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Home > Synergistic Effect of Zirconia and Impurities on the Properties of Mn-Zn Ferrites Synthesized by Mixed Oxide and Auto Combustion Routes

Synergistic Effect of Zirconia and Impurities on the Properties of Mn-Zn Ferrites Synthesized by Mixed Oxide and Auto Combustion Routes

Thesis Info

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External Link

Author

Waqas, Hassan

Program

PhD

Institute

Pakistan Institute of Engineering and Applied Sciences

City

Islamabad

Province

Islamabad

Country

Pakistan

Thesis Completing Year

2011

Thesis Completion Status

Completed

Subject

Engineering & allied operations

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/1419

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727842832

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Two methods namely, conventional mixed oxide and sol gel auto combustion have been adopted to synthesize Mn-Zn Ferrite powder. In sol gel process, nanosized Mn- Zn Ferrite powder was obtained by starting auto combustion reaction in gel containing metal precursors. In each method, electromagnetic properties (saturation magnetization, Curie temperature, magnetic impedance and loss tangent) have been measured after sintering the green compacts (pellets and toroids). The results revealed that Mn-Zn Ferrite synthesized by sol gel auto combustion process had superior electromagnetic properties than conventional mixed oxide method because of possessing single phase and refined microstructure. Apart from the effect of synthesis routes, the role of zirconia (ZrO 2 ) additive (0.2, 0.4 and 0.6 wt%) along with/without impurities i.e. calcia (CaO) & silica (SiO 2 ) on the electrical and magnetic properties of Mn-Zn Ferrite have also been studied. In conventional mixed oxide method, it has been observed that Z2-series (0.2 wt% ZrO 2 along with/without CaO & SiO 2 ) have better electromagnetic properties than pure and other synthesized compositions (Z4-series and Z6-series). It was mainly due to the fine control of grain growth process during sintering. The same series (Z2-series) have also been synthesized by sol gel auto combustion process. Further improvement in magnetic impedance was observed due to the simultaneous effect of zirconia along with impurities and adopted synthesis route. Among all the synthesized compositions, Mn-Zn Ferrite containing 0.2 wt% ZrO 2 & 0.04 wt% CaO synthesized by sol gel auto combustion process possessed optimum properties at high frequency ( > 500 KHz). The presence of smaller grains having faceted morphology and formation of insulating phase along grain boundaries enabled this composition to operate at high frequency band (i.e. 3 MHz to 20 MHz). The operational frequency band of this composition was further broadened (i.e. 100 KHz to 18 MHz) by improving the sintering conditions. Furthermore, light weight and compact size (washer type) toroid core of this selected composition was prepared and tested in lab scale fabricated linear pulse amplifier circuit. The results showed that synthesized core was able to transmit even weak input signals (50 mV) without any loss. It was good achievement regarding the miniaturization of Mn-Zn Ferrite core transformers to meet the demand of modern switch mode power supply units. Beside this bulk study, highly textured Mn-Zn Ferrite films were also developed on glass substrate by using the target prepared by sol gel auto combustion process. Pulse laser deposition technique has been employed to deposit these films under controlled conditions. Results showed that the strain induced during the deposition process was responsible to attain texture in fabricated films. Because of possessing magnificent magnetic properties, fabricated film had a potential to utilize in memory and spintronic devices.
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کواڑی دی کھچڑی

کواڑی دی کھچڑی

اک وار دی گل اے کہ اک بندہ اپنے پنڈ توں دوجے پنڈ کسے کم نال جا رہیا ہوندا اے۔ ایہہ پنڈ اوس دے پنڈ توں بہت دور ہوندا اے۔ سفر کردے ہوئے اوہنوں اک ویران جگہ اُتے شام پے جاندی اے۔ اوتھے اوہنوں کوئی گھر نظر نئیں آندا۔ جتھے اوہ رات گزار سکے۔ تھوڑا ہور فاصلہ کرن توں بعد اوہنوں دوروں اک گھر وچ روشنی نظر آندی اے۔ اوہ اوس روشنی ول سفر کر کے اوس گھر اپڑ جاندا اے۔ اوہدے بوہے اُتے دستک دیون توں بعد گھر وچوں اک مائی نکلدی اے تے اوس کولوں دستک دیون دی وجہ پچھدی اے۔ اوہ آکھدا اے کہ اوہ اک مسافر اے تے اوہنوں سفر وچ شام پے گئی اے۔ اوہ مائی نوں آکھدا اے کہ اج دی رات مینوں ایتھے سون دی اجازت دیو۔ میں سویر چلا جاواں گا۔ مائی اوس نوں اندر لے آندی اے تے سون لئی اک منجی دے دیندی اے۔

مائی بڑی کنجوس ہوندی اے اوہ اوس نوں کھاون لئی کجھ نئیںدیندی۔ کافی دیر بھکھے رہن توں بعد اوس نوں اک خیال آندا اے تے اوہ مائی نوں آکھدا اے کہ اماں توں کدے کواڑی دی کھچڑی کھاہدی اے۔ مائی آکھدی اے کہ نہیں پترا۔ اوہ مائی نوں آکھدا اے کہ میں اج تہانوں کھچڑی بنا کے کھوانا واں بس توں مینوں کواڑی تے برتن دے۔ مائی اوس نوں برتن دے دیندی اے۔ اوہ کواڑی نوں برتن وچ رکھ کے اوہدے وچ پانی پاندا اے تے برتن نوں چلہے اُتے رکھ دیندا اے۔

کجھ دیر توں بعد اوہ مائی نوں آکھدا اے کہ اماں جے ایہدے وچ تھوڑے جیہے چول تے تھوڑی دال پا دتی جاوے تاں کھچڑی بڑی مزے دار بنے گی۔ مائی اوس نوں چول تے دال دے دیندی...

