Spinel oxides are an important class of versatile materials, which exhibit complex and tunable structures and offer exceptional properties for their potential applications in wide range of modern fields. In this dissertation, two important classes of spinel materials based on iron and aluminum are reported to have been synthesized and characterized experimentally. These are also checked theoretically for their possible applications in electronic and spintronic devices.Firstly, iron based spinel i.e., MgFe2O4, NiFe2O4, and CrFe2O4 were synthesized by sol-gel method whilst thin films were deposited on copper substrates by spin coating technique. In case of MgFe2O4, Mg/Fe ratio was varied as 0.4, 0.45, 0.5, 0.55 and 0.6 during sol synthesis. Variation of Mg/Fe ratio strongly affected magnetic and electronic properties along with phase purity of magnesium iron oxide thin films. Peaks corresponding to (220), (222), (400), (331), and (620) planes confirmed formation of MgFe2O4 at a very low annealing temperature of 300 oC with Mg/Fe ratio of 0.55. A single magnetic phase has been achieved with high dielectric constant and low tangent loss at Mg/Fe ratio of 0.55. Semiconducting behavior, revealed by Arrhenius plot, is due to electron hoping between Fe2+ and Fe3+ cations. High saturation magnetization of 163emu/cm3 is achieved which decreased at Mg/Fe values of 0.4, 0.45, 0.5 and 0.6. For NiFe2O4, nickel oxide (NiO) was added to hematite (Fe2O3) and NiFe2O4 phase formation was achieved at 6% Ni dopant concentration. Variation of Ni dopant was observed to strongly affect structural, magnetic and dielectric properties. Particle size of around 10 nm was observed through SEM. High saturation magnetization of 25 emu/g, and dielectric constant of 94 was observed with 6% of Ni dopant concentration. High dielectric constant and low dielectric loss of NiFe2O4 was observed at high frequency that is very interesting for high speed electronic and spintronic devices. Furthermore, antiferromagnetic Cr3+ was added in NiFe2O4 by co-precipitation method. This enhances the utility in magnetic storage, computer memory chips and microwave devices. Single-phase cubic spinel structure was achieved with particle size in the range of 38-49 nm. Structural study revealed phase purity of CrFe2O4 spinel at dopant concentration of 6wt% and again at 9-10wt% with crystal size of 15.45 nm and 14.98 nm respectively. Mixed phases of Fe2O3, Cr5O12, CrFe2O4 or amorphous nature was observed for rest of the dopant concentration ranges. vii Secondly, aluminum based spinel, i.e., FeAl2O4 and ZnAl2O4 were synthesized by sol-gel technique and then the sol was spun on copper substrates with variation in Fe/Al ratio as 0.4, 0.45, 0.5, 0.55 and 0.6. XRD patterns revealed that phase pure FelAl2O4 was observed only for the sample with Fe/Al ratio of 0.4. Whereas, Fe2O3 peaks appeared along with iron aluminum oxide peaks for rest of the ratios. M-H curves showed enhanced magnetic properties of films having 42.325 emu/cm3 saturation magnetization, 10 emu/cm3 remnant magnetization, and 430.19 Oe coercivity. Conductivity measurements showed transition in electrical properties at a temperature of 127 K. Room temperature magnetoresistance ̴ 10% was observed for iron aluminum oxide thin films with Fe/Al of 0.4. For ZnAl2O4, glass substrate was used for preparation of thin films by spin coating. Dopant concentration (1-10%) was carried out beyond the solid solubility limit to allow further reaction of ZnO and dopant oxide for the formation of phase-pure ZnAl2O4. XRD results confirmed formation of phase pure ZnO in undoped films with preferred orientation along (101) plane. ZnO phase persisted with aluminum doping till 3% along with change in preferred orientation from (101) to (001) plane. Mixed ZnO, Al2O3, ZnAl2O4 phases were observed at dopant concentrations of 4-6% and 9-10%. Phase pure ZnAl2O4 was obtained at dopant concentrations of 7-8%. Films showed high transmission in the visible and infrared regions. Highest transmission ~ 91% with band gap of 3.756 eV was observed for ZnAl2O4 films with dopant concentration of 8%. Refractive index of 2.16 at 500nm was observed at this dopant concentration whereas dielectric constant of 64.86 (log f=5.0) was observed due to high grain boundary resistance of 3.218 MΩ as determined by ZView software. Temperature dependent dielectric analysis indicated negative temperature coefficient for ZnAl2O4 thin films with activation energy of 1.86 eV.Thirdly, ab-initio calculations were performed to calculate structural, electrical and magnetic properties for MgFe2O4, CrFe2O4, NiFe2O4, FeAl2O4 and ZnAl2O4 by using Density Functional Theory. Generalized Gradient Approximation (GGA) without and with U (PBE, PAW and modified Becke Johnson (mBJ) potentials) was implemented to accomplish theoretical investigations. Experimental results obtained so far are in good agreement with the theoretical observations.
سید سجاد حیدریلدرم مرحوم ۱۲؍ اپریل ۱۹۴۳ء کی رات کو سید سجاد حیدر مرحوم نے جو ادب کی دنیا میں یلدرم کے نام سے مشہور تھے، قلب کے عارضہ سے دفعتہ وفات پائی، یہ علی گڑھ کالج کے پرانے تعلیم یافتوں میں اور اسی تعلق سے کالج کے ان چند طالب علموں میں تھے جنہوں نے مولانا شبلی مرحوم کے درس اور صحبت سے شعر و ادب کا ذوق حاصل کیا تھا، مرحوم مولانا کے درس کے اس قسم کے واقعات کو مزے لے لے کر بیان کیا کرتے تھے، ان کا اصل وطن نہٹور (یوپی) میں تھا، ۱۹۰۱ء میں بی، اے کی سند پاکر تعلیم سے فراغت پائی۔ ہماری زبان میں اس وقت ادب لطیف کا جو رواج ہے، اس کے پرانے لکھنے والوں میں سب سے پہلا نام سید حیدر مرحوم کا ہے اور چونکہ قادر مطلق کو ان سے یہ کام لینا تھا، اس لئے ان کی زندگی میں اس کا مناسب سامان بھی پیدا کردیا یعنی یہ کہ کالج کے زمانہ ہی میں ان کو ترکی پڑھنے کا خیال ہوا، علی گڑھ میں نواب محمد اسمٰعیل خان صاحب رئیس علی گڑھ کے والد بزرگوار ہجرت کرکے مکہ معظمہ چلے گئے تھے، وہیں نواب محمد اسمٰعیل خاں صاحب کی تعلیم و تربیت ہوئی، اس زمانہ میں ترکی وہاں کی سرکاری زبان تھی، اس لئے ان کو ترکی بھی پڑھائی گئی اور جب وہ ہندوستان آئے تو وہ ترکی ادب کے گویا نمائندہ ہوکر آئے، چنانچہ سرسید کے ’’تماشائے عبرت‘‘ میں وہ اسی ہیئت سے اسٹیج پر آئے ہیں اور معارف علی گڑھ میں جس کے وہ شریک ایڈیٹر تھے، وہی ترکی ادب کی اشاعت کا ذریعہ بنے۔ بہرحال سجاد حیدر مرحوم نے انہی سے ترکی زبان سیکھی اور اس کا یہ فائدہ ان کو پہنچا کہ سرکار انگریزی نے ان کو علی گڑھ...
Like other major religions of the world, sectarian division took place in Islam too. The major cause of this sectarian division was political in its nature rather than religious. Immediately after the demise of the Holy Prophet (SAW), believers were divided over the question of succession to the Prophet (SAW) which later on culminated in the shape of two sectarian factions i.e. Sunni and Shi‘ah. The present paper will give a complete account of the genesis of Islamic sects including the events that directly intensified shi’ism in Islam.
