High-temperature X-ray Diffraction Research Articles

Photoelectrochemical properties of copper pyrovanadate (Cu2V2O7) thin films synthesized by pulsed laser deposition.

Polymorphic phases of copper pyrovanadate (α- and β-Cu2V2O7) were synthesized by solid state reaction and the mechanisms governing the phase transitions have been highlighted by the ThermoGravimetric Analysis (TGA) and the Differential Scanning Calorimetry (DSC). The thermal evolution of the lattice parameters was determined by high temperature X-ray Diffraction revealing negative thermal expansion coefficients. The thermogravimetric analysis coupled with differential scanning calorimetry was also used to determine the optimal conditions to obtain a dense target in order to produce thin films by the Pulsed Laser Deposition (PLD) technique. Thin films elaborated under different oxygen pressures and temperatures exhibit a β-Cu2V2O7 polycrystalline phase and their band gap indicates absorption in the visible range. These oxides can be used as photoanodes and their photoelectrochemical properties were studied for both bulk (α-Cu2V2O7) and thin films (β-Cu2V2O7), as a function of the wavelength and/or intensity of the luminous flux. The best photocurrent efficiency was obtained under 450 nm illumination. Moreover, in the case of thin films, we have observed a linear evolution of the current density with the luminous flux. Finally, the photostability of thin films was measured and shows a reduction in the photocurrent of 8% after 1 h of measurement. This photocorrosion phenomenon was also highlighted by the elemental mapping performed on thin films by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectrometry (EDS).

Rapid wet chemical synthesis of bioactive glass with high yield by probe sonication.

Bioactive glasses (BGs) are inorganic biomaterials which possess favourable properties for bone repair and regeneration. The biological properties of the BGs depend on their physical features. This manuscript describes a simple methodology for rapid synthesis of BG nanoparticles (NPs) with tailored physical properties using ultrasonic disruption produced by an ultrasonic probe. The ultrasonic probe generates stable and transient cavitation which increases the mass transfer and accelerates the chemical reaction. This approach is relatively green as it evades the use of the drastic acidic conditions required for hydrolysis. The prepared BG NPs were characterized by Fourier transform infra-red (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), particle size analysis (PSA), nitrogen adsorption/desorption and BET surface area analysis, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectrometry (ICP-OES), and in situ high temperature synchrotron XRD. The effects of ultrasonic irradiation time, and amplitude on the surface properties were investigated and the results confirmed that both parameters, especially amplitude, have significant effects on the physical properties of the prepared BG NPs. The XPS results showed that both, amplitude and time have a pronounced effect on the bridging and non-bridging oxygen atoms bonded to the Si centre in the BG samples, which play an important role in the bioactivity of the BG NPs. The in situ high temperature XRD patterns indicated a gradual phase transformation for the BG samples synthesized at different ultrasonic irradiation times and amplitudes. The TEM images showed that uniform nano-sized BG particles were obtained at 50% amplitude in only 10 minutes. A bimodal particle size distribution was observed with an increasing reaction time, up to 30 minutes, due to an increase in the formation of vortices at the interface where nucleation starts. All the prepared samples exhibited a glassy structure with the composition 70SiO2 : 25CaO : 5P2O5 and were highly bioactive. The proposed method would give a quick route for the synthesis of bioactive glasses and other ceramics with controlled physical properties.

CO2 conversion to CO by LaCo1−xFexO3 (x = 0, 0.25, 0.5, 0.75, 1) perovskite phases at low temperature

This paper reports conversion of CO2 to CO via reverse water-gas shift chemical looping process on LaCo1−xFeO3 perovskites at low temperature as a potential solution for CO2 mitigation. Reactions of LaCo1−xFexO3 phases with x = 0, 0.25, 0.5, 0.75, 1 under hydrogen atmospheres, and subsequently, carbon dioxide, were investigated by in-situ high-temperature X-ray powder diffraction and thermogravimetry. The perovskites show linear thermal expansion up to around 250 ºC under hydrogen atmosphere, followed by a phase change due to formation of oxygen vacancies, and finally, the materials decompose into La2O3 and metallic Co/Fe. Incorporating Fe improves the stability of the reduced phase. Partial reduction and decomposition temperatures under hydrogen were determined. After reduction of the perovskite samples, reactions with CO2 were analyzed. CO2 conversion increases with Fe loading, with LaCo0.50Fe0.50O3 being the material with optimal balance between RWGS-CL activity and long-term stability during five cycles. It reaches a maximum CO yield of 0.25 mol(molperovskite·cycle)−1 and a maximum rate of 3.9 mmol(molperovskite·min)−1 at 550 °C.

