Editing Cadmium arsenide (section)

=== Phase transition ===

Pure cadmium arsenide undergoes several phase transitions at high temperatures, making phases labeled α (stable), α’, α”  (metastable),  and β.<ref>{{Cite journal | doi = 10.1107/S0567740869003323| title = A refinement of the crystal structure of α"-Cd<sub>3</sub>As<sub>2</sub>| journal = Acta Crystallographica Section B| volume = 25| issue = 5| pages = 988–990| year = 1969| last1 = Pietraszko | first1 = A.| last2 = Łukaszewicz | first2 = K.| doi-access = }}</ref> At 593° the polymorphic transition α → β occurs.

:α-Cd<sub>3</sub>As<sub>2</sub> ↔ α’-Cd<sub>3</sub>As<sub>2</sub> occurs at ~500 K.
:α’-Cd<sub>3</sub>As<sub>2</sub> ↔ α’’-Cd<sub>3</sub>As<sub>2</sub> occurs at ~742 K and is a regular first order phase transition with marked hysteresis loop.
:α”-Cd<sub>3</sub>As<sub>2</sub> ↔ β-Cd<sub>3</sub>As<sub>2</sub> occurs at 868 K.

Single crystal x-ray diffraction was used to determine the lattice parameters of Cd<sub>3</sub>As<sub>2</sub> between 23 and 700&nbsp;°C. Transition α → α′ occurs slowly and therefore is most likely an intermediate phase. Transition α′ → α″ occurs much faster than α → α′ and has very small thermal [[hysteresis]]. This transition results in a change in the fourfold axis of the tetragonal cell, causing [[crystal twinning]]. The width of the loop is independent of the rate of heating although it becomes narrower after several temperature cycles.<ref>{{Cite journal | doi = 10.1002/pssa.2210180234| title = Thermal expansion and phase transitions of Cd<sub>3</sub>As<sub>2</sub> and Zn<sub>3</sub>As<sub>2</sub>| journal = Physica Status Solidi A| volume = 18| issue = 2| pages = 723–730| year = 1973| last1 = Pietraszko | first1 = A.| last2 = Łukaszewicz | first2 = K.| bibcode = 1973PSSAR..18..723P}}</ref>