Hina N. Chaudhari, Robert C. Pullar, Sher Singh Meena, Charanjeet Singh, Sofia Municoy, Martin F. Desimone, Sayed Tathir Abbas Naqvi and Rajshree B. Jotania
{"title":"Al3+ substituted U-type hexaferrites Ba4Co2Fe36−xAlxO60: structural, magnetic, electrical and dielectric properties†","authors":"Hina N. Chaudhari, Robert C. Pullar, Sher Singh Meena, Charanjeet Singh, Sofia Municoy, Martin F. Desimone, Sayed Tathir Abbas Naqvi and Rajshree B. Jotania","doi":"10.1039/D4TC01659A","DOIUrl":null,"url":null,"abstract":"<p >Polycrystalline samples of Al<small><sup>3+</sup></small>-substituted barium–cobalt U-type hexagonal ferrites, with the chemical composition Ba<small><sub>4</sub></small>Co<small><sub>2</sub></small>Fe<small><sub>36−<em>x</em></sub></small>Al<small><sub><em>x</em></sub></small>O<small><sub>60</sub></small> (<em>x</em> = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), were synthesised using a citrate gel auto-combustion route and subsequently heated at 1300 °C for 5 h. To study the influence of Al<small><sup>3+</sup></small> substitution on structural, magnetic, and dielectric characteristics, FTIR, XRD, SEM, EDX, <em>M</em>–<em>H</em> loops, Mössbauer spectroscopy and low frequency (up to 2 MHz) dielectric measurements were performed. Biocompatibility evaluation was also carried out with 3T3 fibroblast cells, and antioxidant capacity and antimicrobial activity were assessed. Agglomerated grains with different surface morphologies were seen in SEM images. EDX examination of all compositions showed the existence of Ba, Fe, Co and Al ions. Saturation magnetisation (<em>M</em><small><sub>S</sub></small>) varied from 32.3 to 52.2 A m<small><sup>2</sup></small> kg<small><sup>−1</sup></small>. A squareness ratio (<em>M</em><small><sub>r</sub></small>/<em>M</em><small><sub>S</sub></small>) of < 0.5 was obtained, signifying that all the samples have multi-domain structures. However, all samples were magnetically soft ferrites, with <em>H</em><small><sub>C</sub></small> kA m<small><sup>−1</sup></small> found to vary from 62.1 Oe to 78.6 Oe (4.94 kA m<small><sup>−1</sup></small> to 6.26 kA m<small><sup>−1</sup></small>). Mössbauer spectra were fitted with five sextets of five magnetic sublattices, and the results were obtained with a variation in Al content at room temperature. The composition <em>x</em> = 0.4 showed the highest value of relative area (12k site), whereas <em>x</em> = 1.0 showed the minimum value at the 12k site, indicating that Al<small><sup>3+</sup></small> begins to replace Fe<small><sup>3+</sup></small> in the 12k site. For compositions <em>x</em> = 0.2 and 0.4, Al<small><sup>3+</sup></small> begins to replace Fe<small><sup>3+</sup></small> in the 4f<small><sub>2</sub></small> site, leading to an increase in the electron density in this site, but this electron density is reduced with further Al<small><sup>3+</sup></small> substitution because as the number of Fe vacancies increases, Al<small><sup>3+</sup></small> favours the 12k site. This results in a non-linear variation in magnetic properties with increasing aluminium substitution. Dielectric parameters such as dielectric constant, dielectric loss tangent, and AC conductivity were analysed as a function of frequency (10 Hz–2 MHz), and analysis results illustrate the typical behaviour of ferrimagnetic materials. The Cole–Cole type plot showed one semi-circle arc for all samples. Simulated impedance plots obtained through electrochemical impedance spectroscopy (EIS) software complied with the measured impedance of the samples and revealed a variation in simulated values of grain and grain boundary parameters, which was in agreement with SEM images. EIS generated simulated impedance plots that agreed with the measured impedance of the samples. The disclosed deviation in the simulated values of grain and grain boundary parameters was consistent with SEM micrographs. The grain morphology influenced the electrical parameters of ferrite samples, and dielectric relaxation was found to be prevalent in the samples.