Tin Sulfide Research Articles

Structural engineering of SnS quantum dots embedded in N, S Co-Doped carbon fiber network for ultrafast and ultrastable sodium/potassium-ion storage

Tin sulfides have received significant attention as potential candidates for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to their abundance, high theoretical capacity, and favorable working potential. However, the inherent drawbacks such as slow kinetics, low intrinsic electronic conductivity, and significant volume change during cycling, have not been adequately addressed. In this study, we propose a rational and effective approach to simultaneously overcome these challenges by embedding stannous sulfide (SnS) quantum dots (QDs) within a crosslinked nitrogen (N) and sulfur (S) co-doped carbon fiber network (SnS-CFN). The well-dispersed and densely packed SnS QDs, measuring approximately 2 nm, not only minimize the diffusion distance of Na+/K+ ions but also buffer the volume expansion effectively. The N, S co-doped carbon fiber network in SnS-CFN serves as a highly conductive and stable support structure that inhibits SnS QDs aggregation, creates ion/electron transport channels, and alleviates volume variations. Density functional theory (DFT) calculations further confirm that the combination of SnS QDs and the N, S co-doped carbon effectively reduces the adsorbed energies in the interlayer of SnS-CFN. These advantages synergistically contribute to the exceptional sodium/potassium storage performance of the SnS-CFN composite. Consequently, SnS-CFN demonstrates exceptional cyclability, retaining a capacity of 251.5 mAh/g over 10,000 cycles, and exhibits excellent rate capability (299.5 mAh/g at 20 A/g) when employed in SIBs. When used in PIBs, a high capacity of 112.3 mAh/g at 2 A/g after 1000 cycles, a remarkable capacity of 51.4 mAh/g at 5 A/g after 10,000 cycles, and a remarkable rate capability with a specific capacity of 55.5 mAh/g at a high current density of 20 A/g have been achieved.

Nanostructured SnS-Si hybrid photodetectors by pulsed laser processed nanocolloids

This research investigates the fabrication of SnS-Si hybrids for photodetection and photocatalysis using nanocolloids of tin sulfide (SnS), monocrystalline silicon (Sim) and polycrystalline silicon (Sip) produced by laser-assisted techniques (pulsed laser fragmentation as well as ablation in liquid). Characterization of the nanocolloids and the hybrid thin films obtained by techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron Spectroscopy (XPS), Raman spectroscopy, UV–Visible spectroscopy and photoluminescence spectroscopy (PL) are presented in this work. Post-deposition annealing improved the material properties of the hybrid films and the films exhibited optical bandgaps between 1.51 and 1.68 eV, suitable for light detection. In the case of hybrid SnS-Si films, SnS-Sim showed two orders of current higher than the SnS-Sip films. The photocurrent dynamic curves (current vs time) and current-voltage (I–V) characteristics are investigated to verify the improved device performances. The photodetector parameters such as sensitivity, responsivity, detectivity are also reported. Compared with conventional SnS thin film devices, all the films (SnS and SnS-Si hybrids) in this work responded to illumination sources of wavelengths up to 1064 nm. This is one of the initial studies on hybrid devices with Si nanoparticles for photodetector applications. All the films showed ultra-short response/recovery times in the range of 400–800 ms and their photodetector parameters were recorded. The films demonstrated good stability and cyclic photocatalytic activity to visible light.

Phase-Controlled Multi-Dimensional-Structure SnS/SnS2/CdS Nanocomposite for Development of Solar-Driven Hydrogen Evolution Photocatalyst.

