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Abstract  

Metal carboxylato-hydrazinates are very good precursors for the synthesis of metal as well as mixed metal oxides as these decompose to nanosized oxides with high surface area most of the times at comparatively lower temperatures. In the present study one such novel precursor nickel manganese fumarato-hydrazinate (NiMn2(C4H2O4)3·6N2H4) has been prepared and characterized by XRD, FTIR and chemical analysis. The thermal decomposition of the precursor has also been studied by isothermal, differential thermal and thermogravimetric analysis. The precursor shows two-step dehydrazination followed by decarboxylation to form NiMn2O4. The infrared spectra show N-N stretching frequency at 965 cm−1, which confirm the bidentate bridging hydrazine. XRD confirms the formation of single phase NiMn2O4.

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Abstract  

The chemistry, structure, and properties of spinel ferrites are largely governed by the method of preparation. The metal carboxylato-hydrazinate precursors are known to yield nanosized oxides at a comparatively lower temperature. In this study, we are reporting the synthesis of one such precursor, cobalt nickel ferrous fumarato-hydrazinate which decomposes autocatalytically to give cobalt nickel ferrite nanoparticles. The XRD study of this decomposed product confirms the formation of single-phase spinel, i.e., Co0.5Ni0.5Fe2O4. The thermal decomposition of the precursor has been studied by isothermal, thermogravimetric (TG), and differential scanning calorimetric (DSC) analysis. The precursor has also been characterized by FTIR, EDX, and chemical analysis, and its chemical composition has been determined as Co0.5Ni0.5Fe2(C4H2O4)3·6N2H4.

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Abstract  

Nickel ferrite is technologically important magnetic material extensively used in high frequency applications such as microwave device due to its high resistivity and sufficiently low losses. It also finds application in the ferrofluids technology. Therefore, ultrafine nickel ferrite was prepared by autocatalytic combustion of novel nickel ferrous fumarato-hydrazinate precursor. The precursor was characterized by IR, AAS, TG and DTA, and a chemical formula of NiFe2(C4H2O4)3·6N2H4 was fixed. This precursor once ignited with a burning splinter at room temperature, glows and the glow spreads over the entire bulk completing the autocatalytic combustion of the precursor to ultrafine ferrite. The single phase formation of ultrafine nickel ferrite was confirmed by XRD, IR spectra and TEM. The average particle size of the ultrafine ferrite was found to be ∼20 nm by TEM. The observed lower value of saturation magnetization for nickel ferrite was due to the superparamagnetic nature of the particles, which increased with the increasing sintering temperature. The ultrafine nickel ferrite was then sintered at 1000°C for 5 h and was characterized by XRD, IR spectra, SEM and TEM. The variation of resistivity, Seebeck coefficient and a.c. susceptibility as a function of temperature was measured for NiFe2O4 and the results are discussed.

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Preparation and characterization of Co0.5Zn0.5Fe2(C4H2O4)3·6N2H4

A precursor to prepare Co0.5Zn0.5Fe2O4 nanoparticles

Journal of Thermal Analysis and Calorimetry
Authors: L. Gonsalves, V. Verenkar, and S. Mojumdar

Abstract  

A good precursor is foremost in the preparation of nanosized metal or mixed metal oxides. In the present study a novel precursor, cobalt zinc fumarato-hydrazinate Co0.5Zn0.5Fe2(C4H2O4)3·6N2H4 has been prepared which decompose at a much lower temperature to give nanosized mixed-metal oxides. X-ray investigations, confirms the formation of single spinel phase. The FTIR spectra show N-N stretching vibration at 965 cm−1 which confirms the bidentate bridging hydrazine. The thermal decomposition of the precursor has been studied by isothermal, thermogravimetric and differential scanning calorimetric analysis. The precursor shows two-step dehydrazination followed by decarboxylation to form Co0.5Zn0.5Fe2O4, the chemical analysis of the sample is corroborative of this.

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Ni0.5Mn0.1Zn0.4Fe2(C4H2O4)3·6N2H4 precursor and Ni0.5Mn0.1Zn0.4Fe2O4 nanoparticle

Preparation, IR spectral, XRD, SEM-EDS and thermal analysis

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

Abstract  

Metal carboxylato-hydrazinates are very good precursors for the synthesis of metal as well as mixed metal oxides as these, most of the times decomposes to nanosized oxides with high surface area at comparatively lower temperatures. In the present study one such novel precursor has been prepared and characterized by XRD, IR, SEM-EDS and chemical analysis. The thermal decomposition of the precursor has also been studied by isothermal, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The precursor shows two-step dehydrazination followed by decarboxylation to form Ni0.5Mn0.1Zn0.4Fe2O4. The infrared spectra show N-N stretching frequency at 972 cm−1 which confirms the bidentate bridging hydrazine. XRD confirms the formation of single phase Ni0.5Mn0.1Zn0.4Fe2O4.

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Abstract

Nanosize Co1−xZnxFe2O4 (x = 0, 0.1, 0.3, and 0.4) have been synthesized by the precursor combustion technique via autocatalytic combustion of the mixed-metal fumarato-hydrazinate precursors. A key feature of these precursors is that they decompose autocatalytically once ignited to give the monophasic nanocrystalline ferrite. This fact is confirmed by X-ray powder diffraction analysis. The thermal decomposition pattern of the precursors has been studied by thermogravimetric and differential thermal analysis. The precursors have also been characterized by FTIR and chemical analysis to fix the chemical composition. The Curie temperature (T c) of the “as-prepared” oxide was determined by alternating current susceptibility measurements.

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Abstract  

Manganese zinc ferrous fumarato–hydrazinate precursor, Mn0.6Zn0.4Fe2(C4H2O4)3·6N2H4 was synthesized for the first time and characterized by chemical analysis, infrared spectral studies, and thermal analysis. Infrared studies show band at 977 cm−1 indicating bidentate bridging nature of the hydrazine in the complex. Thermogravimetric (TG) studies show two steps dehydrazination followed by two steps total decarboxylation. The precursor on touching with burning splinter undergoes self propagating autocatalytic decomposition yielding ultrafine Mn0.6Zn0.4Fe2O4. XRD studies confirms single phase formation as well as nanosize nature of “as prepared” Mn0.6Zn0.4Fe2O4. The saturation magnetization of the “as prepared” Mn0.6Zn0.4Fe2O4 was found to be 31.46 emu gm−1, which is lower than the reported, confirms the ultrafine nature of the oxide.

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Abstract

Nanoparticles of the spinel ferrite, Co1−xNixFe2O4 (x = 0, 0.2, 0.3) have been synthesized by the precursor combustion technique. Novel precursors of metal fumarato-hydrazinate have been employed to yield the nanosized spinel ferrite. A characteristic feature of these precursors is that they decompose autocatalytically after ignition to give the monophasic nanocrystalline ferrite. This fact is corroborated by X-ray powder diffraction analysis. The thermal decomposition pattern of the precursors has been studied by isothermal thermogravimetric and differential thermal analysis. In order to fix the chemical composition, the precursors have been characterized by FTIR and chemical analysis and their chemical composition has been fixed accordingly. The Curie temperature of the “as-prepared” oxide was determined by alternating current susceptibility measurements.

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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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