</p>","PeriodicalId":84,"journal":{"name":"Journal of Materials Chemistry C","volume":null,"pages":null},"PeriodicalIF":5.7000,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Materials Chemistry C","FirstCategoryId":"1","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/tc/d4tc01659a","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Polycrystalline samples of Al3+-substituted barium–cobalt U-type hexagonal ferrites, with the chemical composition Ba4Co2Fe36−xAlxO60 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), were synthesised using a citrate gel auto-combustion route and subsequently heated at 1300 °C for 5 h. To study the influence of Al3+ substitution on structural, magnetic, and dielectric characteristics, FTIR, XRD, SEM, EDX, M–H loops, Mössbauer spectroscopy and low frequency (up to 2 MHz) dielectric measurements were performed. Biocompatibility evaluation was also carried out with 3T3 fibroblast cells, and antioxidant capacity and antimicrobial activity were assessed. Agglomerated grains with different surface morphologies were seen in SEM images. EDX examination of all compositions showed the existence of Ba, Fe, Co and Al ions. Saturation magnetisation (MS) varied from 32.3 to 52.2 A m2 kg−1. A squareness ratio (Mr/MS) of < 0.5 was obtained, signifying that all the samples have multi-domain structures. However, all samples were magnetically soft ferrites, with HC kA m−1 found to vary from 62.1 Oe to 78.6 Oe (4.94 kA m−1 to 6.26 kA m−1). Mössbauer spectra were fitted with five sextets of five magnetic sublattices, and the results were obtained with a variation in Al content at room temperature. The composition x = 0.4 showed the highest value of relative area (12k site), whereas x = 1.0 showed the minimum value at the 12k site, indicating that Al3+ begins to replace Fe3+ in the 12k site. For compositions x = 0.2 and 0.4, Al3+ begins to replace Fe3+ in the 4f2 site, leading to an increase in the electron density in this site, but this electron density is reduced with further Al3+ substitution because as the number of Fe vacancies increases, Al3+ favours the 12k site. This results in a non-linear variation in magnetic properties with increasing aluminium substitution. Dielectric parameters such as dielectric constant, dielectric loss tangent, and AC conductivity were analysed as a function of frequency (10 Hz–2 MHz), and analysis results illustrate the typical behaviour of ferrimagnetic materials. The Cole–Cole type plot showed one semi-circle arc for all samples. Simulated impedance plots obtained through electrochemical impedance spectroscopy (EIS) software complied with the measured impedance of the samples and revealed a variation in simulated values of grain and grain boundary parameters, which was in agreement with SEM images. EIS generated simulated impedance plots that agreed with the measured impedance of the samples. The disclosed deviation in the simulated values of grain and grain boundary parameters was consistent with SEM micrographs. The grain morphology influenced the electrical parameters of ferrite samples, and dielectric relaxation was found to be prevalent in the samples.
期刊介绍:
The Journal of Materials Chemistry is divided into three distinct sections, A, B, and C, each catering to specific applications of the materials under study:
Journal of Materials Chemistry A focuses primarily on materials intended for applications in energy and sustainability.
Journal of Materials Chemistry B specializes in materials designed for applications in biology and medicine.
Journal of Materials Chemistry C is dedicated to materials suitable for applications in optical, magnetic, and electronic devices.
Example topic areas within the scope of Journal of Materials Chemistry C are listed below. This list is neither exhaustive nor exclusive.
Bioelectronics
Conductors
Detectors
Dielectrics
Displays
Ferroelectrics
Lasers
LEDs
Lighting
Liquid crystals
Memory
Metamaterials
Multiferroics
Photonics
Photovoltaics
Semiconductors
Sensors
Single molecule conductors
Spintronics
Superconductors
Thermoelectrics
Topological insulators
Transistors