Crystal Definition and 430 Threads

1) My teacher said that to analyze the properties of entire crystalline solid, we just need to analyze the properties of a unit cell, which is the smallest repeating unit of a crystalline solid. 2) But crystalline solids are known to be anisotropic, i.e. they have different properties in...

What are the reasons behind the different microstructures of steel at different temperatures? I don't understand why steel at high temperatures (austenite phase) would favor an FCC crystal structure while steel at lower temperature (ferrite) would favor a BCC crystal structure.

Hi. I'm wondering if anyone has any info on "quark seeding" like: Is it possible to dope the crystal lattice of a solid material by replacing electrons with quarks ?

Hello everyone, Does anyone know much about the crystal field splitting of the f orbitals in actinides, specifically uranium? I am doing research on the chemistry of uranium and have come across an interesting problem. U(IV) compounds undergo a transition to a non-magnetic singlet ground state...

Hello, We often hear about latent heat of vaporisation for a liquid, which basically corresponds to the energy required to break the hydrogen inter-molecular bonds in the liquid phase to form the gas. I was wondering, what is the equivalent physical explanation for the latent heat of a...

Hi, is there any software that I can use for drawing a crystal structure from atoms coordinates ?

Homework Statement [/B] Hi there! This is a question from a practice problem sheet I got from the lecturer of my Condensed Matter 1 course. Below are the normal vectors to the {111} and {112} lattice planes: Homework Equations [/B] Bragg Condition: \begin{equation} n \lambda = d \sin...

I am trying to solve a problem my camera exhibits. It has a sensor with 6000x3376 pixels. HD video is 1920x1080. In order to reduce the amount of information to the processor the camera throws away 2 out of 3 pixel lines. this creates a problem with thin lines tike telephone lines and makes...

I am currently looking at setting up a particle, with energy 5keV, traveling along the [11bar2 0] direction in Zr but I am struggling to get my head around how to resolve the velocity into the 3 directions to make sure it travels along this specific crystal direction. Could anyone help point...

I have a question that if we use external quartz crystal in Microcontroller and connect it to battery... Crystal gives regular and very accurate electrical frequency... But it should get mechanical vibration from somewhere to give electrical pulses... From where it receives mechanical vibrations?

Dear all, I am recently dealing with crystals. There is one question which puzzles me a lot. How to calculate the energy of crystals? For example, tungsten oxide has severl polymorphs such as alpha, beta , and gamma. What is the energy difference among them. Hope you can help with this...

Suppose that a static electric field E is applied on a conductive crystal. Then, how quantum mechanics describes the electron movements in the crystal? I have been trying to find an explanation, but have not found any. As I understand it, we could treat the E field as a time-dependent...

Homework Statement Use a computer to calculate numerically the potential energy, per ion, for an ifinite 2D square, ionic crystal with separation a; that is, a plane of equally spaced charges of magnitude e and alternating sign. Homework EquationsThe Attempt at a Solution The closest I can...

In explaining x-ray diffraction of crystals, usually the approach is to consider the atoms absorb radiation and scatter it, at some angles constructive interference occur and bright spots can be observed. It seems that it is different from the diffraction of slits or gratings because in these...

I understand that to calculate the potential energy of a paramagnet you use U=2μBBS but is there an equation to calculate the energy of a para-electric crystal. Also, if this equation required S, would that always be N/2 (is a para-electric crystal always completely polarised?)

How much does a Piezoelectric crystal (say PZT) compress when applied the maximum amount of force it can withstand ? also it would be very helpful if someone could tell me how much is this force typically ?

it makes sense that with an inelastic scattering process, a wave approaches a crystal, and then some energy is imparted to the phonons, so that the outgoing wave has a different frequency from the incoming wave. However, with an elastic scattering process, the frequency is unchanged-- how does...

Hi, I have a question. If a crystal absorbs light and the absorption process leads to some excess energy being released as heat . Can one calculate the temperature rise or an experiment would most certainly need to be done? Apart from the heat capacity of the crystal before light absorption...

