Phase Formation Temperature Research Articles

Fabrication of multifilamentary powder in tube superconducting tapes of Bi-2223 with Sr deficient starting composition

Bi2SrxCa2Cu3O10+δ (Bi-2223) precursor powders were fabricated by co-precipitation process with different Sr content of x = 1.93, 1.90, and 1.85. Multi-filamentary Bi-2223 high temperature superconducting tapes were fabricated by the traditional powder in tube process (PIT) with different precursor powders. The influences of Sr content on the phase formation dynamics as well as the superconducting properties of Bi-2223 tapes have been systematically investigated. With decreasing Sr content, the critical temperature of Bi-2223 tapes decreased from 109.9 K to 107.7 K, which implied that the change of Sr content could change the carrier concentration on Cu-O plane, thus led to the variation of intrinsic superconducting transition behavior. Besides, with the decrease of Sr content, the phase formation temperature decreased. Bi-2223 tapes with higher superconducting phase content were obtained with the Sr content of 1.85, which was beneficial to the improvement of intergrain connections. Thus, the Jc-B behavior was enhanced under the magnetic field parallel to the ab plane of Bi-2223. With further optimization of sintering process, the maximum Ic of 128 A was achieved on Sr = 1.85 tape, corresponding to the critical current density, Jc of ~ 25.8 kAcm−2.

Impact of holmium on structural, dielectric and magnetic properties of Cu–Zn spinel ferrites synthesized via sol–gel route

The mixed nano-ferrites materials Cu0.6Zn0.4HoxFe2−xO4 (0.00 ≤ x ≤ 0.12) were prepared via the sol–gel auto combustion technique. The TGA curve established the annealing temperature (500 °C) for phase formation. The single exothermic peak on the DSC plot occurred at 341 °C temperature. XRD patterns of these nano ferrites verified single phase formation of the FCC cubic structure. The lattice constant a was increased from 8.4244 to 8.4419 A and then its value decreased to 8.4319 A. Crystallite size was found in the range of 7 to 16 nm. The surface morphology of the samples was observed from the scanning electron microscope (SEM) images. The grain size was found within the range of 90 nm to 106 nm. Energy-dispersive X-ray (EDX) results showed the significant substitution of Ho in Cu–Zn spinel ferrites. Dielectric parameters such as dielectric constant, dielectric constant factor, and tan loss depicted a decreasing trend with Ho3+ ions concentration. The single-domain ferrimagnetism is confirmed by the squareness ratio, which is < 0.5. The Ms was found to be decreased while Hc was increased. The significant results of the dielectric as well as magnetic properties of these nano ferrites suggested their use in high-frequency devices applications.

Application of Extractive Fermentation on the Recuperation of Exopolysaccharide from Rhodotorula mucilaginosa UANL-001L

Exopolysaccharides (EPS) are high molecular weight biomaterials of industrial interest due to their variety of applications in the pharmaceutical, cosmetic, environmental, and food industries. EPS produced by Rhodotorula mucilaginosa UANL-001 L has sparked interest due to its bio-adsorbent and wide spectrum antimicrobial properties. However, full exploitation and commercial application of EPS has been restrained due to low yields and high production costs. In the present work, the production and separation of EPS from Rhodotorula mucilaginosa UANL-001L was attempted through extractive fermentation in order to increase EPS production while simplifying the recovery process. Extractive fermentation was implemented with a thermoseparating polymer for phase formation (EOPO 970 and EOPO 12,000); culture viability, biomass generation, EPS production, rheological system properties, and phase formation time and temperature were monitored throughout the process. Extractive fermentation of Rhodotorula mucilaginosa UANL-001L with EOPO 970 resulted in a 42% EPS and 7% biomass recovery on the top phase after 5 to 13-min phase formation time and temperatures between 30 and 40 °C. This is the first report of extractive fermentation application for EPS production by yeast of the genera Rhodotorula, resulting in an interesting strategy for EPS production and recovery, although further optimization is needed.

