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Synthesis and Characterization of Some Multiferroic Materials

Thesis Info

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Author

Shafiq Anwar

Program

PhD

Institute

Bahauddin Zakariya University

City

Multan

Province

KPK

Country

Pakistan

Thesis Completing Year

2019

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/12238/1/Shafiq%20Anwar%20physics%202019%20bzu%20prr.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727465287

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Two batches of polycrystalline materials; La1-xKxFeO3 and LaFe1-xCrxO3 were prepared by co-precipitation and sol-gel methods respectively while third batch Bi0.8La0.15Ho0.05Fe1-xMnxO3 (BLHFMO) was synthesized by solid state reaction method. The structural studies have been carried out by employing X-Ray Diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The dielectric, ferroelectric and magnetic properties have also been investigated by employing relevant techniques. In recent years search for magnetoelectric multiferroic compounds has remained a subject of significant interest because they can be triggered by electric and magnetic ferroic orders simultaneously. Recently after identification of multiferroicity in LaFeO3 (LFO), now it is much focused to improve said properties in the compound. Similarly BiFeO3 (BFO) is another compound of tremendous interest for researchers for its multiferroic properties above room temperature. So an effort has been made to improve the multiferroic properties of LFO, BFO and related compounds. In LFO, substituting Cr3+ for Fe improves its magnetic response while dielectric studies above room temperature verified magnetic phase transition. Transitions temperature was found to be decreasing with increasing Cr contents. DC electrical resistivity was also found to be strongly Cr contents dependant; estimation of activation energy suggested P-type semiconducting behaviour of the compound. Similarly hole doping at La site by replacing it by K1+ increased the magnetic property, further P-E loops reflects weak ferroelectric nature of the material. For BLHFMO, with increase in Mn3+ concentration structural transition from rhombohedral to orthorhombic phase was detected from XRD results. Further high values of dielectric constant in the vicinity of Neel temperature are related to the magnetic phase transition. Maximum magnetic response was observed for 10 % manganese concentration.
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فخر کا مقام

فخر کا مقام

فخر کا مقام اس وقت تھا جب بھٹو شہید کی قیادت میں سب عرب رہنما پاکستان تشریف لائے تھے اور سب بادشاہ بھٹو کے ساتھ فرش پر تشریف فرما تھے ۔

 

امام بلاذری بحیثیت سیرت نگار

Ansāb-ul-Ashrāf is one of the most prominent works of Aḥmad Bin Yaḥya Bin Jābir al- Balādhuri, a muslim historiographer of third Hijri Century. This book is, in fact, a genealogical form of writing history and a primary and authentic source of the Holy biography of the Holy Prophet Muḥammad (ﷺ). This article comprises the life, works and especially the methodology of seerah writing of Balādhuri in his book: Ansāb-ul-Ashrāf. The distinctive characteristics of   methodology of seerah writing have been described in this article. He has presented the traditions (Riwayat) about the Seerah of Prophet Muḥammad (ﷺ) in different ways. Sometimes he mentions the whole chain of narrators and sometimes he skips the chain of narrators. The article sheds light on the methodology of seerah writing with special reference to the book Ansāb-ul-Ashrāf.

Design and Fabrication of Switchable Metal Organic Frameworks

Metal organic frameworks (MOFs) are a versatile class of porous crystalline materials constructed from metal nodes and organic linkers. Postsynthetic modification (PSM) has emerged as an important late-stage approach to functionalizing MOFs. The introduction of the desired functional groups via PSM strategies requires chemical handles or tags within the MOFs‟ lattice though appropriate linker molecules during their synthesis. Click reactions offer dynamic covalent chemistries that result in changes of surface properties by allowing very fast and reversible reactions under mild condition. The present work demonstrates the synthesis of amine functionalized metal organic frameworks followed by the post synthetic modification via various strategies involving click chemistry.A thermally reversible Diels– Alder ligation between cyclopendienyl (Cp) groups functionalized MOFs (NH2-MIL-88B-Fe and ML-88B-Fe) and small molecules bearing maleimide groups was employed to fabricate MOFs with switchable chemical nature. The thermally induced Hetero Diels-Alder (HDA) reactions between cyclopendienyl (Cp) groups grafted on NH2-MIL-53-Al and dithioester based moieties were performed to prepare MOFs able to reprogrammable chemical nature. Maleimide group containing molecules of markedly different chemical nature were utilized to demonstrate the reversible switching of functionalities on furan groups containing MOF (NH2-UiO-66-Zr) presenting an unprecedented concept of a MOF that may be transformed to perform distinct functions simply by switching their chemical functionalities. The potential of thiol-ene click chemistry was utilized to postsynthetically modify MOF (IRMOF-3-Zn). The thiol–maleimide Michael addition approach allows the maleimide bearing frameworks to graft cysteine based biomolecules. All the results in the presented thesis were supported by scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) analysis.