Degree Of Amorphization Research Articles

Study of the physical nature of Mn4Si7 crystals formed by the diffusion method using an X-ray diffraction

Mn4Si7 silicide crystals obtained by the diffusion method were studied using an X-ray diffractometer (XRD-6100) SHIMADZU. As a result of research, 14 peaks were identified in the Mn4Si7 crystal, corresponding to the database (COD-1530134).The size of Mn4Si7 silicide crystals (DDiff) ranged from 6.2 × 10−10 m to 9.1 × 10−8 m, the lattice tension between crystal atoms (εDiff) from 0.31 to 3.71, the dislocation density on the surface (δDiff) varied in the range from 1 × 1011 to 3.2 × 1014. It was found that the degree of crystallization of Mn4Si7 was 9.3 %, and the degree of amorphism reached 90.7 %. It has been established that the degree of crystallization of Mn4Si7 silicides is relatively low due to the fact that the Mn and Si atoms are non-stoichiometrically bonded to each other, and the degree of amorphism is high.

Water holding capacity, aggregation, respiration, and chemical character of acid soil amended rice straw biochar enriched with different volumes of liquid extract (sap) of Kappapychus alvarezii

The quality of acidic soil is determined by organic C content produced from rice straw biochar in agriculture. In this context, liquid extract from Kappapychus alvarezii (K-sap) is used as a biochar enrichment agent. Therefore, this research aimed to (i) analyze the character of K-sap enriched rice straw biochar with different volumes, as well as (ii) evaluate the impact on soil water holding capacity, size class distribution, aggregate stability index, respiration rate, and acidic soil chemical characters. The treatment tested was the volume of K-sap kg-1 biochar, namely (i) without biochar, (ii) 0 mL, (iii) 500 mL, (iv) 1,000 mL, and (v) 1,500 mL. Each treatment was repeated three times and placed according to a randomized block design procedure. The area covered by K-sap, pore size, and amorphous degree increased while the pore volume of the biochar surface decreased. The addition of 1,000 mL of K-sap kg-1 biochar released a new peak number associated with the aliphatic and aromatic groups. The K-sap enriched biochar increased the proportion of soil aggregate size of 1-2 mm, water holding capacity, carbon storage, pH, total N, available P and K, exchangeable base cations as well as base saturation. Meanwhile, the concentration of Al3+ and H+ were decreased in the acidic soil solution. The results showed that the performance of rice straw biochar, K-sap volumes, soil chemical quality, water holding capacity, and ability to store carbon of the acidic soil was improved by adding K-sap volume.

A Lab-Scale Evaluation of Parameters Influencing the Mechanical Activation of Kaolin Using the Design of Experiments.

This research investigates the mechanical activation of kaolin as a supplementary cementitious material at the laboratory scale, aiming to optimize milling parameters using the response surface methodology. The study evaluated the effects of rotation speed and milling time on the amorphous phase content, the reduction in crystalline kaolinite, and impurity incorporation into the activated clay through the Rietveld method. The results demonstrated that adjusting milling parameters effectively enhanced clay activation, which is crucial for its use in low-carbon cements. High rotation speeds (300/350 rpm) and prolonged grinding times (90/120 min) in a planetary ball mill increased the pozzolanic activity by boosting the formation of amorphous phases from kaolinite and illite and reducing the particle size. However, the results evidenced that intermediate milling parameters are sufficient for reaching substantial degrees of amorphization and pozzolanic activity, avoiding the need for intensive grinding. Exceedingly aggressive milling introduced impurities like ZrO2 from the milling equipment wear, underscoring the need for a balanced approach to optimizing reactivity while minimizing impurities, energy consumption, and equipment wear. Achieving this balance is essential for efficient mechanical activation, ensuring the prepared clay's suitability as supplementary cementitious materials without excessive costs or compromised equipment integrity.