The quaternary fluoride LiNaCa2Al2F12 in aluminum electrolytes: synthesis, structure, thermal stability

The quaternary fluoride phase LiNaCa2Al2F12 has been obtained by quenching a melt consisting of a stoichiometric mixture of the corresponding simple fluorides at a temperature of 850 ​°C in air. Previously, the phase has been observed by authors as unknown impurity in cooled samples of aluminum production electrolyte. It has been established that the phase does not form solid solution regions with the initial components. The crystal structure has been solved by X-ray powder diffraction technique: a ​= ​5.053(2) Å, c ​= ​17.546(7) Å, V ​= ​448.02 ​Å3, Z ​= ​2, SG. P-421c. Calcium cations and isolated octahedral [AlF6]3- anions form mixed layers, which are separated by flat nets of lithium and sodium cations. Lithium cations occupy positions with a tetrahedral environment of fluorine atoms. The short interatomic distance Li⋯F 1.89 ​Å makes the position unavailable for other cations. Thermal decomposition has been studied by high-temperature X-ray diffraction and thermal analysis. The LiNaCa2Al2F12 phase is stable up to 600 ​°C in air, and then decomposes in the solid state. The final products of decomposition are fluorite and aluminum oxides and aluminates. It has been concluded that the phase was metastable and it was the result of rapid cooling of the melt. The stability at low temperatures has explained by high potential barrier for transformation. The formation of LiNaCa2Al2F12 indicates the presence in the melt with fluorine deficiency of isolated [AlF6]3- anions, the concentration of which increases due to the existence of coordinated Li+-[AlF6]3- pairs in the melt. It is suggested that the presence of [AlF6]3- anions in acidic electrolyte melts ensures the dissolution of alumina.

Thermal stability of rhombohedral α- and monoclinic β-Ga2O3 grown on sapphire by liquid-injection MOCVD

We investigate the thermal stability of single-phase undoped epitaxial rhombohedral α- and bi-axially-symmetric, monoclinic β-Ga2O3 thin films grown on sapphire substrates by liquid-injection metalorganic chemical vapor deposition (LI-MOCVD) by means of in-situ high-temperature X-ray diffraction (HT-XRD) and room temperature (RT) cathodoluminescence (CL). Ga2O3 layers were vacuum annealed up to 1100 °C, while monitoring the respective 303‾0 and 6‾03 reflections of α- and β-phase Ga2O3. α-Ga2O3 layers were found to withstand the vacuum annealing at 700 °C/20 min, 750 °C/10 min, and 800 °C/8 min without notable degradation, however an indication of reversible biaxial in-plane compressive strain was observed for annealing temperatures close to 800 °C. Annealing at temperatures above 825 °C led to complete layer degradation and partial phase transformation to (010) β-Ga2O3. β-Ga2O3 layers showed no notable degradation or structural changes after the annealing at 1100 °C/30 min, however an indication of reversible biaxial in-plane tensile strain was observed for prolonged annealing at 1100 °C. RT CL spectra revealed the Ga2O3 emission consisted of several distinctive luminescence bands (red, green, blue, and two UV bands). Relatively weak but distinctive signal maxima with energy close to the expected bandgap energies of α- and β-Ga2O3, at 5.3 and 5.0 eV, respectively, were observed and attributed to their near band-edge (NBE) emissions.

Ag4B7O12X (X = Cl, Br, I) Heptaborate Family: Comprehensive Crystal Chemistry, Thermal Stability Trends, Topology, and Vibrational Anharmonicity.

Using glass crystallization and solid-state techniques, we were able to complete the family of salt-inclusion silver halide borates, Ag4B7O12X, by the X = Cl and I members. The new compounds are characterized by differential scanning calorimetry, single-crystal and high-temperature powder X-ray diffraction, optical spectroscopy, and density functional theory calculations. In all structures, the silver atoms exhibit strong anharmonicity of thermal vibrations, which could be modeled using Gram-Charlier expansion, and its asymmetry was characterized by the skewness vector. The topology of the silver halide and borate sublattices has been analyzed separately for the first time. Along the I → Br → Cl series, we observe a decrease of the melting point and configuration entropy and an increase of thermal expansion and its anisotropy and thermal vibration anharmonicity, which indicates decreasing stability.

