TY - JOUR

T1 - Synthesis, structure, and properties of eulncuse3 (Ln = nd, sm, gd, er)

AU - Andreev, Oleg V.

AU - Atuchin, Victor V.

AU - Aleksandrovsky, Alexander S.

AU - Denisenko, Yuriy G.

AU - Zakharov, Boris A.

AU - Tyutyunnik, Alexander P.

AU - Habibullayev, Navruzbek N.

AU - Velikanov, Dmitriy A.

AU - Ulybin, Dmitriy A.

AU - Shpindyuk, Daniil D.

N1 - Funding Information: Funding: The study was funded by the Ministry of Science and Higher Education of the Russian Ferderation (Projects AAAA-A21-121011390011-4 and AAAA-A19-119031890025-9), as well as the Government of the Tyumen Region (grant to non-profit organizations No. 2. 89-don, dated 7 December 2020). Funding Information: Acknowledgments: B.A.Z. acknowledge the support by the Ministry of Science and Higher Education of Russia. The work was carried out jointly by Boreskov Institute of Catalysis and Novosibirsk State University. The study was carried out using the equipment of Research and Education Center “Molecular Design and Ecologically Safe Technologies” at the Novosibirsk State University. We would like to express our gratitude to the Tyumen State University Engineering Center for the opportunity to measure microhardness. The authors are grateful to Elena V. Boldyreva and Vladimir V. Boldyrev for their useful pieces of advice, fruitful discussions, and help with manuscript preparation and organizing the XRD studies at the No-vosibirsk State University. The XRPD study was carried out at the Institute of Solid State Chem-istry, UB RAS. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2022/1

Y1 - 2022/1

N2 - EuLnCuSe3 (Ln = Nd, Sm, Gd, Er), due to their complex composition, should be considered new materials with the ability to purposefully change the properties. Samples of the EuLnCuSe3 were prepared using Cu, rare earth metal, Se (99.99%) by the ampoule method. The samples were obtained by the crystallization from a melt and annealed at temperatures 1073 and 1273 K. The EuErCuSe3 crystal structure was established using the single-crystal particle. EuErCuSe3 crystallizes in the orthorhombic system, space group Cmcm, KCuZrS3 structure type, with cell parameters a = 4.0555 (3), b = 13.3570 (9), and c = 10.4602 (7) Å, V = 566.62 (6) Å3. In structure EuErCuSe3, erbium ions are coordinated by selenium ions in the octahedral polyhedron, copper ions are in the tetrahedral coordination, europium ions are between copper and erbium polyhedra layers and are coordinated by selenium ions as two-cap trigonal prisms. The optical band gap is 1.79 eV. At 4.7 K, a transition from the ferri-magnetic state to the paramagnetic state was detected in EuErCuSe3. At 85 and 293 K, the compound is in a paramagnetic state. According to XRPD data, EuLnCuSe3 (Ln = Nd, Sm, Gd) compounds have a Pnma orthorhombic space group of the Eu2 CuS3 structure type. For EuSmCuSe3, a = 10.75704 (15) Å, b = 4.11120 (5) Å, c = 13.37778 (22) Å. In the series of EuLnCuSe3 compounds, the optical band gap increases 1.58 eV (Nd), 1.58 eV (Sm), 1.72 eV (Gd), 1.79 eV (Er), the microhardness of the 205 (Nd), 210 (Sm), 225 (Gd) 235 ± 4 HV (Er) phases increases, and the thermal stability of the phases increases significantly. According to the measurement data of differential scanning calorimetry, the EuNdCuSe3 decomposes, according to the solid-phase reaction T = 1296 K, ∆H = 8.2 ± 0.8 kJ/mol. EuSmCuSe3 melts incongruently T = 1449 K, ∆H = 18.8 ± 1.9 kJ/mol. For the EuGdCuSe3, two (Tα↔β = 1494 K, ∆Hα↔β = 14.8 kJ/mol, Tβ↔γ = 1530 K, ∆Hβ↔γ = 4.8 kJ/mol) and for EuErCuSe3 three polymorphic transitions (Tα↔β = 1561 K, ∆Hα↔β = 30.3 kJ/mol, Tβ↔γ = 1579 K, ∆Hβ↔γ = 4.4 kJ/mol, and Tγ↔δ = 1600 K, ∆Hγ↔δ = 10.1 kJ/mol). The compounds melt incongruently at the temperature of 1588 K, ∆Hmelt = 17.9 ± 1.8 kJ/mol and 1664 K, ∆Hmelt = 25.6 ± 2.5 kJ/mol, respectively. Incongruent melting of the phases proceeds with the formation of a solid solution of EuSe and a liquid phase.

