Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure

The polycrystalline samples with nominal composition FeTe1-xSex (x = 0.1 - 0.5) and FeTe1-xSx (x = 0.1 - 0.3) were prepared via solid-state reaction method. The pellets were sealed inside a stainless steel tube with both ends clamped for sintering at ambient pressure. Argon gas flow was maintained t...

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Main Author:	Lim, Edmund Hua Hang
Format:	Thesis
Language:	English
Published:	2015
Subjects:	Solid state chemistry Superconductivity
Online Access:	http://psasir.upm.edu.my/id/eprint/57070/1/FS%202015%208RR.pdf
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spelling	my-upm-ir.570702017-08-23T03:39:18Z Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure 2015-11 Lim, Edmund Hua Hang The polycrystalline samples with nominal composition FeTe1-xSex (x = 0.1 - 0.5) and FeTe1-xSx (x = 0.1 - 0.3) were prepared via solid-state reaction method. The pellets were sealed inside a stainless steel tube with both ends clamped for sintering at ambient pressure. Argon gas flow was maintained throughout the heat treatment in order to minimize the oxidation. According to the X-ray diffraction (XRD) data, both FeTe1- xSex and FeTe1-xSx were indexed to tetragonal structure with space group of P4/nmm. The lattice parameters a- and c-axis decrease with the substitution of Se and S. SEM images showed that the samples developed into plate-like grain structure gradually with the increase of Se and S concentration. EDX results show that the ratio of Te substituted by Se and S are gradually increased with increasing of the Se and S concentration. For FeTe1-xSex, onset of superconducting transition temperature, Tc was found to increase with Se concentration. The Tc is about 13.8 K and 13.5 K for x = 0.4 and 0.5,respectively compared with 10.6 K for x = 0.1. Substitution of Te with S suppresses the antiferromagnetic transition of the parent compound FeTe as shown by the temperature dependence of magnetic moment measurements. The samples with S content x = 0.25 and 0.30 exhibited diamagnetism suggesting the coexistence of magnetic and superconducting phase in these samples. Both FeTe1-xSex and FeTe1-xSx exhibited ferromagnetic behaviour as shown by the field dependent magnetization. In general, the values of coercivity, retentivity and magnetization (at 10 kG) decrease with Se and S concentration. The values of these magnetic properties are comparable for both Se and S substitution. Both FeTe1-xSex and FeTe1-xSx show negative dielectric permittivity (εr′) and this could be due to the plasma-like behaviour of the electron gas at frequency less than the plasma frequency. Se substitution decreases the dielectric constants εr′, while increased the εr′′ from x = 0.0 to x = 0.5. For S substitution, εr′ decreased while εr′′ increase from x = 0.0 to x = 0.1. However, εr′ increased and εr′′ decreased with increasing S concentration for x = 0.25 and 0.30. FeTe1-xSx (x = 0.1) has greater magnitude of εr′ and εr′′, more rapid energy loss and higher ac-conductivity (ζac) compared to FeTe1-xSex (x = 0.1 - 0.3) at 1 kHz. Solid state chemistry Superconductivity 2015-11 Thesis http://psasir.upm.edu.my/id/eprint/57070/ http://psasir.upm.edu.my/id/eprint/57070/1/FS%202015%208RR.pdf application/pdf en public masters Universiti Putra Malaysia Solid state chemistry Superconductivity
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English
topic	Solid state chemistry Superconductivity
spellingShingle	Solid state chemistry Superconductivity Lim, Edmund Hua Hang Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure
description	The polycrystalline samples with nominal composition FeTe1-xSex (x = 0.1 - 0.5) and FeTe1-xSx (x = 0.1 - 0.3) were prepared via solid-state reaction method. The pellets were sealed inside a stainless steel tube with both ends clamped for sintering at ambient pressure. Argon gas flow was maintained throughout the heat treatment in order to minimize the oxidation. According to the X-ray diffraction (XRD) data, both FeTe1- xSex and FeTe1-xSx were indexed to tetragonal structure with space group of P4/nmm. The lattice parameters a- and c-axis decrease with the substitution of Se and S. SEM images showed that the samples developed into plate-like grain structure gradually with the increase of Se and S concentration. EDX results show that the ratio of Te substituted by Se and S are gradually increased with increasing of the Se and S concentration. For FeTe1-xSex, onset of superconducting transition temperature, Tc was found to increase with Se concentration. The Tc is about 13.8 K and 13.5 K for x = 0.4 and 0.5,respectively compared with 10.6 K for x = 0.1. Substitution of Te with S suppresses the antiferromagnetic transition of the parent compound FeTe as shown by the temperature dependence of magnetic moment measurements. The samples with S content x = 0.25 and 0.30 exhibited diamagnetism suggesting the coexistence of magnetic and superconducting phase in these samples. Both FeTe1-xSex and FeTe1-xSx exhibited ferromagnetic behaviour as shown by the field dependent magnetization. In general, the values of coercivity, retentivity and magnetization (at 10 kG) decrease with Se and S concentration. The values of these magnetic properties are comparable for both Se and S substitution. Both FeTe1-xSex and FeTe1-xSx show negative dielectric permittivity (εr′) and this could be due to the plasma-like behaviour of the electron gas at frequency less than the plasma frequency. Se substitution decreases the dielectric constants εr′, while increased the εr′′ from x = 0.0 to x = 0.5. For S substitution, εr′ decreased while εr′′ increase from x = 0.0 to x = 0.1. However, εr′ increased and εr′′ decreased with increasing S concentration for x = 0.25 and 0.30. FeTe1-xSx (x = 0.1) has greater magnitude of εr′ and εr′′, more rapid energy loss and higher ac-conductivity (ζac) compared to FeTe1-xSex (x = 0.1 - 0.3) at 1 kHz.
format	Thesis
qualification_level	Master's degree
author	Lim, Edmund Hua Hang
author_facet	Lim, Edmund Hua Hang
author_sort	Lim, Edmund Hua Hang
title	Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure
title_short	Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure
title_full	Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure
title_fullStr	Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure
title_full_unstemmed	Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure
title_sort	structural, magnetic and dielectric properties of fete1-xmx (m = se, s) superconductor prepared by solid state reaction at ambient pressure
granting_institution	Universiti Putra Malaysia
publishDate	2015
url	http://psasir.upm.edu.my/id/eprint/57070/1/FS%202015%208RR.pdf
_version_	1747812161896316928

Structural, magnetic and dielectric properties of FeTe1-xMx (M = Se, S) superconductor prepared by solid state reaction at ambient pressure

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