Bulk and Nanomaterials Synthesis Experiment

Bulk and Nanomaterials Synthesis Experiment Introduction In recent years, bulk and nano materials in several areas of pure and applied sciences have captivated a great interest amongst the researchers. Because of their fascinating and tremendous properties with great potential in many applications such as solid state lasers, lamp industry, colour displays, etc (Senthil et al, 2001; Tamrakar et al, 2013â€Å"a†; Tamrakar et al, 2013â€Å"b†; Tamrakar et al, 2014â€Å"a†; Tamrakar et al, 2014â€Å"b†) these bulk and nano materials having great interests of research. Experimental Section 2.1. Materials and Synthesis Samarium oxide (Sm2O3) and samarium nitrate (Sm(NO3)3.6H2O) were used as the rare earth sources of K3Gd(PO4)2:Sm3+ in the following synthesis methods. Urea (NH2CONH2) and citric acid monohydrate (C6H8O7.H2O) were used as fuels in combustion and citrate gel combustion methods. The raw materials in carbonate form were used in solid state method whereas in case of combustion and citrate gel method it could be used in nitrate form. 2.1.1. Synthesis of undoped K3Gd(PO4)2 and Sm3+ doped K3Gd(PO4)2 by solid state method The raw materials potassium carbonate (K2CO3), gadolinium oxide (Gd2O3), ammonium dihydrogen orthophosphate (NH4H2PO4) and samarium oxide (Sm2O3) of high purity were mixed and grounded together with the smallest possible amount of ethanol in an agate mortar for an hour to obtain a homogeneous mixture. The stoichometric amount of starting materials was weighed according to the balanced chemical reactions for the undoped K3Gd(PO4)2 (equation (1)) and Sm3+ doped K3Gd(PO4)2 (equation (2)) and are given as follows: The mixed powder was transferred to the alumina crucible and placed into the muffle furnace at 850  °C for 7 hours. The prepared phosphors were cooled to room temperature and grounded to obtain fine powder. 2.1.2. Synthesis of undoped K3Gd(PO4)2 and Sm3+ doped K3Gd(PO4)2 by combustion method with urea (NH2CONH2) Urea (NH2CONH2) as a fuel used for the preparation of the undoped K3Gd(PO4)2 and Sm3+ doped K3Gd(PO4)2 by combustion method. The reagents used were potassium nitrate (KNO3), gadolinium oxide (Gd2O3), ammonium dihydrogen orthophosphate (NH4H2 PO4), urea (NH2CONH2) and samarium nitrate (Sm(NO3)3.6H2O) of high purity. The materials were weighed according to the balanced chemical reactions (equations (3 4)) given below: The stoichometric ratio of reagents was kept at unity, so that the heat liberated during combustion be maximized for complete combustion. The weighed reagents were dissolved in a small amount of distilled water and thoroughly mixed in an agate mortar to obtain a paste. The obtained paste was transferred to the alumina crucible and inserted into the pre-heated muffle furnace sustained at 600. The combustion process occurs with the evolution of the large amount of gasses. The whole reaction takes 3-5 minutes to complete. The final white foamy product was cooled to room temperature and ground to obtain fine powder. The fine powder then further annealed at 850 for 3 h to get complete crystallanity. 2.1.3. Synthesis of undoped K3Gd(PO4)2 and Sm3+ doped K3Gd(PO4)2 by citrate-gel combustion method with citric acid (C6H8O7.H2O) Potassium nitrate (KNO3), gadolinium oxide (Gd2O3), ammonium dihydrogen orthophosphate (NH4H2 PO4), samarium nitrate (Sm (NO3)3.6H2O), citric acid monohydrate (C6H8O7.H2O) of high purity was used as the starting materials for the preparation of the undoped K3Gd(PO4)2 and Sm3+ doped K3Gd(PO4)2. The citrate gel was prepared according to the following chemical reactions: The reactants in stoichometric amounts were weighed according to equations (5 6) and dissolved together in 10 ml distilled water. The mixed solution was heated to 85 °C on a hot plate with continuous stirring for 2 hours to obtain a viscous gel. The obtained gel was placed into the pre-heated muffle furnace maintained at 600. After several minutes, the gel boiled followed by evolution of huge amounts of gases. Eventually, spontaneous ignition occurred and the gel underwent combustion. The whole process ended within a few minutes. The final products were cooled to room temperature and grounded to obtain fine powder. The fine powder, then further annealed at 850 for 3 h to ensure that all the unwanted impurities were evaporated and only the higher temperature pure monoclinic phase of K3Gd(PO4)2 remains as the final product. 2.2. Characterization The X-ray powder diffraction patterns of the synthesized powders were recorded by using Philips X’pert MPD system with Cu KÃŽ ± radiation (1.5406 Ã…) operated at 40 kV and 30 mA. The 2ÃŽ ¸ was varied in the range of 10 ° ≠¤ 2ÃŽ ¸ ≠¤ 60 ° with step size of 0.01 ° (2ÃŽ ¸) and count time of 18s /step. The lattice parameters were calculated using unit cell program [ †¦]. The diffuse reflectance spectra were recorded using a Shimadzu UV-VIS-2600 double beam spectrophotometer coupled with an ISR (integrating sphere assembly). The photoluminescence (PL) (excitation and emission spectra) and the lifetime measurements of the synthesized phosphors were recorded using a Cary-Eclipse Spectrofluorometer equipped with a 150W Xenon lamp as an excitation source with slit width 5 nm and 2.5 nm for excitation and emission monochromator. All the measurements were performed at room temperature. 3. Results and discussion 3.1. Phase formation The powder XRD patterns of the Sm3+ doped K3Gd(PO4)2 samples synthesized by solid state, combustion and citrate gel combustion methods were measured. The patterns are shown in figure 1 and compared with that of the JCPDS card 049-1085 (K3Gd(PO4)2). The XRD patterns of Sm3+ doped K3Gd(PO4)2 phosphor indicates a pure phase of the standard K3Gd(PO4)2 and all the peaks were in good agreement which belongs to the monoclinic phase with space group P21/m [20]. Also the XRD shows that the formed materials are in crystalline and homogeneous forms. The particle size of the prepared samples have been calculated from the full width half maximum (FWHM) of the intense peaks using Debye Scherer formula. Here, D is particle size, k is the Scherrer’s constant (0.89), ÃŽ ² is FWHM (full width half maximum), ÃŽ » = 1.54 A ° is the wavelength of X-ray source (Cu (KÃŽ ±) radiation), ÃŽ ¸ is Bragg angle of the X-ray diffraction peak. The average particle size of the Sm3+ doped K3Gd(PO4)2 phosphor prepared by solid state method was found approximately 39 nm, while those prepared by combustion and citrate gel methods were found to be 23 nm and 27 nm. The decrease in the particle size is due to increase in the FWHM of the XRD peaks for the phosphor synthesized by combustion method and citrate gel combustion method. The variation of particle size with FWHM is also tabulated in table {}. References

