Am. Zikic et al., AN INSTRUMENT FOR IN-SITU GROWTH-RATE CHARACTERIZATION OF MECHANICALLY STRAINED CRYSTALS, Review of scientific instruments, 69(7), 1998, pp. 2713-2719
The crystal growth and dissolution characteristics of a certain materi
al can be considerably influenced by the strain present in a growing (
dissolving) crystal. Strain can be induced in various ways. One of the
most common and always present in industrial processes, where attriti
on processes are always accompanied by generation of mechanical strain
in a newly formed small crystal fragments, is mechanical stressing, i
n situ, during preparation and handling. To gain deeper insights into
some aspects of this phenomenon, a sophisticated equipment is needed f
or in situ controlled stressing of extremely brittle and fragile cryst
als. For this purpose, we have developed an apparatus which comprises
a specially designed straining cell coupled with a laser Michelson int
erferometer for growth rate measurements. The straining cell is design
ed to accommodate crystals that undergo. fracture below 200 microstrai
ns. The stress imposed on a crystal is computer controlled with a prec
ision of approximately 5%. Details of the instrument are given togethe
r with two examples of straining in situ brittle paracetamol and plast
ic sodium nitrate crystals. The measured changes in growth rate of a p
aracetamol crystal, in the quasi linear region 0-70 kPa are estimated
to be (-9.4+/-0.1) X 10(-11) m/s/kPa. (C) 1998 American Institute of P
hysics. [S0034-6748(98)05606-8]