The effect of Ge4+ substitution in lithium ferrites

Abstract

X‐ray diffraction, infrared, and Mössbauer spectroscopy techniques are used to investigate Li0.5 + 0.5x GexFe2.5 ‐ 1.5xO4; x ≦ 0.5. The polycrystalline samples show single‐phase spinel structure. The lattice constant for x ≧ 0.2 is found to be nearly constant, but smaller than for x = 0. A small component of Fe2+ has been detected in the IR spectra. The Mössbauer absorption patterns give magnetic sextets superimposed on a paramagnetic component that increases with increasing germanium content. The average hyperfine field at the A‐site is found to decrease faster than at the B‐site. A consistent interpretation of the information obtained from the different methods is provided. It is also suggested to give a qualitative explanation for the differential variation of the average hyperfine fields at the two sites on the basis of supertransferred hyperfine interactions.

Structural phase transformation and hysteresis behavior of Cu-Zn ferrites

“…The experimentally determined lattice parameter value in the present study for the sample x = 0 is 8.385 Å has a good coincidence with that of the literature value 8.37 Å [12]. The difference between a th and a exp as shown in Figure 2 can be attributed to the deviation from the formula of cation distribution (3), and this deviation is related to the presence of divalent iron ions Fe 2+ [25] and other crystal imperfections.…”

Structure and Magnetic Properties of Li–Cu Ferrite

“…Several studies [1 to 4] have reported additions of divalent, trivalent and tetravalent ions and various parameters have been measured depending on the desired application. Our previous works have studied X-ray analysis, IR absorption and Mo È ssbauer effect of Li±Ge ferrites [5,6]. Also, the structure and different magnetic properties of Li±Ti ferrites were studied [7 to 9].…”

The Conduction Mechanism of Lithium—Germanium Ferrites

“…A qualitative density of states curve resulting from such a model is illustrated in Fig. 5 which refers to Lio.sFe2.504 that is usually an n-type semiconductor [6, 71. It is observed experimentally that G(a) passes through a sharp minimum at TD, which implies an increase in the conductivity activation energy in the disordered phase, i.e., w = w, + E , (9) where W, is the polaron hopping energy according to Austin and Mott [ll]. The term E may be due to the presence of disorder which should impede the motion of carriers, thus allowing more time for polaron formation and should also create regions in which the electron is more strongly localized.…”

“…The aim of this work is to study the conduction mechanism of polycrystalline Lio ~F e 2 5 0 4 and the effect of Ge4+ ions on this mechanisms. This work is a part of several works on the same composition (X-ray analysis and IR absorption [8], Mossbauer effect [9], and ac conductivity [lo]).…”