Impact of mechanical activation and mechanochemical activation on microstructural changes, leaching rate and leachability of natural chalcopyrite

The influence of mechanical activation (MA) and mechanochemical activation (MCA) with Fe and Fe2O3 on the microstructural changes, leachability and leaching rate of natural chalcopyrite was investigated and compared. MCA pretreatments were carried out by chalcopyrite co-milling with Fe and Fe2O3 for 20 and 50 min. The XRD analysis indicated that even after 50 min MA and MCA, constituent phases of chalcopyrite, Fe and Fe2O3 could be detectable beside the newly formed bornite. Regarding the peak broadening and peak intensity reduction, MCA generally intensified the microstructural changes of chalcopyrite in comparison with MA. The microstructural study performed by the Rietveld method also proved that all microstructural parameters changed in favor of reactivity, such that the amorphization degree and microstrain were increased to 96 % and 0.164 (%), respectively, while crystallite size was reduced to 14.6 nm after 50 min MCA of chalcopyrite with Fe2O3. It could be concluded from the leaching tests that MCA along with Fe and Fe2O3 addition could promote the leachability and leaching rate of chalcopyrite, as compared to MA and nonactivated chalcopyrite. Although both the MCA of chalcopyrite with Fe and Fe2O3 could enhance copper extractions in the 1 M sulfuric acid leaching tests at 80 °C, Fe addition was slightly more effective than Fe2O3. The results obtained from the kinetic study also revealed that the leaching mechanism of nonactivated chalcopyrite, mechanically activated chalcopyrite and mechanochemically activated chalcopyrite with Fe2O3 changed from diffusion control to chemical control due to MCA with Fe. Finally, the combination of kinetic and microstructural studies proved that all microstructural parameters, except for the microstrain parameters of chalcopyrite MCA with Fe2O3, could be effective in chalcopyrite reactivity promotion.

Utilizing Taguchi method and in situ X-ray powder diffraction monitoring to determine the influence of mechanical activation conditions on the physico-chemical properties and Al leachability of K-feldspar

K-feldspar represents an important natural resource of potassium and aluminum. Within the framework of this study, the K-feldspar was mechanically activated in a planetary ball mill under different conditions planned according to 43 Taguchi orthogonal array experimental design. As outputs, specific surface area (SBET), median particle size (d50), amorphization degree of mineral phases , and Al recovery were used. It was found that the initial d50 value of 293 μm could be reduced to 6.7 μm and the SBET value of 4.7 m2/g could be increased up to 32.5 m2/g upon milling. Both microcline KAl3SiO8, and albite NaAl3SiO8 could be almost completely amorphized, whereas quartz SiO2 still maintained some crystallinity even under the most intensive conditions. Increasing SBET and decreasing the d50 values did not lead to a significant improvement in Al leach recovery, whereas a clear relationship between the amorphization of microcline and the recovered aluminum was found. Analysis of Variance (ANOVA) showed that increasing ball-to-powder ratio is the most beneficial for the improvement in Al recovery. In situ powder X-ray diffraction monitoring performed in an oscillation ball mill under synchrotron irradiation has shown very rapid amorphization of microcline phase at the beginning. However, amorphization of microcline was only partial after two hours of the treatment in this mill, apart from almost complete process in the planetary ball mill. In the end, regressions for the calculation of Al recovery by knowing the values of input parameters were calculated. In general, by just using mechanical activation without the subsequent roasting process that is commonly used to boost metal recoveries, it was possible to quantitatively recover aluminum from K-feldspar.

Structural evolution of zirconium diboride under gamma irradiation and thermal annealing

Understanding the thermal properties and enhancing the performance of zirconium diboride (ZrB2) under extreme conditions is crucial, especially given its role as a burnable absorber in nuclear fuel pellets and its potential applications in accident-tolerant fuels. This study explores the structural alterations of ZrB2 crystals induced by gamma irradiation and subsequent thermal annealing. ZrB2 crystals were exposed to absorption doses of 300 kGy, 1000 kGy, 1500 kGy, and 3000 kGy using a 60Co gamma source, followed by thermal treatment at 1173 K under vacuum conditions. Also, Monte Carlo simulations were utilized to analyze the energy deposition and distribution of gamma quanta within the material during irradiation, highlighting Compton effects up to 0.23 MeV. X-ray diffraction analysis elucidated the impact of gamma radiation on ZrB2 crystal lattice parameters, space group, and volume expansion coefficient. Post-irradiation analysis revealed a maximum degree of amorphization and investigated mechanisms governing lattice parameter expansion. Thermal annealing at 1173 K significantly enhanced crystallinity, reducing amorphization to 0.2 % at an absorption dose of 3000 kGy and facilitating the restoration of the crystal's columnar structure. This comprehensive investigation provides insights into the intricate interplay between gamma irradiation, thermal processing, and resulting structural changes in ZrB2 nanocrystals, essential for applications in radiation-exposed environments.

