Crystal Definition and 382 Threads

I need to create a machine that'll help me clean out my crystal decanters. Brown rice and soap work great, just shake and viola...however some decanters need a bit more shaking, or 'spinning' of the rice and soap than I can provide so I've devised a plan with a box fan motor that would create a...

Hello, In my textbook(Serway), Constructive interference of two rays hitting the first and the second planes , respectively, of a crystal lattice is derived as 2dsin(Θ)=mλ , where Θ is the angle shown in the picture. My question is: shouldn't the equation be 2dsin(Θ) = (m+1/2 )λ instead...

As far as I understand wurtzite is the name given to the crystal structure defined by the stacking sequence ABABABAB.. However, I am having a hard time understanding what the unit cell is of wurtzite. From what I know the unit cell is the smallest repetitive unit and in it you specify the...

My teacher wrote down something to day which I wish I had written down myself. It was about the crystal structure of wurtzite, which is an ABABABAB stacking of hexagonal lattices. What he wrote was two different specifications of the unit cell of wurtzite depending on which groups of elements in...

I found the following picture of the Wurtzite and Zincblende structure as viewed from a specific direction. I could do with some help on which basis vectors are chosen for either the [1 1 1] or [0 0 0 1]. Now I am pretty sure that the last one refers to a basis where we have three vectors...

As far as I know, F_ {ext} = d (\hbar k)/dt = d p_{electron} / dt + d P_{crystal} /dt. could one say that \hbar k = P_{electron} + P_{crystal}?

I have recently been learning CTF and energy differences and orbital splitting is starting to make sense to me a bit more. I have not seen any definitive answers yet so any help would be great. In CTF, octahedral complexes are most common and there are 5 d orbitals that participate. Whether it...

compare the number of microstates for crystals consisting of a mixture of A atoms and B atoms if the crystals have 4, 8 and 16 distinguishable sites the question is ambiguous in that it simply states crystals, so I am assuming its the same as given examples and is 2 crystals AAAA and BBBB...

When a photon is absorbed by an electron through a direct transition in a crystal, the crystal momentum of electron would not approximately change. Therefore momentum change of electron would neutralize momentum change of crystal. In other words, the crystal would gain momentum as well as...

Since all the directions are equivalent in an isotropic crystal, can we deduce that the energy band is exactly spherical?

Ashcroft & Mermin, Solid State Physics, page 315: "According to the Bloch theory, an electron in a perfectly periodic arrays of ions experiences no collision at all". But how about the electron at the border of Brillouin zone? How does diffraction take place there?

I have done several exercises concering periodic potentials in crystal. Especially I did one, where I had to show that the Fourier component of the shortest reciprocal lattice vector (call this vector a) in the z-direction was zero. Now solving the problem was just about writing up the right...

Hi, If we pump a beta barium borate (BBO) crystal, we get one circle of vertically polarized photons ##\left|V\right\rangle## and an intersecting circle of horizontally polarized ones ##\left|H\right\rangle##: http://quantum.ustc.edu.cn/old/img/image002.gif At the intersection points of the...

Hello, I am having quite a bit of trouble really grasping Brillouin Zones and their relation to phonons, energy propagation, etc. I've got a few questions, and there will probably be a number of misconceptions, but I figure they'll clarify what I exactly don't understand. I think a lot of the...

Homework Statement The problem is taken from A Modern Approach to Quantum Mechanics by Townsend, and is stated as follows: The answer given in the back of the book is 0.12, though I have not managed to get this result. Homework Equations Classically, light traveling through a crystal...

The problem statement: What I have managed to do: This problem seems a bit tricky at first because it is talking about rotating a crystal while also changing the voltage - changing two variables at the same time makes no sense to me. This is why I assumed that while we change the voltage...

I know that if we shoot narrow beam of electrons at the crystal (we don't change the angle) we will get a diffraction of electrons according to the brag's law. Therefore we get minimums and maximums on the screen around the crystal. Until now we have been dealing with problems where...

