TY - JOUR

T1 - Low-temperature investigation of natural iron-rich oxoborates vonsenite and hulsite

T2 - thermal deformations of crystal structure, strong negative thermal expansion and cascades of magnetic transitions

AU - Biryukov, Yaroslav P.

AU - Zinnatullin, Almaz L.

AU - Cherosov, Mikhail A.

AU - Shablinskii, Andrey P.

AU - Yusupov, Roman V.

AU - Bubnova, Rimma S.

AU - Vagizov, Farit G.

AU - Filatov, Stanislav K.

AU - Avdontceva, M. S.

AU - Pekov, Igor V.

N1 - Publisher Copyright: © 2022 IGI Global. All rights reserved.

PY - 2021

Y1 - 2021

N2 - This work is devoted to an investigation of the magnetic properties and thermal behaviour of the natural oxoborates vonsenite and hulsite in the temperature range 5-500 K. The local environment, the oxidation states of the Fe and Sn atoms, and the charge distribution were determined using Mössbauer spectroscopy and are in accordance with a refinement of the crystal structure of hulsite from single-crystal X-ray diffraction data (SCXRD) in anisotropic approximation for the first time. The magnetic properties were studied by vibrating sample magnetometry (VSM) (5 ≤ T ≤ 400 K) and are reported for the first time for iron-rich hulsite. Both oxoborates show a very complex magnetic behaviour. Cascades of magnetic transitions are revealed and the critical temperatures were determined. The sequences of magnetic transitions in both vonsenite and hulsite with increasing temperature were found to be as follows: magnetically ordered state ! partial magnetic ordering ! paramagnetic state. According to X-ray diffraction data (93 ≤ T ≤ 500 K), these processes are accompanied by anomalies in the unit-cell parameters and thermal expansion of the oxoborates at critical temperatures. A strong negative volume thermal expansion is observed for both oxoborates at temperatures below ∼120 K.

AB - This work is devoted to an investigation of the magnetic properties and thermal behaviour of the natural oxoborates vonsenite and hulsite in the temperature range 5-500 K. The local environment, the oxidation states of the Fe and Sn atoms, and the charge distribution were determined using Mössbauer spectroscopy and are in accordance with a refinement of the crystal structure of hulsite from single-crystal X-ray diffraction data (SCXRD) in anisotropic approximation for the first time. The magnetic properties were studied by vibrating sample magnetometry (VSM) (5 ≤ T ≤ 400 K) and are reported for the first time for iron-rich hulsite. Both oxoborates show a very complex magnetic behaviour. Cascades of magnetic transitions are revealed and the critical temperatures were determined. The sequences of magnetic transitions in both vonsenite and hulsite with increasing temperature were found to be as follows: magnetically ordered state ! partial magnetic ordering ! paramagnetic state. According to X-ray diffraction data (93 ≤ T ≤ 500 K), these processes are accompanied by anomalies in the unit-cell parameters and thermal expansion of the oxoborates at critical temperatures. A strong negative volume thermal expansion is observed for both oxoborates at temperatures below ∼120 K.

KW - crystal structure

KW - hulsite

KW - ludwigite group

KW - Mössbauer spectroscopy

KW - pinakiolite group

KW - vonsenite

UR - http://www.scopus.com/inward/record.url?scp=85128327363&partnerID=8YFLogxK

U2 - 10.1107/S2052520621010866

DO - 10.1107/S2052520621010866

M3 - Article

AN - SCOPUS:85128327363

VL - 77

SP - 1021

EP - 1034

JO - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

JF - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

SN - 2052-5192

IS - 6

ER -