Influence of Zn-substitution on structural, morphological, electrical, and gas sensing properties of ZnxAl2O4 (x = 0.1 to 0.5) synthesized by a sol-gel auto-combustion method

The nanosphere decorated needle-like morphology of zinc-substituted aluminate having general formula ZnxAl2O4 (x = 0.1, 0.2, 0.3, 0.4, and 0.5) (ZAN) samples were synthesized by a sol-gel auto-combustion method. The phase formation and stability temperature were confirmed by TG-DTA analysis. XRD study confirmed the formation of a cubic spinel structure of ZAN samples. The effect of Zn-substitution on structural and morphological properties of aluminate were investigated using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM), and Energy dispersive X-ray analysis (EDAX). The D.C. electrical resistivity study of ZAN samples revealed that resistance decreased with increasing temperature confirmed semiconducting nature. Nanosphere existing on micro-needles of zinc-substituted aluminate gas sensor revealed sensing to several analyte gases such as H2S, Cl2, CH3OH, SO2, and NO2 working at room temperature to 300 °C. The Zn0·4Al2O4 compositional gas sensor produced the highest response at operating temperature 200 °C to 100 ppm H2S. The results revealed that the prepared nanosphere decorated needles of the ZAN sensor was sensitive and selective to H2S gas.

The sintering and electrical properties of Zn-substituted LaCo0·4Ni0·6O3 ceramics based upon experiments and calculations

To explore a low–cost functional phase alternative material for thick film resistors, the thermal behavior, sintering and electrical properties of LaCo0·4Ni0.6-yZnyO3 (y = 0.00–0.08, LCNZ) ceramics were investigated through experiments and density functional theory calculations. Results of simultaneous thermal analysis, thermomechanical analysis, scanning electron microscopy, and DC four–probe method indicated that substitution of Ni-ion by Zn–ion could lower the phase formation and densification temperatures of LCNZ, as well as increase the resistivity and decrease the temperature coefficient of resistance (TCR). The resistivity of 0.94 mΩ cm (y = 0.00) and 1.03 mΩ cm (y = 0.02), as well as TCR value of −312.79 ppm/°C (for y = 0.00) and −872.82 ppm/°C (for y = 0.02) could be achieved as the LCNZ ceramics sintered at 1200 °C. The variations of octahedral bond population, electron density around oxygens, and partial density of states near the Fermi level firmly supported the results of experiments.

Impact of nanosecond laser energy density on the C40-TiSi2 formation and C54-TiSi2 transformation temperature

The formation of Ti based contacts in new image sensor complementary metal–oxide–semiconductor technologies is limited by the requirement of a low thermal budget. The objectives of these new 3D-technologies are to promote ohmic, low resistance, repeatable, and reliable contacts by keeping the process temperature as low as possible. In this work, ultraviolet-nanosecond laser annealing was performed before classical rapid thermal annealing (RTA) to promote the formation at lower RTA temperatures of the low resistivity C54-TiSi2 phase. The laser energy density was varied from 0.30 to 1.00 J/cm² with three pulses in order to form the C40-TiSi2 phase and finally to obtain the C54-TiSi2 phase by a subsequent RTA at low temperatures. The formed Ti-silicides were characterized by four-point probe measurements, x-ray diffraction, transmission electron microscopy, and atom probe tomography. A threshold in the laser energy density for the formation of the C40-TiSi2 is observed at an energy density of 0.85 J/cm² for the targeted TiN/Ti stack on blanket wafers. The C40-TiSi2 formation by laser annealing prior to RTA enables to reduce the formation temperature of the C54-TiSi2 phase by 150 °C in comparison to a single RTA applied after the Ti/TiN deposition. This specific phase sequence is only observed for a laser energy density close to 0.85 J/cm². At higher energy densities, the presence of C49-TiSi2 or a mixture of C49-TiSi2 and C54-TiSi2 is observed. The underlying mechanisms of the phase sequence and formation are discussed in detail.