The quest for water-splitting photocatalysts to generate hydrogen as a clean energy source from two-dimensional (2D) materials has enormous implications for sustainable energy solutions. Photocatalytic water splitting, a major field of interest, is focused on the efficient production of hydrogen from renewable resources such as water using 2D materials. Tin sulfide and tin disulfide, collectively known as SnS and SnS2, respectively, are metal sulfide compounds that have gained attention for their photocatalytic properties. Their unique electronic structures and morphological characteristics make them promising candidates for harnessing solar energy for environmental and energy-related purposes. CdS/SnS/SnS2 photocatalysts with two Sn phases (II and IV) were synthesized using a solvothermal method in this study. CdS was successfully placed on a broad SnS/SnS2 plane after a series of characterizations. We found that it is composited in the same way as a core-shell shape. When the SnS/SnS2 phase ratio was dominated by SnS and the structure was composited with CdS, the degradation efficiency was optimal. This material demonstrated high photocatalytic hydrogenation efficiency as well as efficient photocatalytic removal of Cr(VI) over 120 min. Because of the broad light absorption of CdS, the specific surface area, which is the reaction site, became very large. Second, it served as a transport medium for electron transfer from the conduction band (CB) of the SnS to the CB of the SnS2. Because of the composite, these electrons flowed into the CB of CdS, improving the separation efficiency of the photogenerated carriers even further. This material, which was easily composited, also effectively prevented mineral corrosion, which is a major issue with CdS.

Electrodeposited CZTS loaded titania nanotubes for photocatalytic water splitting

Copper Zinc Tin Sulphide (Cu2ZnSnS4 (CZTS)) is a promising semiconductor material with optimum direct band gap of 1.4-1.6 eV, large light absorption coefficient (> 104 cm-1) and p-type electrical conductivity. In addition, its earth abundant and non-toxic elemental constituents make it a good candidate to replace the CdTe and CIGS absorber layers used in thin film solar cells. Also, it has properties that make it useful as a buffer layer that helps to reduce the effective band gap of TiO2 when used as an anode for photocatalytic splitting of water. We prepared titania nano tube (TNT) arrays by anodization of titanium foil. Raman spectrum of TNT confirmed the presence of pure anatase phase of TiO2. Field emission scanning electron microscopy images were obtained to analyse the surface morphology of TNT. CZTS sensitized titania nano tube arrays were then prepared by the electrodeposition of CZTS thin films over TNT arrays. FESEM images of the CZTS sensitized titania nano tube arrays showed that the electrodeposited CZTS layer had a fibrous structure. A photo electro chemical (PEC) cell was set up with CZTS sensitized titania nanotubes as anode. An anodic current density of 0.19 mA/cm2 was shown by the PEC cell when the anode was irradiated with blue light of wavelength 430 nm at power 50 mW/cm2. The incident photon to current conversion efficiency was 1.1 %.

Performance improvement of CZTS-based hybrid solar cell with double hole transport layer using extensive simulation

The extensive outcomes of the specific modeling method for hybrid photovoltaic solar cells at the illumination condition of AM 1.5G spectrum are shown in this simulation work. This research aims to optimize the efficiency of the device structures by introducing the novel hybrid-absorber layer (AL). The hybrid solar cell (HSC) has higher efficiency with an absorber layer (AL), i.e., Copper Zinc Tin Sulphide. The current simulation uses ZnO, V2O5, and Spiro-OMeTAD as the carrier transport layers (CTLs); both hole/electron transport layer (HTL/ETL) to sandwich the CZTS, which have precise bandgaps of 1.5 eV. Using double HTLs of Spiro-OMeTAD/V2O5 offers a high efficiency of 23.21%. The detailed examination of thickness, total defect density (DD), temperature dependency, and impedance-capacitance analysis of the simulated device structures are also studied simultaneously.

Kesterite CZTS based thin film solar cell: Generation, recombination, and performance analysis

The thin film Copper Zinc Tin Sulphide (CZTS) solar cells (SC) are third-generation SC that has potential use in solar photovoltaics nowadays. The present work aims to raise the output parameter of CZTS-based SC through the generation and recombination process using Solar Cell Capacitance Simulator in one dimension (SCAPS-1D). The proposed configuration of cell ZnO/ZnS/CZTS/SnS has been evaluated by considering SnS as the back surface field (BSF). It is observed that SnS is a suitable material to be used as a BSF. In the present work, the role of variations of the different parameters such as layer thicknesses, defect densities, recombination and generation of charge carriers, and the back contact work function effect on the PV parameter have been studied. Optimized parameters from the studied cell such as power conversion efficiency (PCE) of 18.18%, current density (Jsc) as 27.7899 mA/cm2, open circuit voltage (Voc) of 0.7875 V, and fill factor (FF) of 83.07% have been recorded. This result will pave the researchers working in this field to fabricate earth-abundant, low-cost, highly efficient, and toxic-free CZTS SCs.