The amorphization of crystalline silicon by ball milling

The transformation of crystalline silicon to amorphous silicon during ball milling was quantitatively measured by x-ray diffraction and electrochemical methods. Amorphous silicon was found to form rapidly from the very initial stages of ball milling. Simultaneously, the grain size of the crystalline silicon phase decreased. Under extended milling times it was found that a maximum of 86 % of the silicon became amorphous. Similarly, the grain size of the crystalline silicon phase could not be reduced below 6 nm. This transformation followed an Avrami kinetic model, which is consistent with a system which reaches a steady state. These observations suggest a mechanism in which ball milling generates defects, resulting in silicon amorphization and grain size reduction, where the degree of amorphization is limited in extent because there exists a limiting silicon grain size below which defects are no longer formed.

Copper leaching from complex chalcopyrite-rich ores: Utilizing mechanical activation and wastewater-based sulfuric acid system

Complex chalcopyrite-rich ore is crucial in global copper resources, but is highly refractory in conventional sulfate leaching system. In this paper, we explore the leaching of complex chalcopyrite-rich ores employing a mechanically activated pretreatment combined with wastewater with high concentrations of chloride. The investigation delves into various parameters, including reaction temperature (60 to 90 °C), sulfuric acid concentration (0.005 to 2.0 M), chloride concentration (0 to 1.5 M), liquid/solid ratio (0 to 200), stirring speed (100 to 580 rpm), leaching time (0 to 4 h) and grinding time (0 to 7 h), to evaluate their impact on copper recovery from complex chalcopyrite-rich ores. Furthermore, a comprehensive kinetic analysis of copper leaching behavior was studied, encompassing specific surface area, amorphization degree, grain size, and microstrain. In the sulfuric acid system utilizing wastewater, the presence of mechanical activation and chloride content enhances copper leaching while mitigating the passivating effect of elemental sulfur. Notably, following a leaching period of 4 h at 80 °C, the copper leaching efficiency remarkably reached 89.46 %. In addition, kinetic analysis of copper leaching at temperatures ranging from 60 to 90 °C via a shrinking core model with R2 > 97 %, indicates that the leaching process of copper is primarily governed by solid product layer diffusion, with an activation energy of 54.32 kJ/mol. These findings highlight the efficacy of the proposed approach in optimizing copper recovery from complex chalcopyrite-rich ores, offering insights into the underlying mechanisms driving the leaching process.

Amorphization‐controlled ion release of cobalt‐exchanged zeolite X

AbstractZeolitic carrier materials offer ion release and uptake functionality for a wide range of applications. The release kinetics are controlled by the mobility of the target species within the zeolite framework and at its surface. Here, we achieve control over the release dynamics and the quantity of released Co2+ ions from a faujasitic zeolite through mechanical amorphization of the zeolite framework. We identify a two‐step reaction mechanism in which ion release and reintegration compete on short and intermediate timescales. The competition between these two processes is governed by the degree of amorphization, with a timescale ranging from a few minutes to several days.

The impact of alcohol and ammonium fluoride on pressure-induced amorphization of cubic structure I clathrate hydrates.

We have investigated pressure-induced amorphization (PIA) of an alcohol clathrate hydrate (CH) of cubic structure type I (sI) in the presence of NH4F utilizing dilatometry and x-ray powder diffraction. PIA occurs at 0.98GPa at 77K, which is at a much lower pressure than for other CHs of the same structure type. The amorphized CH also shows remarkable resistance against crystallization upon decompression. While amorphized sI CHs could not be recovered previously at all, this is possible in the present case. By contrast to other CHs, the recovery of the amorphized CHs to ambient pressure does not even require a high-pressure annealing step, where recovery without any loss of amorphicity is possible at 120K and below. Furthermore, PIA is accessible upon compression at unusually high temperatures of up to 140K, where it reaches the highest degree of amorphicity. Molecular dynamics simulations confirm that polar alcoholic guests, as opposed to non-polar guests, induce cage deformation at lower pressure. The substitution of NH4F into the host-lattice stabilizes the collapsed state more than the crystalline state, thereby enhancing the collapse kinetics and lowering the pressure of collapse.