AB - EuLnCuSe3 (Ln = Nd, Sm, Gd, Er), due to their complex composition, should be considered new materials with the ability to purposefully change the properties. Samples of the EuLnCuSe3 were prepared using Cu, rare earth metal, Se (99.99%) by the ampoule method. The samples were obtained by the crystallization from a melt and annealed at temperatures 1073 and 1273 K. The EuErCuSe3 crystal structure was established using the single-crystal particle. EuErCuSe3 crystallizes in the orthorhombic system, space group Cmcm, KCuZrS3 structure type, with cell parameters a = 4.0555 (3), b = 13.3570 (9), and c = 10.4602 (7) Å, V = 566.62 (6) Å3. In structure EuErCuSe3, erbium ions are coordinated by selenium ions in the octahedral polyhedron, copper ions are in the tetrahedral coordination, europium ions are between copper and erbium polyhedra layers and are coordinated by selenium ions as two-cap trigonal prisms. The optical band gap is 1.79 eV. At 4.7 K, a transition from the ferri-magnetic state to the paramagnetic state was detected in EuErCuSe3. At 85 and 293 K, the compound is in a paramagnetic state. According to XRPD data, EuLnCuSe3 (Ln = Nd, Sm, Gd) compounds have a Pnma orthorhombic space group of the Eu2 CuS3 structure type. For EuSmCuSe3, a = 10.75704 (15) Å, b = 4.11120 (5) Å, c = 13.37778 (22) Å. In the series of EuLnCuSe3 compounds, the optical band gap increases 1.58 eV (Nd), 1.58 eV (Sm), 1.72 eV (Gd), 1.79 eV (Er), the microhardness of the 205 (Nd), 210 (Sm), 225 (Gd) 235 ± 4 HV (Er) phases increases, and the thermal stability of the phases increases significantly. According to the measurement data of differential scanning calorimetry, the EuNdCuSe3 decomposes, according to the solid-phase reaction T = 1296 K, ∆H = 8.2 ± 0.8 kJ/mol. EuSmCuSe3 melts incongruently T = 1449 K, ∆H = 18.8 ± 1.9 kJ/mol. For the EuGdCuSe3, two (Tα↔β = 1494 K, ∆Hα↔β = 14.8 kJ/mol, Tβ↔γ = 1530 K, ∆Hβ↔γ = 4.8 kJ/mol) and for EuErCuSe3 three polymorphic transitions (Tα↔β = 1561 K, ∆Hα↔β = 30.3 kJ/mol, Tβ↔γ = 1579 K, ∆Hβ↔γ = 4.4 kJ/mol, and Tγ↔δ = 1600 K, ∆Hγ↔δ = 10.1 kJ/mol). The compounds melt incongruently at the temperature of 1588 K, ∆Hmelt = 17.9 ± 1.8 kJ/mol and 1664 K, ∆Hmelt = 25.6 ± 2.5 kJ/mol, respectively. Incongruent melting of the phases proceeds with the formation of a solid solution of EuSe and a liquid phase.

KW - Chalcogenides

KW - Complex sulfides

KW - Crystal structure

KW - Magnetic properties

KW - Rare earth elements

UR - http://www.scopus.com/inward/record.url?scp=85121715176&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/ca7bbbdf-99ad-33c8-a263-8e860c5e6f3d/

U2 - 10.3390/cryst12010017

DO - 10.3390/cryst12010017

M3 - Article

AN - SCOPUS:85121715176

VL - 12

JO - Crystals

JF - Crystals

SN - 2073-4352

IS - 1

M1 - 17

ER -