Hello everyone my name is Kranthi and our going to explain about different crystal structures where is like as packing voyt’s defense hope you’re a better understanding of what this video’s units this morning’s group of atoms which are also into kristen and from with entire lattice can build up by the repetition in three dimensions like this point of the positions that you can place an atom that for you can find a their interactive vacancies in the lattice points of the crystal structure crystal structure the smallest group of particles in the material that constitute the repeating pattern in the units of the structure the unit cell completely defined the symmetry and structure of the integral actors which is built by the petition translation of the units along its principal axis hi guys my name is Johanna and i’m representing the group already as you know there are seven different types of kristen systems and i’m going to describe to you two of them which are the monoclinic and frankly crystal systems now any crystal system is described by three vectors that are the edge lence it B and C then also described by the interaction angles that are alpha without any drama select me first describe the monoclinic systems there are two dates that is the simple of primitive lattice and the second type is the end standard our basement lattice so let’s start off with the multiplex simple ladders know this is how structure looks like as you can see it is a rectangular prism with the pandal massive space so in this structure two of two vectors are perpendicular that is alpha equal to gamma is equal to 90 degrees and we does not equal to 90 degrees now and none of the incidents are equal that is is not equal to B article to see let’s get like how many spirits are there in the slightest so since the eighth corner atoms that gives 1 by 8 into 8 that is equal to one decimal therefore there is only one spirit and the whole lattice so as you can see the packing density is quite low that’s more than the second day which is the monoclinic and centered lattice now apart from the eight corners beers that are also to face face atoms so in the structure just like the previous one none of the extension equal and two of

none of the extension equal and two of the Kaiser popular so now let’s move on to calculate the number of Spears persisted corner atoms that gives 1 by 8 into 8 that is equal to 1 and apart from that there are also two faced adams and giving one by doing the book is equal to one so when you add them you get two Spears and total so as you can see the packing density is higher when compared to the simple structure now let’s move on to the next type of system and is the dry cleaning system there’s only one type in this and is the simple cubic lattice so this is its structure and in this one none of the extension equal apart from that none of the interaction angles are equal that is our first night he could beat an article drama which is not possible to 90 degrees and then apartment look so let let’s hear some interesting facts about the clinic lattice the track lattice is that be symmetric of all the 14 bravais lattices now there are points of inversion at each lattice and and apart from that that point of investment seven more points for each lattice point and those seven points are the midpoint of their just faces and center points so that’s the triclinic latest only that is that has number of planes I’m local i’m going to expandable monoclinic and try cleaning produces monoclinic it’s more planning practices and it’s possible various less center in itself dr. mode its actual distance our age limits are not equal considering their axial angles of the engine starting 10 and the third the first it may be greater than 90 or less than 90 it can act us in center unit serve to if you see that the examples are more playing sulfur sodium chloride and coming to try cleaning triclinic shows only primitive characteristics all its actual distances are unequal and all the axle and wheels are also unequal and they don’t fall out of a language example sort of protection bichromate and boric acid it no I’m going to explain about various statuses actually there are several types of crystal systems namely cube to travel Arturo ambassador that’s a little more clearly contrary to me and there are four types of universes namely bc simple

four types of universes namely bc simple cubic ccp hcp these ecosystems and these units are together form of 14 provide services in different combinations first witness this sea or the basics of yourself there are three axis let us consider this to be origin this is x-axis y-axis and z-axis the angle between the y-axis an x-axis certainly alpha and angle between the y-axis and z-axis it to be Vita and the angle between that they’re accessing access sister to be gamma and then that play the length agent of the unit along the axis to be a and along the Mississippi and what along that axis it to be easy to see in a cubic system all the agents into this along that is EA equal to be equal to C and handled between the every battle for access is equal to 90 degrees and internal system the agent along x-axis and y-axis the same but they are not equal to that of the taxes and dander between every pair of access the same and equal to 90 degrees and nautical autonomic system the dreams not a totally different along x y&z axis and but the endless between that is the same and you 180 degrees and grow longer hydro system the instrument that is a long XY entered all the same but the angle between that exceptional axis and the angle between the radisson their axis RCM and angle and also the angle between the acceptance into that is your taxes but all these are not equal to 90 degrees and in excellent system day is ruined along x-axis and y-axis him but not along that all these taxes at the angle between acceptance and y-axis and practices that this is equal to anything is what angle between the tracks and exercise is equal to 140 degrees and inorganic system while the influence that is a and we a BNC are unequal and the angle between the words and exes and the angle between the exceptions there at the scene and equal to 10 degrees but it is not equal to angle between the acceptance Andy taxes which is betta and the final system is breaking in that all the all the dreams are different and all the others between the pair of glasses are different and it is a more Stern symmetrical grace that this hi my name is cited and i’m from the luminaries now I’m going to expand your board doesn’t believe it is important

