Temperature evolution of the intra-ion absorption spectra of (NH2(C2H5)2)2CoCl4 crystals in the region of their phase transitions

• Published in: Phase transitions Vol. 92; no. 4; pp. 396 - 405
• Main Authors: Kapustianyk, V., Semak, S., Panasyuk, M., Rudko, M., Rudyk, V.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03.04.2019; Taylor & Francis Ltd
• Subjects: 03.75.Hh; 61.50.Ah; 61.50.−f; 78.20.−e; 78.40.−q; Absorption; Absorption band; absorption coefficient; Absorption spectra; Anomalies; Cobalt; Coordination compounds; crystal field; Crystals; Electron transitions; electronic transition; Evolution; ferroic materials; Parameter identification; Phase transitions; Temperature
• ISSN: 0141-1594; 1029-0338
• DOI: 10.1080/01411594.2019.1591407

On the basis of spectroscopic studies of (NH 2 (C 2 H 5 ) 2 ) 2 CoCl 4 crystals, the absorption bands corresponding to the internal electronic transitions in the Co 2+ ion were identified. The values of the crystal field and Racah parameters were calculated. The temperature evolution of the absorption spectra of (NH 2 (C 2 H 5 ) 2 ) 2 CoCl 4 crystals reveals the anomalies of their parameters at the points of phase transitions. The corresponding changes of the absorption spectra were discussed in terms of distortion of the metal-halogen complex. The temperature dependences of the absorption spectra of (NH 2 (C 2 H 5 ) 2 ) 2 CoCl 4 crystals confirm the presence of the thermochromic phase transitions at 255 and 330 K.