Crystal Definition and 382 Threads

"When you stroke the top edge of a crystal wine glass half full of wine, a musical tone is produced. Is the wine mass part of the determinate of pitch? Is the water vibrating at that pitch?" I asked asked ChatGPT this question. It did not call me an idiot for posting a questionably formed...

Hi. So, i am currently studying reciprocal lattices, and am not quite sure how to find the edge length of a reciprocal lattice. for example I had expected the RL of BCC, which is FCC, to have edge lengths 2pi/a but it turns out it is 4pi/a, how come?

In another message, I discourage a crystal radio as a first project for a kid: Don't get me wrong - I think they are great. But I wouldn't start with one. Anyway, this brought up some issues. (1) The ugly tan earphones that come with the kits. What are they? Piezoelectric? (2) An iron-core...

I have the elastic tensor for a material where C11 aligns with the 100 axis , C22 aligns with the 010 axis and C33 aligns with the 001 axis. I want to rotate it so the the new axis are for a configuration with an axis along 711. How do I come up with the rotation matrix to do this?

A screenshot from a book which describes it: So I am trying to picture this one: 1. A laser is "pumped" through a cylinder made from lithium niobate which is placed at 90 degrees, perpendicularly...so that the laser passes through the body of the cylinder (and not through the 2 round ends)...

Suppose I have a perfect crystal(e.g.TiO2-Rutile, band gap=3ev), under UV light, there should photoconductivity, according to the condensed matter theory, some of these excited conduction band electrons would form small polarons, I am wondering how many percent of the free conduction band...

Hi there, I've been fascinated by using simple coherers to pick up the electromagnetic signal from a spark (in imitation of early radio experiments, for high school education). I am using a push button ignitor (piezoelectric crystal) attached to a simple dipole antenna for the transmitter. When...

When the crystal above is illuminated with light of intensity ##I_0##, what is the intensity at the central maximum? (The picture shown above is a 4 x 4 unit cell of the crystal) The answer is ##(\frac {5} {16} )^2 I_0##. Why? Apparently, Electric field is proportional to the transparent area...

my first youtube video will do better next time ... was an awesome day with a wonderful selection of rocks, minerals fossils etc

This questions is hovering on my mind from a long time. Why would something which does not have life would want to be in such a beautiful neighborhood, while the world is so much disordered. What causes them to be in that regular array and how they choose which crystal structure is suitable for...

Is there a general rule for a crystal structure how many bonds each atom in the crystal lattice will make ?For example Si has a face centered cubic structure so it makes 4 bonds regardless of the fact Si has 4 valence electrons?

When we shine an X-ray beam on a crystal, according to Van Laue formulation, for a sharp intensity peak to be observed on the screen there is a specific direction ##\mathbf{\hat{n}}## , in which for all the X-rays with wavelength ##\lambda## and wavevector...

I thought about writing $$a_q'|0'> =0$$ then develop the U operator in series, after I don't know how to proceed

Here I disagreed with my professor's solution, so I'd like to check with you guys. Each B4+ ion in a perovskite ABO3 structure is displaced by ##0.2 \mathring{A}## parallel to the ##c##-axis w.r.t. the centroid of the unit cell, after the cubic-tetragonal phase transition below the Curie...

Do I do it right guys? The relative amount of low-coordinated atoms is The number of atoms at 8 corners: n_corner=8 1/8=1. The number of atoms at 12 edges: n_edge=12 (n-2)/4=3n-6. The number of atoms at 6 surfaces: n_surface=6 (n^2-4n)/2=3n^2-12n. The relative amount of low-coordinated atoms is...

If light passes into a birefringent material with constant fast and slow directions, ##\hat{x}## and ##\hat{y}##, that are oriented the same way at any point in the crystal, then the electric field is$$\vec{E}(z,t) = E_0\hat{x}\cos{(\theta_0)}e^{i\omega(t - \frac{n_x}{c}z)} +...

