The concentration of aluminum atoms needs to be controlled toWe want to obtain a silicon semiconductor by doping with Al. Find the value of the diffusion coefficient at a temperature of 756°C?Data:Diffusion coefficient of Al in Si (T = 500°C) = 2.69·10-22 cm2/sDiffusion coefficient of Al in Si (T = 1000°C) = 1.806·10-13 cm2/sD0 = 8 cm2/s; R = 8.314 J/mol K

Describe in a few sentences the effect of temperature on a typical ferromagnetic material. Provide a qualitative plot of B vs. T.v

Divalent ionic crystals. Barium oxide has the NaCl structure. Estimate the cohesive energies per molecule of the hypothetical crystals Ba*O¯ and Ba**O¯- referred to separated neutral atoms. The observed nearest-neighbor internuclear distance is R, = 2.76 Å; the first and second ionization potentials of Ba are 5.19 and 9.96 eV; and the electron affinities of the first and second electrons added to the neutral oxygen atom are 1.5 and -9.0 eV. The first electron affinity of the ++ %3D

(b) Using the Crystallographer's formula to determine the density (in g/cm³) of Po: ρ = Σ Ζ * Μ Vell* N You must know that a primitive cubic cell has Z = 1 Since Po is a metal, the value of "i" = 1, since it's the only entity! MM of Po= 208.998 g/mol Vcell (in cm³) = a³ Vcell (3.36 x 10-8 cm)³ = 3.793 x 10-23 cm³ N = 6.022 x 1023 atoms/mol Thus: p = (1 atom/cell) (208.998 g/mol) = 9.16 g/cm³ (3.793 x 10-23 cm³) (6.022 x 1023)

(Unit cell); FCC of potassium (yellow) and Iodide anion (blue), calculate density of the KI solid and calculate the shortest distance between two iodide anions

1.At -185°C and 1 atm ethane (MW = 30.07 g/mol) exists as a solid with a FCC structure.  Using the data provided below: E/k=194.1K,  bo=0.1794 m3/kmol Determine the diameter of one molecule of ethane (in angstroms). 2. What is the void fraction? 3. Find the density of the solid etahne. 4. Calculate the distance of separation (in m) between two ethane molecules when the potential energy is at a minimum. 5. At the separation distance calculated in part (4), determine the minimum value of the potential energy between two molecules (in J).

A sample of silicon doped with antimony is an n-type semiconductor. Suppose a small amount of gallium is added to such a semiconductor. Describe how the conduction properties of the solid will vary with the amount of gallium added.

Calculate the density (in glam'3) for a ceramic AX, type 3having 6 cations associated with its cubic unit cell (6 cations/unit cell). The chemical formula for this ceramic is A The atomic weight in g/mol) for A and X are 184 and 213, respectively. The side length of the cube (a) is 0.34 cm Give the answer in an exponential form using 3 decimal numbers. For example: 3.1716-31

Clausthalite is a mineral composed of lead selenide (PbSe). The mineral adopts the rock salt structure. The length of an edge of the PbSe unit cell is 6.13 ÅÅ= at 25 ∘C. Determine the density of PbSe in g/cm3. Express the density in grams per cubic centimeter to four significant figures.

In the early days of X-ray crystallography there was an urgent need to know the wavelengths of X-rays. One technique was to measure the diffraction angle from a mechanically ruled grating. Another method was to estimate the separation of lattice planes from the measured density of a crystal. The mass density of NaCl is 2.17 g cm−3 and the (100) reflection using radiation of a certain wavelength occurred at 6.0°. Calculate the wavelength of the X-rays.