Comparative Study of Microstructure and Phase Composition of Amorphous-Nanocrystalline Fe-Based Composite Material Produced by Laser Powder Bed Fusion in Argon and Helium Atmosphere.

Laser powder bed fusion (LPBF) is a prospective and promising technique of additive manufacturing of which there is a growing interest for the development and production of Fe-based bulk metallic glasses and amorphous-nanocrystalline composites. Many factors affect the quality and properties of the resulting material, and these factors are being actively investigated by many researchers, however, the factor of the inert gas atmosphere used in the process remains virtually unexplored for Fe-based metallic glasses and composites at this time. Here, we present the results of producing amorphous-nanocrystalline composites from amorphous Fe-based powder via LPBF using argon and helium atmospheres. The analysis of the microstructures and phase compositions demonstrated that using helium as an inert gas in the LPBF resulted in a nearly three-fold increase in the amorphization degree of the material. Additionally, it had a beneficial impact on phase composition and structure in a heat-affected zone. The received results may help to develop approaches to control and improve the structural-phase state of amorphous-nanocrystalline compositional materials obtained via LPBF.

Atomic insights into the solid-state amorphization mechanism of amorphous/crystalline dual-phase Mg alloys

The amorphous/crystalline (A/C) dual-phase structure is a new design strategy to improve the comprehensive performance of Mg alloys. However, the regulation mechanism of the amorphous phase size of the dual-phase Mg alloys is still unclear. Here, the mechanism and size effect of solid-state amorphization of the dual-phase Mg alloys is investigated using molecular dynamics/Monte Carlo simulations. The results indicate that the degree of solid-state amorphization of the dual-phase Mg alloys depends on three factors: the original size of amorphous phase, the diffusion of rare earth element Y, and A/C interface (ACI). The degree of solid-state amorphization of the alloys exhibits a significant size effect on the original size of amorphous phase. Except for the two models with the smaller original size of the amorphous phase, the degree of solid-state amorphization of the alloys decreases significantly with the increase of the original size of amorphous phase. It is worth noting that after relaxation, as the original size of amorphous phase increases, the distribution of Y atoms in the amorphous phase undergoes a transition from uniform distribution to segregation, and the larger the original size of amorphous phase, the more obvious the segregation phenomenon becomes. The results indicate that the segregation of Y atoms in the amorphous phase suppresses the solid-state amorphization of the alloys. The results show that the segregation of Y atoms in the alloys requires a larger original size of the amorphous phase and the presence of ACI, both of which are essential.

Role of carbide grit size and in-flight particle parameters on the microstructure, phases, and nanoscale properties of HVOF sprayed WC-12Co coatings

Effects of particle temperature and velocity on crystallinity and phase composition of WC-Co coating are successfully decoupled. The effect of grit size on the dissolution and decarburization process is established analytically. The nanostructured coatings were found to be less crystalline than their conventional counterpart for similar in-flight parameters. The cooling rate and the degree of carbide dissolution in the binder phase govern the crystallinity of the as-sprayed coatings. An increase in either of these factors results in a higher degree of amorphization of as-sprayed coatings. The phases present in the coating were quantified, and correlated with particle temperature and velocity independently. The degree of decarburization increased with an increase in particle temperature. The calculated change in Gibbs free energy justified these observations. The effect of particle velocity on crystallinity or phase composition was not significant. The nano hardness of the carbide grits was increased with particle temperature owing to the formation of a hard W2C phase. Similarly, the dissolution of carbides in the binder and the formation of the Co3W9C4 phase increased the binder hardness. The energy analysis revealed brittleness of the binder matrix increased significantly with deposition temperature owing to the formation of the Co3W9C4 phase.

