Possible ways to develop alloys in which the distance between interstitial positions is small are discussed. The potential wells in these alloys would have to be deep enough to capture a deuteron. The substitution of relatively small ions for relatively large ones in a crystal results in a displacement of the deuterons toward the smaller ions. Accordingly, isolated smaller ions in such a substitutional alloy would become deuteron collectors. A possibility for increasing the deuteron density near vacancies in subtraction solutions is also discussed.