Influence of buckwheat hulls on the mineral composition and strength development of easily fusible clay body

In order to replace the traditional burning-out additive, sawdust, with another, but not less effective, substituent, the influence of buckwheat hulls and their ash on the development of the mineral composition and the physical-mechanical properties of a ceramic body from hydromicous easily fusible clay was studied. By X-ray diffraction, simultaneous thermal analysis, dilatometry and optical microscopy, it has been established that the composition of the newly formed phases depends on the nature and amount of burning-out additives. Buckwheat hulls, like sawdust, reduce the vitreous phase formation temperature in the samples by ~100 °C and accelerate the breakdown of clay mineral structures. As a result, anorthite starts to crystallize at temperature lower by ~60 °C and increases its amount in the ceramic body. Buckwheat hull ash promotes the formation of leucite. These changes in mineralogical composition, among other factors, affect the increase in the compressive strength of the ceramic body. Buckwheat hulls can be used successfully in the production of porous ceramic products because the technological process does not change, and the values of compression strength are close or even better than the values of the ceramic body without additives.

Effect of Y on the hot tearing susceptibility of 3Y2O3/Al5Cu composite

Hot tearing susceptibility (HTS) refers to the casting defect that existed owing to the appreciable shrinkage at the final stage of solidification. Present research studied the effect of Y on the HTS of 3Y2O3/Al5Cu composite. After 0.3%, 1% and 2% Y (in wt.%) added, the HTS value of 3Y2O3/Al5Cu composite decreased by 2.1%, 39.5% and 61.9%, respectively. Mechanism analysis indicated that the refined grain size and reduced solidification temperature range contributed to the HTS improvement. The grain size of 3Y2O3/Al5Cu was 36.7 μm, while the grain size refined to 32.99 μm, 24.35 μm and 20.9 μm for the 0.3Y-3Y2O3/Al5Cu, 1Y-3Y2O3/Al5Cu and 2Y-3Y2O3/Al5Cu. The result indicated that the increase of grain growth restriction factor, which was caused by the Y element, improved the grain refinement efficiency. Furthermore, adding Y resulted in the novel Al8Cu4Y phase formation and solidification temperature range reduction. In addition, the Al8Cu4Y and Al2Cu phases promoted grain boundary bridges formation and prevented the cracks initiation and growth during solidification process.

Production of nanostructure Zr–ZrCr2–Cr composite via MA process and subsequent heat treatment

ABSTRACT In this study, the nanophase ZrCr2 intermetallic compound was produced by the mechanical alloying (MA) and subsequent heat treatment. The phase transformations, crystallite size, lattice strain, and stored energy were studied at different milling times. The results indicated that MA caused to form a nanocomposite of the Cr(Zr) and Zr(Cr) supersaturated solid solutions. After 32 h of milling, the stored energy of Cr-reach phase in the powder mixtures reached to about 7.407 kJ/mol. Also, the 32 h milled powders were heated up to 750°C by the differential thermal analysis in argon atmosphere which the XRD results of the heated powders revealed that the nanostructure ZrCr2 intermetallic compound was formed in the Zr and Cr matrix. Indeed, MA reduced the formation temperature of the ZrCr2 intermetallic phase from 1673 °C to 608 °C which confirmed that MA and subsequent heating is a proper technique at low temperatures. In addition, a kinetics analysis implied that the Johnson-Mehl-Avrami (JMA) model can explain the kinetics formation of ZrCr2 phase during the heat treatment which confirmed that the dominant mechanism of the intermetallic phase formation was the process controlled by the volume diffusion phenomenon, so that the nuclei grow in three dimensions of space.