Interlayer expanded SnS/N-doped carbon/SnS ultra-thin composite driven from layered tin chalcogenides as advanced anode for lithium and sodium ion battery

The unique 2D-layered structure of tin (II) sulfide (SnS) compounds has led to the emergence of strong intensities, showcasing their significant potential in lithium (LIBs) and sodium (SIBs) ion batteries. However, the commercialization process of SnS compounds remain hindered due to the poor cycle stability caused by its substantial volume expansion during cycling in battery applications. In this study, a simple and scalable synthesis of ultra-thin composite with a well-connected structure SnS/N-doped carbon/SnS (SnS/NC/SnS) is reported. The structure is directly derived from layered tin chalcogenides (A2Sn3S7·xH2O, where A represents an organic cation). Within this configuration, SnS nanosheets are decorated on the N-doped carbon material. The composite exhibits an expanded layer of 9.7 Å, enabling rapid movement of Na+ ions (approximately 7 times the diffusion coefficient of bulk SnS). This expansion also aids in accommodating volume changes during the discharging and charging processes. Concurrently, theoretical calculations demonstrate that the structure maintains a relatively stable state at the interlayer spacing mentioned. The SnS/NC/SnS composite material exhibited significant potential for application in both SIBs and LIBs. In SIBs, it demonstrated excellent long-term cyclic stability, maintaining a capacity of 190 mA h g−1 even under high current density conditions of 2.5 A g−1 after 300 cycles. In LIBs, it exhibit a superior discharge capacity of 990 mA h g−1 and retains 94.1 % of its capacity after 150 cycles at 0.2 A g−1. Notably, this synthesis method is versatile, as the interlayer spacing can be adjusted by varying the type of organic cations used in the process.

Ultrafast Hole Migration at the p-n Heterojunction of One-Dimensional SnS Nanorods and Zero-Dimensional CdS Quantum Dots.

The p-n heterojunctions fabricated from one-dimensional (1D) p-type tin sulfide nanorods (SnS NRs) decorated with n-type zero-dimensional (0D) cadmium sulfide quantum dots (CdS QDs) have gained significant research attention in energy storage devices. Herein, we have successfully synthesized a 1D/0D SnS@CdS heterostructure (HS) using a hot injection method. Structural and morphological studies clearly suggest that CdS QDs are uniformly anchored on the surface of SnS NRs, resulting in intimate contact between two components. The photoluminescence (PL) study revealed the transfer of photoexcited holes from CdS QDs to SnS NRs, which was further confirmed by transient absorption (TA) studies. TA measurements demonstrate the hole transfer from the valence band of CdS QDs to SnS NRs and delocalization of electrons between the conduction band of SnS NRs and CdS QDs in SnS@CdS HS, resulting in efficient charge separation across the p-n heterojunction. These findings will open up a new paradigm for improving the efficiency of optoelectronic devices.

Investigation of Temperature-Dependent Phonon Anharmonicity and Thermal Transport in SnS Single Crystals.

Tin sulfide has outstanding thermoelectric properties in the b-axis direction of crystallography as a IV-VI group layered compound, which arouses great attention. In this study, temperature-dependent Raman spectroscopy (TDRS) is used to quantify the phonon anharmonicity in SnS crystals from 77 to 475 K, where the three-phonon process dominates in this temperature region. Moreover, integration of the four-phonon process and lattice thermal expansion will better describe the temperature-dependent Raman experimental phenomenon. The good agreement between the calculated and experimental lattice thermal conductivity confirms the three-phonon scattering process is the dominant scattering mechanism at this temperature range. Further, combining the atomic thermal displacement and charge density through density functional theory calculation, the inherently low thermal conductivity of SnS is because of strong lattice anharmonicity, which is brought by the presence of asymmetric chemical bonding resulting from the Sn 5s2 lone pair electrons. These results provide key insights for studying thermal properties of other low-dimensional materials.

