SU971922A1 - Method for measuring rate of growth of crystals from solution - Google Patents

Description

The invention relates to the field of growing single crystals, in particular to the technique of determining the parameters of the kinetics of the process of growing crystals from solution.

Methods are known for determining the rate of growth of crystals from solutions by measuring in one way or another the amount of solid phase crystallizing from a solution at a given time 1.

However, all these methods during mass crystallization in large volumes are characterized by low accuracy, since it is very difficult to follow the change in the size of all crystals.

These drawbacks are eliminated in methods for determining the growth rate of crystals in small volumes, such as capillaries.

The closest to the proposed method is the method for determining the kinetics of crystallization from a solution-melt in capillaries with the registration of the process with noMoiim optical and x-ray methods, as well as measuring the growth rate from the change in volume

solution during crystallization, which is fixed by changing the level of the solution in capillary pe 2.

However, the use of these methods to determine the growth rate of crystals from high-temperature (above 1000 ° C) solutions is impossible.

Solutions for growing single crystals of an important class of ferrogranates and ferrochsins, include lead compounds (PbO, PbFj) and are opaque in both the optical and x-ray frequency ranges.

The change in solution volume during crystallization is small, since solutions with a concentration of crystal-forming components of 8–10 mol% are used for cultivation.

When crystals are grown from such solutions in the capillaries, the growth does not occur along the

20 axis of the capillary::, as in the known methods of growing from melts, and in the radial direction, which cannot be fixed

known methods.

Claims (1)

A method for determining the crystal growth rate from a solution by the precipitation of a solid phase on the inner wall of the capillary, heme is 45, which, for the purpose where О _о is the initial diameter of the capillary (de-growth); P ° is the maximum pressure in the gas bubble at the initial time; 50 - maximum pressure in a gas bubble after time At. Example. Determination of the crystal growth rate of yttrium-iron garnet from the solvent PbO — PbF ₂ —B ₂ O ₃ —CaO. 55 VNIIPI Order 8497/11 повышенияι to increase the accuracy and speed up the measurement, gas bubbles are passed through the capillary and the growth rate is judged by the change in the maximum pressure in the bubbles.