[Lewis R]

It is well known that thermal vibrations of molecules produce thermal radiation or photons (infrared and visible); but in which directions?
I can understand in a gas or liquid the molecules will be rotating in all directions somewhat uniformly and, thus, photon emission will be uniform in all directions (diffuse).
But in a solid or crystal, with the molecules being restrained somewhat, would not the photon emission be in preferred directions?
Specifically, construct a simple capacitor - two metal plates separated by a dielectric material. The dielectric material will emit thermal photons in a diffuse manner from its surfaces not covered by the metal plates (i.e. from the edges of the capacitor). If a low DC voltage (up to 100 volts) is applied to the plates, will the dielectric molecules align with the electric field and, thus, emit thermal photons in a more concentrated manner, hopefully parallel to the metal plates?  And what dielectric would be best for this result?
Thanks