N Bands Research Articles

Measurements and calculations of Xe-broadening and shift parameters of water vapour transitions in a wide spectral region

The water vapour line broadening (γ) and shifting (δ) coefficients for 687 lines of 14 vibrational bands ν1, ν3, 2ν2, ν1 + ν2, ν2 + ν3, 3ν2, 2ν2 + ν3, ν1 + 2ν2, ν1 + ν3, 2ν1, 2ν3, 4ν2, 6ν2, and 3ν2 + ν3 induced by xenon pressure were measured with Bruker IFS 125 FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm−1 and in a wide pressure range of Xe. The broadening and shift coefficients were calculated using a semi-classical method. The intermolecular potential was taken as the sum of the anisotropic atom–atom potential and vibrationally and rotationally dependent isotropic Lennard-Jones potential. The optimal sets of potential parameters that gave the best agreements with measured coefficients γ and δ for each vibrational band were found. The measured coefficients γ were combined with the data found earlier for the ν1 + ν2 + ν3 bands as well as with those reported in literature for the ν2, ν1, ν3, 2ν1 + 2ν3, 2ν1 + 2ν2 + ν3 and 3ν1 + ν3 bands and N = 820 coefficients γ of19 vibrational bands of H2O perturbed by Xe were fitted to the empirical functions. The computed coefficients γ and δ derived from the semi-classical method as well as from the fitted parameters were compared statistically to measurements.

Structural and magnetic properties of cobalt ferrite nanoparticles doped with cadmium

The magnetization of CoFe2O4 nanoparticles is often less than the bulk value of 3.6 μB (86 emu/g), corresponding to an inverse distribution of cations in the spinel structure. This paper investigated the Cd doping on cobalt ferrite nanoparticles' structural and magnetic properties. Cobalt ferrite nanoparticles doped with cadmium (Co1-xCdxFe2O4, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by using hydrothermal method. X-ray diffraction (XRD) analysis confirmed cubic spinel structure, and the crystallite size is estimated at around 56–59 nm. Micrographs obtained by scanning electron microscopy (SEM) showed an average particle size of about 60 nm, which is in agreement with the XRD analysis. The absorption band ν1 for samples obtained from the infrared spectrum (FTIR) varies from 586 up to 570 Cm-1 by Cd doping, indicating Cd's replacement on the tetrahedral site. Magnetization values of 71 and 81 emu/g are obtained for x = 0 and x = 0.1 samples, respectively. But the magnetization decreased as the amount of Cd doping further increased due to the decreasing superexchange interaction between tetrahedral and octahedral sites. The rearrangement of Fe3+ and Co2+ cations on tetrahedral and octahedral sites and spin disorder at the surface of nanoparticles can reduce the magnetization below the bulk value. The coercivity field (Hc) value of 1.1 kOe is obtained for the x = 0, and the Hc values decrease with Cd doping. This is due to the decreasing magnetocrystalline anisotropy by substituting cobalt with cadmium.

Matrix-isolation infrared study of acetaldehyde: Host-dependent vibrational features

The infrared spectra of acetaldehyde were measured in inert gas matrices (Ar, Kr, and N2). The vibrational features were dependent on the host atoms. In particular, in the CO stretching region, the fundamental band (ν4) is bifurcated for Ar, whereas it remains isolated for Kr and N2. The bifurcation could be interpreted as a Fermi-diad where host–guest interactions in the Ar matrix cause the accidental energy tuning of ν4 and 2ν9 levels, which is in contrast with the energy detuning observed for the formic acid dimers reported previously [J. Chem. Phys. 128 (2008) 114310.].

High resolution spectroscopy of strongly interacting bands ν-=SUB=-4-=/SUB=-, ν-=SUB=-6-=/SUB=-, ν-=SUB=-7-=/SUB=-, ν-=SUB=-8-=/SUB=-, and ν-=SUB=-10-=/SUB=- of deuterated ethylene, C-=SUB=-2-=/SUB=-H-=SUB=-3-=/SUB=-D

Rotational structure of strongly interacting bands ν4, ν6, ν7, ν8, and ν10 of the C2H3D molecule is spectroscopically studied. Spectra were recorded by Fourier spectrometer Brucker 125HR in the laboratory of physical and theoretical chemistry of Technical University of Braunschweig. 27950 transitions with maximum values of Jmax = 40 and Kmaxa= 20 were assigned to the studied bands. The effective Hamiltonian parameters were determined in the model including the ν3 resonating state. The 4028 upper energy levels were used as incoming data. They are reproduced with root mean square deviation of drms =1.7· 10-4 cm-1. Corresponding value for more than 24000 line positions is drms = 2.1 · 10-4 cm-1. Keywords: ethylene, high resolution spectroscopy, strongly interacting bands, Fourier-spectroscopy.