Melting behavior of sulfur-bearing silicate–phosphate glass batches

The main purpose of the research was to explain the differences between nominal and actual chemical compositions of silicate-phosphate glasses in the SiO2-P2O5-K2O-MgO-SO3 system. The actual compositions of the materials were determined with X-ray fluorescence (XRF) analyses. Changes in the chemical composition were explained by examining the melting processes for selected glass batches with differential scanning calorimetry-thermogravimetry-related gas analysis by mass spectrometry (DSC-TG-EGA (MS)) and high-temperature X-ray diffraction (HT-XRD). It was found that changes in the chemical composition of the sulfur-bearing glasses were associated with the release of gaseous products. The main gases released during thermal decomposition of the selected glass batch were water vapor, carbon dioxide, carbon monoxide, and ammonia. Since these glasses have potential for use as glassy fertilizers, there is no doubt that the present study is important from an environmental point of view.

Crystal structure, dielectric and thermal properties of cobalt doped bismuth tantalate pyrochlore

A phase-pure pyrochlore of the Bi1.49Сo0.8Ta1·6O7.0 composition (space group Fd-3m:2, 10.54051 (3) Å, Z = 8 (No. 227)) obtained by the solid-phase synthesis was characterized. It was found that the pyrochlore structure is disordered, bismuth ions are shifted to the 96 g position, and oxygen ions replace the 48f and 32e positions. Co(II) cations are characterized by a mixed placement in the 96 g and 16b positions. The samples have a dense, low-porosity microstructure. According to high-temperature X-ray diffraction data, cobalt pyrochlore is stable up to a temperature of 1080 °C. With a further temperature increase, it thermally dissociates with the formation of CoTa2O6. The thermal expansion coefficient increases uniformly and weakly from 3.4 to 7.5·10−6 °С−1 in the range of 30–1020 °C. The electrical properties of the pyrochlore were studied by impedance spectroscopy. No ionic processes in the sample were detected. The Bi1·49Co0·8Ta1·6O7.0 is weakly dependent on temperature and frequency. At RT, the permeability varies in the range of 25–28. The dielectric losses tangent decreases with increasing frequency and at a frequency of 106 Hz is equal to ∼0.005. The conductivity activation energy in the range of 22–450°С is 0.58 eV.

High-temperature X-ray diffraction study of anorthite-tialite materials

ABSTRACT The structure of two mixtures of anorthite and tialite (10 mol-% tialite + 90 mol-% anorthite, 15 mol-% tialite +85 mol-% of anorthite) has been investigated using XRD at different temperatures in solid and liquid states. Such mixtures are used as refractory materials in the lining furnaces for metals with a high melting point. All measurements were carried out using a high-temperature vacuum chamber under a purified helium atmosphere. It has been found that the XRD patterns of the solid samples show reflections of various modifications of tialite and anorthite. Weak reflections of mullite can be identified at temperatures above 1000°C. A structural model of the investigated melts has been proposed based on nanocrystal clusters located in a disordered diffuse matrix. The environment of the disordered part of the matrix is formed by particles (atoms, atomic clusters) that do not participate in nanocrystal clusters.

Phase diagrams guide synthesis of highly ordered intermetallic electrocatalysts: separating alloying and ordering stages.

Supported platinum intermetallic compound catalysts have attracted considerable attention owing to their remarkable activities and durability for the oxygen reduction reaction in proton-exchange membrane fuel cells. However, the synthesis of highly ordered intermetallic compound catalysts remains a challenge owing to the limited understanding of their formation mechanism under high-temperature conditions. In this study, we perform in-situ high-temperature X-ray diffraction studies to investigate the structural evolution in the impregnation synthesis of carbon-supported intermetallic catalysts. We identify the phase-transition-temperature (TPT)-dependent evolution process that involve concurrent (for alloys with high TPT) or separate (for alloys with low TPT) alloying/ordering stages. Accordingly, we realize the synthesis of highly ordered intermetallic catalysts by adopting a separate annealing protocol with a high-temperature alloying stage and a low-temperature ordering stage, which display a high mass activity of 0.96 A mgPt-1 at 0.9 V in H2-O2 fuel cells and a remarkable durability.

