Crystal Structure Author Sachin Patil ‘Basis and Lattice ’ The basic building blocks of Crystalline state ‏ ‏

Objectives: After interacting with this Learning object; you will be able to: 1.Identify crystal structure formed given a lattice and a basis.

Master layout or diagram Make a schematic diagram of the concept Explain the animator about the beginning and ending of the process. Draw image big enough for explaining. In above image, identify and label different components of the process/phenomenon. (These are like characters in a film)‏ Illustrate the basic flow of action by using arrows. Use BOLD lines in the diagram, (minimum 2pts.)‏ In the slide after that, provide the definitions of ALL the labels used in the diagram INSTRUCTIONS SLIDE

Master Layout (Lattice)‏ Lattice FIG 1:

Master Layout (Basis )‏ Basis (a)‏(b)‏ (c)‏ (d)‏ FIG 2: A list of basis

Master Layout (Crystal structure)‏ (a)‏ (b)‏ (c)‏ (d)‏ FIG 3: Crystal structures formed with lattice (fig1) and basis (fig2) Each crystal structure refers to its respective basis fig 2

Master Layout (Crystal Structure [lattice +basis]) FIG 4: Basis LatticeCrystal structure formed

Master Layout (Crystal Structure [lattice +basis]) FIG 5: Basis LatticeCrystal structure formed

Master Layout (3D 2 layer Crystal Structure [lattice +basis]) FIG 6: 2 layer lattice Basis 1Basis 2 Basis 3Basis 4

Master Layout (3D 3 layer Crystal Structure [lattice +basis]) FIG 7: 3 layer lattice Basis 1Basis 2 Basis 3Basis 4

Definitions of the components: Basis  Group of atoms is called ‘Basis’  Basis may consist of single atom or a group of atoms. Lattice  Lattice is a regular periodic array of points in space.  ‘Lattice’ can be assumed as a series of points (which can go up to infinity) in two dimension space.  The arrangement of points about a given point is identical with that about any other point.

Definitions of the components: Crystal Structure  When Basis (group of atoms) is repeated in space, it forms a ‘crystal structure’.  In other words, the structure of all crystals can be described in terms of a lattice, with a group of atoms attached to every lattice point.

Stepwise description of process The goal of the IDD is to provide instructions to an animator who is not a expert. You have to describe what steps the animator should take to make your concept come alive as a moving visualization. Use one slide per step. This will ensure clarity of the explanation. Add a image of the step in the box, and the details in the table below the box. You can use any images for reference, but mention about it's copyright status The animator will have to re-draw / re-create the drawings Add more slides as per the requirement of the animation

Step 1: ActionDescription of the actionAudio Narration For (a) Basis result is (a) in fig 3 in the master layout. The basis is shown coming one by one on each point. After animation with one is over other three appear then other two till all basis are shown. A crystal structure is formed when a group of atoms or molecules, called the basis, is attached identically to each lattice point. Basis (a)‏ Lattice Crystal structure

Interactivity Step 2: Interactivity type and action Options Boundary limit Feedback Results Single selection Drop down for options (basis) to be chosen by the learner Choose any one basis and click on the correct crystal formation: (a) (b) (c) The lattice appears after the basis is chosen and the crystal structures with it along with plus and equal too sign Wrong answer chosen then “ Look carefully at the basis and the crystal structure and try again!” Correct answer “ try another basis” Basis (a) correct answer 1 Basis (b) correct answer 2 Basis (c) correct answer 4 (a)‏ (b)‏ (c)‏ LatticeBasis 1‏1‏ 2‏2‏ 4 Crystal structure

Step 3: ActionDescription of the actionAudio Narration Click to choose any one basis from the given list of basis to see the crystal structure formation Click on the basis the others disappear and the animation begins. Once the learner chooses any one basis from the list of basis the result for (b) and (c) in fig 3 in the master layout. The basis is shown coming one by one on each point. After animation with one is over other three appear then other two till all basis are shown List of basisLattice (b)‏ (c)‏

