TBD Lecture 10
Crystal Structure and Diffraction - answer
Q: What causes the regular discrete spots in a crystal diffraction pattern? - answer The
regular, repeating arrangement of the crystal lattice.
Q: What fundamental law relates the angle of diffraction to the spacing of crystal
planes? – answer Bragg's Law: 2𝑑sin𝜃=𝑛𝜆
Q: What is a unit cell? - answer The smallest repeating unit in a crystal that generates
the entire lattice through translation.
Q: Why does a crystal produce discrete diffraction spots instead of a continuous
pattern? - answer Because of the periodic, repeating nature of its lattice structure.
Q: What is required for diffraction to be in phase? - answer The plane spacing must
divide the axis at integral values.
Miller Indices - answer
Q: What do Miller Indices (h, k, l) represent? - answer The orientation of planes in a
crystal lattice.
Q: What does it mean when Miller Indices are not integers? - answerThe planes do not
intersect the axes at regular intervals and the waves go out of phase.
Q: How are Miller Indices determined from a plane? - answerTake the reciprocal of the
fractional intercepts with the axes and clear fractions.
Q: What is the Miller Index for a plane that cuts x at 1, y at 1/2, and z at 1/3? - answer(6,
3, 2)
Q: What is the significance of higher Miller Indices? - answerThey represent planes that
are more closely spaced.
Reciprocal Lattice - answer
Q: What is the reciprocal lattice? - answerA mathematical construct inversely related to
the real lattice used to describe diffraction.
Q: How are distances in the reciprocal lattice related to real space? - answerThey are
inversely proportional to real space spacings.
Crystal Structure and Diffraction - answer
Q: What causes the regular discrete spots in a crystal diffraction pattern? - answer The
regular, repeating arrangement of the crystal lattice.
Q: What fundamental law relates the angle of diffraction to the spacing of crystal
planes? – answer Bragg's Law: 2𝑑sin𝜃=𝑛𝜆
Q: What is a unit cell? - answer The smallest repeating unit in a crystal that generates
the entire lattice through translation.
Q: Why does a crystal produce discrete diffraction spots instead of a continuous
pattern? - answer Because of the periodic, repeating nature of its lattice structure.
Q: What is required for diffraction to be in phase? - answer The plane spacing must
divide the axis at integral values.
Miller Indices - answer
Q: What do Miller Indices (h, k, l) represent? - answer The orientation of planes in a
crystal lattice.
Q: What does it mean when Miller Indices are not integers? - answerThe planes do not
intersect the axes at regular intervals and the waves go out of phase.
Q: How are Miller Indices determined from a plane? - answerTake the reciprocal of the
fractional intercepts with the axes and clear fractions.
Q: What is the Miller Index for a plane that cuts x at 1, y at 1/2, and z at 1/3? - answer(6,
3, 2)
Q: What is the significance of higher Miller Indices? - answerThey represent planes that
are more closely spaced.
Reciprocal Lattice - answer
Q: What is the reciprocal lattice? - answerA mathematical construct inversely related to
the real lattice used to describe diffraction.
Q: How are distances in the reciprocal lattice related to real space? - answerThey are
inversely proportional to real space spacings.