Influence of the deposition process on the Cr2AlC phase formation during heat treatment of Cr-Al-C thin films

This paper focuses on the Cr2AlC phase formation during annealing post-treatment, with amorphous Cr-Al-C and (Cr,Al)2C as initial phases in the as-deposited state. The influence of the deposition process on the Cr2AlC formation, texture, and phase composition is investigated and an in-depth discussion of the intermediate phase is carried out. Cr-Al-C thin films were deposited by Direct Current Magnetron Sputtering and High Power Pulsed Magnetron Sputtering with the variation of the deposition temperature. To investigate the microstructure, phase composition, and texture, in situ synchrotron and high-temperature X-ray diffraction experiments were conducted and accompanied by electron microscopy. The Cr2AlC formation can be described as a temperature and time-dependent process with one intermediate state characterized by the formation of the disordered-Cr2AlC phase. Disordered-Cr2AlC shows a similar unit cell to Cr2AlC with an increased c/a ratio. The ratio decreases during the phase formation resulting from an ordering process. Formation temperatures depend on the initial phase, with a decreased formation temperature for (Cr,Al)2C, and the deposition process. While the (002) fiber texture of (Cr,Al)2C inherited to Cr2AlC, Cr2AlC originated from amorphous Cr-Al-C showed no preferred orientation. The coatings contained Cr7C3 as an additional phase, dependent on the deposition process and initial phases.

Thermal expansion and microstructure evolution of atmospheric plasma sprayed NiCrAlY bond coat using in-situ high temperature X-ray diffraction

The paper focuses on in-situ high-temperature X-ray diffraction (HT-XRD) study on atmospheric plasma sprayed NiCrAlY coating. The sample was in-situ heated from 25 °C to 1150 °C in a controlled atmosphere (3 × 10−4 bar), and the corresponding X-ray diffraction patterns for different temperatures were recorded. The effect of temperature on crystallite size, lattice strain, and coefficient of linear thermal expansion was studied. Major phases identified are γ-Ni, γ’-Ni3Al, β-NiAl, and α-Cr. The formation of stable α-Al2O3 and spinel was found above 1000 °C. The transformation of β to γ’ and γ phase was observed as a function of temperature. The equilibrium phases and the thermal expansion of disordered Face Centered Cubic (FCC) and Body Centered Cubic (BCC) phases were predicted and supported by Thermo-Calc prediction for the stable temperature range. Results showed that the non-equilibrium microstructure produced by thermal spray process did not alter the thermal expansion behaviour. In-situ treatment resulted in microstructure and elemental homogenization. The thermal expansion and mechanism of phase evolution were discussed.

Electrospinning synthesis and negative thermal expansion of one-dimensional Sc2Mo3O12 nanofibers

Orthorhombic Sc2(MoO4)3 nanofibers have been prepared by ethylene glycol assisted electrospinning method. The effects of annealing temperature, precursor concentration, spinning distance and solvent on the preparation of Sc2(MoO4)3 nanofibers were characterized by XRD, SEM, HRTEM, EDX and high-temperature XRD. XRD analysis shows as-prepared nanofibers are amorphous. Orthorhombic Sc2(MoO4)3 nanofibers can be fabricated after annealing at different temperatures in 500–800 °C for 2 h. The crystallinity of Sc2(MoO4)3 nanofibers improves and the nanofiber diameter decreases gradually as the annealing temperature increases. However, the nanofiber structure was destroyed at the annealing temperature above 700 °C. Higher precursor concentration results in a slight increase of diameter and decrease in destroying temperature of Sc2(MoO4)3 nanofibers. Spinning distance also affects the diameter of nanofibers, and the nanofiber diameter decreases as the distance increases. One-dimensional orthorhombic Sc2(MoO4)3 nanofibers exhibit anisotropic negative thermal expansion. In 25–700 °C, the coefficients of thermal expansion (CTE) of αa, αb and αc are −5.81 × 10−6 °C−1, 4.80 × 10−6 °C−1 and -4.33 × 10−6 °C−1, and the αl of Sc2(MoO4)3 nanofibers is −1.83 × 10−6 °C−1.

Metastable to stable phase transformation in atmospheric plasma sprayed Yb-silicate coating during post-heat treatment

Yb-silicate is used as volatilization barrier material in environmental barrier coating applications. In this study, metastable to stable phase transformation in highly amorphous atmospheric plasma sprayed Yb-silicate coating was investigated during post-heat treatment. High-temperature X-ray diffraction (HT-XRD) was used to analyze the phase composition of the coating at elevated temperatures. Three metastable phases (Yb2Si2O7 (P-1), Yb2SiO5 (P21/c), Yb4.67Si3O13 (P63/m)) and two stable phases (Yb2Si2O7 (C2/m), Yb2SiO5 (I2/a)) preferentially crystallized from the amorphous coating starting at 1000 °C. Metastable phases transformed into stable Yb2Si2O7 and Yb2SiO5 at higher temperatures. HT-XRD data were used to estimate the volume expansion in the coating due to the phase transformation and the results were compared to the dilatometry measurements. The estimated expansion from HT-XRD data was larger than the measured expansion in dilatometry. Microstructural investigation revealed crack healing in the coating during the measurements which was associated with the lower expansion measured in dilatometry.