Step 4: Action Description of the actionAudio Narration 1. Click on the 3 dimensional lattice layer of your choice. 2. Next click to select any one basis to see the crystal structure formed. 3. Now choose another basis Only choice in layer appears with the action 1. Then click on the basis of their choice with action 2. After the choice the crystal structure for that basis and that layer is shown with the basis replacing the grey circles on the lattice one by one. (ref fig 6&7) Action 3. appears and learner is asked to chose another basis till all are over with the lattice 2 layers 3 layers List of basis (a)‏ (b)‏ (c)‏

Step 5: Action Description of the actionAudio Narration 1. Now choose another lattice layer. 2. Now click on any of the basis to see the crystal structure formed. 3. Choose another basis. Only choice in layer appears with the action 1 (with only other layer lattice clickable) Then click on the basis of their choice with action 2. After the choice the crystal structure for that basis and that layer is shown with the basis replacing the grey circles on the lattice one by one. (ref fig 6&7) Action 3. appears and learner is asked to chose another basis till all are over with the lattice 2 layers 3 layers List of basis (a)‏ (b)‏ (c)‏

Interactivity Step 6: Interactivit y type and action Options Feedback Boundary limits Results Select a layer and a basis and click on the correct crystal structure Drop down for the basis and lattice layers options Basis: (a) (b) (c) Lattice 2 or 3 layer ones fig 6-8 Wrong answer chosen then “ Look carefully at the basis and the crystals structure and try again!” Correct answer “ try another basis” No of Lattice layers 2 – 3 Only three basis All the three (a, b, and c) crystal structures appear depending on layer chosen: If 2 layers chosen then fig 6 crystals structures for basis 1, 2 and 3 appear. Same is with 3 layer lattice. Basis (a) correct answer 1 for each layer Basis (b) correct answer 2 for each layer Basis (c) correct answer 3 for each layer Basis (d) correct answer 4 for each layer Lattice Basis: Result ref to fig 6-7 Lattice ref to Fig 6-7

Interactiv ity type and action Options Feedback Boundary limits ResultsAudio Narration Drop downChoose the basis that forms the crystal structure for the given lattice. Feed back for wrong answer: “Look care full at the crystal structure and try again.” Feed back for wrong answer: “Congratulations you have got it right.” One lattice only One crystal structure a., b., d. are wrong answers: c is the correct answer Now you are provided with the final crystal structure and the lattice and you have to choose the correct basis to form this crystal structure. (a) ‏ (b) ‏ (c) ‏ Basis (d) ‏ LatticeCrystal structure Show the chosen basis Interactivity Questions Step 7:

Animation design Please see the design template provided in the next slide. This is a sample template, and you are free to change as per your design requirements. Try and recreate the sections/subsections as shown in the template

Want to know more… (Further Reading) ‏ Definitions Formula with derivation (if any) ‏ Graphs/Diagram (for reference) ‏ Animation Area Test your understanding (questionnaire) ‏ Lets Learn! Concepts Assumptions (if any) ‏ Lets Sum up (summary) ‏ Interactivity options Sliders(IO1) ‏ / Input Boxes(IO2) ‏ /Drop down(IO3) ‏ (if any) ‏ Play/pauseRestart What will you learn Credits BasisLattice 2 Layer 3 Layer

Interactivity and Boundary limits In this section, you will add the ‘Interactivity’ options to the animation. Use the template in the next slide to give the details. Insert the image of the step/s (explained earlier in the Section 3) in the box, and provide the details in the table below. The details of Interactivity could be: Types: Drop down, Slider bar, Data inputs etc. Options: Select one, Multiple selections etc Boundary Limits: Values of the parameters, which won’t show results after a particular point Results: Explain the effect of the interaction in this column Add more slides if necessary

Interactivity : Interactivity type and action Options FeedbackBoundary limits Results For interactivity refer to slide no 16 and 20 step No 2 and 6

Links for further reading Reference websites: Books: Solid State Physics – A J Dekker Introduction to Solid State Physics – Charles Kittel Solid State Physics – Ashcroft / Mermin

Summary: Every point in lattice can hold only one basis set of the same type. The selected basis is repeated at all the points throughout the lattice. Similar type 2D layers contribute to 3D Crystal Structure (with constant distance between them).