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board doesn’t believe it is important simple cubic lattice atoms are located only at the corners of the cube and it is very closely packed the coordination number of a simple give Atlanta c 6-r very low packing density well if you see in this picture the other corners and there are eight corners are iconic for this tube so totally eight corners into 10 14 / 1 by 8 is equal to one atom so in simple cubic lattice there is only one Adam now the side of the cube this is a sort of the QB and radius of each particle radius of each particle art collector as a is equal to also our is a h2 x there are in this simple cubic now we are we’re going to see about the atomic packing options atomic packing fraction generally what is a dynamic packing fraction atomic packing fraction these are volume of the items in a unit volume of our atoms in the unit cell volume of the unit cell here really indicate the volume of items in your advice movie and volume of you had sold by capillary now here and into 4 by 3 pie r cube or by QB is a volume of Adam and yet and reference to the number of atoms per unit cell transport unit itself so any 24 x provide killed by one you marshal units outside in deciding to site so that you here 4 by 3 into play into our radius means zero audiences are backed by if you take s1 they did 0.5 I already not one bite to it so if you calculate and calculate and subject is 3.14 and / 6 will get a 0.4 it so it is 52-percent body-centered cubic in a body centered cubic structure all sides are the same lengths and angles between the faces are all 80 degrees the number of atoms in a body centered cubic structure is to atomic radius is defined as half the distance between the nearest neighboring academic listed for the BCC structure it is root 3 by 4a as Adams touch along the diagonal coordination number it is defined as the number of nearest neighbors that a particle has a unit cell and for the BCC structure it is it because the center Duchess for on the top and four on the bottom packing efficiency is the percentage of total space filled by the particles the packing efficiency for the BCC structure is 68 person and can be calculated by dividing the volume occupied by atoms in the unit cell by the total volume and

the unit cell by the total volume and multiplying it in 200 have you some tennis balls and then world to show how the HTTP and HTTPS stands for cubic close packing FCC’s and spot based on the cubic structure at FCPS for excellence cubic packing now it’s cpn CPR one of the forms in which a cubic lattice atoms and the HTC is one of the types of images now in a cubic lattices are in the first two layers are any regular pattern when we are about to play the third layer we have two possibilities first place and a diminutive bride words this gives rise to a backing of a baby every type and this type of packing is known as people when we play the items from the update avoids the packing is ABC ABC there’s not a ccp know sometimes we also call it to the face-centered close structure but remember the FCC all just and part duex ok said the board game packing fractions how great the water watch which looks exactly like a bastard and with unity the mountains which take CC packing art nickel silver copper gold aluminium the mountains which takes EP packing hard cadmium cobalt magnesium titanium and think now coming to bc when we chop it off you can see the eight points 8 vertices having 18 contribution and within them we can see one atom which is closely packed by the other eight points therefore if we take a cross section instead of the surface we will find that radius of one corner through the central at on giving us hole diameter or place the radius and radius of another corner from a point here to a point here we can conclude by using Pete horses theorem that if the site is a the diagonal through the cube will be a 23 bringing out the relation again we have for our equals 3 which concludes equals 24 RBI 3r articles to aid in 3 by 4 again here because include the number of homes as 18 contribution and what 8.1 18 28 which is one and one central at on leaving as one total number of atoms giving us to their therefore volume of total items is 2 into 4 by 3 pie r cube and volume of the cell is again a cube which can be brought into 4 x 23 RQ packing fraction is volume of the items / the volume of the cell in 200 which gives us approximately 68 percept hello this is radish and i’ll be explaining you about lean it lean effects and nothing but this location causes the misalignment of the plane of atoms in a Christian there are basically two types of dislocations that edge dislocations and screw dislocations it as a thought type that makes this location can also occur which comprises of both the dislocations and a single status when we talk about specifications it is nothing but positive the termination of a plane of atoms in the middle of the practice the accent paint tend to bend down diversity minute mein to get a perfectly ordered person it can be taught off about step of paper and visual insert half a piece of paper it anywhere between the stack that is the dominated the second type is to dislocations with effort to shear stress it can be thought of as a metal block then given the stress from one and begin student it is a simple structure comprised of a delicate part race by the plane of atoms along the line of defect the romantic diagram showing the crystal structures having planner effect in the clinical boy so this is the winner grain boundary with the games that are aligned and different different positions and their respective owners topical recovering is planned effects sound effects is nothing that existence of grain boundaries that separate regions of different crystalline orientations with within the politics plan solid the items in the Greenlanders will not be in perfect peace line alignment this grain boundaries Arizona uneven growth within the solid during the formation of the Christian different stacking sequences of clothes back crystals can also cause planar defects examples of planar defects can be seen and Nikolai’s and aluminum aluminum back to debate so there is actually something I this thing is now between this one example so these are so these are limited items for you we are going to be like this with this then this is well as be acceptable eight so if this is the scene and this thing is going to be played with this and this is not actually is it could be so with this again so that this again I understand you know that solids can because lang other models crystalline solids exhibit a pediatrician structure the positions of atoms or molecules occurred on repeating existences determined by the unit cell parameters however the arrangement of atoms or molecules and mostly slam materials is not perfect the regular patterns are interrupted by crystallographic defense i’ll be explaining point effects in this video point effects that effects that occur only at around a single lattice point they are not extended in space in any dimension and i’m going to be demonstrating the point defects in a two-dimensional you can see the effects on lattices which would be occupied in a perfect listed but and bacon so as you can see in a perfect crystal this position would also have been occupied by an atom or molecule but in the different this space is left empty the vacancy moves in the opposite direction to the site which used to be occupied by the moving Adam so when the atom moves here the vacancy moves in the opposite direction and so forth in the end I crystal structure as as the atoms occupied the vacancies the vacancies move in the opposite direction vacancy in an ionic solid is also sometimes called Shakti effect now into skilled effects are actions that occupy site in the crystal such a twister is usually not an atom so in this crystal lattice the atoms are fully occupied here but there are some sites called interstitial sites in between the atoms so another atom can occupy these sites so this is how you get an interest in effect they are generally high-energy configurations small atoms in some Christians can occupy interesting pieces without highlands such as hydrogen and helium and another practical example by the interstitial different can be used to good effect is in building semiconductor chips such as silicon by doping so this is why the interesting side effects and actually advantageous to us