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Density Functional Studies of the Functional Magnetic Materials

Thesis Info

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Author

Irshad, Zainab

Program

PhD

Institute

Pakistan Institute of Engineering and Applied Sciences

City

Islamabad

Province

Islamabad

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/8407/1/Zainab_Irshad_Materials_Science_HSR_2017_PIEAS_22.11.2017.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676725817755

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Spin polarized calculations based on FP-(L)APW+lo method were performed on non-magnetic, ferromagnetic and antiferromagnetic phase of Bi2Fe4O9. Antiferromagnetic phase was energetically favourable. All exchange correlation functionals accurately describe structural properties of Bi2Fe4O9 but failed to calculate correct band structure. All exchange correlation functionals with U gave bandgap values (2.05 - 2.2eV) closer to experimental values (1.9 - 2.1 eV). The calculated DOS showed hybridization between Fe 3d and O 2p states along with minor overlap between Bi 6p and O 2p states in upper valance band. Lower conduction band was composed of Fe 3d states. Magnetic properties of Bi2Fe4O9 were due to Fe3+ ions having magnetic moment ~4μB. Induced magnetic moments at other atomic sites depend on their local environment. Charge density plots reveal slight covalent character and strong ionic character between Fe-O atoms and Bi-O atoms. In absorption spectrum peak at 1.5 eV was attributed to d-d transition of Fe3+ ions. While peak at 2.05 eV was ascribed to transitions from O 2p valence band to conduction band Fe 3d levels. Static dielectric constant and refractive index were 17.61 and 4.4 respectively. Reflectivity has peak at 15.75 and 18.37 eV (λ = 78.66 and 67.44 nm). Peak in energy loss spectrum at 21.99 eV corresponds to abrupt decrease of reflectivity. Spin polarized calculations of Fe doped ferromagnetic EuO (Eu0.75Fe0.25O, Eu0.50Fe0.50O and Eu0.25Fe0.75O) using mBJ+U method show that lattice constant linearly decrease with increasing doping concentration of Fe atoms. Semiconductor EuO shows metallic character when doped with Fe atoms. Doped EuO exhibit extra peaks of Fe atom 3d states between -10 to 3.5 eV in valence band. Decrease in bandgap was due to increased spd exchange interaction between band electrons and localized 3d electrons of transition atom. Effect of doping was found to be dependent on the location of dopant ions. Electronic and magnetic properties of ferromagnetic EuFeO3 were calculated using mBJ+U exchange correlation functional that better describe energy bandgap values of strongly correlated 4f system. The calculated bandgap 2.7 eV agrees with experimental value. EuFeO3 was found to be charge transfer insulator due to existence of bandgap between O 2p and Eu 4f states.
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خیر النساء حضرت فاطمۃ الزھراؓ

خیرالنساء فاطمۃ الزھراؓ کے حضور!

شرم و حیا کا اوج ہیں ، پیکر رضا کی ہیں
زوجہ علی کی، بیٹی رسولِ خدا کی ہیں
معیار بے نظیر ہے اُن کے حجاب کا
عورت کا ہیں وقار تو زینت حیا کی ہیں

التماسك النصي وعلاقته بالنص القرآني دراسة نظرية في ضوء التراث النقدي والبلاغي

The concept of cohesion is not only a semantics one that exists within the meaning of text; it refers to grammatical relations of the Text The concept of cohesion is not only a semantics one that exists within the meaning of text; it refers to grammatical relations of the Text that exist within surface structure of the text, and that define it as a text. That is why the study of cohesion is important in text linguistics, especially in the Text of holy Qur‘ān.  Therefore the ancient researchers have chosen it in different ways in the Qur‘ānic textual analysis. The ancient Arab started the study of Cohesion to prove the Qur‘ānic text as “Mojza” and “ijaaz” because of its organization and arrangement of text according the “Nazem” “Insijaam” “Ittisaaq” “Iltehaam” and many others. The English term that substitutes these terms is just Cohesion and Coherence. So we can say that the Arab was doing well about the discourse/textual analysis of the texts, especially the Qur‘ānic textual cohesion was their main goal. This research work differ from previous works in many aspects, while  the researcher focuses on the concept of cohesion and its various aspects, particularly in terms of the cohesion and coherence in Arabic Language in the light of Qur‘ānic text. That exist within surface structure of the text, and that define it as a text. That is why the study of cohesion is important in text linguistics, especially in the Text of holy Qur‘ān.  Therefore the ancient researchers have chosen it in different ways in the Qur‘ānic textual analysis. The ancient Arab started the study of Cohesion to prove the Qur‘ānic text as “Mojza” and “ijaaz” because of its organization and arrangement of text according the “Nazem” “Insijaam” “Ittisaaq” “Iltehaam” and many others. The English term that substitutes these terms is just Cohesion and Coherence. So we can say that the Arab was doing well about the discourse/textual analysis of the texts, especially the Qur‘ānic textual cohesion was their main goal. This research work differ from previous works in many aspects, while  the researcher focuses on the concept of cohesion and its various aspects, particularly in terms of the cohesion and coherence in Arabic Language in the light of Qur‘ānic text.

Aunty, Cat Chair Pe Bethi Hai - Using Stories to Support and Assess the Development of Vocabulary of Two Year Old Bilingual Children Through a Collaborative Action Research

Vocabulary has been found to be a predictor of later language development (Lee, 2011). Research indicates stories to be great stimulators of language, especially in enhancing children’s vocabulary. Pakistan’s National Curriculum for Early Childhood Education (2007) also emphasizes on the importance of supporting children’s vocabulary development. Through a collaborative action research, I explored the role of stories, told monolingual and bilingually, to support vocabulary development of two years old bilingual children at a private English-medium school in Karachi, Pakistan. Two teachers, facilitating this age group and four randomly chosen children from the classroom participated with me in the study. Data was gathered through various tools including, interviews, classroom teaching, and reflective conversations. Anecdotes of the four participant children were also maintained throughout the study. Findings revealed that stories supported children’s vocabulary development. Children enjoyed both monolingual (English or Urdu) and bilingual stories (Urdu and English). Moreover, vocabulary development can further be supported by reinforcing the key vocabulary through play and language games. A change in the teachers’ and my perception regarding the power of stories and storytelling, both monolingual and bilingual stories, was seen as a result of the intervention. The study also brings to light the importance of having bilingual stories to support language development in both the home and classroom languages. It also raises questions about assessing progress in both languages. It also highlights that along with stories, the storyteller, in this case the teacher helps support vocabulary development in children. It also raises questions about supporting the professional development of these teachers, about the use of stories as a teaching pedagogy as well as different strategies of telling stories.