Perhaps you should try some spelling variations:
acoustical materials » acoustic materials, acoustic material, optical materials
optic materials » optical materials, basic materials, organic materials
ionic materials » basic materials, inorganic materials, photonic materials

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: %((((optic materials) OR (ionic materials))) OR (acoustical materials))%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((((optic materials) OR (ionic materials))) or (acoustical materials))%22".
• Adding a wildcard symbol may retrieve word variants: %((((optic materials) OR (ionic materials))) or (acoustical materials))%22*.