Studies on the Low-Temperature Synthesis of Fine α-Al2O3 Powder by Precipitation Route

Fine alpha-alumina (α-Al2O3) powder was prepared by simple precipitation technique using aluminium salt and ammonia as a precipitating agent. In this method, an aqueous solution of aluminium nitrate and ammonia were mixed with continuous stirring both in the presence and in the absence of polyethylene glycol (PEG). A controlled pH range of 7.5–8.5 was maintained throughout the synthesis process. A comparative study between the alumina powder prepared in the presence and absence of PEG was drawn into attention. The washing of the precipitate was deliberately avoided in one case to study the effect of washing on phase formation temperature. The synthesized powders were calcined at different temperatures and characterized by X-ray diffraction study, thermal analysis, infrared analysis, microstructural study, and particle size analysis. The results showed less agglomerated fine alumina powder formation in its pure α-Al2O3 phase at 1050°C in the presence of PEG.

Comparative study on utilization of different types of municipal solid waste incineration bottom ash for clinker sintering

In this study, two types of municipal solid waste incineration (MSWI) bottom ash (BA) (MSWI-BA-A, water quenched, MSWI-BA-B, natural cooling), are utilized as alternative materials for clinker sintering. Fixed clinker modulus (lime saturation ratio = 0.90 ± 0.01, silica modulus = 2.6 ± 0.1 and alumina modulus = 1.5 ± 0.1), designed gradient addition ratio of MSWIBA (0, 3%, 6%, 9% and 12%) and same sintering temperature (1723.15 K) are adopted to conduct the experiments. Raw materials are characterized by XRF, X-ray diffraction and differential thermal analysis. Clinkers are analyzed and evaluated by XRF, X-ray diffraction, petrographic analysis, compressive and flexural strength tests and toxicity characteristic leaching procedure. The major difference of the two types of MSWIBA is LOI value which is supposed to be the most probable reason for huge difference between liquid phase formation temperature variation and incremental introduction of MSWI. MSWI-BA-A increases liquid phase formation temperature. Liquid phase formation temperatures and MSWI-BA-B samples addition ratios nearly present negative linear correlation. All clinkers sintered with addition of MSWIBA slightly reduce water demand for normal consistency. MSWIBA addition poses relatively obvious influence on initial setting time and little effect on final setting time. There is an increase in initial strength and a decrease in 28-day strength of clinkers sintered with MSWIBA, 28-day compressive strength decreases with the incremental introduction of MSWIBA. Distinct characteristics, such as free lime, periclase, orthorhombic tricalcium aluminate (C3A) crystal and secondary Belite crystal, are observed by petrographic analysis. MSWIBA is significant source of free lime and periclase in clinkers. Incremental input of alkali introduced by MSWIBA influences clinker sintering and mineral crystallinzation, further results in orthorhombic C3A crystal and indistinct Alite edge caused by corrosion. Leaching concentration of heavy metals from mortars prepared with the sintering clinkers is lower than corresponding concentration of the Chinese National Standard GB 30760-2014.

Impact of sintering conditions and zirconia addition on flexural strength and ion conductivity of Na-β”-alumina ceramics

Na-β”-alumina ceramics are applied as electrolytes in high-temperature Na/NiCl2 and Na/S batteries. Although featuring excellent sodium-ion conductivity in the order of 0.2 S cm−1 at 300 °C, the brittleness associated with ceramic materials makes Na-β”-alumina electrolytes vulnerable to mechanical stresses, e.g. during battery operation. In this study, the impact of grain size and density on the flexural strength of Na-β”-alumina ceramics is investigated. For constant composition but largely varying grain sizes, we report a constant flexural strength of 163 ± 10 MPa for sintering temperatures between 1560 °C and 1620 °C and dwell times ≤ 30 min. Addition of 5 vol % zirconia improves the flexural strength by 30 %, but reduces the conductivity by 15 %. Furthermore, we show that the addition of zirconia reduces the onset temperature of the liquid phase formation during sintering. These findings show promise for using lower sintering temperatures in the presence of zirconia, which is beneficial on an industrial level.

Effect of Palygorskite on the Sintering Process and Kinetics of Bone China.