The radiation resistance and chemical stability optimization of analog actinide nuclides incorporated Gd2Zr2O7 ceramics via grain size control

Gd2Zr2O7 is considered a promising host material for immobilizing high-level radioactive waste. However, its interplay between grain sizes, radiation resistance and chemical stability is not well understood yet. Herein, Gd1.7Nd0.3Zr0.5Ce1.5O7 ceramics with defect-fluorite phase and three different grain sizes (96, 390 and 1959 nm) were successfully fabricated and irradiated by 140 keV He ion beam up to a fluence of 8 × 1017 ions/cm2. Phase evolutions, microstructure changes and chemical stabilities were investigated. The nano-grained ceramic exhibits the lowest degree of amorphization and a delayed irradiation-induced lattice expansion and damage evolution process, demonstrating an enhanced ability in suppressing the coalescence of He bubbles inside the grain. Grain boundaries parallel to the surface were found to be more favorable sinks for irradiation-induced defects. Chemical stability tests showed that the 42 days leaching rates of all elements were between 10−7∼10−5 g/m2·d. All samples have maintained this superior chemical stability even after irradiation. Interestingly, the leaching test results also suggested that grain size may be not the primary factor influencing the long-term leaching rate.

Oxygen reduction reaction platinum group metal-free electrocatalysts derived from spent coffee grounds

The annual generation of coffee waste has overtaken 6 million metric tons, becoming a serious environmental problem. Herein, we report the fabrication of bimetallic electrocatalysts synthesized by 1) pyrolyzing spent coffee grounds (SCGs) at 400, 600, 800 and 1000 °C, 2) activating the as-obtained char with KOH and 3) functionalizing the activated carbon with iron(II) and manganese(II) phthalocyanine. The final electrocatalysts showed a high degree of amorphousness, defectivity (increasing with temperature) and high specific surface area (up to 1820 m2 g−1). In half-cell compartment (0.1 M KOH electrolyte), the top-notch material in terms of oxygen reduction reaction (ORR) activity and selectivity was CFeMn_600, which showed the same half-wave potential (E1/2) compared to Pt/C standard along with a lower peroxide production. These outstanding results could be attributed to a high surface area, a Fe-Mn synergy, and an abundance of C-N defects. The performance of CFeMn_600 as a cathode material in alkaline exchange membrane fuel cells (AEMFC) showed an open circuit voltage (OCV) of 0.890 V and power density of 30 mW cm−2. Notwithstanding, this research is one of few cases where a waste-derived electrocatalyst is tested in a real AEMFC, thus becoming a pioneer in the fuel cell study of waste-derived electrode materials.

Biocomposites Based on Wheat Flour with Urea-Based Eutectic Plasticizer and Spent Coffee Grounds: Preparation, Physicochemical Characterization, and Study of Their Influence on Plant Growth.

In this study, we conducted the first plasticization of wheat flour (WF) with the addition of choline chloride:urea (1:5 molar ratio) eutectic mixture as a plasticizer and spent coffee grounds (cf) as a filler. Thermoplastic wheat flour (TPWF) films were obtained via twin-screw extrusion and then thermocompression. Their physicochemical characterization included mechanical tests, dynamic mechanical thermal analysis (DMTA), and sorption tests. XRD analysis revealed that the eutectic plasticizer led to a high degree of WF amorphization, which affected the physicochemical properties of TPWF. The results indicated that it was easy for the TPWF biocomposites to undergo thermocompression even with a high amount of the filler (20 pph per flour). The addition of the cf into TPWF led to an increase in tensile strength and a decrease in the swelling degree of the biocomposites. Biodegradation tests in soil revealed that the materials wholly degraded within 11 weeks. Moreover, a study of cultivated plants indicated that the biocomposites did not exhibit a toxic influence on the model rowing plant.

