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Title: Suitability of cation substituted cobalt ferrite materials for magnetoelastic sensor applications

Abstract

The results of a study on the suitability of materials derived from cobalt ferrite for sensor and actuator applications are presented. The mechanism responsible for the superior sensor properties of Ge-substituted cobalt ferrite compared with Ti and other cation substituted cobalt ferrite materials is believed to be due to the tetrahedral site preference of Ge4+ and its co-substitution with Co2+. Results also showed that the higher strain derivative of Ge-substituted cobalt ferrite compared with Ti-substitution is due to a higher magnetostrictive coupling in response to applied field in the material.

Authors:
 [1];  [1]
  1. Ames Laboratory
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1166902
Report Number(s):
IS-J 8491
Journal ID: ISSN 0964-1726
DOE Contract Number:
DE-AC02-07CH11358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Smart Materials and Structures (Print); Journal Volume: 24; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Nlebedim, Ikenna Catjetan, and Jiles, David C. Suitability of cation substituted cobalt ferrite materials for magnetoelastic sensor applications. United States: N. p., 2015. Web. doi:10.1088/0964-1726/24/2/025006.
Nlebedim, Ikenna Catjetan, & Jiles, David C. Suitability of cation substituted cobalt ferrite materials for magnetoelastic sensor applications. United States. doi:10.1088/0964-1726/24/2/025006.
Nlebedim, Ikenna Catjetan, and Jiles, David C. Sun . "Suitability of cation substituted cobalt ferrite materials for magnetoelastic sensor applications". United States. doi:10.1088/0964-1726/24/2/025006.
@article{osti_1166902,
title = {Suitability of cation substituted cobalt ferrite materials for magnetoelastic sensor applications},
author = {Nlebedim, Ikenna Catjetan and Jiles, David C},
abstractNote = {The results of a study on the suitability of materials derived from cobalt ferrite for sensor and actuator applications are presented. The mechanism responsible for the superior sensor properties of Ge-substituted cobalt ferrite compared with Ti and other cation substituted cobalt ferrite materials is believed to be due to the tetrahedral site preference of Ge4+ and its co-substitution with Co2+. Results also showed that the higher strain derivative of Ge-substituted cobalt ferrite compared with Ti-substitution is due to a higher magnetostrictive coupling in response to applied field in the material.},
doi = {10.1088/0964-1726/24/2/025006},
journal = {Smart Materials and Structures (Print)},
number = 2,
volume = 24,
place = {United States},
year = {Sun Feb 01 00:00:00 EST 2015},
month = {Sun Feb 01 00:00:00 EST 2015}
}
  • No abstract prepared.
  • This project investigates the behavior of iron-gallium (Galfenol) alloys in elastic bending to facilitate the design concepts for using Galfenol in novel sensor applications at the macro to nanoscale. A series of experiments are conducted on the magnetic response of cantilevered beams to dynamic bending loads. The samples studied include polycrystalline and single crystal rods of varied dimension with compositions ranging from 16 to 21 at % Ga. Results of initial testing show that sinusoidal bending produces measurable induction that increases with applied magnetic bias. Other results examine the effect of material composition and sensor location, as well as themore » broadband response.« less
  • Manganese (Mn) substituted cobalt ferrites (CoFe{sub 2−x}Mn{sub x}O{sub 4}, referred to CFMO) were synthesized and their structural, magnetic, and dielectric properties were evaluated. X-ray diffraction measurements coupled with Rietveld refinement indicate that the CFMO materials crystallize in the inverse cubic spinel phase. Temperature (T = 300 K and 10 K) dependent magnetization (M(H)) measurements indicate the long range ferromagnetic ordering in CoFe{sub 2−x}Mn{sub x}O{sub 4} (x = 0.00–0.15) ferrites. The cubic anisotropy constant (K{sub 1}(T)) and saturation magnetization (M{sub s}(T)) were derived by using the “law of approach” to saturation that describes the field dependence of M(H) for magnetic fields much higher than the coercive fieldmore » (H{sub c}). Saturation magnetization (M{sub s}), obtained from the model, decreases with increasing temperature. For CoFe{sub 2}O{sub 4}, M{sub s} decreases from 3.63 μ{sub B} per formula unit (f.u.) to 3.47 μ{sub B}/f.u. with increasing temperature from 10 to 300 K. CFMO (0.00–0.15) exhibit the similar trend while the magnitude of M{sub s} is dependent on Mn-concentration. M{sub s}-T functional relationship obeys the Bloch's law. The lattice parameter and magnetic moment calculated for CFMO reveals that Mn ions occupying the Fe and Co position at the octahedral site in the inverse cubic spinel phase. The structure and magnetism in CFMO are further corroborated by bond length and bond angle calculations. The dielectric constant dispersion of CFMO in the frequency range of 20 Hz–1 MHz fits to the modified Debye's function with more than one ion contributing to the relaxation. The relaxation time and spread factor derived from modeling the experimental data are ∼10{sup −4} s and ∼0.35(±0.05), respectively.« less
  • Manganese (Mn) substituted cobalt ferrites (CoFe{sub 2-x}Mn{sub x}O{sub 4}, referred to CFMO) have been synthesized by the solid state reaction method and their dielectric properties and ac conductivity have been evaluated as a function of applied frequency and temperature. X-ray diffraction measurements indicate that CFMO crystallize in the inverse cubic spinel phase with a lattice constant ∼8.38 Å. Frequency dependent dielectric measurements at room temperature obey the modified Debye model with relaxation time of 10{sup −4} s and spreading factor of 0.35(±0.05). The frequency (20 Hz–1 MHz) and temperature (T = 300–900 K) dependent dielectric constant analyses indicate that CFMO exhibit two dielectric relaxations at lowermore » frequencies (1–10 kHz), while completely single dielectric relaxation for higher frequencies (100 kHz–1 MHz). The dielectric constant of CFMO is T-independent up to ∼400 K, at which point increasing trend prevails. The dielectric constant increase with T > 400 K is explained through impedance spectroscopy assuming a two-layer model, where low-resistive grains separated from each other by high-resistive grain boundaries. Following this model, the two electrical responses in impedance formalism are attributed to the grain and grain-boundary effects, respectively, which also satisfactorily accounts for the two dielectric relaxations. The capacitance of the bulk of the grain determined from impedance analyses is ∼10 pF, which remains constant with T, while the grain-boundary capacitance increases up to ∼3.5 nF with increasing T. The tan δ (loss tangent)-T also reveals the typical behavior of relaxation losses in CFMO.« less