Patterning the Internal Structure of Single Crystals by Gel Incorporation

Single crystals are usually homogeneous, whereas heterogeneous internal structures can be constructed by incorporation of foreign materials. The existence of the homogeneous and heterogeneous states (termed as state "0" and "1") inspires the idea to transform crystals between them so that the internal structures in the crystals become patternable. Here, gel-grown potassium dihydrogen phosphate single crystals transforming between "0" and "1" states (without and with gel incorporation) are demonstrated by oscillating the crystallization conditions of growth rates (slow for "0" fast for "1") or growth media (solution for "0" gel for "1"). As a result, crystals in the sequences of "010", "001", "011", "100", "110", and "101" have been obtained. By showing the patterned structure through gel incorporation, this work presents one more degree of freedom for structural modification of crystals.