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Preparation and Characterization of Zno Based Diluted Magnetic Semiconductor Dms Materials

Thesis Info

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Author

Saleem, Murtaza

Program

PhD

Institute

University of the Punjab

City

Lahore

Province

Punjab

Country

Pakistan

Thesis Completing Year

2011

Thesis Completion Status

Completed

Subject

Physics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2741/1/3118S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726992750

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ZnO based diluted magnetic semiconductors (DMSs) have been extensively studied during last decade because of their potential applications in spintronic devices. The search for completely new DMS materials with room temperature (RT) ferromagnetism, as well as designing and modification in existing DMS materials are some important and recent issues regarding DMSs. The achievement of RT ferromagnetism in these materials is itself a great challenge. The controversies among researchers suggest that ferromagnetic behavior and its origin in DMSs depends on composition, synthesis conditions, annealing parameters and additional dopants for varying the concentration of carriers as well. A meaningful devotion has been given to magnetic elements (Mn, Ni, Co, and Fe) doped ZnO. Moreover, these compositions have also been treated with some additional thermal treatments and doping of Al for brief and consequential observations. An attention to bulk materials has also been given in this research for more precise studies. We have successfully synthesized the phase pure compositions of Zn0.95Mn0.05O, Zn0.95-xMn0.05AlxO (x = 0, 0.05, 0.10), Zn0.95Ni0.05O, Zn0.95Co0.05O and Zn0.90Co0.05Al0.05O DMSs using sol-gel based auto-combustion and chemically derived co-precipitation techniques. XRD studies revealed the formation of phase pure compositions in most cases without any second or impurity phase. However, some traces of manganese oxide in Mn doped ZnO in Ni doped ZnO were detected in samples thermally treated at higher temperatures and synthesized with co-precipitation technique, respectively. EDX analysis confirmed the incorporation of utilized dopants into ZnO matrix. Morphological studies by SEM and FESEM were carried out to analyze the proportion, uniformity, quality and size of grains. Temperature dependent electrical resistivity measurements depicted the semiconducting behavior of materials. Room temperature ferromagnetism was successfully achieved in Zn0.95Mn0.05O composition. The similar composition of Mn doped ZnO was thermally annealed at various temperatures (400, 600, and 800 °C) for 8 hours. It was observed that crystallinity of the samples improved with increase of temperature of thermal treatment. This improvement in crystallinity also affected the resistivity and magnetization attributed to the dependence of physical properties upon structural arrangement. Temperature dependent electrical resistivity measurements showed a decreasing trend with the doping of Al in ZnMnO, which is attributable to the enhancement of free carriers. The results indicate that Al doping results in significant variation in the concentration of free carriers and correspondingly the carrier-mediated magnetization. Auto-combustion and co-precipitation techniques were employed to prepare the Zn0.95Ni0.05O samples. Room temperature ferromagnetism was detected only in sample synthesized with auto-combustion technique. It was confirmed that synthesis techniques strongly influenced the various properties of diluted magnetic semiconductor materials. Room temperature magnetic measurements reveal the absence of ferromagnetism in Co doped ZnO, while Co and Al co-doped sample display the clear room temperature ferromagnetic behavior. The decrease of resistivity and presence of ferromagnetic behavior in Al doped ZnCoO system corroborates the significant role of free carriers.
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اپنی مثال آپ

اپنی مثال آپ
ڈاکٹر غلام شبیر اسدؔ
ہر چند شاعری تخلیقی محرک کی محتاج ہوتی ہے مگر موضوعی شاعری دراصل اس وقت زور دارہوتی ہے جب فیضان و عقل، جذبِ درروں اور بیدار قوتِ فیصلہ یا پھرشعور و لاشعور کے دھارے آپس میں مل جاتے ہیں۔یہ وہ مقام ہوتا ہے جہاں عرفان و وجدان اور فہم وخرد کی توانائی ایک دوسرے کو سہارتے ہوئے باہم آمیز ہو جاتے ہیں۔یہ حقائق اپنی جگہ بجا لیکن جب بھی کسی تخلیق کار کو اخلاقی موضوع کا سامنا کرنا ہوتا ہے تو شرطِ اوّل کے طور پر ذہنی وقلبی،نزہت و متانت ، نیاز مندی ،عاجزی و انکساری اور مثالی اسلوبِ کلام کا حامل ہونا لازم آتا ہے۔متحرک و منور اسلوب کی بنیادی غذا ،تخلیق کار کی شخصیت، حُبِ موضوع ،مقام کا حاملعلم و کردار ،تقویٰ و ایمان ،طبعی مناسبت، تہذیب کے اِساسی زاویوں سے آگاہی اور وفورِ شوق سے تیار ہوتی ہے۔اردو نعتیہ سرمائے کی متنوع جہات میں سیرتِ النبیﷺ کے حتی الامکان پہلوئوںکواجاگر کرنا کسی بھی شاعر کے لیے آزمائش سے کم نہیں ، پھر اس سے بڑی آزمائش ہیئت مسدس میں اظہار، جس کا مزاج ہمیشہ متقاضی رہا ہے کہ مترنم اور رواں دواں وسہل اوزان کے ساتھ ساتھ دلوں میںاترتا شفاف کومل لہجہ اورآبِ زُلال سے دھلی زبان شیتل سی مخمور لے پوری قدرتوں کے ساتھ بہم ہو۔میں سمجھتا ہوں کہ یہ سب لطائفِ پر نور روحِ بندگی سے میسر آتے ہیں۔ اگر ایسا نہ ہو تو معلومات کو شعر میں لانے سے ثقالت کا احساس حاوی رہتا ہے، جس کامسدس متحمل نہیں ہو سکتا۔
انھی موضوعی اور معروضی خوبیوں کے سبب پورے وثوق سے کہا جا سکتا ہے کہ مسدس ہی ایک ایسی صنفِ سخن ہے جسے دنیا بھر کی مستند و اعلیٰ نظموں کے مدِ مقابل رکھا جاسکتا ہے۔
انیس، دبیر حالی ، چکبست ،امانت...

