 1.8-fold significant increase in hBMSCs seeded on wollastonite and cHA scaffold, respectively, on day 14 as compared with day 1. The immunohistochemistry analysis on Type-I collagen (Col1) and Bone morphogenetic protein-2 (BMP2) expression on day 14 confirmed the osteogenic differentiation of hBMSCs seeded on wollastonite and comparable with cHA scaffold. In conclusion, wollastonite scaffold has a greater potential to substitute bone grafts in orthopaedic applications.

Tuning of physical properties of multifunctional Mg-Zn spinel ferrite nanocrystals: a comparative investigations manufactured via conventional ceramic versus green approach sol-gel combustion route

This work focused on the impact of synthesis routes on the structural, microstructural, magnetic, electrical and dielectric characteristics of Mg1−x Zn x Fe2O4 (x = 0.00, 0.25, 0.50, 0.75, and 1.00) nanocrystals manufactured via the ceramic and green approach sol–gel route. The powder X-ray diffraction (XRD) analysis reveals that the entire synthesized ferrite solids crystallize in single phase spinel structure. The XRD outcomes highlight the impact of the synthesis routes and Zn2+ replacement on the morphology, crystallite size and structural parameters of magnesium nano-ferrites. The transmission electron microscopy (TEM) images illustrate that the process of synthesis causes extensive lessening of grain and crystallite sizes. The magnetic study reveals that the magnetic properties of magnesium ferrite can be tuned by zinc substitution. The saturation magnetization (Ms), retentivity (Mr), coercive force (Hc) and magneton number diminutions meaningfully with the replacement of diamagnetic Zn2+ ions in Mg-ferrite for both the synthesized systems. The deterioration of magnetic parameters with Zn2+ substitution can be clarified on the base of the random spin canting model. Likewise, the magnetic parameters, enhanced meaningfully for sol-gel derived samples this can be attributed due to decline of crystallite size effect. The DC electric resistivity displays NTCR behaviour like ideal semiconducting materials for all the produced samples. The DC resistivity values of sol-gel produced samples were found to be little bit higher than that of ceramic derived samples. The experimental dielectric constant as a function of frequency behaviour can be elucidated with the support of the heterogeneous model of the polycrystalline structure of ferrites. The dielectric constant and loss tangent decreases with Zn2+ content for both the systems. The dielectric constant enhances for sol-gel derived samples; however, lower values of loss tangent were found. The obtained outcomes can be suitable for multifunctional applications in electronics devices and biomedical field.

A preliminary study of oxides of Fe doped with Ba, Co, Cu and synthetized by the citrate sol–gel combustion route

In the present work we report the synthesis of mixed ferrites doped with Co2+, Cu2+ and Ba2+ cations, using citrate sol–gel combustion route in air atmosphere, at 950 °C for 3 hours, produced substituted M-type barium ferrites powders particles with crystallite sizes varying between 145 and 155 nm. The percentages of yield obtained were on average 42%. The synthesized ferrites were characterized by techniques such as powder X-ray diffraction, evidencing the formation of M-type barium hexaferrite and copper and cobalt substituted M-type barium ferrite with hematite in smaller proportion. The possible growth of M-type barium ferrite with copper and cobalt may be due to a larger size of the cobalt atom with respect to copper and that a higher proportion of cobalt salt was used in the synthesis route. Increase in the metal ion substituted content leads to a decrease in the lattice strain and may be responsible for an increase in the crystallite size because greater tensile strain leads to elongation of the particles. The particle size of the synthesized ferrites differs significantly when they are doped, with Ferrite doped with copper having the smallest particle size compared to Ferrite doped with cobalt. We also performed spectroscopic analyses, RAMAN that showed, the substitution of cooper or cobalt in the M-type barium ferrite powders particle leads to a minor intensity of resonance band when compared with the parent compound and the differences between Fe3+, Cu2+ and Co2+ ions in a tetrahedral coordination is their ionic radii. The increase in the ionic radii causes a local distortion and vibrational bands of distorted polyhedra in substituted M-type barium ferrites. The chemical composition of this sample was determined as Ba1.0Fe11.83O19.22, Ba1.0Co1.02Fe11.01O18.35 and Ba1.02Cu0.56Fe11.35O18.26 using an AAS device. Both are very close to the theoretical formula. The influence of the synthesized ferrite samples was explored in the ozonation of a dye of unknown chemical structure. The effect was evidenced by visible ultraviolet spectroscopy technique. The results obtained show that the ink could be decolorized by applying oxidation by ozonation, however, when substituted M-type barium ferrite is added, the discoloration increases when this is doped with copper and cobalt, being higher using this last ferrite. The degradation process by ozonation presented in this work, carried out in the presence of copper and cobalt substituted M-type barium ferrites, would constitute an example of technology for the environment.

