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Biryukov YP, Zinnatullin AL, Levashova IO, Shablinskii AP, Bubnova RS, Vagizov FG, Ugolkov VL, Filatov SK, Pekov IV. Crystal structure refinement, low- and high-temperature X-ray diffraction and Mössbauer spectroscopy study of the oxoborate ludwigite from the Iten'yurginskoe deposit. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2023; 79:368-379. [PMID: 37669151 DOI: 10.1107/s2052520623006455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 07/25/2023] [Indexed: 09/07/2023]
Abstract
This paper reports an investigation of the chemistry, crystal structure refinement and thermal behavior (80-1650 K) of ludwigite from the Iten'yurginskoe deposit (Eastern Chukotka, Russia). Its chemical composition was determined by electron microprobe analysis, giving an empirical formula (Mg1.70Fe2+0.29Mn0.01)Σ2.00(Fe3+0.90Al0.08Mg0.02)Σ1.00O2(BO3). A refinement of the crystal structure from single-crystal X-ray diffraction data (SCXRD) was provided for the first time for ludwigite from this deposit (R = 0.047). The structure can be described as a framework composed of [MO6]n- octahedra and isolated [BO3]3- triangles located in triangular interstices of the framework. Based on a comprehensive analysis of SCXRD and Mössbauer spectroscopy data, the M1 site is occupied by Mg, M2 and M3 by Mg and Fe2+, M4 by Fe3+, Mg and Al. There are also oxo-centered [O4M4]n+ and [O2M5]n+ polyhedra building up a framework with the [BO3]3- triangles located in its hexagonal interstices. No indications of magnetic ordering are found in the temperature range investigated. The Fe2+ → Fe3+ oxidation occurs above 600 K, and is accompanied by a decrease of the unit-cell parameters and subsequent incomplete solid-phase decomposition with the formation of hematite, warwickite and magnetite. The mineral melts at temperatures above 1582 K. The thermal expansion of ludwigite is slightly anisotropic, which is explained by a dense packing of the [MO6]n- octahedra as well as a virtually perpendicular orientation of the oxo-centered double chains to each other. At room temperature, maximum expansion is along the c axis (αc = 9.1 × 10-6 K-1) and minimum expansion is in the ab plane (αa = 8.6 × 10-6, αb = 7.6 × 10-6 K-1), which is due to the preferred orientation of the [BO3]3- triangles. A comparison of the thermal behavior of three oxoborates of the ludwigite group, namely azoproite (Mg,Fe2+)2(Fe3+,Ti,Mg,Al)O2(BO3), vonsenite (Fe2+,Mg)2(Fe3+,Mn2+,Sn,Al)O2(BO3) and ludwigite (Mg,Fe2+,Mn)2(Fe3+,Al,Mg)O2(BO3), is provided.
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Affiliation(s)
- Yaroslav P Biryukov
- Institute of Silicate Chemistry of the Russian Academy of Sciences (ISC RAS), Makarova Emb., 2, Saint Petersburg, 199034, Russian Federation
| | - Almaz L Zinnatullin
- Institute of Physics, Kazan Federal University, Kremlyovskaya Str., 18, Kazan, 420008, Russian Federation
| | - Irina O Levashova
- Institute of Silicate Chemistry of the Russian Academy of Sciences (ISC RAS), Makarova Emb., 2, Saint Petersburg, 199034, Russian Federation
| | - Andrey P Shablinskii
- Institute of Silicate Chemistry of the Russian Academy of Sciences (ISC RAS), Makarova Emb., 2, Saint Petersburg, 199034, Russian Federation
| | - Rimma S Bubnova
- Institute of Silicate Chemistry of the Russian Academy of Sciences (ISC RAS), Makarova Emb., 2, Saint Petersburg, 199034, Russian Federation
| | - Farit G Vagizov
- Institute of Physics, Kazan Federal University, Kremlyovskaya Str., 18, Kazan, 420008, Russian Federation
| | - Valery L Ugolkov
- Institute of Silicate Chemistry of the Russian Academy of Sciences (ISC RAS), Makarova Emb., 2, Saint Petersburg, 199034, Russian Federation
| | - Stanislav K Filatov
- Institute of Earth Sciences, Department of Crystallography, Saint Petersburg State University, Universitetskaya Emb., 7/9, Saint Petersburg, 199034, Russian Federation
| | - Igor V Pekov
- Faculty of Geology, Moscow State University, Leninskie Gory, 1, Moscow, 119991, Russian Federation
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Kazak N, Arauzo A, Bartolomé J, Belskaya N, Vasiliev A, Velikanov D, Eremin E, Gavrilkin S, Zhandun V, Patrin G, Ovchinnikov S. Temperature- and Field-Induced Transformation of the Magnetic State in Co 2.5Ge 0.5BO 5. Inorg Chem 2022; 61:13034-13046. [PMID: 35947773 DOI: 10.1021/acs.inorgchem.2c01193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A tetravalent-substituted cobalt ludwigite Co2.5Ge0.5BO5 has been synthesized using the flux method. The compound undergoes two magnetic transitions: a long-range antiferromagnetic transition at TN1 = 84 K and a metamagnetic one at TN2 = 36 K. The sample-oriented magnetization measurements revealed a fully compensated magnetic moment along the a- and c-axes and an uncompensated one along the b-axis leading to high uniaxial anisotropy. A field-induced enhancement of the ferromagnetic correlations at TN2 is observed in specific heat measurements. The DFT+GGA calculation predicts the spin configuration of (↑↓↓↑) as a ground state with a magnetic moment of 1.37 μB/f.u. The strong hybridization of Ge(4s, 4p) with O (2p) orbitals resulting from the high electronegativity of Ge4+ is assumed to cause an increase in the interlayer interaction, contributing to the long-range magnetic order. The effect of two super-superexchange pathways Co2+-O-B-O-Co2+ and Co2+-O-M4-O-Co2+ on the magnetic state is discussed.
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Affiliation(s)
- Natalia Kazak
- Kirensky Institute of Physics, FRC SB RAS, 660036 Krasnoyarsk, Russia
| | - Ana Arauzo
- Instituto de Nanociencia y Materiales de Aragón, CSIC-Universidad de Zaragoza and Departamento de Física de la Materia Condensada, 50009 Zaragoza, Spain.,Servicio de Medidas Físicas, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - Juan Bartolomé
- Instituto de Nanociencia y Materiales de Aragón, CSIC-Universidad de Zaragoza and Departamento de Física de la Materia Condensada, 50009 Zaragoza, Spain
| | | | - Alexander Vasiliev
- Kirensky Institute of Physics, FRC SB RAS, 660036 Krasnoyarsk, Russia.,Siberian Federal University, 660041 Krasnoyarsk, Russia
| | - Dmitry Velikanov
- Kirensky Institute of Physics, FRC SB RAS, 660036 Krasnoyarsk, Russia
| | - Evgeny Eremin
- Kirensky Institute of Physics, FRC SB RAS, 660036 Krasnoyarsk, Russia.,Siberian Federal University, 660041 Krasnoyarsk, Russia
| | | | | | - Gennadiy Patrin
- Kirensky Institute of Physics, FRC SB RAS, 660036 Krasnoyarsk, Russia.,Siberian Federal University, 660041 Krasnoyarsk, Russia
| | - Sergey Ovchinnikov
- Kirensky Institute of Physics, FRC SB RAS, 660036 Krasnoyarsk, Russia.,Siberian Federal University, 660041 Krasnoyarsk, Russia
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