Crystal Structure Basis and Lattice The basic building

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

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

INSTRUCTIONS SLIDE 1 Master layout or diagram 2 3 4 5 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 2 pts. ) In the slide after that, provide the definitions of ALL the labels used in the diagram

1 Master Layout (Lattice) FIG 1: 2 3 4 5 Lattice

1 Master Layout (Basis ) FIG 2: A list of basis 2 (a) (b) 3 Basis (c) 4 5 (d)

Master Layout (Crystal structure) FIG 3: Crystal structures formed with lattice (fig 1) and basis (fig 2) (a) (b) (c) Each crystal structure refers to its respective basis fig 2 (d)

1 2 3 4 5 Master Layout (Crystal Structure [lattice +basis]) FIG 4: Basis Lattice Crystal structure formed

1 2 3 4 5 Master Layout (Crystal Structure [lattice +basis]) FIG 5: Basis Lattice Crystal structure formed

1 2 Master Layout (3 D 2 layer Crystal Structure [lattice +basis]) FIG 6: 3 2 layer lattice Basis 1 Basis 2 4 Basis 3 5 Basis 4

1 2 Master Layout (3 D 3 layer Crystal Structure [lattice +basis]) FIG 7: 3 3 layer lattice Basis 1 Basis 2 4 Basis 3 5 Basis 4

1 Definitions of the components: 2 Basis 3 Lattice 4 5 Group of atoms is called ‘Basis’ Basis may consist of single atom or a group of atoms. 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.

1 Definitions of the components: 2 Crystal Structure 3 4 5 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.

1 Stepwise description of process 2 3 4 5 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

1 Step 1: Lattice Basis 2 Crystal structure (a) 3 4 Action Description of the action For (a) Basis result is (a) in fig 3 in the master layout. The basis is shown coming one by one on each point. 5 After animation with one is over other three appear then other two till all basis are shown. Audio Narration

1 Interactivity Step 2: Basis Lattice Crystal structure (a) 2 1 (b) (c) 3 2 Interactivity type and action 4 5 Single selection Drop down for options (basis) to be chosen by the learner Options Boundary limit Choose any one basis and click on the correct crystal formation: (a) (b) ---- Feedback Wrong answer chosen then “ Look carefully at the basis and the crystal structure and try again!” (c) The lattice appears after the basis is chosen and the crystal structures with it along with plus and equal too sign Correct answer “ try another basis” 3 Results Basis (a) correct answer 1 Basis (b) correct answer 2 Basis (c) correct answer 3

1 Step 3: List of basis Lattice 2 (b) 3 4 5 (c) Action Click to choose any one basis from the given list of basis to see the crystal structure formation Description of the action 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) (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. Audio Narration

1 Step 4: List of basis 2 (a) (b) 3 4 5 (c) 2 layers Action 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 3 layers Description of the action 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 are over with the lattice Audio Narration

1 Step 5: List of basis 2 (a) (b) 3 4 5 (c) 2 layers Action 1. Now choose another lattice layer. 2. Now click on any of the basis to see the crystal structure formed. 3. Choose another basis. 3 layers Description of the action 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 are over with the lattice Audio Narration

1 Interactivity Step 6: Basis: Lattice 2 Lattice ref to fig 6 -7 Result ref to fig 6 -7 3 4 5 Interactivity type and action Options Select a layer and a basis and click on the correct crystal structure Basis: (a) (b) (c) Drop down for the basis and lattice layers options Lattice 2 & 3 layer lattice fig 6, 7 Feedback Wrong answer chosen then “ Look carefully at the basis and the crystals structure and try again!” Correct answer “ try another basis” Boundary limits Results No of Lattice layers All the three (a, b, and c) crystal structures appear depending on layer chosen: 2– 3 If 2 layers chosen then fig 6 crystals structures for basis 1, 2 and 3 appear. Same is with 3 layer lattice. Only three basis Basis (a) correct answer 1 for each layer Basis (b) correct answer 2 for each layer Basis (c) correct answer 3 for each layer

1 Interactivity Questions Step 7: Lattice Crystal structure Basis 2 Show the chosen basis 3 Options Interactivity type and action 4 Drop down Choose the basis that forms the crystal structure for the given lattice. (a) (b) (c) 5 (d) Feedback 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 proceed to the next question. ” Boundary limits One lattice only One crystal structure Results a. , c. , d. are wrong answers: b is the correct answer

1 Interactivity Questions Step 8: Lattice Crystal structure a. Basis c. 2 b. 3 4 Interactivit y type and action Drop down Options Change the lattice. Given the basis and the new lattice what is the crystal structure formed? Option: hexagonal lattice 5 Show this fig Feedback Feed back for wrong answer: “You are incorrect, follow the link to see the animation. ” (give the link for the hexagonal IDD) Feed back for wrong answer: “Congratulations you have got it right confirm your answer and follow the link to see the animation. ” (give the link for the hexagonal IDD) Boundary limits One lattice only One crystal structure Results a. , b. , are wrong answers: c is the correct answer

1 2 Animation design 3 4 5 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.

Credits What will you learn Lets Learn! Definitions Basis Play/pause Lattice 2 Layer 3 Layer Concepts Assumptions (if any) Formula with derivation (if any) Graphs/Diagram (for reference) Test your understanding (questionnaire) Lets Sum up (summary) Want to know more… (Further Reading) Animation Area Restart Interactivity options Sliders(IO 1) / Input Boxes(IO 2) /Drop down(IO 3) (if any)

1 Interactivity and Boundary limits 2 3 4 5 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

1 Interactivity : 2 3 4 5 Interactivity type and action For interactivity refer to slide no 16 and 20 step No 2 and 6 Options Feedback Boundary limits Results

Links for further reading Reference websites: www. wikipedia. com 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 2 D layers contribute to 3 D Crystal Structure (with constant distance between them).