Our Poor Reading Culture Essay

One of the cruel jokes that are often made at the expense of the black man is that, if you want to hide something from him, simply put it inside a book. The idea is that, he does not have the habit of reading for pleasure and knowledge and as such is not likely to go near any secret kept in a book. Another variant of this joke is that, if you want to hide something from a fool, simply hide it inside a book because a fool does not read. Whichever of the variants of these jokes, we are familiar with hardly matters. What is important is that, in Ghana today, particularly in our universities and other tertiary institutions, there is a low level of reading habits among students. Very few students read anything outside the prescribed texts for their studies. Many adults as such loathe reading just to broaden their horizon. Yet an informed citizenry with a broad outlook on life is necessary for good governance and for the successful practice of democracy. It is unfortunate that our race has been identified for the lack of wisdom in most of its people in not reading as much as we ought to. The joke at our particular expense should serve as a wakeup call on all students and blacks to embrace the culture of reading. We should begin to ask ourselves whether it is a mere coincidence that the black race is today the poorest, the least developed and the most backward technologically of all the races or there is somehow a connection between the poor reading culture among the blacks and their relative backwardness. People of all races particularly, we the blacks ought to read because; the wisdom of the ages is contained in books. Educators, psychologist neurologist have all confirmed that, reading is one of the most valuable tools for brain development. The decline in reading nowadays can be traced principally to some of the following causes: Harsh economic reality which affects the buying of books; Poor educational system; inadequate reading materials in the library; Laziness on part of students; Problem of awareness of the need to read lastly, the Poor method of teaching â€Å"reading’’. Since food for the body is more important, than the one specifically meant for the brain, many have chosen to sacrifice books in favour of other more urgent needs. The rise of the computer with all their addictive games, have also conspired against book reading. However, while TV and the computer are other tools of education and entertainment, they cannot completely replace books in equipping the citizenry in the task of personal and national development. Reading is a skill that should be acquired and not inculcated. Nature did not deem it fit to just bestow it on us, therefore, we students have a serious role in getting ourselves back to the book, parents, lecturers, the government and NGO’s alike also have a role to play in getting the society back to the book. The time has come for us to end that old- fashioned and cruel joke about us being fools, because we do not want to read.

