Dilute magnetic semiconductor (DMS) nanoparticles of Co doped Zn0.95Cr0.05O were synthesized by sol-gel auto-combustion technique. Crystallographic analysis was made by using X-ray diffraction (XRD) technique. Rietveld refined X-ray diffraction patterns confirm the single phase wurtzite type crystal structure with space group p63mc. Replacement of larger Zn 2+ ions by smaller Co 2+ reduces the lattice parameters 'a' and 'c'. Average crystallite estimated from Scherrer equation is found increasing from 17.6 to 22.0 nm with the addition of Co 2+ ions.Scanning electron micrographs (SEM) were used to understand the surface morphology of the samples. Average grain size obtained from SEM analysis is observed in the range 22.1 to 26.5 nm. Enriched ferromagnetism is observed for Co 2+ doped samples and the saturation magnetization increases from 0.0514 to 0.1026 emu/gm. At lower frequency region both dielectric constant () and dielectric loss tangent (tan ) have higher values and decreases with increasing frequency and becomes almost constant at higher frequency region. Energy band gap (Eg) is decreases from 3.26 to 2.69 eV with the addition of Co 2+ ions in Zn-Cr oxides. Enriched ferromagnetism and higher dielectric constant at low frequency make these materials suitable for spintronic devices.
Ferrite nanoparticles of Ni[Formula: see text]Mn[Formula: see text]Zn[Formula: see text]Fe[Formula: see text]CexO4 ferrite system were produced using sol–gel auto combustion technique. X-ray diffraction analysis confirms the single phase cubic spinel structure of the samples with space group Fd-3m. Replacement of Fe[Formula: see text] ions by Ce[Formula: see text] ions increases the lattice parameter 8.4105 Å to 8.4193. Average crystallite size obtained from Scherrer method varies from 21.73[Formula: see text]nm to 22.71[Formula: see text]nm with replacement of Fe[Formula: see text] ions by Ce[Formula: see text] ions. Williamson–Hall and strain-size plot analysis confirms the nanocrystalline nature of the samples and the micro-strain induced in the cubic crystals is of tensile type. Cation distribution suggests that Zn[Formula: see text] ions occupy tetrahedral — A-site while Ni[Formula: see text] ions occupy octahedral — B-site. Majority of the Mn[Formula: see text] ions prefer A-site and majority of the Ce[Formula: see text] ions replace Fe[Formula: see text] ions at octahedral — B-site. High resolution transmission images confirm the homogeneity and nanoparticle nature of the samples. Two main characteristics absorption bands corresponding to spine structure are observed in the Fourier transmission infra-red spectra within the wavenumber range of 350–600[Formula: see text]cm[Formula: see text]. Stiffness constant, Young’s modulus, rigidity modulus, bulk modulus and Debye temperature were estimated using FTIR data. Debye temperature obtained from the Waldron equation varies from 676[Formula: see text]K to 692[Formula: see text]K with the addition of Ce[Formula: see text] ions. Higher values of elastic moduli are suitable for industrial applications due to increased mechanical strength.
A 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.
Yttrium (Y3+) substituted Co-Zn spinel ferrite nanoparticles with compositional formula Co0.9Zn0.2YxFe1.9-xO4 (x = 0.0, 0.015, 0.030, 0.045, 0.06) were synthesized by using sol-gel auto-ignition route. The structural and mechanical properties of Co-Zn ferrites were tailored by the replacement of Fe3+ ions by Y3+ ions. Rietveld refined X-ray diffraction patterns of all the samples confirm the cubic spinel structure. Lattice parameter increases with the substitution of Y3+ ions which may be due to the difference in ionic radii. The crystallite size obtained from XRD analysis is found in the nanometer range of 16.8 – 24.7 nm. Distribution of cations over tetrahedral – A and octahedral – B sites have been studied by using X-ray diffraction data and it is found that Y3+ ions prefers the octahedral – B site. Infrared spectra of all the samples were recorded in the wave number range of 300 cm−1 to 800 cm−1 which shows splitting of the two fundamental absorption bands. Two absorption bands (ν1 and ν2) observed in the range 380 – 610 cm−1 are belongs to tetrahedral – A and octahedral – B interstitial sites. The force constants (KO and Kt) and corresponding elastic parameters were determined by using IR data. The stiffness constant (C11), Young’s modulus (E), rigidity modulus (G), bulk modulus (B) and Debye temperature (θD) were found increases with the addition of Y3+ ions.
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