Magnetic interactions in Cu-substituted manganese ferrites

Maqsood

2011

Nanoferrites of composition Mn 0.50 Cu 0.5−x Ni x Fe 2 O 4 (0.00 ≤ x ≤ 0.50) are prepared by chemical coprecipitation method. The prepared nano-ferrites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), two probe resistivity apparatus, and vibrating sample magnetometer (VSM) to study the compositional, structural, morphological, electrical, and magnetic properties with varying concentration (x) in the composition of the prepared nanoferrites. XRD confirmed formation of single phase spinel ferrite with crystalline size in the range of 16-29 nm. The lattice parameter (a) decreases with a decrease of Cu concentration. Further information about the structure and morphology of the nanoferrites was obtained from SEM and results are in good agreement with XRD. FTIR gives information about distribution of cations and anions by confirming the presence of high and low frequency bands due to tetrahedral and octahedral sites, respectively. The electric properties were measured and analyzed by using homemade two probe resistivity apparatus showing semiconducting behavior of synthesized ferrites. The magnetic hysteresis curves clearly indicate the soft nature of the prepared samples. Various magnetic parameters such as saturation magnetization (M s ), and remanence (M r ) are calculated from the hysteresis loops and observed compositional dependent. Saturation magnetization and magnetic moment increase with Ni content. This is due to the existence of localized canted spin. Coercivity and A. Faraz ( ) · A. Maqsood

Section: Electrical Propertiessupporting

confidence: 93%

“…An increase in the Y-K angle is characterized by a decrease in A-B interaction and this leads to lower the T c in ferrites. The values of T c are tabulated in Table 1 which are in agreement with the observation in [24,32].…”

Section: Electrical Propertiessupporting

confidence: 84%

Synthesis, Structural, Electrical, Magnetic Curie Temperature and Y–K Angle Studies of Mn–Cu–Ni Mixed Spinel Nanoferrites

Maqsood

2011

“…It is observed that with increase in dopant concentration (x) Curie temperature (T c ) decreases, which may be attributed due to decrease/weak A-B interaction due dopant incorporation. The weak A-B interaction is confirmed by increase in Y-K angle values [27][28][29].…”

Section: Electrical Studiesmentioning

confidence: 79%

Effect of Mn2+ and Cd2+ on the Physical Properties of Li-Mixed Spinel Nanoferrites

Maqsood

2011

The mixed Li-ferrites with dopants Mn 2+ and Cd 2+ are synthesized by chemical co-precipitation method. Structural and morphology analysis with X-ray diffraction (XRD) and SEM, respectively, confirmed the spinel structure with uniform distribution of the nanoparticles of the size in the range 17-36 nm. The dopant concentration affects the lattice parameter by incorporating Cd 2+ , lattice parameter increases in the range 8.3-8.7 Å. This increase is attributed due to difference in ionic radii of cations. The dc electrical resistivity (ρ dc ) and drift mobility (μ d ) confirmed a semiconducting-like behavior. The increase in dopant concentration decreases the activation energy ( E). A small amount of Cd 2+ causes a sudden increase in saturation magnetization (M s ) and remanence (M r ) values. It is observed that up to x = 0.30 M s increases, while further incorporation of Cd 2+ decreases magnetization. This is due to canted spin and can be explained on the basis of the canted spin model. The decrease in Curie temperature with increase in Cd 2+ is due to interaction between tetrahedral (A) and octahedral (B) lattice sites.

“…The non-zero Y-K angles' values suggest that magnetic behavior cannot be explained on the basis of Neel two sub-lattice model due to spin canting at B-sites. This decreases the A-B interaction and consequently increases the B-B interaction [34]. Y-K angle has been calculated with the help of Bohr magneton using standard relation [35]:…”

Section: Electrical Propertiesmentioning

confidence: 99%

Effect of Concentration of Zr4+ and Ni2+ Dopants on Electrical, Magnetic and Y–K Angle of Mg–Cu Complex Spinel Nanoferrites

2011

The complex Mg-Cu nanoferrites with composition Mg 0.5 Cu 0.5 Fe 2−2x Ni x Zr x O 4 (0.00 ≤ x ≤ 0.80) were synthesized by incorporating dopants Zr 4+ and Ni 2+ with the help of chemical co-precipitation method. The synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), dc electrical and magnetic properties through laboratory-made two-probe resistivity apparatus and vibrating sample magnetometer (VSM). XRD confirmed the formation of single phase spinel nanoferrites having crystalline size in range 16-29 nm. The particle size (t) and lattice parameter (a) increase with the increase in concentration of dopants. The XRD results are in good agreement with SEM results. FTIR give valuable information about the presence of tetrahedral (A) and octahedral (B) sites by considering higher and lower frequency bands, respectively. The electrical properties, e.g. dc electrical resistivity (ρ d ), drift mobility (μ d ) and activation energy (E), were calculated. Resistivity data confirm semiconducting behavior of material. And it is observed that an abrupt increase in resistivity occurs up to x = 0.40. While further increase in dopants concentration leads to decrease in resistivity. Magnetic hysteresis loops confirmed soft nature of synthesized material. Interesting magnetic behavior is observed that up to x = 0.40 the value of saturation magnetization (M s ), remanence (M r ) and Bohr magneton (n B ) increase and after that decrease in trend occurs. For x = 0.40, minimum coercive force (H c ) is observed. Y-K angle increases with increase in dopant concentration. So it is confirmed that A. Faraz ( ) Thermal Transport Laboratory (TTL), School of chemical and materials Engineering (the incorporation of dopant in small amount (x ≤ 0.40) enhances magnetic properties and further increase of Zr 4+ can weaken magnetic properties.