I am wondering how can I solve following problem. I would like to see how can it be solved.

Hi, I need to calculate the velocity of a particle acting along a specific crystal direction. For example a PKA acting along the [135] direction in a crystal with a certain velocity, how do I find the velocity along the x, y and z direction? Also if I am looking at a hcp crystal, would this...

Homework Statement The polyacetylene chain is a 1D chain of Carbon atoms with single bonds and double bonds in succession. Spacing for single bond is ##a_s = 0.144~nm## and spacing for double bond is ##a_d = 0.136~nm##. Describe the structure using a "lattice" and a "basis". Sketch the...

Why are atoms taken to be spheres, and not of some other shape, in the calculation of the packing fraction of different crystal lattices? In other words, what experimental evidence and theoretical reasoning motivates this form of the atomic shape?

Hello, I've been having some trouble with a paramagnetism problem from my Statistical Mechanics class textbook (F. Mandl, Statistical Physics, 2nd edition, p. 25). The problem is as follows 1. Homework Statement 2. Homework Equations 1. The temperature parameter \displaystyle{ \beta =...

I had a roommate that is a regular user of meth. I recently found out that smoking meth leaves a residue behind that can be absorbed through the skin, which worries me because I let him borrow my car and he smoked meth in it before. I'm kind of a hypochondriac when it comes to health issues like...

Hi, I am currently reading the Feynman Lectures on Physics, and I have just finished the chapter about the geometry and the symmetries of crystals, and there is something I do not quite understand. There are 230 different possible symmetries which are grouped into seven classes (triclinic -->...

Homework Statement A simple model for liquid crystals confined to 2 dimensions is o assume each molecule can only align in one of 2 perpendicular directions. To construct a landau model its convenient to define order parameter, s : s = 2 ( Np - 0.5Nt ) / Nt Np - number molecules...

Hello! Does anybody know how to calculate the DOS as a function of Neff and λ/Λ? Thanks.

Homework Statement Investigate electronic bands in one-dimensional crystal in weak potential $$V(x)=\sum _n V_0(H(x-na)-H(x-na-a/3))$$ if ##H(x)## is Heaviside Theta function. a) Determine primitive cell, reciprocal mesh and first Brillouin zone. b) Calculate the difference between energy...

Hello! I know how to calculate band structure and density of states of photonic crystal (example is pic.1) Does anybody know how to plot such DOS maps? The second picture is from the article about photonic crystal fibers by Rodrigo Amezcua.

It's Ti2Ni, which is in FD-3M spacegroup. I have its .cif file which can be loaded by many crystal building program. So I try to build the structure according to the loaded images. I started building a structure with FD-3M lattice. But when I tried to add atoms at the position read from the...

Hi everyone, I'm trying to simulated the XRD pattern of Bi2Sr2Ca2Cu3O10, but I'm having a problem of finding the basis of atom(and their respective position). Also its JCPDS is quite hard to find, so if anyone working with this, may you provide a link or articles about my problem. Thanks...

We know the rule of cross product or Why here |absinΘ| = , and = c cos Φ in the above picture? Thanks for explanation.

GaAs crystal structures have basis atoms: Ga: (0 0 0), (0.5 0.5 0),(0.5 0 0.5),(0 0.5 0.5) As: (0.25 0.25 0.25),(0.75 0.75 0.25),(0.75 0.25 0.75),(0.25 0.75 0.75) i'm trying to find intensities at all of its plane, using this equation: I = (F^2)*m*Lf (m= multiplicity, Lf=lorentz factor)...

Hi All, From the Schrodinger wave equation, I kind of understand what a wave function and hence a wave vector is, so I understand what a wave vector of an electron wave is. However while talking about crystals, there is also a 'crystal wave vector'. Is this a vector sum of wave vectors of...

