Ba2Ln1−xMn2Te5 (Ln = Pr, Gd, and Yb; x = Ln vacancy): syntheses, crystal structures, optical, resistivity, and electronic structure

Panigrahi, G. and Bhattacharjee, P. P. and Niranjan, M. K. and Prakash, J. and et al, . (2021) Ba2Ln1−xMn2Te5 (Ln = Pr, Gd, and Yb; x = Ln vacancy): syntheses, crystal structures, optical, resistivity, and electronic structure. Dalton Transactions, 50 (19). pp. 6688-6701. ISSN 1477-9226

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Abstract

Three new isostructural quaternary tellurides, Ba2Ln1-xMn2Te5 (Ln = Pr, Gd, and Yb), have been synthesized by the molten-flux method at 1273 K. The single-crystal X-ray diffraction studies at 298(2) K showed that Ba2Ln1-xMn2Te5 crystallize in the space group -C2/m of the monoclinic crystal system. There are six unique crystallographic sites in this structure's asymmetric unit: one Ba site, one Ln site, one Mn site, and three Te sites. The Ln site in the Ba2Ln1-xMn2Te5 structure is partially filled, which leaves about one-third of the Ln sites vacant (□) for Pr and Gd compounds. These structures do not contain any homoatomic or metallic bonding and can be charge-balanced as (Ba2+)2(Gd/Pr3+)2/3(Mn2+)2(Te2-)5. The refined composition for the Yb compound is Ba2Yb0.74(1)Mn2Te5 and can be charge-balanced with a mixed valence state of Yb2+/Yb3+. The crystal structures of Ba2Ln1-xMn2Te5 consist of complex layers of 2∞[Ln1-xMn2Te5]4- stacked along the [100] direction, with Ba2+ cations separating these layers. The Ln atoms are bound to six Te atoms that form a distorted octahedral geometry around the central Ln atom. Each Mn atom in this structure is coordinated to four Te atoms in a distorted tetrahedral fashion. These LnTe6 and MnTe4 units are the main building blocks of the Ba2Ln1-xMn2Te5 structure. The optical absorption study performed on a polycrystalline Ba2Gd2/3Mn2Te5 sample reveals a direct bandgap of 1.06(2) eV consistent with the DFT study. A semiconducting behavior was also observed for polycrystalline Ba2Gd2/3Mn2Te5 from the resistivity study. The temperature-dependent magnetic studies on a polycrystalline sample of Ba2Gd2/3Mn2Te5 did not reveal any long-range magnetic order down to 5 K. The effective magnetic moment (μeff) of 10.37μB calculated using the Curie-Weiss law is in good agreement with the theoretical value (μcal) of 10.58μB.

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IITH Creators:

IITH Creators	ORCiD
Bhattacharjee, Pinaki Prasad	http://orcid.org/0000-0002-6422-2601
Prakash, Jai	UNSPECIFIED
Niranjan, Manish K	UNSPECIFIED

Item Type:

Article

Uncontrolled Keywords:

Atoms; Barium compounds; Electronic structure; Gadolinium compounds; Light absorption; Magnetic moments; Manganese; Manganese compounds; Praseodymium compounds; Single crystals; Tellurium; Tellurium compounds; Ytterbium compounds;Crystallographic sites; Effective magnetic moments; Long range magnetic order; Monoclinic crystal systems; Optical absorption studies; Polycrystalline samples; Semiconducting behavior; Single-crystal X-ray diffraction studies

Subjects:

Materials Engineering > Materials engineering

Divisions:

Department of Material Science Engineering

Depositing User:

. LibTrainee 2021

Date Deposited:

24 Jun 2021 10:32

Last Modified:

22 Feb 2022 09:03

URI:

http://raiithold.iith.ac.in/id/eprint/7996