Edge VS Screw dislocations?

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How can we judge if a dislocation is edge or screw?

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In an edge dislocation, the dislocation moves in the direction of stress, but in a screw dislocation, it moves perpendicular to the direction of stress.

They’re also different in their geometry. If you imagine standing on one of the atomic planes, with the line of the dislocation going vertically upwards relative to you, and then walking around it (you’re in a crystal, so you can imagine e.g. walking three steps forward, three steps left, three steps back, and three steps right, orbiting around the dislocation) then with a screw dislocation, you’ll end above or below your starting point, and with an edge dislocation, you’ll end up at the same height as your starting point, but one step off laterally.