Complete Micro‐Structural Analysis and Elastic Properties of Sm3+‐Doped Ni‐Mn‐Zn Mixed Spinel Ferrite Nanoparticles

AbstractA series of Ni‐Mn‐Zn mixed spinel ferrite doped with Sm3+ ions is prepared by using sol‐gel auto‐combustion technique. Single phase cubic spinel structure of all the samples is confirmed by using XRD analysis. Incorporation of Sm3+ ions in Ni‐Mn‐Zn ferrites increases the lattice parameter from 8.4105 to 8.4134 Å. Williamson – Hall (W‐H) and strain size plot (SSP) analysis confirms the tensile‐type strain induced in the crystal lattice, which increases with the addition of Sm3+ ions. Average crystallite size estimated from Scherrer equation is found in the range 21.7–24.9 nm, which in good agreement with the results obtained from W‐H and SSP analysis. Infrared spectra recorded in the range 350–800 cm−1 reveals the characteristic features of spinel ferrites. Higher frequency band ν1 is observed near 580 cm−1 and lower frequency band ν2 is observed near 380 cm−1. By using the IR data, elastic constant (stiffness constant) and elastic moduli (Young's modulus, bulk modulus, and rigidity modulus) are estimated. Debye temperature obtained from Anderson formula ranging from 535 to 562 K and from Waldron equation ranging from 676 to 713 K with the substitution of Sm3+ ions.

Determination of temperature-dependent Fermi resonance in acetonitrile-water binary solution by two-dimensional correlation Raman spectroscopy.

Acetonitrile (AN), as an organic solvent, has a wide range of applications. The C≡N stretching vibration mode (ν2) and the combination mode (ν3 + ν4) are coupled by Fermi resonance (FR). In this work, the phase transition and the interaction mechanism of the 60% AN-water binary solution (AN-Water) were analyzed by calculating FR parameters and two-dimensional correlation Raman spectroscopy (2DCRS). The change in the ν2 band and the base bands ν3 and ν4 caused energy transfer by anharmonic interaction, which led to a change in FR parameters. With a reduced temperature, the energy transfer was caused by microheterogeneity and the energy transfer effect (293-273K), the phase separation (263-233K), and the phase transition of AN (223-173K). The 2DCRS and Gaussian deconvolution provided more information on FR, which revealed the interaction mechanism of the Fermi doublet. The polarity and binding modes of molecules provided a new perspective for analyzing the transmission of electrons and ions in the electrolyte at different temperatures.

Study of structure, magnetic and electrical properties of CoFe2-xCrxO4 nanocomposites synthesized using sol-gel method

The effect chromium doping in cobalt ferrites, in the nano scale, has been studied. Structure, morphology, electrical and magnetic transport of CoFe2-xCrxO4 (x = 0, 0.5, 1, 1.5) has been investigated in detail. Sol-gel method has been used to get nano crystalline size of the prepared spinel structure. The formed gel has been fired at 600 °C temperature. Single cubic crystal phase is formed according to analysis of X-ray diffraction patterns and infra-red spectra. The decrease in both the lattice constant and the crystalline size has been observed as a result of Cr doping. Moreover, the electron density inside the unit cell has decreased as a result of Cr doping. All samples have been homogenously formed in the nano-crystallized size in the range from 7 to 16 nm. There has been a phase transformation (exothermic peak) at point 342 °C for x = 0.0 and 362 °C for samples containing extra Cr ions for the DSC curve. The two essential absorption bands ν1 and ν2 have been observed in the range 560–610 (for all prepared samples) and 420 cm−1 (for all doped samples with Cr ions), respectively for infra red analysis. The electrical properties have showed semiconductor behavior. The magnetic properties of these compounds have been studied. They have demonstrated ferrimagnetic ordering type. From the magnetic hysteresis loop, it has been noted that the coercivity HCi has decreased as a result of the substitution of iron with chrome. CoFe2O4 has been higher coercivity of 1595.4G and the coercivity has decreased to be 114.6G for CoFe0.5Cr1.5O4.

