Crystallography at non-ambient conditions and physical properties of the synthesized double-perovskites Sr2(Co1-xFex)TeO6

Zaraq, A., Orayech, B., Igartua, J., El Bouari, A., Gregory, D. H. and Gesing, T. M. (2023) Crystallography at non-ambient conditions and physical properties of the synthesized double-perovskites Sr2(Co1-xFex)TeO6. Dalton Transactions, 52(13), pp. 4086-4102. (doi: 10.1039/D2DT03543J) (PMID:36880967)

Abstract

Polycrystalline double perovskite-type Sr2(Co1-xFex)TeO6 with various stoichiometric compositions (x = 0, 0.25, 0.5, 0.75, and 1) were synthesized by solid-state reactions in air. The crystal structures and phase transitions of this series at different temperature intervals were determined by X-ray powder diffraction, and from the obtained data the crystal structures were refined. It has been proven that for the compositions x = 0.25, 0.50, and 0.75 the phases crystallize at room temperature in the monoclinic space group I2/m. Down to 100 K, depending on the composition, these structures experience a phase transition from I2/m to P21/n. At high temperatures up to 1100 K their crystal structures show two further phase transitions. The first one is a first-order phase transition, from monoclinic I2/m to tetragonal I4/m, followed by a second-order phase transition to cubic Fm3 @#x0305;m. Therefore, the phase transition sequence of this series detected in a temperature range from 100 K to 1100 K is: P21/n → I2/m → I4/m → Fm3 @#x0305;m. The temperature-dependent vibrational features of the octahedral sites were investigated by Raman spectroscopy, which furthermore complements the XRD results. A decrease of the phase-transition temperature with increasing iron content has been observed for these compounds. This fact is explained by the progressive diminishing of the distortion of the double-perovskite structure in this series. By means of room-temperature Mössbauer spectroscopy, the presence of two iron sites is confirmed. The two different transition metal cations Co and Fe on the B sites give the opportunity to explore their effect on the optical band-gap.

• Item Type: Articles
• Additional Information: AZ gratefully acknowledged the Deutsche Forschungsgemeinschaft (DFG) for financial support through ZA 1170/1-1. The authors thank University of Bremen for assistance with the experimental work. One of the authors, JM Igartua, acknowledges the support from the project Nº IT-1714-22 Gobierno Vasco.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Gregory, Professor Duncan
• Authors: Zaraq, A., Orayech, B., Igartua, J., El Bouari, A., Gregory, D. H., and Gesing, T. M.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Dalton Transactions
• Publisher: Royal Society of Chemistry
• ISSN: 1477-9226
• ISSN (Online): 1477-9234
• Published Online: 31 January 2023
• Copyright Holders: Copyright © 2023 Royal Society of Chemistry
• First Published: First published in Dalton Transactions 52(13): 4086-4102
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher