Characterization of nanostructured spinel NiFe2O4 obtained by soft mechanochemical synthesis

Abstract

Powdery nickel ferrite, NiFe2O4 has been obtained by soft mechanochemical synthesis in a planetary ball mill. Ni(OH)2 and Fe(OH)3 are used as initial compounds. This mixture was mechanically activated for 25h, uniaxial pressed and sintered at 1100°C for 2h. The phase composition of the sintered sample was analyzed by X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and Raman spectroscopy. Morphologies were examined by scanning electron microscopy (SEM). The electrical DC/resistivity/conductivity at different temperatures was measured using a Source Meter Keithley 2410. An Impedance/Gain-Phase Analyzer (HP-4194) was used to measure the impedance spectra (100Hz - 10MHz) at different temperatures. [Projekat Ministarstva nauke Republike Srbije, br. III 45003 i br. III 45015

Magneto-structural properties of Ni–Zn nanoferrites synthesized by the low-temperature auto-combustion method

“…The interest for using these materials permanently increases because of their usability under extreme conditions. 2 Nickel ferrite has been intensively investigated as one of the magnetic nanomaterials. [3][4][5][6] Magnetic properties of ferrites can be changed by substituting various kinds of A 2+ (Zn 2+ , Mg 2+ , Mn 2+ , Ni 2+ , Co 2+ , Fe 2+ , etc.)…”

Impedance spectroscopy of nanocrystalline MgFe2O4 and MnFe2O4 ferrite ceramics: Effect of grain boundaries on the electrical properties

“…8 shows the temperature dependence of σ DC . It can be clearly noticed that the nature of the variation is linear and well obeys the Arrhenius relation that is defined by equation [20]:…”

“…It is important to note that a proposed circuit, two parallel RC elements connected in series, refers to the ideal Debye-like behaviour in ceramic materials. But in practice, the most electroceramics exhibit non-ideal Debye-like behaviour, so that a constant phase element (CPE) is used in the equivalent circuit to illustrate more fully the deviation from an ideal capacitor [15], as shown Fig 1b. The CPE has impedance defined as [20] [ ] ,…”

“…The diffraction peaks are fairly broad, which is caused by nanometer size of the crystallites. The average crystallite sizes were calculated from the most intense peak (311) using Scherer's formula [20]. The average particle sizes have been found to be 12 nm and 16 nm for magnesium and manganese ferrites, respectively.…”

Electronic Transport Phenomena of Electric Charge in Semiconductors Ni1−xCdxFe2O4

“…Это будет повышать степень проводимости ферритов путём содействия прыжковому механизму Вервея. Заметим, что за создание электрического тока в исследуемых ферритах могут отвечать также В-В-прыжки дыр между ионами Ni 2 и Ni 3[14].Кроме этого, росту  dc также содействует увеличение объёмной усадки ∆V/V и, соответственно, плотности ферритов d m с ростом концентрации ионов Сd 2+ в системе Ni 1x Cd x Fe 2 O 4 (рис. 6).…”