High resolution FTIR study of the ν5, ν6, and ν9 fundamental bands of CH2D37Cl

The first high-resolution infrared spectra of CH2D37Cl have been investigated in the region 650–1100 cm−1 where the lowest fundamental bands ν5 (826.2626 cm−1), ν6 (708.4307 cm−1), and ν9 (986.3405 cm−1) occur. These vibrations perturb each other by different weak interactions and the v5 = 1 and v6 = 1 states were treated according to a model which accounts for a c-type Coriolis resonance. The spectral analysis resulted in the identification of 1664, 2550 and 2657 ro-vibrational transitions for ν5, ν6, and ν9 bands respectively, and to the determination of accurate spectroscopic parameters by using the Watson’s A-reduction Hamiltonian in the Ir representation. The simulations of the ro-vibrational structure of the ν5, ν6, and ν9 bands performed in different spectral regions adequately reproduce the experimental data.

Structural and magnetic properties of Sb3+ ions doped Ni–Ba–Co ferrite prepared by sol–gel method

In the present work, nanocrystalline Sb3+ ions doped Ni0.2Ba0.1Co0.7Fe2−xSbxO4 (0 ≤ x ≤ 0.1, step by 0.025) ferrites were prepared via sol–gel method. The spinel-phase structure of samples can be confirmed by X-ray diffraction (XRD) patterns. The composition and structure were further studied by Fourier transform infrared spectroscopy (FTIR). There were two typical characteristic bands ν1 and ν2 in FTIR spectra, which related to the stretching vibrations in spinel ferrite. Energy-dispersive spectrometer (EDS) analyzed the elements of samples. It indicated that the elements of Ni, Ba, Co, Fe, O, and Sb existed in the samples. Vibrating sample magnetometer was used to characterize magnetic properties. The saturation magnetization decreased from 57.65 to 44.50 emu/g with the increasing Sb3+ ions content, which is attributed to Fe3+ ions replaced by the Sb3+ ions. Remanent magnetization and coercivity first decreased and then increased slightly.

Synthesis and characterization of Al3+ substituted Ni–Cu–Zn nano ferrites

Ferro spinels with composition Ni0.2Cu0.2Zn0.6Fe2−xAlxO4 (x = 0.0 to 1.0 in steps of 0.2) were synthesized by co-precipitation method, in oxygen atmosphere, from corresponding analytical grade metal sulfates. Thermogravimetric (TG) analysis shows total mass loss around 30% up to 873 K temperature. X-ray diffraction studies confirm all composition with single-phase spinel, cubic structure with crystallite size 11–21 nm range. With increasing trivalent Al3+ content, lattice parameter ‘a’ decreases. Infrared spectra shown two major absorption bands, the lower frequency band ν2 observed in the range 433–463 cm−1, is assigned to octahedral site and higher frequency band ν1 observed in the range 565–593 cm−1, assigned tetrahedral site. The microstructures of the calcinated samples investigated by scanning electron microscopy and transmission electron microscopy indicate ferrite samples are porous in nature. The magnetic properties such as saturation magnetization and magneton number decrease with increasing Al3+ concentration.

Structural and optical properties of chromium-doped hematite (α-Fe2O3) nanoparticles

Cr-doped hematite nanoferrites series were synthesized by calcination of Cr-doped magnetites at 1100 °C for 4 h. This study revealed that the samples have decomposed into hexagonal hematite materials (α-Fe2O3 and α-Cr2O3) by calcining effect. The crystallite size R, density Dx, the energy band gab Eg showed decrease with increase of Cr3+ ion concentration x, whereas the lattice constants (a and c), unit cell volume, specific surface area S, the strain Ԑ, Debye temperature ӨD and jump rate showed increase. Two absorption characteristic bands ν1 and ν2 of hematite nanoferrites were observed in IR spectra. Two absorption bands are recorded in the UV–vis absorption spectra of calcined CrxFe(3-x)O4 nanoparticles 287 nm and 372 nm. The observed XPS spectra of the samples have revealed structural transformation of the magnetite to hexagonal hematite (α-Fe2O3 and α-Cr2O3) suggesting a hopping process between Fe3+ and Cr3+ ions among the B-sites.

