Crystal Definition and 382 Threads

Hello, Does anyone know any (free) software for generating simple crystal structures like forms of SiO2 or TiO2? It must be a really common problem. My current strategy is to search the web for hours until I get lucky. There are online databases which have really complicated structures from...

Homework Statement Draw the position of the atoms in the two neighboring planes of the GaAs crystal perpendicular to vector [010]. Find the type of the lattice and the basis of 2D crystal which is made by singling out those two neighboring layers from 3D lattice. Homework Equations...

Simple explanation for non-physicist, please!

As I know, electrical conductivity is a second rank tensor. So in a cubic structure, there is no orientation dependence of electrical conductivity (isotropic). But how come Si has higher electron conducitivity along [001] and hole conductivity along [110]?

Homework Statement Show that because a pure rotational displacement field u(r) has no effect, that the energy of a crystal only depends on the symmetric strain tensor epsilon_ij. Homework Equations As in Ashcroft & Mermin (22.72), the energy of a crystal as a function of displacement field...

Hello experts! Q#1) Write down the family members of {110} plane in a cubic crystal. Attempted Answer) According to my study the this family has 6 members. But what are they? Are these the members (110),(101),(011),(-1-10),(-10-1),(0-1-1)? Q#2) Describe the method to construct the...

I need to create a 10 MHz square wave clock signal which gets terminated into a 50 ohm resistor for use by a waveform generator. The specifications for the waveform generator suggest a 12 to 14 dBm power level for the input clock. ie. a power level of ~16-25mW. So I've been looking to...

To calculate the intensity of the scattered radiation from a crystal after irradiating with X-rays, one can add up all electromagnetic fields of the oscillating electrons (calculated using the Liénard–Wiechert potential). Taking the time-average of the norm of the Poynting vector of the...

I have been acquiring some nice molecular models of graphene, buckyballs, and things like the model below. http://www.indigo.com/images/product/172.jpg One thing I have not been able to find are crystal models with the different orientations like face-centered cubic, body-centered cubic...

Hi there, I'm measuring the voltage on the output of an amplified photodiode circuit that is capturing light emitted by an Liquid Crystal Display (LCD) projector and there is a periodic voltage drop which I don't know the reason. The projector is projecting an all-white image. I've been...

I'm trying to learn crystallography and I've had trouble with this concept since the very beginning of the course. It's been so long since it's been introduced that I'd be embarrassed to ask the prof. Right now, I seem to understand the principles of diffraction based on the Miller model; that...

Recently did an exercise calculating the theoretic heat capacity of a metal. In the solutions manual they put the degrees of freedom f=6. Why is that? I know that a rigid body has 6 degrees of freedom but does that apply to each atom in the crystal?

[FONT="Times New Roman"]I need to derive the lattice parameter in terms of the Zn-S separation distance, l. I looked up the value and I've found it to be a = \frac{4}{\sqrt{3}}l The way that I started my derivation was saying that each tetrahedron has a sulfide ion in the center, so then we...

Homework Statement I'm in grade 11 working on a science fair project I found on this site: http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_p014.shtml Grade 11 physics doesn't cover much so I'm confused about why the radio is set up the way it is... I know that...

Hi there, I am reading some introduction of crystal and the book mention that we can use the x-ray to explore the structure of the crystal. I more or less understand the idea between that, it is kinda like scatter the incoming wave and observe the outgoing wave. But the mystery stated in the...

Hi there, I am reading Kittel's Introduction to Solid State Physics and I am quite wondering how the Madelung constant was derived for ionic crystal as in the example. In the book, he consider the repulsive potential of the form \lambda \exp(-r/\rho) and the interaction energy can be written...

user meopemuk mentioned this: In the case of a crystal model with periodic boundary conditions, basis translation vectors e1 and e2 are very large (presumably infinite), which means that basis vectors of the reciprocal lattice k1 and k2 are very small, so the distribution of k-points is very...

This is two questions really in crystal-field theory. For tetrahedral crystal fields, why are the 't' and 'e' orbital sets switched in energy with the case in octahedral crystal fields? For square planar crystal fields, why do we discard the ligands along the z-axis? Why not discard the...

What decides that which salt will take up which crystal lattice? Some salts have cubic lattice , some have hexagonal , some have orthorhombic - but what factor decides which crystal system the salt will take over. Most of the examples i have seen consist of cubic lattice system. Is it becasue...

Homework Statement A doped silicon ingot is to be grown by the Czochralski technique with a dopant concentration of 1016boron atoms/cm3. If k0 = 0.9 for boron/Si, what concentration of boron atoms should be in the melt? Homework Equations Cs/C0 = k0 (1 - m/m0) k0-1 k0 = Cs / Cl The...

How do crystallographers go from a diffraction pattern to actually determining the structure of the crystal? http://pwatlas.mt.umist.ac.uk/internetmicroscope/micrographs/microscopy/decr5a-a-big.jpg

Homework Statement Be the vectors a, b, c such as: | a | = | b | = | c | = 10.5 Angstron The angles between these vectors are: alpha = beta = gamma = 109.5 degree These vectors represent the lattice vectors of a crystal. Find out their components (a_1, a_2, a_3, b_1...

Homework Statement We have that for a crystal the lattice parameters (in angstrom and degree) are: a b c (in Angstrom) 10.5 10.5 10.5 \alpha β γ (in degree) 109.5 109.5 109.5...

Hi, this is my first post. I have a problem to solve: "Given the plane (1 1 1) of 3 lattice sc, bcc and fcc, says in which case there is diffraction" I hope that someone helps me... Thanks for helpers

Why does a crystal oscillator need load capacitors? Is it because there will be some capacitive load across the xtal pins?

