3.1. Powder X-ray Diffraction (XRD) analysis
Fig. 1. shows the powder X-ray diffraction pattern was used to record the crystal information of zinc ferrite nanoparticles synthesized by both conventional and microwave assisted combustion method. The phase identification was carried out by comparing the obtained data with standard diffraction patterns. The diffraction peaks at 2θ of 29.90º, 35.22º, 36.84º ,42.80º, 53.09º, 56.59º, 62.13º, 70.47º, 73.48º, 74.48º, and 78.40º can be ascribed to the reflection of (220), (311), (222), (400), (422), (511), (440), (620), (533), (622), and (444) planes of the ZnFe2O4 spinel, respectively. All the detectable peaks in the XRD patterns could be indexed with the standard JCPDS data (82-1042). There is no
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The average crystallite size of ZnFe2O4-CCM (sample A) was 74.0 nm. For ZnFe2O4-MCM (sample B) it was found to be 37.0 nm. As the calcinations temperature increases (sample A), the corresponding peaks become stronger in intensity, which implies that the crystallinity is higher and the crystallite size is larger in the sample prepared by conventional method. For sample B, single phase cubic ZnFe2O4 produced within the shorter time which give rise to lower crystallinity and smaller crystallite …show more content…
Fig. 4(a-b) represents the HR-SEM images of the agglomerated ZnFe2O4 nanoparticles prepared by CCM (sample A). Fig. 4 (c-d) reveals the formation of ZnFe2O4 nanoparticles prepared by MCM (sample B). All the samples exhibit a compact arrangement of homogeneous nanoparticles. The shape of the ZnFe2O4-MCM particles is basically globular and the particle diameters are in the range of 25-45 nm. The average particle size of the ZnFe2O4-CCM is in the range of 350-800 nm. The micrographs indicate that the particles are nearly spherical with uniform agglomeration to give large and irregular crystals, which may be due to the preparation method, defects, effect of annealing and the presence of magnetic interactions among the particles. It is a well-known fact that the temperature and reaction time are the two essential factors in determining the morphology of the nanomaterials. In contrary to the conventional heating, during the time of microwave heating, the heat is produced internally within the material, rather than from external heating sources, and hence inverted temperature gradient is produced. In microwave method, the nanoparticles have been produced, due to the rapid heating achieved in short time duration, and suppressed diffusion process [34]. Thus, higher temperature of combustion in a furnace caused grain growth compared to the volumetric and rapid microwave
The nano-thermal analysis method is capable of studying the specific regions of a sample irrespective of its composition. In a multi-component sample, the analysis methods make it possible for the researchers to distinguish between the different components and identify the different characteristics found in each of the sample (Craig, 2002). During the analysis of any sample, the nano-thermal method does not necessarily require the physical alteration of the sample. In its place, it is capable of analyzing any sample through surface studies.
In 1895, Professor Wilhelm C. Roentgen, a German physicist, was working with a cathode ray tube, much like our fluorescent light bulb. The tube consisted of positive and negative electrodes encapsulated in a glass envelope. On November 8, 1895, Roentgen was conducting experiments in his lab on the effects of cathode rays. He evacuated all the air from the tube and passed a high electric voltage through it after filling it with a special gas. When he did this, the tube began to give off a fluorescent glow. Roentgen then shielded the tube with heavy black paper and discovered a green colored fluorescent light could be seen coming from a screen located a few feet away from the tube.
Zirconia has three crystalline forms: monoclinic phase, tetragonal phase and cubic phase. Monoclinic phase exists in zirconia stable up to temperature 1170˚C. Above 1170˚C, the monoclinic phase transforms to tetragonal phase and further transform to cubic phase above 2370˚C. While cooling down below 1070˚C, tetragonal phase becomes unstable and start transformation of monoclinic phase. Thus tetragonal phase is hard to exist at the room temperature.
Ceramics are most commonly used in dental applications as restorative materials for crowns, cements and dentures.
Scanning electron microscopy (SEM) technique was employed extensively through want this study to examine and obtain images of prepared samples. The associated analytical facility of Energy dispersive X-Ray (EDX) analysis was used to identify and quantify the elemental composition of the prepare samples.
According to recent statistics, zinc is the third most commonly used nonferrous metal in the United States. This unassuming metal was among the first minerals exploited by Man, used as a decorative material for thousands of years, although it never achieved the fame and notoriety of other metals such as gold or silver. In more recent times, new extraction and processing methods have allowed Man to produce higher-quality zinc than ever before, and to use it in an astonishingly high number of chemical and high-tech applications.