Given a crystal basis ##\{\vec{a}, \vec{b}, \vec{c} \}##, the two lattice vectors ##\vec{r}_1 = u_1 \vec{a} + u_2 \vec{b} + u_3 \vec{c}## and ##\vec{r}_2 = 2u_1\vec{a} + 2u_2 \vec{b} + 2u_3 \vec{c}## both obviously point in the same direction whilst ##\vec{r}_2## is twice as long as...

I was wondering which cleanroom ISO class is suitable for liquid crystal research?

Since the crystal spacing is given to be 0.4 nm, so d = 0.4 nm = 4e-10 m in Bragg's law formula For θ = 90° & n = 1, I got λ = 2d = 8e-10 m Using this value in De-broglie wavelength, I got p = h/λ = 8.28e-25 Now kinetic energy of the electrons is given by E = p^2/2m Using value of p, I am...

I need some advice and help please -Is There a two body force field suitable to study silica crystal or alpha quartz crystal? it's okay to gives Approximate results. - Is the BKS force field suitable for silica crystal? - If there are other simple terms of force field for studying the silica...

I don't even know where to start with this problem. What kind of slit makes linearly polarized light circularly polarized? The correct answer is d = lambda/(4(n1 - n2)) = 856nm. But how do I get there? Thanks in beforehand!

We are incorporating a PDLC layer into a product being developed by us and it requires almost constant activation to remain transparent. The PDLC draws 0.557 Watts of power per hour at 60VAC. The goal is to get a battery/power source (of any type even proprietary) to last the upwards of 26,000...

In particular I would like to have a resource for the relation between group theory, crystal field symmetries and breaking of degeneracies of orbitals. I've taken a graduate condensed matter course and graduate quantum mechanics courses. I have some basic knowledge of group theory but can learn...

In a hypothetical, electrically neutral, ideal crystal, where all unit cells are identical, even the ones at the surface: What would the average value of the electrostatic potential be compared to that of the vacuum outside the crystal? Would it be the same or more positive? As a simple example...

I bought a raltron crystal oscillator. I connected it to a programmable frequency divider. It is supposed to cause a diode to blink on and off. The crystal oscillator has a rated frequency of 100 megahertz. The programmable frequency divider can divide a frequency by up to 2,147,483,648. Diode...

It turns out that the solid form is the same for the two situations but the liquid is two different isomers depending on external conditions during melting. https://physicstoday.scitation.org/do/10.1063/PT.6.1.20190606a/full/

Hello, we are studying potato periderm before/after digestion and dewaxing and native vs wounded. One of the techniques is XRD, hence my user name. Among other things we are trying to use XRD to determine the arrangement of fatty acids, esters, and other long-chain aliphatics that are present...

I've been trying to grow a KDP (potassium dihydrogen phosphate) crystal, but I'm having trouble growing anything. I've been adding potassium phosphate fertilizer to distilled water in a bottle I cleaned out and heating it to dissolve the chemicals, but so far haven't gotten much results. It's...

If anybody here has any experience with building a crystal radio, I would appreciate a response. My grandson and I are doing radio projects. This involves basic crystal build using a coil, diode, and resistor. The system is grounded and uses an antenna with no external power and a high...

Can you build a fm transmitter with A crystal oscillator? I already have a 100 megahertz crystal oscillator. I can't find instructions on how to do That on the internet.

People found silica opals exist on the planet Mars, what does this imply about geochemical conditions on Mars?

Hi all! I was thinking if it is possible to revert the Faraday effect. If I have a magnetic field, it interacts with EM wave (light) by changing its polarisation. Can I got a variable magnetic field interacting with polarised light so that I can get induced current in a coil? I can understand...

I'm trying to go through chapter III of the vol.8 of Landau and Lifshitz series. (Fortunately the book is uploaded to the archive.org, I guess it is in the public domain.) At page 87 ( << Archive.org link deleted by the Mentors because of copyright violation >> ), they speak about the Joule...