Structural, electrical, and weak ferromagnetic-to-antiferromagnetic nature of Ni and La co-doped BaTiO3 by sol–gel combustion route

We report on structural, electrical, and weak ferromagnetic-to-antiferromagnetic possessions of Ba(1−x)LaxNi0.01Ti0.99O3 (BLNT) samples with x = 0.00, 0.25, 0.50, and 0.75%. The X-ray diffraction (XRD) and Raman spectra show that the sol–gel combustion route synthesized samples are successfully incorporated with La3+ ions into BaNi0.01Ti0.99O3 (BNT) lattice. The EPR signals at g = 1.967 and g = 2.003 are attributed to the V(Ba) and V(Ti) defects, respectively. For x = 0.75%, V(Ba) signal disappears due to the subtle charge-compensation mechanism present in the BLNT sample. The BNT ceramics exhibit a weak ferromagnetic nature; upon La ion doping, the weak ferromagnetic (WFM) tends to exhibit strong antiferromagnetic (AFM) nature in BLNT. This magnetic phase transition can be described in the stipulation of the change in the oxidation state. Escalating in the dielectric constant and ac conductivity was due to the higher doping concentration of La3+ ion in BNT ceramics. BLNT clearly shows that as La3+ ion-doping concentration increases, the diameter of the impedance semicircle decreases due to the increased conducting nature of the samples. The ferroelectric property was deliberately investigated by a P–E hysteresis loop and its saturation polarization was found to decrease with increasing concentrations of La3+ ion doping, and the observed results are discussed.

One-step synthesis of pure γ-FeNi alloy by reaсtive sol–gel combustion route: mechanism and properties

A pure crystalline γ-FeNi alloy powder was fabricated through the one-step process of sol–gel combustion. An experiment was conducted in inert atmosphere with the hexamethylenetetramine (HMTA) used as an oxygen-free fuel and metal nitrites as oxidizers. It was demonstrated that fuel-to-oxidizer ratio is a critical parameter to produce pure γ-FeNi alloy. A concentration of the fuel necessary for the alloy synthesis is three times higher (φ = 3) than at the stochiometric molar ratio. The ~1100 K maximum temperature, 830 K/s heating and 170 K/s cooling rates and the total reaction time of ~3 s are characteristics of the optimized sol–gel combustion synthesis of the γ-FeNi alloy powder. A mechanism of the alloy formation through the coordination metals—HMTA complex was proposed and experimentally verified. Microstructural and magnetic properties of the synthesized material are also investigated and discussed.

Defects and oxygen vacancies tailored structural, optical, photoluminescence and magnetic properties of Li doped ZnO nanohexagons

In this study, Zn1-xLixO (x = 0.02, 0.04, 0.06, 0.08 and 0.10) nanohexagons were prepared by sol-gel combustion route and characterized using standard techniques for understanding their crystallography, surface morphology, optical, photoluminescence and magnetic properties. Single phase wurtzite type hexagonal crystal structure of the synthesized Li doped ZnO nanoparticles was identified from the Rietveld profile refinement of the powder XRD patterns and HRTEM & SAED analysis. HRTEM micrographs and XRD peak profile analysis confirmed formation of highly crystalline Li doped ZnO nanohexagons (ZnO:Li NHs) with average crystallite size in the 20–40nm range. Formation of functional Zn(Li)–O bonds in ZnO:Li NHs was confirmed by FTIR. SEM micrographs of the prepared samples showed random shaped, uniform distribution and well dispersed grains of ZnO:Li NHs. All the ZnO:Li NHs absorbs significant light in the UV band and the band gap energy monotonically decreases with increasing Li concentration in ZnO:Li NHs. Photoluminescence spectra exhibited two characteristic emission bands in all the ZnO:Li NHs and the UV emission band showed red shifting with increasing Li concentration, which is ascertained with the optical absorbance spectrums. Visible band spectral analysis of the PL data revealed formation of neutral, mono, and divalent oxygen vacancies along with the other defects like Zn vacancy in the ZnO lattice by Li doping and synthesis mechanism. All the ZnO:Li NHs exhibited weak ferromagnetism at RT. Lattice defects and oxygen vacancies created by Li1+ ions in the host ZnO lattice play significant role in band gap narrowing, photoluminescence in orange-red region and weak ferromagnetic ordering in ZnO:Li NHs.