جانوروں کے مسائل و مشکلات اور ان کا اسلامی حل

There are countless cases of cruelty and abuse of animals in the present era which are not mentioned in Islamic law, It is a pity that most of these atrocities are taking place in the so-called civilized western countries. However, it is heartening to see that the protest against the cruel exploitation by many western animal rights activists is well organized and it is hoped that this will eventually prevail and the animals will be given their due legitimate rights will remain together. What is worrying is that the developing countries, most of which are Islamic countries, have begun to follow their Western masters. They use the West's (Intensive Farming Methods) pesticides, which are harmful to humans and animals and do more harm to the environment than benefit crops, and lead to millions of animals being traded, exported or Similarly, the experiments that are done with reference to new products that are behind the maximum profit and follow them in the form of other similar luxuries. This article describes instructional teachings offered by Islam in such matters, which are very helpful and useful in raising awareness.

Biomass Derived Adsorbents for Chromium Vi Treatment from Industrial Wastewater

Environmental concerns are being aggravated with the industrial progress of the country. Untreated wastewater disposal into the aquatic bodies pose a serious environmental threat through heavy metals‘ contamination of food chain, especially the chromium (Cr(VI)). This metal is well known for carcinogenicity and mutagenicity in humans. Inexpensive wastewater treatment technologies with local input of raw materials can be an optimal choice for large scale application for the industries of the developing countries, like Pakistan. Therefore, the major objective of the proposed research was to explore and develop the efficient adsorbents from the locally available biomass resources for Cr(VI) removal from aqueous solution. For this purpose, plenty of waste biomasses were collected, processed and subjected to batch screening for the respective Cr(VI) treatment. All the screened adsorbents, i.e., Eucalyptus camaldulensis sawdust (ECS), Eucalyptus bark, white cedar sawdust and tobacco stem showed maximum Cr(VI) removal efficiency at pH 2. The potential and an abundantly available precursor waste adsorbent, i.e., ECS, was converted to highly efficient (≥ 80% removal) activated carbon (AC-ECS) through two stage phosphoric acid activation (method V). A mesoporous activated carbon, i.e., AC-ECS was developed successfully and it displayed highly efficient Cr(VI) removal of 87% at pH 3. The morphological changes were detected through scanning electron microscopy. An increase in surface area of AC-ECS was noticed i.e., 217 m2 g-1 than its precursor biomass of ECS, i.e., 40 m2 g-1 using Brunauer–Emmett–Teller analysis. The evidence of Cr(VI) ions adsorption was confirmed through shift of wave number of the various surface functional groups and the appearance of crystalline peaks using fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analyses respectively. Cr(VI) adsorption data of AC-ECS exhibited the best fit to Langmuir isotherm (R2 = 0.999) revealing monolayer adsorption than its precursor biomass, i.e., ECS, where Cr(VI) adsorption data displayed best fit to Freundlich isotherm (R2 = 0.992) showing multilayer adsorption. Kinetic studies demonstrated the chemisorption as the rate limiting step. Thermodynamic studies exposed the non-spontaneous nature of reaction in non-activated adsorbents, while only AC-ECS displayed spontaneous reaction on the basis of Gibbs free energy. Fixed bed column studies of both AC-ECS and its precursor ECS showed that the exhaust time reduced with an increase of solution flow rate and contaminant concentration, whereas an inverse trend was observed with increasing bed height. ECS and AC-ECS packed columns indicated the increased breakthrough time from 670-1270 min and 5595-12270 min with respect to bed height (5 to 15 cm), respectively. However the increasing flow rate (5 to 15 mL min-1) and contaminant concentration (50-90 mg L-1) resulted the decrease in breakthrough time from 670-20 min and from 670-90 min for ECS packed column, respectively and from 5595-1330 min and 5595-800 min in case of AC-ECS packed column, respectively. Column study confirmed that AC-ECS packed columns were found more effective for Cr(VI) removal than ECS, as the AC-ECS exhibited the high exhaust and breakthrough times than ECS. Economic feasibility showed that total cost for the preparation of 1 kg non-activated ECS was approximately 4.4 PKR, while the cost of phosphoric acid activated carbon, i.e., AC-ECS prepared in the lab was found to be 4493 PKR. 1 kg of AC-ECS can treat approximately 1562 L of wastewater containing Cr(VI), which is larger than ECS (1388 L). It can be concluded that Eucalyptus camaldulensis sawdust is a good adsorbent for Cr(VI) adsorption among other tested non-activated forms of biomasses, and this is a good lignocellulosic material for the development of highly efficient activated carbon, i.e., phosphoric acid activation. The study recommends to assess the Cr(VI) adsorption performance of both ECS and AC-ECS in multiple solutes mixtures and to uncover the interference of other salts or metal ions through further batch and column studies at pilot scale and ultimately for the launch of these adsorbents for field scale treatment of wastewater.