Lattice Expansion and Crystallite Size Analyses of NiO-BaCe0.54Zr0.36Y0.1O3-δ Anode Composite for Proton Ceramic Fuel Cells Application

This study reports on the structure analyses of NiO-BCZY (BCZY = BaCe0.54Zr0.36Y0.1O3-δ) anode composite materials with the ratio of 50:50 for proton ceramic fuel cells (PCFCs) application. A product of sintered NiO-BCZY was developed to understand the structural properties of the anode materials. The objectives of this work were (a) to investigate the lattice expansion of the anode by using a high-temperature XRD (HT-XRD) from 400–700 °C; and (b) to calculate the crystallite size of the sample by using Scherrer’s and Williamson Hall’s methods. The results obtained from the HT-XRD revealed that the diffraction peaks of NiO and BCZY are matched with the cubic phase perovskite structure. For example at T = 400 °C, the lattice parameter of NiO is a = 4.2004 Å and BCZY is a = 4.3331 Å. The observation also showed that the lattice expansion increased with the temperature. Furthermore, analyses of the Scherrer and Williamson Hall methods, respectively, showed that the crystallite size is strongly correlated with the lattice expansion, which proved that the crystallite size increased as the operating temperature increased. The increment of crystallite size over the operating temperature contributed to the increment of conductivity values of the single cell.

Study on Crystallization Process of Li2O-Al2O3-SiO2 Glass-Ceramics Based on In Situ Analysis.

In this paper, we used differential scanning calorimetry (DSC), high-temperature X-ray diffraction (HT-XRD), and confocal scanning laser microscopy (CSLM) to investigate the Li2O-Al2O3-SiO2 glass crystallization process. At 943 K, lithium disilicate (Li2Si2O5) phase crystals began to precipitate in the Li2O-Al2O3-SiO2 glass with a crystal size of 50-70 nm. At the temperature of 1009 K, petalite (LiAlSi4O10) crystals began to precipitate in the vitreous phase, forming composite spherical crystals of LiAlSi4O10 and Li2Si2O5 with size in the range of 90-130 nm. Furthermore, the Kissinger method and KAS method of the JMAK model were used to calculate the crystallization activation energy and the Avrami index "n". It was found that the precipitation mechanism of the two kinds of crystals is whole crystallization; accordingly, the selection of crystallization heat treatment system was guided to determine the nucleation and crystallization temperature.

Powder metallurgical processing of CrMnFeCoMo high entropy alloy: Phase evolution, microstructure, thermal stability and mechanical properties

The outstanding properties of the high entropy alloys (HEAs) are attributed to various factors like composition, microstructure, phase formation, synthesis route etc. In this regard, the present investigation deals with phase evolution, microstructure, thermal stability and microhardness properties of an equiatomic quinary Cr-Mn-Fe-Co-Mo high entropy alloy synthesized by mechanical alloying followed by pressure-less sintering. The structure and phase evolution with milling time was studied by x-ray diffraction technique. After completion of 40 h of milling, two simple solid solution phases with BCC structure (a = 3.146 ± 0.002 Å and 2.873 ± 0.002 Å) along with a minor amount of undissolved α-Mn were identified. Phase formation, chemical composition, thermal stability etc. were also evaluated using electron microscopy and differential thermal analysis (DTA) methods as well as in-situ high temperature x-ray diffraction technique. In the sintered sample, four phases consisting of two BCC solid solutions, σ (sigma) and μ (mu) type phases are observed to coexist and to be stable up to the melting point. The phase formation was predicted by Thermo-Calc approach and was compared with the experimental observation as well as other calculated results. The sintered samples were tested by instrumented hardness tester for evaluation of mechanical properties and was found to exhibit high hardness (9.3 ± 0.3 GPa) and Young’s modulus (∼245 ± 6 GPa).

