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Lecture - Intro to Crystallography
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- Опубликовано: 18 авг 2024
- Quiz section for MSE 170: Fundamentals of Materials Science.
Recorded Summer 2020
There are some odd cuts in the lecture to protect students' identities.
Leave a comment if I got something wrong. Happy to receive feedback.
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I'm a Jordanian geology student from the University of Jordan, and I wanna thank you for the wonderful explanation of crystallography🤩✨️
This is such a comprehensive introduction! Saved, thank you!
bro called that introduction , thats literally my whole lecture thamks
Where you have written out, (32’4) @ 51:00, they might’ve been asking, why would there ever be any negative number at all when we are looking at a plane intercepting a lattice space? Would that not require us to first translate our plane A by a value of -2 in the y direction of our lattice and make the plane go in the other direction, in which case, technically not have a plane at all even intercepting our lattice?
If I instead look at it as the size of my plane held within my given lattice space for that specific unit edge of my lattice, then I would always have positive values. I’m taking up 2/3 of the x edge, 1 of the y edge, and 1/2 of my z edge. Leading to (324). What exactly makes the y negative?
The original A plane intersects the x, y, and z axes at the origin, which cannot be solved. We must translate the plane away from the origin in any direction to solve. The easiest translation is to shift the A plane along the y-axis by -1. Then the x,y,z intercepts become 2/3, -1, and 1/2.
Thank you for the lecture! I'm curious: besides bifringence, what optical properties do crystals have? Clarity, color and reflectivity come to mind but I wonder if there are more.
Another question: besides simple recognition and measurement of angles is there a go-to method for determining the system of a crystal? Is there a relationship between refractive index and crystal system for systems other than cubic?
Ad note. Crystal glass and dishwashers dont mix.
Good to know, I hand wash my crystalware. Why shouldn't you use dishwashers? Is it the detergent or something else?
@@ZGNeale good boy. Never wash anything of any value in a dishwasher. The very alkaline detergents leach minerals out causing the glass to go milky. I'm Rusty on the exact chemical process.
at around 30:35 ,
it was discussed that CsCl does NOT make a BCC lattice... [but is simple cubic]
then what about CH4 (29:45)... why is it FCC [it has 2 different types of atoms... wouldnt it make it a simple cubic?]
also thank you so much for this video!!
Hello Raja,
This is a good question. CH4 is a molecule, and the molecule (of 5 atoms) can be translated to each of the lattice points in the fcc lattice. Each molecule is on a fcc lattice point with no other atoms elsewhere, so it has the FCC crystal structure. Many gases will arrange themselves into close-packed lattices (although not necessary cubic) because this is the lowest energy arrangement for Van der Waals solids. CsCl is an ionic solid, and can arrange in more interesting structures. The important point to make is that CsCl does not have the BCC crystal structure, and also does not have a BCC crystal lattice, it has the "Cesium Chloride" crystal structure. Other ionic compounds like CsBr and CsI also have the "Cesium Chloride" crystal structure, but CsF has the "Rock Salt / Halite" crystal structure like NaCl.
Another way to look at it is that "crystal lattice" are points in space that define the symmetry of the crystal, and "crystal structure" is how the atoms arrange or molecules arrange on or near the lattice points.
@@ZGNeale thank you so much! this explained a lot :)
Hello sir, thank you very much for this interesting course ! I was wonderring, is ice a crystal ?
Yes, ice is a good example of a crystal. The water molecules arrange themselves into a periodic structure. Do an image search of "snowflake microscope" and the crystal symmetry of ice will become apparent. Also, watch the first minute of my other lecture that introduces the different phases of ice: ruclips.net/video/BOALc3pVLgk/видео.html
Yes,ice is made from crystals but is it a mineral? Ice is the solid state of water, which of course has five states.
@@geoffgeoff143 yes ice is mineral when it is in solid condition,but we know that often water is liquid so it is not mineral,so this is really complicated
@@geoffgeoff143 ice is not a mineral, go back and see d definition of minerals
@@sabamacharadze8356 ice is not a mineral, u can actually say it's crystalline buh it's no mineral
That was awesome. Thank you so much
Great job
Nice explanation
25:03 anyone else notice the ffc structure is the same as the kabbalah tree of life?
Atoms and and the science of how crystals form weather it’s rain/snow/fire/air ctrl /admin absorbed info about fossils and crystals and how molecules and bonded together thank you 😘
it's fun that i apparently know more than the students ^^