Cu2SnS3 based photovoltaic structure with improved open circuit voltage for air stable self-driven enhanced NIR photodetection

Copper tin sulfide (Cu2SnS3) is an environmentally benign and economical semiconductor comprising earth-abundant, non-toxic elements with flexible optoelectronic properties for photovoltaic energy conversion and photodetection. The optimization of sulfurization temperature resulted in significant improvement in structure, morphology, elemental composition, optical and electrical properties. A substantial advancement in photovoltaic performance was achieved by integrating a thin layer of SnS and the same enhancement theoretically predicted using SCAPS-1D simulation. Photovoltaic structure with optimized monoclinic Cu2SnS3 as an absorber layer and thin SnS layer (Glass/FTO/CdS/SnS/Cu2SnS3/Ag) resulted in photovoltaic parameters: Voc = 415 mV, Jsc = 17.2 mA.cm−2, and PCE = 2.12 %. We demonstrate the first self-powered SnS/Cu2SnS3 based photodetector which delivers high detectivity of 1.41 × 1011 Jones under the illumination of an 840 nm laser with rapid rise and decay time of 10.2 and 10.1 ms, respectively. Economic and environmentally benign Cu2SnS3 thin films based photovoltaic structures will be beneficial for harvesting sustainable energy and paving a strong platform for self-powered, air-stable, and spectral selective photodetection.

Reduced thermal conductivity and improved ZT of Cu-doped SnS-based bulk thermoelectric materials via compositing SnS nano-fiber strategy

Tin sulfide (SnS), as a low-cost and eco-friendly thermoelectric (TE) material, exhibits relatively poor phonon and charge transport capacities when the long-range ordered layered crystal structure is broken by the grain boundaries of polycrystalline. Nevertheless, doping and compositing are effective strategies for improving the electrical and thermal conductivity. Herein, utilizing the composite powders synthesized via Cu-doped SnS nanosheets grown in-situ on the surface of Cu-doped SnS nanofibers, we design a homogeneous nanofibers composited Cu-doped SnS polycrystalline bulk to boost its TE performance. Comparing with pure phase SnS, Cu doping can effectively increase the carrier concentration and mobility of SnS, realizing an increase of electrical conductivity from 4.11 S·cm−1 to 31.57 S·cm−1. Simultaneously, quite a number of fiber/matrix composite interfaces for phonon scattering are formed due to incorporating of composite nanofibers, which significantly reduce the lattice thermal conductivity of Cu-doped SnS polycrystalline bulk. The results show that thermal conductivity reduced as low as 0.64 W·m−1 K−1 at 324 K when the additive amount of nanofibers was fix at 2 wt%. Ultimately, the power factor and ZT value are markedly enhanced at low and medium temperature ranges (300–500 K) compared with SnS polycrystalline bulk without fiber incorporation. This provides an effective strategy for optimizing the thermoelectric performance of SnS-based polycrystalline.

Substitution effects on physical and chemical properties of Cu2Fe1-xCoxSnS4 thin films synthesized by the sol-gel technique

The impact of iron and cobalt substitution on the structural, morphological and optical properties of the copper iron cobalt tin sulfide Cu2Fe1-xCoxSnS4 thin films was studied. Employing the simple and easy sol-gel spin-coating technique on soda-lime glass substrates without sulfurization phase, Cu2Fe1-xCoxSnS4 (x = 0, 50 and 100%) compound was formed with the (112) preferential orientation for all thin films in the tetragonal stannite structure at space-group I42 m. By performing X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy, Energy Dispersive analysis and UV–Vis–NIR spectrophotometry, the physical and chemical properties were examined. The substitution was observed to provide a slight variation of the lattice parameters. The crystallite size was found to vary between 14 and 32 nm and decreased by increasing the cobalt content. The Raman spectra confirm the result of the XRD via the appearance of two peaks located at 321 and 284 cm−1, corresponding to the A1 vibration mode. The morphological analysis showed homogenous film surfaces. Optical characterizations showed that all thin films exhibit a band-gap energy, estimated between 1.1 and 1.53 eV, with an absorption coefficient greater than 104 cm−1. The possible use of thin films as an absorber for solar cells, with an adjustable optical band gap is proven.

