Metal to insulator transition in Ba2Ge2Te5: Synthesis, crystal structure, resistivity, thermal conductivity, and electronic structure

Malladi, Sairam K and Niranjan, Manish K and Jai, Prakash and et al, . (2022) Metal to insulator transition in Ba2Ge2Te5: Synthesis, crystal structure, resistivity, thermal conductivity, and electronic structure. Materials Research Bulletin, 147. pp. 1-10. ISSN 0025-5408

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Abstract

A monophasic polycrystalline sample of Ba2Ge2Te5 has been synthesized for the first time using the sealed tube solid-state method. The Rietveld refinement of a polycrystalline Ba2Ge2Te5 and a single crystal X-ray diffraction study confirm that Ba2Ge2Te5 crystallizes in the orthorhombic polar C2v9-Pna21 space group. Each of the Ge atoms in the Ba2Ge2Te5 structure is covalently connected to one Ge and three Te atoms making one-dimensional (1D) chains of 1∞[Ge2Te5]4− that are separated by Ba2+ cations. The (Ba2+)2(Ge3+)2(Te2−)5 can be charge-balanced as per the Zintl-Klemm concept. A resistivity study of Ba2Ge2Te5 shows a metallic behavior till 18 K below which metal to insulator transition was observed. Thermal conductivity of Ba2Ge2Te5 was found to decrease gradually on heating the sample with a minimum of about 0.41 Wm–1K–1 at 773 K. The DFT studies predict semiconducting nature for Ba2Ge2Te5 with a narrow indirect bandgap of about 0.6 eV. © 2021 Elsevier Ltd

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IITH Creators:

IITH Creators	ORCiD
Malladi, Sairam K	https://orcid.org/0000-0002-0322-8137
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 No. ECR/2017/000822), and IIT Hyderabad for seed grant and research facilities. SJ thanks MOE and IIT Hyderabad for the research fellowships. MI thanks DST India (Grant No. ECR/2017/000822) and IIT Hyderabad for the research fellowship. 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. The authors thank Gopabandhu Panigrahi (Dept. of Chemistry, IIT Hyderabad) for helping in the preparation of samples for SEM and EDS studies. SA wishes to thank DST (ASEAN, PURSE, FIST, JSPS, MES, and SERB), UGC-DAE CSR (Indore), MHRD-RUSA (R&I), TANSCHE (Chennai), and BRNS (Mumbai) for the financial support.

Uncontrolled Keywords:

A. chalcogenides; C. electron microscopy; C. X-ray diffraction; D. crystal structure; D. thermal conductivity

Subjects:

Others > Metallurgy Metallurgical Engineering
Physics
Chemistry
Materials Engineering > Materials engineering

Divisions:

Department of Chemistry
Department of Material Science Engineering
Department of Physics

Depositing User:

. LibTrainee 2021

Date Deposited:

18 Jul 2022 12:09

Last Modified:

18 Jul 2022 12:09