Effect of Carbonization Temperature on the Structure of Pitch Carbon and Its Low-temperature Lithium Storage Properties

Introduction:: Lithium-ion batteries were one of the most promising battery systems for electric vehicles. Currently, lithium-ion batteries are required to have higher energy density and cycle stability. The traditional graphite negative electrode cannot meet the requirements. Pitch has many advantages such as wide source, low cost, high carbon residue rate and easy graphitization, as a carbon precursor has been widely used in lithium-ion battery anode and anode materials. Method:: In this paper, pitch carbon was prepared by carbonization at different temperatures and studied. Result:: The results showed that with the increase of carbonization temperature, the interlayer spacing decreased gradually, the degree of amorphousness decreases gradually, the specific surface area and pore volume also decrease gradually, the initial coulombic efficiency and capacity retention increased, and the discharge-specific capacity decreased. Galvanostatic Intermittent Titration Technique (GITT) tests show that there are two main mechanisms of lithium ions intercalation in the material, surface adsorption and interlayer intercalation. Conclusion:: The difficulty of diffusion of lithium ions between pitch carbon layers at low temperatures is the main reason for the decrease of its capacity at low temperature. The carbon material obtained by carbonization of pitch at 800℃ has the best low temperature performance, with discharge specific capacities of 335, 272, 232 and 187mAh/g at 25, 0, -20 and -40℃, of which 55.8% of the discharge specific capacity at room temperature can be retained at -40℃. The amorphous carbon material has certain low temperature charge-discharge performance.

Boron carbide based composites densified via Ti3SiC2 boronizing with excellent mechanical properties and amorphization tolerance

Consolidated boron carbide (B4C) composites are extremely hard but have been shown to undergo stress-induced amorphization when subjected to high velocity impact. This localized amorphization has been related to the sudden loss of their strength and poor ballistic protection. In this work, dense B4C based composites were spark plasma sintered through in-situ reactions involving with Ti3SiC2 and boron. Hierarchical structures composed of TiB2–SiC–Si reinforcement and B4C matrix were finally built and the degree of amorphization was markedly reduced as the increment of boron amounts. As-generated composites with tough and hard reinforcement possess enhanced amorphization resistance without compromising their mechanical properties. Due to the co-doping of Si and B in boron carbide, the amorphization degree yields a reduction of up to 73 %. The dominant amorphous tolerance is associated with the chain retention and atomic-level local lattice distortion in boron carbide. Therefore, Ti3SiC2 boronizing route may present itself a promising strategy to design boron carbide based composites with better ballistic performance.

Designing Compatible Ceramic/Polymer Composite Solid-State Electrolyte for Stable Silicon Nanosheet Anodes.

The commercialization of silicon anode for lithium-ion batteries has been hindered by severe structure fracture and continuous interfacial reaction against liquid electrolytes, which can be mitigated by solid-state electrolytes. However, rigid ceramic electrolyte suffers from large electrolyte/electrode interfacial resistance, and polymer electrolyte undergoes poor ionic conductivity, both of which are worsened by volume expansion of silicon. Herein, by dispersing Li1.3Al0.3Ti1.7(PO4)3 (LATP) into poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP) and poly(ethylene oxide) (PEO) matrix, the PVDF-HFP/PEO/LATP (PHP-L) solid-state electrolyte with high ionic conductivity (1.40 × 10-3Scm-1), high tensile strength and flexibility is designed, achieving brilliant compatibility with silicon nanosheets. The chemical interactions between PVDF-HFP and PEO, LATP increase amorphous degree of polymer, accelerating Li+ transfer. Good flexibility of the PHP-L contributes to adaptive structure variation of electrolyte with silicon expansion/shrinkage, ensuring swift interfacial ions transfer. Moreover, the solid membrane with high tensile limits electrode structural degradation and eliminates continuous interfacial growth to form stable 2D solid electrolyte interface (SEI) film, achieving superior cyclic performance to liquid electrolytes. The Si//PHP-L15//LiFePO4 solid-state full-cell exhibits stable lithium storage with 81% capacity retention after 100 cycles. This work demonstrates the effectiveness of composite solid electrolyte in addressing fundamental interfacial and performance challenges of silicon anodes.