Light -- stopped or trapped inside a crystal? In the below experiment: http://www.extremetech.com/extreme/162289-light-stopped-completely-for-a-minute-inside-a-crystal-the-basis-of-quantum-memory Opaque crystal of yttrium silicate doped with praseodymium1. Is light stopped or trapped (i.e...

I have an obsolete, proprietary crystal oscillator. It is a 200MHz, 10 pin, SMT component. The number on the unit is 200N1. I cannot find another C.O. like it in size, number of pins or footprint. What I don't understand is 9 of the pins are grounded. Only one pin is used and it obviously puts...

Homework Statement Some atoms emit X-rays at transition from excited to ground state. Energy of an excited state of the atom ##\scriptsize^{57}_{26}\textrm{Fe}## is ##\scriptsize14.4keV## larger than than the energy of it's ground state. The mass of the atom is...

Homework Statement With increasing the temperature, can the crystal particle expand? Actually, what really happen to the structure when increase the temperature? Why its look bigger size compare to actual size. Does it mean the crystal of particle expand? or something happen to the...

I have been trying to find information on the crystal structure or phase of solid elemental metals at temperatures close to absolute zero, but I can only find information on there ambient structures. Does anyone know of any sources that would have thermodynamic tables for solid metals at low...

Homework Statement Given a crystal (cube) with regularly arranged atoms (Total 27 atoms) The mass of each atom is 3.5*10^-25. The density of the crystal is 9.2*10^3 What is the shortest distance between the centres of two adjacent atoms? Homework Equations density = mass / volume The...

Dear all! Somebody, please tell me which crystal is soluble in hot water but not in cold water. I am looking for some crystalline chemicals which are strong enough to bind something like glass beads. As I mentioned, it should be highly soluble in hot water (or change into liquid on high...

Hello experts…i am new in the RF field and i need some help… So i have a double balanced mixer (ZAD-6+ of Mini Circuits) that need +7dBm Local OsC power and 30MHz Loca.osc frequency. At the time i use signal generator for l.o How can i make a crystal oscillator with these parameters? Can...

1. Hey, the question I believe should be fairly simple to solve but it's been a while since I've looked over such content. There are two light waves that enter a crytstal at the same time, one linearly polarised parallel to the optic axis and one perpendicular to the optic axis, they have...

what is this answer choices: a. Primitive cubic with an octahedral hole b. Body centered cubic with an octahedral hole c. Face centered cubic with an octahedral hole d. None of the above e. Not enough information to determine We didn't talk about this in class, and this was a question...

Does a single crystal specimen have a smaller Young's Modulus than a polycrystalline specimen? I think a single crystal would have a lower elastic mudolus since it has less grain boundaries and probably less dislocations than a polycrystalline specimen. I'd appreciate any ideas thanks

Homework Statement A two-dimensional rectangular crystal has a unit cell with sides a 6.28Å and b 3.14Å. A beam of monochromatic neutrons of wavelength 5.0 Å is used to examine the crystal. Using either the Laue condition for diffraction or Bragg's Law, determine whether it would be...

I use transfer matrix method. I try to plot the phase Φ(ω) versus frequency ω graph in the vicinity of a band gap. The transmission coefficient t(ω) is t(ω) = |t(ω)|*exp(i*Φ(ω)) from which I get the transmission phase Φ(ω) = atan(t_imaginary(ω)/t_real(ω)). Since I assume that -pi/2 ≦ Φ ≦...

It seems to me that there should only be three degrees of freedom for each atom in a crystal, one for each direction of vibration; but apparently there are six? Can someone explain? Thanks.

I am working on a project. could you please help me in piezo crystal. I just want to know the load vs current values. on what load the respective value of piezo crystal??

