Examples of artificially grown crystals

potassium dihydrogenphosphate 

Crystals of potassium dihydrogenphosphate (KDP) grown in the presence of the red dye amaranth. KDP crystals have oriented and overgrown organic chromophores in {101} growth sectors. The dyeing is controlled by the specificity of noncovalent interactions between the colored molecules and the growing crystal interfaces.
[Contributed by Bart Kahr - Massimo Moret on 06 May 2014]          

Crystal details

Compound name potassium dihydrogenphosphate
Formula KH2PO4
Dimensions 10 x 7 x 5 mm
Mass 0.5-1.0
Colour transparent with red ‘bow-ties’
Keywords inorg

Growth conditions

Technique temperature decrease
Temperature 350
Growth rate
Solvent amaranth (Color Index No. 16185)
Doping procedure amaranth (Color Index No. 16185)
Keywords sol


Application(s) Fluorescent KDP crystals can be exploited for self-frequency doubled single crystal dye lasers in which the functions of emission, polarization, and frequency doubling are accomplished in a single crystal gain medium.
Link(s) http://chemistry.fas.nyu.edu/object/bartkahr; B. Kahr, R. W. Gurney, Dyeing Crystals, Chemical Reviews (2001) vol. 101 p. 893-951 (DOI: 10.1021/cr980088n)
Other remarks Recipe for preparing cm sized crystals of KH2PO4 dyed by amaranth (C20H11N2Na3O10S3, Color Index No. 16185) in the {101} growth sectors: (a) Dissolve 17 g of KH2PO4 (potassium dihydrogenphosphate, potassium phosphate monobasic) in a 250 mL beaker charged with 50 mL of water (de-ionised water is preferred but "soft" tap water is sufficient for growing crystals of good quality). (b) Warm the beaker while stirring to ensure dissolution. The hot solution may be filtered but this is not critical. (c) Add 4 mL of a 1 mg/mL solution of amaranth to the KH2PO4 solution and stir for approximately 2 min with glass rod or spoon (a magnetic stir-bar works well in the laboratory) (d) Carefully transfer the solution to a 100 mL crystallising dish placed upon a vibration-free surface. (e) KH2PO4 crystals containing red ‘bow-ties’ of dye molecules will crystallize within 4–6 h.

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