Annotated Bibliography On Terrorism And Terrorism - 945 Words

Formal Outline Topic: Terrorism General Purpose: To Persuade Specific Purpose: To Persuade the reader that terrorism exists and that is important for the U.S to increase their security in order to decrease the terrorism in the country. Thesis: Although terrorism has caused most of the world to increase their security, it still seems to not be enough to make the world safe, Therefore the U.S. should increase their security more by doing more background checks and watch more closely for who is going through the borders. I. Introduction 1.Terrorism is increasing domestically and internationally every year. 2.There has been 130,000 terrorism-related fatalities worldwide between 2006 and 2013 (â€Å"Bloch† 1). 3.Terrorism is the threat of violence used to achieve a political or religious goal, it could be carried out by individuals or groups (â€Å"Briggle† 1) 4.Although terrorism has caused most of the world to increase their security, it still seems to not be enough to make the world safe, Therefore the U.S. should increase their security more by doing more background checks and watch more closely for who is going through the borders. II.The Problem A.The History of Terrorism 1.1961-1990 a.The first United States aircraft to be hijacked was by a Puerto Rican on May 1, 1961 who forced the plane to fly to Havana, Cuba, where he was given asylum. (â€Å"Chronology† 1) b.The New People’s Army (NPA)Show MoreRelatedAnnotated Bibliography Of The Bibliography1341 Words   |  6 Pages1. 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Sample Chemistry Lab Report

A lab report is a brief description and a summary of a chemical experiment written for the purpose of describing the way it was conducted and its outcome. A sample chemistry lab report is an example of how to write an appropriately formatted, informative, and comprehensible lab report, which would enable people to use the results of a current experiment in their future science activity. A sample chemistry lab report will help to understand a typical structure of this document and basic requirements for it. Title: Bases and Acids. Date: Jan 17th, 2017. Purpose: To determine which products in a typical household contain acids or bases. Apparatus: Eight glass vials, bowl, colanders, eye-dropper, water, eleven leaves of a red cabbage; Vinegar, lemon juice, washing powder, baking soda, milk, white wine, liquid drain cleaner, shampoo. Procedure: Eleven red cabbage leaves were chopped and put into a bowl filled with 500 ml of boiling water. In thirty minutes, when water changed its color into purplish and was cooled, with a help of colanders the cabbage juice was separated from leaves. Eight separate vials were filled with vinegar, lemon juice, washing powder, baking soda, milk, white wine, liquid drain cleaner, and shampoo. With a help of an eye-dropper, a small quantity of the cabbage juice was added into each of the vials. Time: 35 minutes. Data: Vinegar in the vial number 1, lemon juice in the vial number 2, soda in the fourth one, white wine in the sixth one changed their color into light pink. It indicated that those products were examples of acids. Washing powder in the third jar, milk in the vial number five, drain cleaner in the seventh one, and shampoo in the eighth turned green; therefore, those are bases. Results: Acids and bases are opposite chemical classes, which neutralize each other. Most acids are quite corrosive so they are able to dissolve some metals. Bases can produce a reaction with acids, which results in salt and water. A generally accepted method of identifying a chemical nature of a liquid is a litmus test, and if a paper turns red or blue, the chemical is acid or base respectively. However, an experiment with cabbage juice is productive as well as a litmus one since this juice is an efficient, simple, and affordable acid-base indicator, and when it is mixed with a certain chemical, the substance changes its color into either pink or green. In the first case, it indicates an acid, while in the second case, it determines a base. Furthermore, it is safe and inexpensive; therefore, it can be used in amateur chemical experiments at home, in a learning process in schools or colleges, or in science activities. This experiment can be used in order to prove that there are lots of examples of bases and acids in a household. Most cleaning substances and a few food products, in particular, dairy are bases by their chemical nature. The vast majority of beverages, fruits, vegetables, and medicines are acids. As a rule, bases are soapy and slippery while acids are corrosive, bitter or sour, and quite frequently with an acidic smell.