At school I and a handful of other kids are devising an experiment to send up to ISS to test it over a period of 30 days next year. (Yep, we're quite fortunate to have this opportunity!) We've chosen to grow piezoelectric crystals using (super)saturated solution of the piezoelectric crystal...

Homework Statement I'm not sure if this is a forum for these kinds of things. But anyways, at school I and a handful of other kids are devising an experiment to send up to ISS to test it over a period of 30 days next year. (Yep, we're quite fortunate to have this opportunity!) We've chosen to...

Homework Statement In picture, first-order reflection from the reflection planes shown occurs when an x-ray beam of wavelength ##0.260 nm## makes an angle ##\theta=63.8°## with the top face of the crystal. What is the unit cell size ##a_0##? Homework Equations Bragg law $$d=\frac{ n...

Dear Forum member, I want to pursue research in Liquid Crystal Physics / Engineering, are you aware of any laboratories or university departments actively researching in this field in Canada or Germany? I will be very if you are aware of active groups and share their names. Thanks

Homework Statement In a monatomic crystalline solid each atom can occupy either a regular lattice site or an interstitial site. The energy of an atom at an interstitial site exceeds the energy of an atom at a lattice site by an amount ε. Assume that the number of interstitial sites equals the...

Will air pressure induce a voltage of a piezoelectric crystal or does it need to be mechanically compressed? My guess is that it would depend on the permeability of the crystal

Hi all, I have a few questions. Thanks in advance! Phonons: Can phonons be thought of as a quantised wave of sound, in the same manner photons being a quantised light wave? Also, can they be taken as particles of sound in the same way that photons can be particles of light? Crystal momentum...

Dear all, Hi, I am looking for a non-destructive method of determining the crystal orientation of a smaller-than-50x50x50 μm single crystal, mounted on a quartz substrate. I've considered several x-ray methods like Laue method, or microfocused XRD, but there are some experimental difficulty...

I need to know what is the typical extention of the (spatial) wavefunction of an atomic nucleus in a crystal, in particular I am interested to the case of a Germanium cristal. Please together with the actual number of the size of the nuclei wavefunctions, let me know the references (articles or...

Hello! I would love to get help on this particular question that I find extremely difficult to answer. -"Bariumtitanate can under a certain set of conditions crystallize in the given structure. With the help of the compounds symmetries, explain how it is possible for it to achieve such a...

Homework Statement Homework EquationsThe Attempt at a Solution So i got the answer by finding the diagonal of the square and then find the radius of A. ([(2x0.17)2 ]x2 )1/2 = 2a + 2x0.17 And find out a= 0.14 nm , however the answer is 0.124nm, please help

I would like to understand the reason that tuning fork crystals have the negative parabolic temperature coefficient shape. Is it the material, the crystal cut or how its mounted. What is the physics behind that. Thank you

I've learned that in a crystal, the crystal momentum is conserved. When one considers the electrons as Bloch waves, they have a momentum that doesn't commute with the Hamiltonian and they have well definite energies, hence they cannot have a well definite momentum, because there is no basis in...

I need to make my own smart film for some experiments. I've read enough articles on it to know the required components, how they are mixed and applied. I have a 1:1 mixture of liquid crystal and UV curable resin and glass bead spacers that I need to apply between two ITO PETs and UV cure to...

I am able to find methods on how to index Bragg peaks for powder diffraction, and was wondering if the method is the same for single cubic crystals of NaCl? I have tried and cannot get the expected sequence of allowed reflections for cubic lattices (h^2 + k^2 + l^2= 3, 4, 8, 11, 12, 16, 19...

I need help regarding piezolectric effect... If I add DC voltage to piezoelectric crystal it will change its dimension (length) and vice versa: if I put pressure on piezoelectric crystal it willl produce DC voltage on its surfaces... But I am wondering how long this voltage will last? If I keep...

Hey guys, can't seem to make sense of this question from phys. It goes.. "A crystalline solid consists of atoms stacked up in a repeating lattice structure. Consider a crystal as shown in Figure a. The atoms reside at the corners of cubes of side L = 0.200 nm. One piece of evidence for the...