Thermal, microstructural and magnetic properties of manganese substitution cobalt ferrite prepared via co-precipitation method

Manganese-substituted cobalt nano-ferrites, Co(1−x)Mn(x)Fe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized using chemical co-precipitation method. Physical properties of Co(1−x)Mn(x)Fe2O4 nano-ferrites were then characterized using thermal gravimetric—differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrometer, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). TGA/DTA study indicates that the thermal stability of the prepared manganese doped cobalt ferrite nanoparticles. X-ray diffraction patterns of all the prepared ferrite samples show good in quality, pure nanosized, single-phased cubical spinel structures, with ferromagnetic behavior. We demonstrated that the expansion of lattice constant (a) and crystallite size (D) induced by manganese substituted of cobalt ferrites exerted remarkable effects on its structural and magnetic properties. The lattice constant (a) and crystallite size (D) increase with increasing manganese substituted cobalt ferrites. Williamson–Hall (W–H) method was used to evaluate the crystallite size and lattice strain of the Co(1−x) Mn(x)Fe2O4 nanoparticles samples by peak broadening. The calculated crystal size of Co(1−x) Mn(x)Fe2O4 nanoparticles on the W–H plots were highly intercorrelated with the HR-TEM and results of Scherrer Deby equation. The other physical parameters, such as X-ray density, hopping length, ionic radius, bond length, tetrahedral edge, octahedral edge, and unshared octahedral edge values were estimated from the highest intensity peak (311) of X-ray diffraction. The Fourier transform infrared (FT-IR) spectrometer of the Co–Mn ferrite nanoparticles systems were recorded in the frequency range of 200–1000 cm−1. FT-IR spectra show the two fundamental absorption bands of interstitial sub-lattice sites (M–O). The high absorption band (ν1) and the low absorption band (ν2) corresponds to the tetrahedral [A] and octahedral (B) sites, respectively, confirming the formation of single cubic spinel ferrite lattice system. The TEM results show that the ferrite nanoparticles have a nearly spherical shape with some agglomerations. From the analysis of VSM, the values of saturation magnetization (Ms) increases from 31.46 to 37.16 emu/g, then decreases with increasing Mn2+ ions substitution in the Co-ferrite system. The coercivity of the Mn2+ ions substituted cobalt ferrites increases up to x = 0.6 followed by a decrease. The optimized magnetic parameters suggest that the material with composition Co0.6Mn0.4Fe2O4 may be suitable for longitudinal magnetic recording media and other various technological applications.

Evolution of structure and improvement in dielectric properties of praseodymium substituted YFeO3 nanomaterials synthesized via a sol-gel auto-combustion method

In this work, Y1−xPrxFeO3(0≤x≤0.16) ceramics were fabricated via the auto-combustion sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM) associated with EDS mapping, and Fourier transform infrared spectroscopy (FTIR) were employed for structural and morphology analysis. The substitution of praseodymium (Pr) modified the orthorhombic structure into a hexagonal structure. However, small traces of Fe2O3 and Y2O3 appeared in all samples. The lattice constant ‘a' was increased from 3.523 to 5.530 Å upon substitution up-to x = 0.12, afterward this started to decrease from 5.530 to 5.529 Å. Pure orthorhombic YFeO3 (o-YFeO3) has cell volume 223.61 (Å3), while the cell volume of Pr substituted hexagonal YFeO3 (h-YFeO3) showed a decreasing trend (125.61–125.43 Å). Bulk density was thoroughly decreased from 5.009 to 4.634 (g/cm3) by increasing the Pr concentration. Frequency dependence of the dielectric behavior was investigated at room temperature in a comprehensive frequency range of 1 MHz ~ 3 GHz. SEM results exhibited the average grain size 149.28 nm, 66.78 nm, and 69.36 nm for the samples 0.00, 0.08, and 0.16, respectively. The identification of o-YFeO3 was confirmed by two main absorption bands ν1 (449.86 cm-1) and ν2 (567.12 cm-1) and these bands indicate a clear shift upon the addition of Pr. The force constant of absorption bands at tetrahedral and octahedral sites showed increasing trend and this ranges from 1.633dyn/cm2x105 to 1.912dyn/cm2x105 and 2.818dyn/cm2x105 to 8.832dyn/cm2x105, respectively. The substitution of Pr significantly enhanced the dielectric constant. The shifting of peaks at higher frequencies demonstrates that an increase of dopant concentration resulted in the shifting of peaks that may follow the Maxwell-Wagner-Sillars polarization mechanism. Pr substituted YFeO3 exhibited microwave frequency response in a range of 1.6 GHz–2.9 GHz which might be suitable for high-frequency applications.