I have one hollow core fiber, the core is around 20um, Numerical Aperture is 0.03. The spot size of Ti:Sapphire laser is around 2~2.5mm. So I used focal length 50mm. But only very few power can be achieved (6uw). I wonder the reason. Could someone please give me some suggestions?

How can one derive the relationship for a cubic crystal: d= \frac{a}{\sqrt{h^2 + k^2 + l^2}} It is shown here. This is probably trivial but I am having trouble proving it as the Miller indices are reciprocals but the reciprocal is not distributive. This isn't for homework by the way - I...

What is an optic axis of a calcite crystal ?

im just curious and i just want to know, do you need a Beta-barium borate crystal to entangle photons? are there any alternatives? can you use sodium chloride crystals as a possible option? what makes a Beta-barium borate so special and different from any other crystals? please provide good info...

How to dehydrate a solid crystal? I have a solid crystal with structural channels in it which are filled with water molecules. The size of each channel is 2.5 to 5 angstrom and a water molecule is 2.7 angstrom on its longest side. What is the best way to dehydrate it? I have tried heating it...

Hello, I'm really confused by something. Cscl is simple cubic. But how it this possible? With the cl in the middle it looks like a bcc structure. Also howcome when you have 2 caesium its bcc and not simple cubic? its the same structure yet it changes to bcc. Is it because they are both atoms...

Like quinacridones or HgS and HgS \gamma. I don't understand how crystal phase can act on the resonace of the electrons...Please reference! Thank!

Sorry this is largely chemistry based, but delves into electron theory. I'm a little confused about how the colour of transition metal compounds arises. I understand that say for [Cu(H2O)6]2+, you have an octahedral arrangement around the central atom, and the specific positioning of these...

Considering only the 4 lower-right atoms (one unit cell), I'm somewhat confused as to why the coordinates for the center atom (b) is (1/3, 2/3, 1/2) with respect to (a1, a2, c). c is pretty self explanatory, but I don't quite get the other 2. I think one of my main confusions is where the...

In this diagram I can't figure out what that barycentre part of the diagram means. The first section of the diagram represents the energy of the d orbitals before the ligands come into the picture and the 3rd section represents the energy of the d orbitals after the 6 ligands have arranged in...

Homework Statement You wish to study a material with a cubic crystal structure with three orthogonal sides of length a = 0.3nm. What is the longest possible wavelength of the X-ray source you could use to reveal the (211) Bragg peak of the crystal? Homework Equations nλ =...

Homework Statement The potential Energy per atom in a covalent crystal with interatomic spacing r may be written φ(r) =2ε [A (σ/r)^12 -B (σ/r)^ 6 ] Derive expressions for the equilibrium interatomic spacing and the cohesive energy of the crystal. Homework Equations Again the problem is...

So how many pounds does it take for quartz to break into several diffrent peices?

My lab needs to purchase a new bbo doubling crystal for our femtosecond laser. I have been looking around but cannot find any. Our old one is from Thor Labs but they discontinued making them. Does anyone know a company that sells them?

Say I have a 25MHz Crystal that's connected to a Microprocessor/Microcontroller or spread spectrum clock generator. Does the crystal emit Electromagnetic radiation at its fundamental frequency or it's harmonic frequencies? I keep hearing - " I see a peak at ~50MHz, it must be the 2nd harmonic...

Given a crystal structure and the cell edges (a,b,c) , angles (alpha, beta, gamma) and the fractional coordinates of all atoms in the unit cell. Also given an arbitrary unoccupied site P by fractional coordinates (s1,s2,s3). How can I determine all the sites that are crystallographically...

Hi! I'm new to these forums. To get right to it, My head'z been spinning wondering .. Is there a high symmetry point in a crystal about which *all* point operations can be re-centered? I can show this for a simple lattice. Does anyone know if this is true for any complex crystal as...

Homework Statement In a particular Low Energy Electron Diffraction (LEED) study of a solid surface, electrons at 45 eV were diffracted at \phi = 53 degrees. Calculate the crystal spacing d. Homework Equations n\lambda=2dsin(\phi) \lambda = hc/E wavelength = c/v E = vh(n + 1/2) Note here v...

If I am correct, crystal frequencies depend on the size, shape/cut, and purity of a crystal(?) How can you measure (what instrumentation) the frequency/ies of a natural crystal (other than just quartz)?

Homework Statement 10 g Fe and x ml H2SO4 forms y gFeSO4*7H2O Write a balanced chemical equation for the reaction, and determine the coeffisients y and x. The H2SO4 is 1 M. Homework Equations n=V*c n=m/Fm The Attempt at a Solution First thing I was trying to set up the chemical...

I'm not sure what is the correct equation for motion of electron in a crystal lattice under the influence of magnetic force. On may easily proof that for electric force the following equation holds (the proof might be found in http://ajp.aapt.org/resource/1/ajpias/v54/i2/p177_s1" ): \hbar...

hey everyone I am new to the site an new to physics ( bare with me if I am not as smart as some ) , =) ok, i have this friend who is world widly known for his work, but cut this short, he uses electricity an crystal an can do some out of the ordinary stuff with this he has been in numerous...

Is it at all possible for the crystal sugar from one package to be qualitatively different from crystal sugar from another package (brand, etc.)? In other words, if I need sucrose for an experiment, could it affect the results if I use crystal sugar from different packages or of different...

Hi It is know that the colour exhibited by coordinate compound is because of d-d electron transitions. These d-d transition lead to absorption of photons of a paticular frequence. AND when a electron become exited due to absorption of photon it should radiate electromagnetic wave of frequency...

Let's consider we have a crystal and we search the energy relation of the bands as function of the reciprocal lattice vectors. We would do that theoretical by applying the Tight-binding method. Let's consider that each band is associated with some kind of orbital ( for instance, 3d orbitals). Is...