The investigation of elemental composition, crystal structure and thermal behavior of vonsenite and hulsite from the Titovskoe boron deposit in Russia is reported. The structures of the borates are described in terms of cation‐centered and oxocentred polyhedra. There are different sequences of double chains and layers consisting of oxocentred [OM₄]ⁿ⁺ tetrahedra and [OM₅]ⁿ⁺ tetragonal pyramids forming a framework. Elemental composition was determined by energy‐dispersive X‐ray spectroscopy (EDX). Oxidation states and coordination sites of iron and tin in the oxoborates are determined using Mössbauer spectroscopy and compared with EDX and X‐ray diffraction data (XRD). According to results obtained from high‐temperature Mössbauer spectroscopy, the Fe²⁺ to Fe³⁺ oxidation in vonsenite and hulsite occurs at approximately 500 and 600 K, respectively. According to the high‐temperature XRD data, this process is accompanied by an assumed deformation of crystal structures and subsequent solid‐phase decomposition to hematite and warwickite. It is seen as a monotonic decrease of volume thermal expansion coefficients with an increase in temperature. A partial magnetic ordering in hulsite is observed for the first time with T_c ≃ 383 K. Near this temperature, an unusual change of thermal expansion coefficients is revealed. Vonsenite starts to melt at 1571 K and hulsite melts at 1504 K. Eigenvalues of thermal expansion tensor are calculated for the oxoborates as well as anisotropy of the expansion is described in comparison with their crystal structures.

中文翻译：

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通过原位高温Mössbauer光谱，X射线衍射和热分析研究了含有[OM4] n +和[OM5] n +含氧多面体的混合价硼酸铁钒酸铅矿和亚硫酸盐的热行为。

据报道，对俄罗斯的Titovskoe硼矿床中的钒铁矿和亚硫酸盐的元素组成，晶体结构和热行为进行了研究。硼酸盐的结构用阳离子中心和含氧中心的多面体来描述。由氧中心的[O M ₄ ] ^{n +}四面体和[O M ₅ ] ^{n +}组成的双链和层的序列不同四角形金字塔形成一个框架。元素组成通过能量色散X射线光谱法（EDX）确定。使用Mössbauer光谱法确定了含硼酸盐中铁和锡的氧化态和配位点，并将其与EDX和X射线衍射数据（XRD）进行了比较。根据高温穆斯堡尔光谱法获得的结果，Fe ²⁺至Fe ³⁺vonsenite和hulsite中的氧化分别发生在大约500和600 K处。根据高温XRD数据，此过程伴随着晶体结构的假定变形以及随后的固相分解为赤铁矿和Warwickite。随温度升高，体积热膨胀系数单调下降。在hulsite的部分磁性排序首次与观察Ť _Ç ≃383 K.近该温度下，热膨胀系数的一个不寻常的变化显示出来。膨润土在1571 K处开始熔化，硫酸铁盐在1504 K处熔化。计算了含氧硼酸盐的热膨胀张量的特征值，并描述了膨胀的各向异性及其晶体结构。