Reactive molten-flux assisted syntheses of single crystals of Cs19Ln19Mn10Te48 (Ln = Pr and Gd) crystallizing in a new structure type

Panigrahi, Gopabandhu and Jana, Subhendu and Narayanswamy, S. and Bhattacharjee, Pinaki Prasad and Niranjan, Manish K. and Jai, Prakash (2021) Reactive molten-flux assisted syntheses of single crystals of Cs19Ln19Mn10Te48 (Ln = Pr and Gd) crystallizing in a new structure type. CrystEngComm, 23 (47). pp. 8418-8429. ISSN 1466-8033

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Abstract

Two new quaternary tellurides, Cs19Ln19Mn10Te48 (Ln = Pr and Gd), were synthesized by the reactive molten-flux method at 1273 K using an excess of CsCl as a reactive flux. The single-crystal X-ray diffraction studies reveal that these compounds are isostructural and crystallize in a new structure type in the space group C32h-C2/m of the monoclinic crystal system with two formula units. There are forty-nine unique crystallographic sites in the unit cell of the structure: ten Cs sites, ten Ln sites, five Mn sites, and twenty-four Te sites. All atoms have a site symmetry of.m. except for Cs(10) and Ln(10), which have a site symmetry of 2/m. The unique crystal structure of Cs19Ln19Mn10Te48 consists of complex layers of 2∞[Ln19Mn10Te48]19- that are separated by filling of Cs+ cations between the layers. The Ln atoms are bonded to six Te atoms that form a distorted octahedral geometry around the central Ln atom, whereas Mn atoms are coordinated to four Te atoms in a distorted tetrahedral fashion. The building blocks of these structures (LnTe6 octahedra and MnTe4 tetrahedra) are fused in a complex fashion to create 2∞[Ln19Mn10Te48]19- layers. These structures do not contain any homoatomic bonding and hence, can be easily charge-balanced as (Cs1+)19(Ln3+)19(Mn2+)10(Te2-)48 as per the Zintl-Klemm concept. The optical absorption study on finely ground single crystals of the Gd-compound reveals a direct bandgap of about 0.5(1) eV. The DFT studies also suggest both systems to be semiconductors with bandgaps of ∼0.5 eV consistent with the experimental value. © The Royal Society of Chemistry.

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IITH Creators:

IITH Creators	ORCiD
Bhattacharjee, Pinaki Prasad	http://orcid.org/0000-0002-6422-2601
Niranjan, Manish K	https://orcid.org/0000-0002-4417-5107
Jai, Prakash	https://orcid.org/0000-0002-4078-9662

Item Type:

Article

Additional Information:

JP thanks DST-SERB, Government of India for the financial support under the early career research (ECR) award (Grant number: ECR/2017/000822), and IIT Hyderabad for seed grant and research facilities. GP and SJ thank MOE, India and IIT Hyderabad for the research fellowships. The authors also gratefully acknowledge DST-FIST (SR/FST/ETI-421/2016) for the SEM-EDS facility and DST-FIST (SR/FST/PSI-215/2016) for computational resources used in this work.

Uncontrolled Keywords:

Crystallographic sites; Flux methods; Isostructural; Monoclinic crystal systems; Reactive flux; Single-crystal X-ray diffraction studies; Site symmetry; Space Groups; Structure type; Synthesised

Subjects:

Physics
Chemistry
Materials Engineering > Materials engineering

Divisions:

Department of Chemistry
Department of Material Science Engineering
Department of Physics

Depositing User:

. LibTrainee 2021

Date Deposited:

21 Sep 2022 13:57

Last Modified:

21 Sep 2022 13:57

URI:

http://raiithold.iith.ac.in/id/eprint/10647