The sintering process of bone china bodies containing 0, 2, 4, and 6 wt % palygorskite was studied by X-ray diffraction (XRD), differential scanning calorimetry and thermogravimetry (DSC/TG), and dilatometric tests. According to the XRD and DSC/TG results, the increment of palygorskite increased the content of the amorphous phase and reduced the formation temperature of the early liquid phase in the bone china bodies. The shrinkage data showed that the starting sintering temperature and maximum shrinkage temperature of bone china bodies in the stage of liquid-phase sintering decreased by 20 and 15 °C via adding 6 wt % palygorskite, respectively. Also, the maximum shrinkage rose with increasing amount of palygorskite. Moreover, the kinetic analysis of shrinkage data was conducted by the Salem model. The value of the mechanism-characteristic exponent, m, rose from 0.62 to 0.91 by adding 6 wt % palygorskite. In addition, with increasing palygorskite, the value of activation energy, Ea, linearly reduced, and the value of rate constant A increased.

Bi aliovalent substitution in Li7La3Zr2O12 garnets: Structural and ionic conductivity effects

We report on the synthesis of cubic-phase garnet-type solid-state electrolytes based on Bi-doped Li7La3Zr2O12 (LLZO). Bi aliovalent substitution of Zr in LLZO utilizing the Pechini processing method is employed to synthesize Li7−xLa3Zr2−xBixO12 compounds. A strong dependence of the ionic conductivity on Bi content is observed, and under our synthesis and sintering conditions, a &amp;gt;100-fold increase over the un-doped sample is observed for x=0.75. Cubic-phase Li6La3Zr1BiO12 compounds are generated upon annealing in air in the temperature range 650 °C–900 °C. In contrast, in the absence of Bi, the cubic garnet phase of Li7La3Zr2O12 is not formed below 700 °C and a transformation to the tetragonal phase is observed at ∼900 °C for this un-doped compound. The role of Bi in lowering the formation temperature of the garnet cubic phase and in the ionic conductivity improvements is investigated in this work. We ascribe the effect of Bi-doping on ionic conductivity increments to changes in Li+-site occupancy and lattice parameters and the reduction in the formation temperature for the cubic-phase formation to rate enhancements of the solid-state reaction. To identify the site occupancy of Bi in the garnet structure, we employ synchrotron extended x-ray absorption fine structure spectroscopy. Our results indicate that Bi additions occupy the Zr-type sites exclusively, to within the accuracy of the measurements.

Influence of tin substitution on negative thermal expansion of K2Zr2-xSnxP2SiO12 (x = 0 - 2) phosphosilicates ceramics

In this research work, compounds of the chemical formula K2Zr2-xSnxP2SiO12 (x = 0, 0.5, 1, 1.5, 2) were synthesized by solution method and characterized by powder X-ray diffraction and spectroscopic techniques. Powder XRD analysis revealed that the phase formation temperature vary with the substitution of Sn4+ for Zr4+ at the octahedral site of langbeinite structure. The stretching and bending vibrational modes of PO43− and SiO44− tetrahedra were identified in the region of 407 cm−1 - 1094 cm−1. Thermogravimetric analysis proved that the compounds K2Zr2P2SiO12 and K2Sn2P2SiO12 were thermally stable up to 1000 °C and 650 °C, respectively. Interestingly, negative thermal expansion coefficient was observed for the solid solutions K2Zr2-xSnxP2SiO12 (X = 0, 0.5, 1, 1.5, 2). The average thermal expansion coefficients of K2Zr2P2SiO12, K2Zr1.5Sn0.5P2SiO12, K2ZrSnP2SiO12, K2Zr0.5Sn1.5P2SiO12 and K2Sn2P2SiO12 in the temperature range 30 °C–600 °C were found to be −7.01 × 10−6/°C, −4.96 × 10−6/°C, −1.08 × 10−5/°C, −1.53 × 10−5/°C and −1.27 × 10−5/°C, respectively. Coefficient of thermal expansion was increased by the substitution of tin for zirconium. The increase was obvious up to 250 °C and stabilized after 300 °C. The ionic radii, bond strength, structural distortion, density and microstructures were considered to explain the variation in thermal expansion.

Effect of MC carbide formation on weld solidification cracking susceptibility of austenitic stainless steel

The effect of secondary phase formation such as MC carbide during welding on solidification cracking susceptibility of fully austenitic stainless steels with various amounts of alloying elements and carbon was investigated. The solidification cracking susceptibility of Fe-24mass%Cr-26mass%Ni stainless steels with various amounts of niobium, titanium, zirconium, and carbon was evaluated by the Trans-Varestraint test.The addition of alloying elements such as niobium, titanium, and zirconium increased the brittle temperature range (BTR). The BTRs depend on the type and combination of the alloying elements and carbon content. Titanium was the most influential element on the increase in BTR compared to the other elements. The increase in carbon content tended to decrease the BTR, especially for the specimen containing titanium. The alloying elements formed phases such as the film-like MC-type carbide (MC) phase and granular Laves phase in the specimens containing 0.05% C, and a lot of the acicular MC phases in the specimens containing 0.20% C. The start temperature of the secondary phase formation differed depending on the type of the alloying element, and the temperature tended to increase with increasing carbon content. When the additions of niobium and titanium were compared, the amount of titanium segregation during solidification was smaller due to the formation of MC phases. Solidification simulation revealed that a higher amount and faster formation of the MC phase during solidification in 2Ti–20C contributed to reducing the BTR by increasing the carbon content. Thus, it is considered that the weld solidification cracking susceptibility depended on the type and amount of formation morphology, as well as start temperature during solidification corresponding to the composition of alloying elements and carbon.

Organodiphosphonate Metal‐Organic Frameworks Derived Ni‐P@C Catalyst for Hydrogenation of Furfural

Tetraethyl p-xylenediphosphate is used as the organic ligand to prepare the Ni−P-MOFs material belonging to the category of organic phosphoric acids, through pyrolysis and in-situ reduction reaction of Ni−P-MOFs material during the high-temperature carbonization process, Ni−P@C catalyst with graphitized carbon-covering Ni2P particles is prepared. Compared with Ni−P catalyst prepared through coprecipitation method, Ni−P@C catalyst prepared with Ni−P-MOFs material can obviously decrease the formation temperature of Ni2P active phase and retain the schistose morphology of the Ni−P-MOFs material, which is of high specific area, and meanwhile effectively suppresses the agglomeration of Ni2P particles. It is indicated by research on furfural hydrogenation performance that, Ni−P@C catalyst presents a high activity and stability in furfural hydrogenation. Products of furfural hydrogenation catalyzed by Ni−P@C catalyst mainly contain furfuryl alcohol, 2-methylfuran and 2-methyltetra hydrofuran, and the reaction temperature and reaction time have great influence on the distribution of products. The carbon-covering structure of Ni−P@C catalyst can effectively protect the active components of Ni2P, thus presenting a high stability and good reusability.

Tunable emission and optical trapping of upconverting LiYF4:Yb,Er nanocrystal

Present work investigates about hydrothermally prepared LiYF4:Yb,Er nanocrystals with novel tunable emission and optical trapping results. Optical trapping effect of LiYF4:Yb,Er upconversion nanocrystal under 980 nm diode laser interaction is reported and a single nanoparticle trapping is demonstrated. Optical trapping force of 10.8 fN is exerted on LiYF4:Yb,Er upconversion nanocrystal of size ~238 nm at laser power 50 mW and the result is in agreement with the reported values. At 980 nm excitation, tunable green to red upconversion emission is achieved by calcination. It depends on orthorhombic and tetragonal phases that confirmed by XRD. The nanocrystals calcined at 450 and 600 °C resulted in a decay time of 26 and 19 µs respectively and the upconversion emission mechanism is explained. FESEM and HRTEM examinations showed the hydrothermally synthesized nanocrystals are in trapezohedral, pyramidal, bi-pyramidal and tetragonal morphologies. The differential scanning calorimetry revealed the tetragonal phase formation temperature is lower at 450 °C compared to the reported value of 750 °C. The UV–VIS-NIR spectra of LiYF4:Yb,Er showed high absorption at 380, 480, 520 and 660 nm due to Er3+ ion and the broad absorption from 900 to 1000 nm centered at 980 nm is owing to Yb3+ ion. The crystalline phase, morphology, upconversion emission and optical trapping behaviors of LiYF4:Yb,Er nanocrystal are explained elaborately.