Перетворення довгополуменевого вугілля в нанопористий вуглецевий матеріал при карбонізації з гідроксидом калію

DOI: 10.31081/1681-309X-2024-0-2-32-43 Specialty 161. U.D.C. 552.576.1: 66.040.2: 661.183.2 CONVERTING LONG-FLAME COAL INTO NANOPOROUS CARBON MATERIAL DURING CARBONISATION WITH POTASSIUM HYDROXIDE © V.O. Kucherenko, Doctor of Chemical Scienses, Y.V. Tamarkina, Ph.D. in Chemical Sciences, A.V. Redko (L.M. Litvinenko Institute of Physical-Organic and Coal Chemistry of the National Academy of Sciences of Ukraine, 02160, Kyiv, Kharkiv Highway St., 50, Ukraine) The article is devoted to the study of changes in the supramolecular and porous structure of longflame coal during its transformation into a nanoporous material in the process of carbonisation with potassium hydroxide at a low KOH/coal ratio RKOH = 1.0 g/g. Samples of carbonaceous materials (CM) were prepared in argon by heating (4 deg/min) to a given temperature t (in the range of 350-825 °C), isothermal holding for 1 h, cooling, alkali washing, and drying. The samples are denoted as СM(t). The yield and elemental composition of CM were determined. The supramolecular structure of the CM was studied by XRD (Bruker D8). The interlayer distance in crystallites d002, height Lc, average diameter La and crystallite volume Vc, intensity I002 of the reflex (002) were determined. Based on the low-temperature (77 K) nitrogen adsorptiondesorption isotherms by the 2D-NLDFT-NS method, the integral and differential dependences of the specific surface area of SDFT (m2/g) and the pore volume V (cm3/g) on the average pore diameter (D, nm) were calculated (SAIEUS software). From these, the volumes of ultramicropores (Vumi), supermicropores (Vsmi), and micropores (Vmi) were calculated. The total pore volume was calculated from the amount of nitrogen adsorbed at a relative pressure of p/p0~1.0. Similarly, the specific surfaces of ultramicropores (Sumi), supermicropores (Ssmi), and micropores (Smi) were determined. It has been established that under conditions of alkaline carbonisation with KOH, long-flame coal is converted into СM with a yield of 45.3-70.2 %, a specific surface area of up to 1530 m2/g and a total volume of adsorbing pores of up to 1.091 cm3/g. With increasing temperature, the carbon content of CM decreases from 77.2 % to 71.3 % (at 500 °C), and then increases to 85.9 % (at 825 °C). The oxygen content increases to a maximum at 500 °C due to reactions in which KOH is a donor of Oatoms, and then decreases due to thermal destruction of functional groups and condensation reactions that increase the size of polyarenes of the secondary framework of the СM and form single Car-Car bonds between them. The main changes in the supramolecular structure occur above 400 °C and lead to an increase in d002 from 0.407 nm to 0.446 nm, a decrease in Lc from 0.872 nm to 0.699 nm, and an increase in the size of polyarenes La from 1.46 nm to 3.30 nm. Judging by the ~3-fold decrease in the I002 intensity, the crystallite content decreases significantly with increasing temperature, and the degree of amorphousness of the spatial framework of the CM increases. It was found that the thermally initiated reactions of coal with KOH form mainly pores with D ≤ 5 nm. With increasing temperature, the total pore volume and micropore volume increase monotonically. The values of Vumi and Vsmi increase up to 600 °C, and at 600-825 °C, the volume of Vumi decreases, since ultramicropores (D ≤ 0.7 nm) are transformed into supermicropores (D = 0.7-2.0 nm) due to the burnout of pore walls. The proportion of ultramicropore volume is maximum (23.9 %) in the sample СM(600). The proportion of the specific surface area of ultramicropores is maximum (56.3 %) in СM(500). The proportion of the micropore surface is dominant (92.6-97.0 %) in the CM obtained at t≥450 °C. The distributions of pore volume and specific surface area are characterised by maxima corresponding to subnanopores with D ≤ 1 nm, supermicropores and mesopores with D = 3-5 nm. For the СM samples obtained at 450-750 °C, there are no supermicropore maxima, but their formation occurs. It was determined that the most microporous CM are formed at 785-825 °C and are characterised by a specific surface area of 1514-1522 m2/g, a pore volume of 1.047-1.091 cm3/g, and a micropore surface area of 1415-1443 m2/g, which is not less than 93 % of the total surface. Keywords: long-flame coal, alkaline treatment, carbonisation, carbonaceous material, supramolecular structure, porosity. Corresponding author Y.V. Tamarkina, e-mail: tamarkina@nas.gov.ua