Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi

This study involves investigation on physical properties of charge ordered (CO) monovalent-doped orthorhombic Pro.75Nao.25-xKxMn03(x=0-0.20) and Pro.75Nao.25 Mn ixNixO3(x=0-0.10) manganites and density functional theory (DFT) computations of electronic properties of insulating Pro.75Nao.25Mni-;tNix0...

全面介绍

Saved in:

书目详细资料
主要作者:	Rajmi, Rozilah
格式:	Thesis
语言:	English
出版:	2019
主题:	Electricity and magnetism
在线阅读:	https://ir.uitm.edu.my/id/eprint/31484/1/31484.pdf
标签:	添加标签没有标签, 成为第一个标记此记录!

id	my-uitm-ir.31484
record_format	uketd_dc
spelling	my-uitm-ir.314842024-01-03T07:56:29Z Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi 2019 Rajmi, Rozilah Electricity and magnetism This study involves investigation on physical properties of charge ordered (CO) monovalent-doped orthorhombic Pro.75Nao.25-xKxMn03(x=0-0.20) and Pro.75Nao.25 Mn ixNixO3(x=0-0.10) manganites and density functional theory (DFT) computations of electronic properties of insulating Pro.75Nao.25Mni-;tNix03 (x = 0, 0.25 and 0.50) manganites using LDA+t/method. The CO manganites were substituted with K+ and Ni2+ atNa- and Mn-sites of the Pro.7sNao.25Mn03 respectively, to activate its electronic and magnetic properties. Both substitutions successfully suppressed the CO state and induced ferromagnetic to paramagnetic (FM-PM) transition, accompanied by metal to insulator (M-I) transition. The inducement of FMM-PMI transition for K+-substitution increased Curie temperature (7c) and M-I transition temperature (TMI) which was attributed to the reduction in Mn06 octahedral distortion which leads to the enhancement of double exchange (DE) interaction. Meanwhile, for Ni-substituted samples the induced FMM-PMI transition caused lowering of Tc and TMI which were suggested due to enhanced antiferromagnetic superexchange interactions involving Mn3+-0-Mn3+, Mn4+-0-Mn4+ and Ni2+-0-Ni2+ which decreased the ferromagnetic superexchange interaction between Ni2+-0-Mn4+ leading to reduction of DE interaction. DFT calculation of orthorhombic Pro.75Nao.2sMn03 with FM phase via LDA+C/with UMH =2 eV showed better agreement with the experimental crystal volume and bandgap results. Meanwhile, DFT calculations on orthorhombic Pro.75Nao.25MmxNu03 (x = 0, 0.25 and 0.50) with AFM phase with U value for Mn 3d set at 2 eV (JC = 0) and 6 eV(x = 0.25, 0.50) while for both Pr 4f and Ni 3d the U values were set at 6 eV to compensate for the strong Coulomb repulsion of 3d electrons for Ni. The calculated crystal volume structure and bandgap for Ni free and Ni-substituted (x = 0.25 and 0.50) samples showed better agreement with the experimental data for the selected U values. DOS calculations revealed that all the FM and AFM samples showed half-metallic (HM) character. Partial DOS results showed Mn, Ni and O atoms contributed more significantly to the electronic states at EF for the spin down channel with higher degree of hybridization between the Mn 3d/Ni 3d and O 2p electrons. 2019 Thesis https://ir.uitm.edu.my/id/eprint/31484/ https://ir.uitm.edu.my/id/eprint/31484/1/31484.pdf text en public phd doctoral Universiti Teknologi MARA (UiTM) Faculty of Applied Sciences Yahya, Ahmad Kamal Hayati
institution	Universiti Teknologi MARA
collection	UiTM Institutional Repository
language	English
advisor	Yahya, Ahmad Kamal Hayati
topic	Electricity and magnetism
spellingShingle	Electricity and magnetism Rajmi, Rozilah Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi
description	This study involves investigation on physical properties of charge ordered (CO) monovalent-doped orthorhombic Pro.75Nao.25-xKxMn03(x=0-0.20) and Pro.75Nao.25 Mn ixNixO3(x=0-0.10) manganites and density functional theory (DFT) computations of electronic properties of insulating Pro.75Nao.25Mni-;tNix03 (x = 0, 0.25 and 0.50) manganites using LDA+t/method. The CO manganites were substituted with K+ and Ni2+ atNa- and Mn-sites of the Pro.7sNao.25Mn03 respectively, to activate its electronic and magnetic properties. Both substitutions successfully suppressed the CO state and induced ferromagnetic to paramagnetic (FM-PM) transition, accompanied by metal to insulator (M-I) transition. The inducement of FMM-PMI transition for K+-substitution increased Curie temperature (7c) and M-I transition temperature (TMI) which was attributed to the reduction in Mn06 octahedral distortion which leads to the enhancement of double exchange (DE) interaction. Meanwhile, for Ni-substituted samples the induced FMM-PMI transition caused lowering of Tc and TMI which were suggested due to enhanced antiferromagnetic superexchange interactions involving Mn3+-0-Mn3+, Mn4+-0-Mn4+ and Ni2+-0-Ni2+ which decreased the ferromagnetic superexchange interaction between Ni2+-0-Mn4+ leading to reduction of DE interaction. DFT calculation of orthorhombic Pro.75Nao.2sMn03 with FM phase via LDA+C/with UMH =2 eV showed better agreement with the experimental crystal volume and bandgap results. Meanwhile, DFT calculations on orthorhombic Pro.75Nao.25MmxNu03 (x = 0, 0.25 and 0.50) with AFM phase with U value for Mn 3d set at 2 eV (JC = 0) and 6 eV(x = 0.25, 0.50) while for both Pr 4f and Ni 3d the U values were set at 6 eV to compensate for the strong Coulomb repulsion of 3d electrons for Ni. The calculated crystal volume structure and bandgap for Ni free and Ni-substituted (x = 0.25 and 0.50) samples showed better agreement with the experimental data for the selected U values. DOS calculations revealed that all the FM and AFM samples showed half-metallic (HM) character. Partial DOS results showed Mn, Ni and O atoms contributed more significantly to the electronic states at EF for the spin down channel with higher degree of hybridization between the Mn 3d/Ni 3d and O 2p electrons.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Rajmi, Rozilah
author_facet	Rajmi, Rozilah
author_sort	Rajmi, Rozilah
title	Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi
title_short	Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi
title_full	Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi
title_fullStr	Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi
title_full_unstemmed	Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi
title_sort	effects of k+ and ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / rozilah rajmi
granting_institution	Universiti Teknologi MARA (UiTM)
granting_department	Faculty of Applied Sciences
publishDate	2019
url	https://ir.uitm.edu.my/id/eprint/31484/1/31484.pdf
_version_	1794191817730686976

Effects of K+ and Ni2+ substitution on structural,magnetic, electrical transport and electronic properties of charge ordered monovalent-doped pro.75nao.25mn03 manganites / Rozilah Rajmi

相似书籍