Evolution of microstructure, magneto-structural transformation, and magnetocaloric effect in (Fe72-0.9xNi8-0.1xCo8)Zr7B4Cu1Gax (0 ≤ x ≤ 6 at.%) alloys

We report the evolution of microstructure, magnetic properties, and magnetocaloric effects in a series of (Fe72-0.9xNi8-0.1xCo8)Zr7B4Cu1Gax (0 ≤ x ≤ 6 at.%) alloys. The high temperature X-ray diffraction, calorimetric, and thermomagnetic studies revealed that the α-Fe → γ-Fe transformation occurred in the range of 691–733 K in arc-melted ingots (AMIs), whereas the same occurred at 660–723 K in as-spun ribbons (ASRs). The Curie temperature of γ phase lies in the range of 1126–1140 K and 1106–1126 K for AMIs and ASRs, respectively. Addition of Ga reduces the saturation magnetization and induce nanocrystallization in ASRs. A second-order magnetic transition has been identified in x = 0 ASR using Arrott plot exhibiting magnetic entropy change (|ΔSM|) of 0.973 J/kg.K at TCγ under magnetic field of 0.976 T. The refrigeration capacity of x = 0 and x = 6 ASRs has been estimated to be 12.78 J/kg and 22.98 J/kg, respectively, at 0.976 T.

Structural and Electronic Transitions in Liquid FeO Under High Pressure.

FeO represents an important end-member for planetary interiors mineralogy. However, its properties in the liquid state under high pressure are poorly constrained. Here, in situ high-pressure and high-temperature X-ray diffraction experiments, ab initio simulations, and thermodynamic calculations are combined to study the local structure and density evolution of liquid FeO under extreme conditions. Our results highlight a strong shortening of the Fe-Fe distance, particularly pronounced between ambient pressure and ∼40GPa, possibly related with the insulator to metal transition occurring in solid FeO over a similar pressure range. Liquid density is smoothly evolving between 60 and 150GPa from values calculated for magnetic liquid to those calculated for non-magnetic liquid, compatibly with a continuous spin crossover in liquid FeO. The present findings support the potential decorrelation between insulator/metal transition and the high-spin to low-spin continuous transition, and relate the changes in the microscopic structure with macroscopic properties, such as the closure of the Fe-FeO miscibility gap. Finally, these results are used to construct a parameterized thermal equation of state for liquid FeO providing densities up to pressure and temperature conditions expected at the Earth's core-mantle boundary.

X-ray diffraction and Mössbauer spectroscopy study of oxoborate azoproite (Mg,Fe2+)2(Fe3+,Ti,Mg,Al)O2(BO3): an in situ temperature-dependent investigation (5 ≤ T ≤ 1650 K)

This work is devoted to an investigation of elemental composition, crystal structure and thermal expansion of natural oxoborate azoproite from the Tazheran massif (Siberia, Russia) in the temperature range 5–1650 K. Elemental composition was determined by energy-dispersive X-ray spectroscopy (EDX). Its empirical formula based on five oxygen atoms is (Mg1.81Fe2+ 0.19)∑2.00(Fe3+ 0.36Ti0.26Mg0.26Al0.12)∑1.00O2(BO3). Local environment, oxidation states and ratio of Fe atoms are determined using Mössbauer spectroscopy and compared with EDX and single-crystal X-ray diffraction (SCXRD) data. A refinement of the crystal structure from SCXRD data collected at 293 K was provided for the first time. The structure could be described both in terms of cation- and anion-centered polyhedra. It is composed of vertex- and edge-sharing metal–oxygen [MO6] n − octahedra that form extended zigzag chains along the a axis building up a framework with the [BO3]3− triangles located in its distorted trigonal channels. From the other point of view, there are double chains consisting of oxocentred [OM 4] n + tetrahedra and [OM 5] n + tetragonal pyramids forming six-membered rings with the triangles in its cavities. Four non-equivalent Mn + sites are occupied by cations as follows: M(1) (2a) and M(2) (2d) – Mg, M(3) (4g) – Mg and Fe2+, M(4) (4h) – Fe3+, Ti4+, Mg and Al3+. According to differential scanning calorimetry, low- and high-temperature powder X-ray diffraction (LT- and HT-XRD) data, Mössbauer spectroscopy and magnetometry data (5 ≤ T ≤ 1650 K), there are no phase transitions obtained in the temperature range investigated. However, some anomalies in temperature dependencies of unit-cell parameters caused by a partial Fe2+ → Fe3+ oxidation are found in the range 873–1173 K. Azoproite melts at a temperature higher than 1600 K. Eigenvalues of the thermal expansion tensor are calculated for the oxoborate and thermal expansion is described in comparison with its crystal structure.