Universal Function for the Calculation of Broadening of Absorption Lines of the H2S Molecule by Monoatomic Gases

A universal analytical model is proposed for calculating coefficients γ of broadening of absorption lines of the H2S molecule by inert gas atoms A (helium, neon, argon, krypton, and xenon). In this model, only one parameter depends on the broadening atom A; other parameters are common for all atoms. This parameter determines the ratio γ(A)/γ(A′) for the A and A′ atoms. The model parameters are determined from values of γ calculated for the fundamental bands ν1, ν2, and ν3 of the H2S molecule, as well as from known experimental values of γ. Values of γ calculated using the model are compared with available experimental data. For some lines from the ν1 and ν3 bands, there is a significant discrepancy between the experiment and calculation.

Spectral, electrical, magnetic and radiation shielding studies of Mg-doped Ni–Cu–Zn nanoferrites

Nanoferrites of Ni0.1Cu0.2MgxZn(0.7−x)Fe2O4 (x = 0.0, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70 wt%) system fabricated using flash auto combustion technique. All investigated samples annealed for 2 h at 600 °C. XRD, FTIR and TEM were utilized to evaluate the structural characterization of as-prepared samples. The electrical DC resistivity of the investigated samples is evaluated as a function of frequency and temperature. The initial magnetic permeability (μi) is dependent on the temperature and was measured at constant frequency 1 kHz and 10 kHz of the sinusoidal wave. A single-phase of spinel structure was formed and with increasing Mg content the peak (311) of 100% intensity decreases, which demonstrates the presence of Mg, which slows down the growth of the crystal as X-ray result. The FTIR spectra of the prepared ferrite samples are distinguished by the presence of two strong absorption bands (ν1 = 554 cm−1) and (ν2 = 449 cm−1). The morphological observation is determined by the transmission electron microscopy (TEM) and shows that the particles size ranged between 26 and 39 nm. It can notice shifted Curie temperature (Tc) to a higher temperature by increasing Mg content. Mass attenuation coefficient (μm), mean free path (λ), half value layer (X1/2), tenth value layer (X1/10) and effective atomic numbers (Zeff) for the studied samples, have been simulated using FLUKA (2020.0beta.2), while energy change from 15 × 10–3 to 153+ keV with increasing Mg concentration, both μm and Zeff decrease. The largest value of μm and Zeff when x = 0% while sample x = 0.35% has a minimum value of λ, X1/10 and X1/2.

Effect of chromium ions on the structural, magnetic, and optical properties of manganese–zinc ferrite nanoparticles

The present work describes the synthesis of Mn0.5Zn0.5CrxFe2−xO4 (x = 0.1, 0.2, 0.3) ferrite nanoparticles by solution combustion method and their detailed structural, electrical, magnetic, and optical characterizations. X-ray pattern represents the creation of a single spinel structure. In addition to this, the distribution of cations is also approximated from X-ray study which is then authenticated by the magnetization technique also. The crystalline size (23–21 nm) and lattice parameter (8.39–8.30 A) are found to shrink with the rise in chromium ions. A decrease in saturation magnetization (0.80–0.64 emu/g) and remanent magnetization (0.05–0.03 emu/g) is found with the rise in chromium ions, while the coercivity is found to increase (83–123 Oe) through the adding of chromium ions. FTIR predicted the two absorption bands (ν1 and ν2) near 600 and 400 cm−1. Dielectric constant and loss tangent were observed to decrease with an increase in frequency, whereas AC conductivity attains a nearly constant value at a lower frequency and observed to increase at higher frequencies with the addition of dopant.

Preparation and study of lattice structure and magnetic properties of Bi3+ ion-doped Ni–Mg–Co ferrites by sol–gel auto-combustion method

In this paper, Bi3+ ion-doped Ni–Mg–Co ferrite nanomagnetic materials were prepared by sol–gel auto-combustion method using high-purity nitrates and citric acid experimental materials. The effect of Bi3+ ion content on the lattice structure and magnetic properties of nanoferrite was also studied. XRD diffractogram analysis shows that the Ni–Mg–Co ferrite samples with x = 0 and 0.025 have single-phase cubic spinel structure. It is found that when the doping amount is 0.05 or >0.05, the secondary-phase Bi2O3 peak appears. The average crystallite size of the sample was calculated by Debye–Scheller formula. It was found that the average grain size of the sample was affected by the doping concentration. With the increase in Bi3+ ion content, the average crystallite size increases from 8.3797 nm to 8.3940 nm. The structure of Bi3+ ion-doped Ni–Mg–Co ferrite was further characterized by FT-IR. There are two absorption bands ν1 and ν2 at 584 and 397 cm−1, which further prove the spinel structure. The morphology of the sample particles was observed by SEM, and the distribution of the particle size was calculated. The chemical components of powder samples were analyzed by EDS. Through VSM analysis, the Bi3+ ion-doped Ni–Mg–Co ferrite has the characteristics of ferromagnetism. With the increase in Bi3+ ion content, the residual and saturation magnetization decreased; the magnetic stability is also reduced. The results show that the magnetic properties of Bi3+ion-doped Ni–Mg–Co ferrite are decreased.

