CsLiSO4/NH4LiSO4 system investigated by EPR

• Published in: Phase transitions Vol. 79; no. 6-7; pp. 557 - 568
• Main Authors: Zapart, W., Zapart, M. B., Czaja, P., Barasiński, A.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.06.2006
• Subjects: Double sulphates; Electron paramagnetic resonance; Ferroics; Phase transitions
• ISSN: 0141-1594; 1029-0338
• DOI: 10.1080/01411590600892492

The single crystals of CsLiSO 4 and the solid solutions Cs x (NH 4 ) (1− x ) LiSO 4 have been investigated using the EPR technique. Two kinds of vanadyl doped samples were considered - as-grown from the aqueous solutions of appropriate compounds and after a thermal treatment. It has been established that in as-grown crystals the EPR spectra of vanadyl ions were very complex due to the presence of more than one paramagnetic site in the lattice. At least two such sites were identified and spin Hamiltonian parameters were calculated for all the sites. After annealing the crystals at about 400 K, a significant decrease in the intensities of the EPR lines of VO 2+ complexes was observed. In well-annealed samples the complexity of the EPR spectra has been found to disappear. Additionally, the third kind of vanadyl complexes were created during this treatment. It has also been shown that the EPR spectra of Cr 3+ ions in CsLiSO 4 could be observed without any additional sample treatment reported in literature like an irradiation or thermal decomposition. It was established that the VO 2+ and Cr 3+ , being sensitive to structural phase transition in the CsLiSO 4 , can be used as a probe for the structural changes in the CsLiSO 4 /NH 4 LiSO 4 system.