Enhancement on the exchange coupling behavior of SrCo0.02Zr0.02Fe11.96O19/MFe2O4 (M = Co, Ni, Cu, Mn and Zn) as hard/soft magnetic nanocomposites

Hard/soft SrCo0.02Zr0.02Fe11.96O19/MFe2O4 (M = Ni, Co, Cu, Mn and Zn) nanocomposites have been fabricated efficiently via one-pot sol-gel combustion route. The influence of different type of spinel were examined by XRD (X-ray diffraction), SEM – TEM (scanning and transmission electron microscopies) systems and VSM (vibrating sample magnetometer). The XRD investigation of Hard/soft nanocomposites revealed the tailoring between hexaferrite and spinel ferrite phases. Magnetization measurements (M vs. H) were performed at room (T = 300 K) and low temperature (T = 10 K) and diverse magnetic parameters comprising Ms (saturation magnetization), Mr (remanence), coercivity (Hc), and so on were determined. Smooth M vs. H curves and single peaks in dM/dH vs. H plots were observed for various prepared nanocomposites. The Henkel plots and maximum energy products were also determined and analyzed. Various prepared hard/soft nanocomposites indicated relatively high values of diverse magnetic parameters. Diverse findings disclosed the incidence of exchange-coupling spring behavior among various soft and hard magnetic phases. Measurements of ZFC-FC magnetizations showed the existence of a peak temperature values, which are largely ascribed to competition between the motion of magnetic domain walls and thermal activations. It is revealed that one-pot sol-gel combustion route is valuable to attain strong exchange coupling among hard and soft nanoparticle phases grown near to each other. The obtained findings indicated that these nanocomposites are promising candidates for numerous practical applications.

Influence of nano-copper oxide concentration on bactericidal properties of silver–copper oxide nanocomposite

The study investigated influence of copper oxide nanoparticle (CuO NP) concentrations on the bactericidal properties of silver-copper oxide (Ag/CuO) nanocomposite against Escherichia coli PTCC 1329, Klebsiella pneumoniae PTCC 1290 and Staphylococcus aureus PTCC 1189. Silver–copper oxide nanocomposite with varying concentrations of CuO was synthesized using a facile sol–gel combustion route. Formation of Ag/CuO crystalline structure and particle size were characterized by X-ray diffraction, Transmission Electron Microscopy and Field Emission Scanning Electron Microscopy. Elemental analyses were performed by energy dispersive X-ray. Morphologies of CuO NPs showed that Ag/CuO nanocomposite consisted of interconnected nanoparticles with a porous channel. Ag/CuO nanocomposite with higher CuO NPs content exhibited superior bactericidal effects. Bacterial growth profile also confirmed superior bactericidal effects of the nanocomposite at higher CuO NPs concentrations. A facile sol–gel technique with enhanced bactericidal effects at higher concentration of CuO NPs is promising for the development of cost-effective and efficacy-enhanced nanomaterials.

Biomineralization, antibacterial activity and mechanical properties of biowaste derived diopside nanopowders

This work reports on the preparation and characterization of mesoporous nano diopside (CaMgSi2O6) using a simple and cost-effective sol-gel combustion route. Stoichiometric oxidant/fuel ratio was adopted for the combustion reaction. Eggshell was used as a calcium source, glycine (fuel) as reductant, magnesium nitrate and nitric acid as oxidant were used in the preparation. The thermal behavior of the precursor was studied by thermo-gravimetric analysis (TGA) and heating microscopy. The temperature required for the transformation of the precursor into pure diopside was optimized at 1100 °C. Rietveld refinement method was utilized to confirm the phase purity of diopside. The resultant powder contains 36 nm particle with a specific surface area of 51 m2/g. The appearance of Ca, Mg, Si, and O peaks in EDX pattern confirmed the existence of essential elements. The rapid consumption of calcium and phosphorus ions from the simulated body fluid during dissolution indicated their involvement in apatite deposition on the surface of the nano diopside. FT-IR spectra showed that the SiO and SiOSi groups were replaced by phosphate bands due to hydroxyapatite deposition. The mechanical stability of the diopside after bioactivity studies was found to be superior to the cancellous bone. The release of alkaline earth ions (Ca2+ and Mg2+) from the diopside sample into the bacterial culture medium increases the pH (7.4), which inhibits the bacterial growth. The surface properties, concentration, and type of bacteria are the other factors responsible for the antibacterial activity of the nano diopside.