Measurements and calculations of Kr-broadening and shift parameters of water vapour transitions in a wide spectral region

The water vapour line broadening (γ) and shifting (δ) coefficients for 497 lines of 16 vibrational bands ν1, ν3, 2ν2, ν1 + ν2, ν2 + ν3, 3ν2, 2ν2 + ν3, ν1 + 2ν2, ν1 + ν3, 2ν1, 2ν3, 6ν2, 2ν1 + ν2,ν2 + 2ν3, ν1 + 3ν2, and 3ν2 + ν3 induced by krypton pressure were measured with Bruker IFS 125 HR Fourier transform spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm−1 and in a wide pressure range of Kr (0.303–0.980 atm). The calculations of the broadening and shift coefficients γ and δ were performed in the framework of the semi-classical method. The intermolecular potential was taken as the sum of the anisotropic atom–atom potential and the vibrationally and rotationally dependent isotropic Lennard-Jones potential. The measured coefficients γ and δ were combined with literature data for the ν2 and rotational bands, and optimal sets of potential parameters that gave the best agreements with the measured broadening coefficients for each vibrational band separately were found. Experimental data for ten vibrational bands of H2O perturbed by Kr were used to determine the analytical dependence of some of the potential parameters on the vibrational quantum numbers. Combined experimental data for the coefficients γ of 19 vibrational bands of H2O perturbed by Kr were fitted to the empirical function. The computed coefficients γ and δ derived from the semi-classical method and the fitted parameters were compared statistically to the measurements. The vibrational dependence of the potential as well as of the coefficients γ and δ is discussed.

High-resolution analysis of the ν3 band of radiocarbon methane 14CH4

We present the first high-resolution measurements and rotational analysis of the fundamental asymmetric stretching vibrational band ν3(F2) of radiocarbon methane. A spectrometer consisting of a mid-infrared continuous-wave optical parametric oscillator and a cantilever-enhanced photoacoustic detector was employed to determine the wavenumbers of 43 rovibrational lines. A spectroscopic model could reproduce all the observed transition wavenumbers within the accuracy of the experiment. Our work contributes to the development of radiocarbon methane detectors based on laser spectroscopy.

Effect of Al3+ ion-substituted Ni–Mg–Co ferrite prepared by sol–gel auto-combustion on lattice structure and magnetic properties

In this paper, Al3+ ion substituted Ni–Mg–Co ferrite nano-magnetic material by sol–gel auto-combustion method. Citric acid is used as a complexing agent, and high-purity nitrate and deionized water are used as raw materials. And the effect of Al3+ ion substitution on the structure and magnetic properties of Ni–Mg–Co ferrite nanoparticles was studied. XRD analysis showed that all the samples have the characteristic peak of spinel ferrite. No impurity peaks were found, indicating that the ferrite has a single-phase structure. The average crystallite size was calculated by Debye–Scheller formula. With the increase of Al3+ ion substitution, the average crystallite size decreased from 58.3378 to 51.5249 nm. The structure of Ni–Mg–Co ferrite was characterized by FT-IR. There are two absorption bands ν1 and ν2 at 588 cm−1 and 389 cm−1, respectively, which further prove the spinel structure. The morphology of the samples was observed by SEM, and the particle size of the nanoparticles was calculated. The chemical composition of the sample was analyzed by EDS. The elements Ni, Mg, Co, Fe, Al, and O were found in the samples. By VSM analysis, it is found that Al3+ ion-substituted Ni–Mg–Co ferrite has ferromagnetic characteristics. With the increase of Al3+ ions substitution, the remanent magnetization (Mr), saturation magnetization (Ms), coercive force (Hc), anisotropy constant (K), magnetic moment (μB), and Yafet–Kittel angle (αYK) all decreased.