Polymorphism refers to the ability of the crystal to exist in different lattice structure depending on the environmental conditions. In this case, FePO4 displays two kinds of lattice structure depending on the temperature and pressure of the environment. As mentioned previously, FePO4 crystals exist in alpha-structure in low temperature and pressure and changes to beta-structure in high temperature and pressure. The temperature at which the FePO4 crystals change phase is around 980K. In the alpha structure, the tetrahedral is arranged such that the structure of the cell is trigonal and has a space group of P3221. The changes in the two symmetrically independent intertetrahedral Fe-O-P bridging angle and the correlated tilt angles is the main factor of the thermal expansion of the alpha structure. The volume and cell parameters of the alpha structure increases non-linearly as a function of temperature. The thermal expansion coefficient is found to be α (K-1) = 2.924 x 10-5 + 2.920 x 10-10 (T-300)2. As the temperature increase, the bond angles and the bond distance changes significantly especially as it increases towards the 980k where the structure will change from alpha to beta. As the temperature increase, the crystal structures realign to form the beta structure. The tetrahedral shifts such that the structure changes from trigonal to hexagonal and has a space group of p6222. It must be noted that there was no breaking of bonds and the atoms are still surrounded by the same neighbouring atoms. There is lesser symmetry in the beta structure as compared to the alpha structure. In addition, as the temperature rise, the bond distance between Fe and O in the tetrahedral actually increases, which corresponds to that of alpha quartz. This non-physical behaviour is most probably due to the increase in enthalpy of the atoms at high temperature, resulting in high amplitude and energetic vibrations. A fall in the time-averaged bond distance
In the early 1600s in England, King James ruled over the country. King James was named the successor to Queen Elizabeth I, whose reign covered the years from 1558-1603. During Elizabeth's rule over England, she enacted laws that were very harsh to those practicing Catholicism. Many had hoped that the anti-Catholic laws would change or even be overturned under King James I, whose wife was Catholic, but that didn't prove to be true. Not only did he "keep the old religious laws restricting Catholic worship, he even put new ones in place" (Barrow). Since the Catholic laws became more strict, people like Guy Fawkes decided to rebel and put a plan into action which would later be known as the Gunpowder Plot.
This paragraph will compare and discuss the crystal structure and chemistry between quartz (SiO2), iron phosphate (FePO4) and also looking into the α and β phase of FePO4. From the understanding of the given materials and crystal structure of both SiO2 and FePO4, both of the crystal are quartz-type crystal, the crystal arrangement are quite similar except for the difference in structural parameters tilt angle δ and bridging angle θ. This similarly carries on from the fact that both crystals had a α-β transition. However, from figure 2, the transition temperature for SiO2 and FePO4 are dramatically different, where one is at 846K while the other is 980K respectively. This is due to the tilt and bridging angle is lower than SiO2. Also from figure 2, we can show that both SiO2 and FePO4 thermal expansion in α phase are non-linear and control by angular variations and similarly no thermal expansion in β phase due to the lack
7 A. L. Chamberlain, W. G. Fahrenholtz, G. E. Hilmas, and D. T. Ellerby, ‘‘High Strength ZrB2-Based Ceramics,’’ Journal of the American Ceramics Society, 87 [6] 1170–2 (2004).
The materials with perovskite structure have numerous studies in last decade. Their structure, electrical and magnetic properties has been established up to a great extent. However, a detail study relating to double perovskite type of materials is still lacking in the literatures. In this report an effort is made to study in detail the behaviour of few double perovskite materials and then compared with their perovskite counterpart specifically their structure, morphology and electrical behaviour. These short of studies will provide a base line to select these materials for technological applications.
Orphans are kids without parents. In some cases, these children never know their biological parents, or others deal with the heart-breaking separation. After reading the novel, A Single Shard a reader learns about the main character Tree-ear. He is a twelfth century orphan with a guardian who cares for him plus gives him love and affection from a young age. Ruckel is a more modern-day orphan, but he lives in an orphanage with a bunch of children. He is a twentieth century orphan, but does not a lot of attention from anyone; he is with other kids. As the reader can see, Ruckel and Tree-ear have some similarities and differences.
Dry Powder Dry Powder is a play written by Sarah Burgess. The characters are as follows Seth, who works at KMM a New York Capital management as a managing director, then there is Jenny who is also a managing director, Rick who is the Founder/CEO, and Jeff who is the CEO of the Luggage Company. The play was basically about Wall Street and the fight between morality and money. Rick the CEO of KMM, threw an extravagant party and the protesters of Wall Street are calling him out on his fraudulence, money hungry attitude and extravagant life style. Now, it is up to the team to come up with a plan to clean up his image.
To investigate the temperature change in a displacement reaction between Copper Sulphate Solution and Zinc Powder
Since crystallization is often the first step when the pure solid product is separated from the liquid solution it represents a crucial process to tailor the solid properties, such as crystal size distribution (CSD), shape, polymorphic form and purity. Since these physical characteristics have a strong effect on the final product properties as well as on the efficiency of the downstream processes (such as filtration, drying etc.), the proper design and control of crystallization processes can have a significant effect on the overall efficiency of the solid production process and the quality of the final product.