Given only 2theta and intensity, how to know the crystal structure (except cubic) of non cubic crystals, and also determine their lattice parametera,b,and c, if there's a link or website discussing techniques to determine crystal structure of all crystals, please don't hesitate to put it here...

Hi guys, I'm assume that you already know the 7 crystal system, each crystals have unique way of determining the family of planes, for example in cubic, we all know (111) plane is same (-1-1-1), and so on ((-1-11),(-11-1)...) a total of 8, in fact there is pattern to determine how many possible...

My high school chemistry teacher tossed us the task and told us to figure it out ourselves. As far as I can understand, the trick is to supersaturate the solution, put a seed on a string and hope for the best. I'm just posting here to ask if anyone happens to know any good sites I might not have...

I have calculated the band structure of an infinite photonic crystal structure by COMSOL. So, I have an array of meanings of K-vector and different values of frequency V. I need to calculate density of states (DOS). How can I calculate it? Thanks.

Hi All! A little background info. I'm working with cardiac pacemaking devices with the overall scope of implementing piezoelectric energy harvesters into the devices. I'm in the initial stages of research and development. Okay, so this is my conundrum: I have an output pulse circuit as shown...

For violet phophorus,it seems that the crystal structures given by two websites are not the same.In Openstax CNX,the link is http://cnx.org/contents/f46e8679-ee00-4073-9f5e-a87ca9955a9e@25.9:67/Chemistry_of_the_Main_Group_El and the Figure 12 displays it as follows: But in Chemwiki,the link is...

Homework Statement I'm trying to hook up crystal oscillator package on breadboard and test for expected operation: I'm not sure how and cannot find any data sheets for the pin connection diagrams, I attached an image I found of the kind of package I'm using. There are four pins. Homework...

Hi Guys, please help me. how can i derive the primitive vector of copper oxide (I)? basically this is cuprous oxide having a cubic crystal structure but since it has oxygen in it the directions and magnitude of primitive vector are far different compare to basic cubic structure. also please help...

I'm working on a school project that requires me to build a RF oscillator that is able to be started and stopped at about 100kHz. Ceramic or crystal oscillators would be good because of their tiny size, however, the high Q factor creates a problem. So my question was, can placing a resistor in...

Hey all, This is a problem I can't really wrap my head around. 1.) The lanthanoid series is formed through the progressive filling of the 4f subshell, whereas the first row transition metal series is formed through the progressive filling of the 3d subshell. a) What is the relative...

Background information: The wave function for an electron in a crystal lattice is modeled by a Bloch wave. A Bloch wave is a function with the periodicity of the lattice multiplied times a complex exponential function. This exponential function has a wave vector k, called the crystal momentum...

Hey guys, I'm actually had a hard time in figuring out about our assignment in crystallography of semiconductors, the problem said that, Identify the atomic line lattice axes in a, b,c axis and basal plane diagonal, face plane diagonal, and body plane diagonal of TiO2 and Aluminum Nitride...

in my previous thread i was trying to build a sine oscillator and an amplifier. decided to give up on the idea and purchase. any chips out there that can give me 30-40volts peak to peak. the frequency is not an issue as long as it is above 1 MHz. i guess i can use any crystal oscillator as long...

So i don't really understand why the change in momentum of a crystal involves a reciprocal lattice vector. Surely it is just the change in momentum due to the change in the number and frequency of the phonons before and after whatever event/scattering/collision takes place. Can somebody please...

Suppose I have a substance that has been crystallized. Now suppose I break down those crystals into powder, grains, etc. How can I reconstruct that powder into a crystal again? Do I just dissolve it into a solvent and then evaporate the solvent? Another quick question - is it possible to...

Homework Statement Calculate the Young’s moduli for Van der Waals solids with sc, bcc, and fcc structures.Homework Equations Definition of Young's Modulus $$Y=\frac{stress}{strain}$$ Total energy due to Van der Waals interaction: $$U_{tot}=\frac{1}{2}N(4 \epsilon) \left( \sum_j{ \left( \frac{...