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Abstract

Nanoparticles of the spinel ferrite, Co0.6Ni0.4Fe2O4 have been synthesized by the precursor combustion technique. This synthetic route makes use of a novel precursor viz. metal fumarato hydrazinate which decomposes autocatalytically after ignition to yield nanosized spinel ferrite. The X-ray powder diffraction of the “as prepared” oxide confirms the formation of monophasic nanocrystalline cobalt nickel ferrite. The thermal decomposition of the precursor has been studied by isothermal, thermogravimetric and differential thermal analysis. The precursor has also been characterized by FTIR, and chemical analysis and its chemical composition has been fixed as Co0.6Ni0.4Fe2(C4H2O4)3·6N2H4. The Curie temperature of the “as prepared” oxide was determined by ac susceptibility measurements.

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Nano-crystalline Mn0.3Ni0.3Zn0.4Fe2O4 obtained by novel fumarato-hydrazinate precursor method

Synthesis, characterization and studies of magnetic and electrical properties

Journal of Thermal Analysis and Calorimetry
Authors:
U. B. Gawas
,
V. M. S. Verenkar
, and
S. C. Mojumdar

Abstract

Carboxylate hydrazinate complex involving mixed metals have been synthesized and used as precursor for preparing the nanocrystalline Mn–Ni–Zn ferrite. Chemical composition of complex was fixed from chemical analysis results, infrared studies, thermogravimetric and differential scanning calorimetric analysis and isothermal weight loss studies. Nano-crystalline Mn–Ni–Zn ferrite particles obtained by thermal autocatalytic decomposition were characterized using X-ray diffraction studies, infrared spectral studies and TEM measurement. Two peaks in the region of 340–420 and 550–660 cm−1 observed in the infrared spectrum of “as synthesized” oxide are characteristics of spinel ferrites. Average particle size of “as synthesized” Mn–Ni–Zn ferrite was found to be 10 nm. “As synthesized” Mn–Ni–Zn ferrite showed Curie point at 313 °C. Saturation magnetization (44.7 emu/g) observed for “as synthesized” Mn–Ni–Zn ferrite is lower than bulk material which is indicative of its nano-crystalline nature. Seebeck coefficient measurement has shown that the material exhibits n-type semiconducting behavior.

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Abstract

Cobalt zinc ferrite, Co0.8Zn0.2Fe2O4, nanoparticles have been synthesized via autocatalytic decomposition of the precursor, cobalt zinc ferrous fumarato hydrazinate. The X-ray powder diffraction of the ‘as prepared’ oxide confirms the formation of single phase nanocrystalline cobalt zinc ferrite nanoparticles. The thermal decomposition of the precursor has been studied by isothermal, thermogravimetric and differential thermal analysis. The precursor has also been characterized by FTIR, and chemical analysis and its chemical composition has been determined as Co0.8Zn0.2Fe2(C4H2O4)3·6N2H4. The Curie temperature of the ‘as-prepared oxide’ was determined by AC susceptibility measurements.

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Abstract

Ni0.6Zn0.4Fe2O4 nano-particles have been synthesized by self-propagating auto-combustion of nickel zinc ferrous fumarato-hydrazinate complex. The precursor complex has been characterized by chemical analysis, IR, AAS, thermal analysis and isothermal mass loss studies. The precursor on ignition undergoes self-propagating auto combustion to give Ni0.6Zn0.4Fe2O4. The X-ray diffraction studies confirmed the single phase formation of nano-size ‘as synthesized’ Ni0.6Zn0.4Fe2O4. TEM observation showed the average particle size to be 20 nm. Infrared and magnetization studies were also carried out on the ‘as synthesized’ Ni0.6Zn0.4Fe2O4. The lower value of saturation magnetization and higher Curie temperature of ‘as synthesized’ ferrite also hint at the nano size nature.

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Abstract

The influence of the s-, p-, d-, and f-block elements (Cs, Sb, Pd, and Ce) doping on the properties of ammonium dihydrogen phosphate (ADP) crystals has been described. Incorporation of small quantity of dopants into the crystalline matrix is well confirmed by energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma (ICP) techniques. The reduction in the intensity observed in powder X-ray diffraction (XRD) of doped specimens and slight shifts in vibrational frequencies confirm the lattice stress. Surface morphological changes due to doping of metals are observed by scanning electron microscopy (SEM). The differential scanning calorimetry (DSC) curves show only a slight variation in endothermic peak temperatures. The sharpness of the DSC peaks shows the good degree of crystallinity of the material. The cell parameters have been determined using single crystal XRD analysis of pure ADP and ADP:Cs/ADP:Sb/ADP:Pd/ADP:Ce specimens. The influence of metals on the second harmonic generation (SHG) efficiency is also investigated.

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Abstract

Single crystals of pure and cupric ion (Cu(II))-doped magnesium rubidium sulfate hexahydrate (MRSH) were prepared by slow evaporation of saturated solution technique (SEST) and the influence of dopant Cu(II) on the MRSH crystals has been investigated. Incorporation of Cu(II) into the crystalline matrix was confirmed by energy dispersive spectroscopy (EDS) and electron paramagnetic resonance (EPR) spectroscopy. Thermogravimetric (TG) analysis of the doped sample reveals the faster rate of degradation. EPR spectrum of the MRSH both at room temperature and at 77 K indicates the presence of Cu(II) in the interstitial position. The grown crystals were also characterized by UV–VIS and IR spectroscopy. The surface morphology of the doped sample studied by scanning electron microscopy (SEM) indicates different morphology at various magnifications. The non-linear optical (NLO) property measured using second harmonic generation (SHG) efficiency test reveals that the non-linearity is not facilitated by doping of Cu(II).

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Abstract

The influence of sodium doping on the properties of bis(thiourea)zinc(II) chloride crystals has been described. The reduction in the intensity observed in powder X-ray diffraction of doped specimen and slight shifts in vibrational frequencies confirm the lattice stress as a result of doping. The incorporation of Na(I) into the crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Surface morphological changes due to doping of the alkali metal are observed by scanning electron microscopy. The TG–DTA studies reveal the purity of the material and no decomposition is observed up to the melting point. The high resolution X-ray diffraction studies reveal that the crystalline quality is improved considerably by doping with alkali metal. High transmittance is observed and cut off λ is ~270 nm.

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Journal of Thermal Analysis and Calorimetry
Authors:
H. Rathore
,
K. Ishratullah
,
C. Varshney
,
G. Varshney
, and
S. Mojumdar

Abstract  

Copper diethyldithiocarbamate, cadmium diethyldithiocarbamate, lead diethyldithiocarbamate, nickel diethyldithiocarbamate and zinc diethyldithiocarbamate have been synthesized. They have been characterized using TG, DTA, IR spectroscopy, X-ray and atomic absorption spectrophotometry. The thermal conversion of the compounds is 54.36–88% at 1000°C. Their solubility in sodium hydroxide, mineral acids, organic solvents, distilled water and salts solution has been measured. Fungicidal activity of the dithiocarbamates has been tested by well or cup diffusion method using five fungi species. Their activity has also been tested by broth dilution method using six bacterial species. Minimum Inhibitory Concentration (bactericidal) is 6.25–25.00 μg mL−1.

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