Germanium has the same structure as silicon, but the unit cell size is different because Ge and Si atoms are not the same size. If you were to repeat the experiment described in the previous problem but replace the Si crystal with a Ge crystal, would you expect the X rays to be diffracted at a larger or smaller angle u?

Video transcript

Hi everyone here, we have an X ray diffraction experiment. We have germanium crystal can be used instead of silicon crystal because silicon and germanium have the same bonding properties and you will essentially achieve the same result and were asked is this assumption correct? Germanium and silicon are on the same group on the periodic table that they have the same bonding properties and the same crystal structure. But they have different crystal size Romania, has a larger bonding atomic radius and has a larger unit cell in silicon and has largely D spacing. If you look at the bag equation, this is n times the wavelength of the X ray equals two. How is the distance between the lattice planes? Um Sign of the incident angle. Now, if we rearrange this for D. We get D equals and times the wavelength to sign of data in D. And data are inversely proportional Romanian has a larger spacing, so it's gonna have a smaller angle. The germanium crystal were the x rays with the same wavelength at a smaller angle than the silicon crystal. So the assumption is incorrect. Thanks for watching my video and I hope it was helpful