COMPARISON OF SCIATIC NERVE GLIDING AND LOWER EXTREMITY DYNAMIC STRETCH ON HAMSTRING FLEXIBILITY IN ATHLETES

Background: Hamstring muscles are targeted among football players. Sciatic nerve gliding improve hamstring flexibility among football players. Objective: To compare the effects of sciatic nerve gliding and lower extremity stretching on hamstring flexibility among football players. Methodology: In this randomized clinical trial 20 male athletes were selected which divided in two groups. One group was given sciatic nerve gliding while other lower extremity stretches. Athletes with age of 18-30 years, male foot ballers who regularly exercise 2 to 3 times a week for 30 minutes for 6 weeks were included. Goniometer was used to collect data by performing straight leg raise and Active knee extension test. Results: The results showed that the mean age and SD was 21.30±1.809. Comparison of treatment within group was checked by Wilcoxon Rank test showed significant results (P was less than 0.05 )and between group comparisons was checked by Mann Whitney test and found sciatic nerve gliding gave more improvement in Athletes performance (  p value was less than 0.05 for straight leg raising and active knee extension test. Conclusion: It was concluded that sciatic nerve gliding gave more effective results than lower stretching in increasing hamstring flexibility among football players.

Regional Scale Sediment Yield Modeling Using Gis and Remote Sensing

A grid based Regional Scale Sediment Yield Model RSSYM was setup different catchments of Indus basin using coarse resolution grid data. When coarse grid data is used, the land slope decreases and sediment delivery is reduced. In this study the slope averaging effect was minimized by using the fractal analysis approach. The fractal constant (α) and fractal dimension (D) equations were correlated with the standard deviation on elevation by Zhang et al. (2000). These equations for fractal constant and fractal dimension were developed using Digital Elevation Model of 1 km2 resolution (DEM) for local topography. The slope was computed for 250 m and 50 m downscaling from 1 km2 grid. A comparison was made between fractal constant equation and fractal dimension to scale down the slope parameter. Both equations were incorporated in RSSYM. The model was applied to Phulra catchment. The results showed that fractal dimension equation gives better results as compared to fractal constant. So the fractal dimension equation was incorporated in RSSYM. The RSSYM was applied on three catchments of Indus basin namely Soan, Gariala and Phulra. For Phulra catchment of Siran river the total observed sediment was 0.304 million tons whereas the simulated sediment was 0.291 million tons. The coefficient of efficiency (COE) was 0.85 and the coefficient of determination was 0.83 which shows that there is a good correlation between the observed and simulated values. In Gariala catchment the observed sediment was 6.01 million tons whereas simulated sediment was 6.80 million tons. The coefficient of efficiency for Gariala catchment was 0.91 and the coefficient of determination observed and simulated hydrograph was 0.81. Similarly for the Soan catchment the observed sediment was 10.61 million tons and simulated sediment was 12.29 million tons. The coefficient of determination and coefficient of efficiency for this catchment was 0.95 and 0.98 respectively. The snowmelt runoff model SRM was applied to Astor catchment to test the applicability of temperature index approach for Indus basin. The terrain is difficult to measure the hydrological and hydraulics data. Most of the data was available at the outlet of the catchments. The input data included daily temperature and precipitation, dividing the catchment in to different zone depending on the elevation difference. The elevation zones were generated from the DEM of the area. The snow depletion curves were made for the snow covered area derived from the satellite data analysis on monthly basis. The model output was discharge hydrograph. The COE was 0.91 which shows that there is a good correlation between the observed and simulated values. The statistical test showed that model performance was good. The results of SRM model encouraged to use temperature index approach for snowmelt runoff estimation in the Indus basin. A snowmelt runoff model was developed using temperature index approach. The model was coupled with regional scale sediment yield model RSSYM. The coupled model was named as modified regional scale sediment yield model (MRSSYM). The MRSSYM model was applied to Astor and Gilgit catchments. For the Astor catchment total observed sediment load was 3.98 million tons whereas the simulated sediment load was 4.34 million tons. The coefficient of the model was 0.89 whereas the coefficient of determination was 0.83. Similarly for Gilgit catchment the measured and simulated sediment loads were 4.50 and 4.48 million tons respectively. The coefficient of efficiency and coefficient of determinations were 0.95 and 0.88 respectively. From the results it can be concluded that MRSSYM can be applied with confidence to various catchments of Indus basin where runoff is due to snowfall and snow melting.