Homework Statement A two dimensional crystal process is modeled by an Avrami equation phi(t)= 1-exp(-k*t^2), where k>0. Experimental observation suggests that the inflection point of phi occurs at t=2 hours. Find the dimension and numerical value of k. Homework Equations I know how to...

Homework Statement The scattering amplidtude, F, of a, by a crystal, diffracted beam is defined to be: (1) F=\sum{_\vec{G}}\int n_{\vec{G}}e^{i(\vec{G}-\delta\vec{k})\cdot \vec{r}}\mathrm{d}V The integral is over all the volumeelements, dV, of the crystal. n_{\vec{G}} is the local...

Hi, I have a question regarding the following picture of a lattice of ice: Why does it form the shape that it does? Is it because of the repulsion of charges from the valence electrons? Thanks,

The relative ordering of energy in the crystal field of d4 ions are arranged as 4A1g, 4T2g and 4T1g. How can I determine this? What is the rule for describe the relative energy of the terms for dn ions?

Crystal Oscillators -- accuracy versus temperature I have done quite a lot of desk research and spoken to a few manufacturers, but I am still not clear about the specifications for crystal oscillators and I hope someone can help me out. It is a multi-part question. 1) The accuracy of an XO...

Hello all, I am trying to make an FM transmitter that operates at only 1 frequency. I need the frequency tolerance to be very high, so I'd like to choose a crystal instead of an LC circuit. This is the circuit I'm building: http://cappels.org/dproj/FMdist/fmdis.htm If I were to replace...

Hello, This is a multi-part question that stems from understanding how X-ray diffraction occurs in crystals (eg. protein crystals). 1. Diffraction occurs when Bragg's Law is satisfied, but I'm sure the waves aren't actually being reflected. The x-ray's are scattering. What type of...

Quartz crystals are used in clocks to regulate time measurement. Does a quartz crystal convert heat energy to AC electrical energy? Duordi

Homework Statement A certain crystal has a set of planes 0.33 nm apart. A beam of neutrons strikes the crystal at normal incidence and the first maximum of the diffraction pattern occurs at ∅= 38°. What is the de Broglie wavelength of the neutrons? Homework Equations nλ = Dsin∅ where D...

Hi, suppose I want to look up the crystal structure of a pure element (for example, the structure of pure Tellurium), is there an online database or reference to easily find this information? Thanks.

For metals for instance, is the metallic bond that determines the crystal structure(i.e. FCC (face centered cubic), HCP (hexagonal close packed)) or is the crystal structure that determines the type of bond? In other words, if someone were to ask me what kind of bond an element with an FCC...

So, I read an article yesterday about a potential design for a spacetime crystal. The idea behind a spacetime crystal/4-dimensional crystal is pretty interesting and I'm curious to know what others think about them/this...

Bear with me (Two part question), In the ideal case, an electron in a lattice under the influece of a static force will undergo bloch oscillations. A simple hamiltonian for this system would be: H=H° +Fx and V(x+d)=V(x) If I used the kronig-Penney Model would I be able to derive...

I am currently building a circuit that produces a 200khz signal with a potential difference of 3 - 12 volts, depending on the force applied to a strain gauge. The input voltage is a 12V, 50hz source. With no force applied to the strain gauge, the output is to be 3V and 12V at breaking force...

32 point group system "mmm" in Orthorhombic crystal Hello, I am trying to understand the mmm symmetry in a orthorhombic crystal. Looking from the diagram I know there are 5 diads which will give me 10 unique planes in the same form. But how do I know the exact planes that are in the form given...

Need on urgent basis as to design supercell lattice of pcf

Hi all, Can anyone help explaining how during a phase transition, crystal will be more symmetric at high temperature

Hi, my name is Ofek and its my first post here. hope to be clear and if not I'll try to be more specific next time. Link for the article: http://arxiv.org/pdf/cond-mat/9708043.pdf Writen by N. S. Branco The model H = J*ƩSiSj + ƩΔi(Si)^2 - first sum over nearest neighbors and second sum...