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Alexandrite

Tsarstone collectors guide


Thermochroism

Thermochroism
The science of high temperature of one subject to change its color, because by increasing of temperature expands the bond length of lattice, reduced the ligand field. A red compound of 10% Cr2O3 and 90% Al2O3 by increasing the temperature to over 400 C the color turn to gray and a little about 400 C to green. Thermochroism seen both in both reversible and irreversible. Thermochroism seen in organic compositions combined with color change when the ligand field is in transfer with metal ion and when temperature change. the color change is reversible in solution such as yellow anil dye to red anil dye by heat, but in the solid, the change may remain permanent on cooling.
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