Fundamental physics concepts

Lattice Dynamics 2.1 Introduction The discussion has been done in chapter1 about the nature crystal structure of Silicon Carbide and its properties was under the equilibrium condition, which means the location of each atom is restricted at its lattice site. The vibration of atoms about their equilibrium sites will be considered in this chapter. The fundamental reason of this vibration is thermal and the lowest achievable energy (i.e. zero-point energy). The forces acting on atoms tend to always make them return to the equilibrium position. The relation between atomic forces and thermal motion can be called lattice dynamic. The atomic force at equilibrium is described by the following formula: F=-∇ ⃑ U=0 where U is binding energy "potential…

Electrical properties Figure. 8 shows the temperature dependence of resistivity of the Co(II), Ni(II) and Cu(II) complexes. As seen, the data reveal a semiconductor behavior where the resistivity decreases with the increases of temperature. The decrease of the electrical resistivity with increase of temperature is resulted from the increase of the charge carriers that can overcome the energy barrier and participate in the electrical conduction where in metal complexes, the metal…

during polarization. This case, Ag nanoparticles occupy the free volume holes (amorphous phase) and fill the interstitial positions between the PVA chains in the amorphous phase and connected these chains to some bonds by a charge interchange process between the Ag and PVA chain network. Moreover, this complex formation increases with the time of reaction. As a result, both charge carrier density and the films conductivity are increased. there is a decrease in the interfacial barrier, caused by…

SYMMETRY WRITING EXERCISE PARAGRAPH I FePO4 is a type of -quartz, and when the temperature is relatively low, FePO4 still has the tetrahedral structure as seen in Figure 1. The Fe-O-P bridging angles are more similar between the FePO4 and -quartz. Change in the cell parameters become more significant between temperatures of 294K and 1073K, and it slowly acquires an octahedral structure as the temperature increases. When temperature reaches 980K, the compound transitions and the tilt angles…

Two computation cases were introduced, one with a polyurethane graft and another with a silicon rubber graft. The computations were done under a pulsatile flow. Both cases were computed under maximum peak pressure as mentioned in the method section. The flow volume rate is expressed by integrating on surface as followed: Q=∬_A^ ▒v.dA (5) By integrating flow volume rate in time…

Heat of Combustion of Magnesium Hypothesis: Hess’s law states that “the enthalpy change for the conversion of reactants to products is the same whether the conversion occurs in one step or several steps” (DiGiuseppe et al,2012,p.314 ). A series of two experiments will perform in this lab in order to find ΔH1 and ΔH2 . In addition, ΔH3 will be obtained by reference. It is predicted that the combustion of magnesium will have a negative enthalpy, since combustion is an exothermic reaction. Also…

Glass. In modern times this substance is used as a basic necessity for windows, car windshields, bottles, jars, glasses, dishes, etc. Glass was discovered by Egyptians in the sixteenth century B.C. when experimenting with their pottery. During the fifthteenth century, the Egyptians started venturing into glass vessel making. Later, the Phoenicians and Mesopotamians followed suit by developing a fairly adequate method of glass blowing. To describe glass blowing in brief, glass must first be…

Rosseland Radiation Model The Rosseland Model (Diffusion approximation model) is applicable when the medium is optically thick i.e. the optical thickness is much greater than 1 where a is the absorption coefficient of the medium, σ is the scattering coefficient of the medium and L is the average path length. The radiative heat flux is approximated as [3], (2.13) where qr is the radiative heat flux, Γ is the radiative diffusivity and G is the incident radiation. In contrast to the P-1 model…

1. Temperature : A temperature is an objective measurement of hot or cold. It is measured by thermometer (Paul S. Welch,1938). Its most common unit is celcius. It is an important physical property of water because temperature controls the rate of most of the chemical reaction. As temperature affects the growth, reproduction and immunity of living organisms, therefore, drastic temperature changes can be fatal to living organisms. 2. pH : pH is a numeric scale used to specify the acidity or…

Theoretical analysis for HPHX's performance by using dimension analysis theory. Assumptions Steady operation conditions exist. The surface temperature of the condenser section is equal to the temperature of Refrigerant R-22. Properties The exit temperature of air, and thus the mean temperature, is not known. We evaluate the air properties at the assumed mean temperature of 42OC (will be checked later) and 1 atm as following: K= 0.02722 (W/m.K) …