Structural and morphological characterization of iron-doped sol-gel derived mullite powders

The structural and morphological properties of iron-doped mullite powders are the subject of the present study. The powders of undoped and iron-doped mullite in the composition range of 3–15 wt% Fe2O3 were synthesized by a combination of sol-gel and combustion methods. The excess of water and urea were introduced in reaction solutions to enhance the copolymerization of aluminum and silicon species. The results of structural characterization revealed that the synthesized mullite powders were amorphous of a hybrid type. The specific surface area of the undoped mullite powder was 262 m2 g-1 with a maximum pore radius (dp) of 2 nm classifying it into mesoporous materials. The addition of iron has reduced the specific surface area, while the pore size value remained the same except for the sample with 3 wt% Fe2O3 (SBET = 278 m2 g-1; dp = 3 nm). The presence of iron caused lowering the temperature of liquid phase formation, while present urea combusted providing the increase of the temperature locally that caused the sintering and formation of agglomerates of smaller particles. However, the results of the particle size analysis are not straightforward. The values of mean volume diameter (D[3,4]) indicated that the particle size increased to 6 wt% Fe2O3 (123.6 μm), and then decreased and for the sample with 12 wt% Fe2O3, it was equal to 96.6 μm. Thus, the added iron contributed to the more uniform particle size distribution. The SEM analysis has also shown the coarse powder particles consisted of the coalesced smaller particles.

Physical, Structural and Dielectric Parameters Evaluation of New Mg1-x Cox NiyFe2-yO4 nano-ferrites Synthesized via Wet Chemical Approach

Department of Chemistry, Institute of Natural Sciences, University of Gujrat, Gujrat 50700, Pakistan The surfactant assisted co-precipitation method has been used to synthesize the Co2+ and Ni2+ substituted magnesium nanoferrites. The Co2+ and Ni2+ ions substitute the Mg2+ and Fe3+ ions from the magnesium ferrites, respectively. To study the effect of substituted ion concentrations on the dielectric performance of the MgFe2O4 spinel ferrites. The substituted magnesium nanoferrites with the compositions Mg1-x Cox NiyFe2-yO4 (x, y = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) were synthesized to notice the effect of substituted ions concentration on the dielectric properties. Thermogravimetric analysis of the precursor precipitates was taken to investigate the stable spinel phase formation temperature. The X-ray diffraction analysis of the all substituted samples confirms the successful formation of the stable spinel phase and also exposes the effects of substituted ions on the crystal structure and unit cell constants. The presence of a characteristic absorption band (400 cm−1, 550 cm−1) of spinel ferrites in the Fourier Transform Infra Red (FT-IR) spectrum of substituted magnesium nanoferrites also confirms the formation of desire phase. The effect of temperature on the conductivity of the all substituted samples was observed within the temperature range of 25°C–300°C by two-probe direct current electrical resistivity measurements. Dielectric measurements of the substituted magnesium nanoferrites were carried out to study their magnetic behavior. The inverse relation of the dielectric parameters of the all substituted magnesium nanoferrites with frequency shows their excellent potential for devices that operate at higher frequencies.Department of Chemistry, University of Okara, Renala Khurd, Okara, Pakistan Department of Chemistry, Allama Iqbal Open University, H-8, Islamabad 45320, Pakistan.