Soil contamination with heavy metals (HMs) is global issue, especially in developing countries where the knowledge and awareness regarding the hazardous contaminants is lacking grossly in rural people. Therefore, they are more vulnerable to toxic contaminants because of improper mining activities and open dumping of wastes. These contaminants with the passage of time make their way to nearby agricultural fields and enter food chain. Present study area has chromium-manganese reservoirs at larger scale and its mining has been continue since long ago. Pi results indicated that, manganese (Mn), chromium (Cr), copper (Cu), lead (Pb) and zinc (Zn), are present in higher concentrations from their MPL in nearby agriculture fields, posing potential threats to food safety, human health and soil quality. Use of biochar for the stabilization of selected HMs is environmentally friendly technique. Three different studies were conducted to accomplish objective of the study. The experiment one is about application of biochar to reduce health risks via consumption of rice (Oryza sativa) grown in Cr-Mn mine contaminated soil. Hard wood biochar (HWB) (3% w/w) was applied to three kinds of soil obtained from agriculture fields adjacent to chromium, manganese, and chromium-manganese mix ores. Two varieties of rice (DR83 and IR6) were cultivated in it and stems, leaves and grains were analyzed for HMs. Results revealed that HWB reduced the absorption of HMs significantly (P<0.05) in both varieties of rice. Dietary intake (EDI), hazard quotient (HQ) were reduced significantly (P < 0.01) in V2. HWB reduced Pb concentrations in V1 (22 to 36 %) and V2 (95 to 98%) in rice grains, is particularly more important as exposure to Pb through contaminated rice consumption may cause cancer. The HWB application significantly (P≤0.01) decreased Pb cancer risk via consumption of rice. Hence, the results concluded that HWB effectively decreased the mobility of HMs in amended soils as compare to control soils. Results of the study are in support of the use of HWB to mitigate HMs accumulation in rice and hence reducing the exposure to HMs. In second study the efficacy of HWB was investigated for bioavailability of selected metals (Cr Zn, Cu, Mn and Pb) in degraded soil of mining and their bioaccumulations in vegetables and related health risks. Application of HWB to Cr-Mn mine degraded soil @ 3% to examine the efficacy of HWB for 2nd crop (in crop/vegetable rotation technique). Spinach (Spinaccia oleracea) and Cilantro (Coriandrum sativum) and were cultivated as 2nd crop in the same amended pot, which were previously used for rice cultivation as first crop. HWB reduced the concentrations of Cr, Zn, Cu, Mn, and Pb in cilantro by 25.5%, 37.1%, 42.5%, 34.3%, and 36.2% respectively, in comparison to control. For spinach, reduction was observed for Cr 75.0%, Zn 24.1%, Cu 70.1%, Mn 78.0%, and Pb 50.5% as related to control. HWB significantly decreased (P<0.01) HMs uptake in spinach grown in amended soil. Results obtained from calculation of BAF also indicated that, amendment decreased HMs bioaccumulation in vegetables thus minimized health risk. Third study focused on a remediation technique using poplar wood biochar (PWB) and sugarcane bagasse biochar (SCBB) at 3% and 7% application rates, subsequently called PWB3, PWB7, SCBB3 and SCCB7, for the immobilization of Cr and Pb in mineimpacted agricultural soils. In a greenhouse experiment, lettuce was cultivated in contaminated soil to examine the effect of selected biochars on minimization of HMs bioaccumulation and associated human health risk. Both amendments PWB7 and SCBB7 has reduced the bioavailable Pb and Cr significantly (P<0.01) in amended soil with increase in biomass of lettuce in comparison with control treatment. Risk assessment results signified that PWB and SCBB efficiently reduced the daily intake of metal (DIM) in addition with their associated risk due to lettuce consumption as compared to the control. The Pb human health risk index (HRI) for children and adults were decreased (P<0.01) significantly with SCBB7 in comparison with PWB7 and control treatment. Efficiency of both biochars (SCBB and PWB) at application rate of 7% to reduce Cr and Pb uptake in lettuce was (69%, 73.7%) and (57% ,47.4%) respectively. For both amendments, HRI values for Cr were within safe limits for children and adults. Values of HRI for Pb were not within safe limits except for SCBB7. The results of the study indicated that SCBB7 application to mine impacted agricultural soil effectively increased plant biomass and reduced bioaccumulation, DIM and associated HRI of Cr and Pb as compared to PWB3, PWB7, SCBB3 and the control. Based on above studies results it is concluded that biochar can enhance soil fertility, increase yields and decrease bioaccumulation of HMs. Hence, biochar could play a key role in reclaiming mine-degraded soil and decreasing the possible human health risks.