Flashcard: Fundamentals of Crystallography and Diffraction — 22 carte

Crystal structure — definition?

Arrangement of atoms or molecules in a crystal.

Symmetry — role?

Defines invariance under specific operations, classifying crystal symmetry.

Lattice parameters — include?

Lengths (a, b, c) and angles (α, β, γ).

Motif — function?

Atomic group attached to each lattice point.

Bravais lattice — total types?

14 distinct periodic arrangements.

Atomic position — expressed?

Fractional coordinates within the unit cell.

Crystal system — classification?

Seven groups based on symmetry and lattice parameters.

Space group — total?

230 unique symmetry groups.

Unit cell — smallest?

Repeating structural unit of a crystal.

Lattice — defines?

3D periodic array of points.

Diffraction — cause?

Wave interference from crystal lattice scattering.

Bragg law — formula?

2d sinθ = nλ.

Diffractometer — components?

X-ray source, sample holder, detector.

Diffractogram — analysis?

Identify phases by peak positions and intensities.

Quantitative analysis — measures?

Phase proportions via peak areas.

Structural analysis — determines?

Atomic arrangement via peak refinement.

Microstructure — studied by?

Peak broadening, grain size, defects.

Texture — refers to?

Preferred grain orientation.

Sample prep — importance?

Ensures accurate diffraction data.

Experimental conditions — affect?

Data quality and phase stability.

States of matter — include?

Solid, liquid, gas, amorphous phases.

Crystal structure — key?

Ordered atomic arrangement defining material properties.