TY - JOUR
T1 - Ba2Ln1-xMn2Te5(Ln = Pr, Gd, and Yb; X = Ln vacancy)
T2 - Syntheses, crystal structures, optical, resistivity, and electronic structure
AU - Panigrahi, Gopabandhu
AU - Jana, Subhendu
AU - Ishtiyak, Mohd
AU - Narayanswamy, S.
AU - Bhattacharjee, Pinaki P.
AU - Ramanujachary, K. V.
AU - Niranjan, Manish K.
AU - Prakash, Jai
N1 - Funding 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. SJ and GP thank MHRD, IIT Hyderabad for the research fellowships. MI thanks DST India 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 Prof. James A. Ibers (Northwestern University, USA) for helpful discussions on crystal structure refinements.
Publisher Copyright:
© 2021 The Royal Society of Chemistry.
PY - 2021/5/21
Y1 - 2021/5/21
N2 - 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.
AB - 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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U2 - 10.1039/d1dt00057h
DO - 10.1039/d1dt00057h
M3 - Article
C2 - 33908515
AN - SCOPUS:85106170963
VL - 50
SP - 6688
EP - 6701
JO - Dalton Transactions
JF - Dalton Transactions
SN - 1477-9226
IS - 19
ER -