Hydrothermally modified tin(II) sulfide binder-free battery grade electrode for supercapattery

In the initiative of diminishing the current research gap related to the limited electrochemical performance of supercapacitor, various hybrid supercapacitor combinations were introduced. However, the energy storage capacity and power are still limited. Thus, a new type of hybrid device known as supercapattery was introduced by combining a battery grade electrode with capacitive type electrode to improve the energy and power densities. In the midst of material exploration on battery grade materials suited for supercapattery, transition metal sulfides have grabbed intense attention for their excellent electrochemical properties and conductivity. Herein, a novel tin (II) sulfide (SnS) binder free electrode materials were synthesized through hydrothermal method as a battery grade material for supercapattery. In this work, the electrodes were fabricated by differing metal precursor to reducing agent ratios (1:2,1:4, and 1:6) followed by fine tuning the physio-chemical characteristics of SnS by differing hydrothermal temperature. The synthesized materials were structurally characterized using X-ray diffraction analysis. The surface morphology and particle size were investigated through field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The SnS fabricated using ratio 1:4 at 150 °C exhibited fascinating specific capacity/specific capacitance (325.20Cg−1/668.45Fg−1) with 89.73% rate capability. The SnS was then combined with activated carbon (AC) to produce supercapattery. The fabricated supercapattery demonstrated fascinating stability of 98.61% over 15,000 cycles with maximum energy and power density of 8.77 Wh kg-1 and 3,095.20 W kg−1, respectively.

Exploring the performance of perovskite solar cells with dual hole transport layers via SCAPS-1D simulation

The potential of perovskite solar cells (PSCs) to produce high efficiency (over 25 %) is well known, but the poor stability of these solar cells is still a concern for practical applications. Thus, improving the stability is essential for furthering the development of PSCs. To address this issue, researchers found that incorporating inorganic materials into the hole transport layers (HTLs) can improve the stability of PSCs, yet charge recombination at the interface between the perovskite and inorganic HTLs can still reduce the efficiency of the PSCs. This study simulated the performance and mechanism of methyl ammonium lead iodide (MAPbI3) PSCs with a dual HTL using Solar Cell Capacitance Simulator-one Dimension (SCAPS-1D). A dual HTL formed by combining Spiro-OMeTAD (spiro), a highly efficient hole transport material, and copper zinc tin sulfide (CZTS), a highly stable hole transport material, leads to a PSC with a power conversion efficiency (PCE) of 23.47 % and significantly improved stability. Simulation results of the electric field at the interfaces of PSCs indicated that the PSC with spiro/CZTS as dual HTL have enhanced charge separation and reduced recombination. Furthermore, the simulation results have also revealed the influence of different parameters, such as absorber thickness, absorber defect density, HTL thickness, HTL/absorber interface defects, temperature, series resistance, and shunt resistance, on solar cell’s characteristics.

Enhanced solar cell efficiency: copper zinc tin sulfide absorber thickness and defect density analysis

Enhanced solar cell efficiency: copper zinc tin sulfide absorber thickness and defect density analysis

Anchoring SnS nanoflakes on CuCo2O4 acicular sprouts for overall water splitting

Employing a bifunctional electrocatalyst capable of simultaneously performing Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) under the same conditions of temperature, pressure, and pH is beneficial for realizing compact and efficient electrolyzers. In the pursuit of cultivating the superior abilities of ternary transition metal oxides and sulphides in OER and HER, an Argyrophylla-like heterostructure electrode consisting of Copper Cobalt Oxide (CuCo2O4) and Tin Sulfide (SnS) have been fabricated through a facile two-pot hydrothermal method. The surface level morphology and electrochemical active sites of binder-free SnS/CuCo2O4/NF heterostructure bifunctional catalyst were modified to achieve lower overpotentials for both OER (315 mV @ 20 mA/cm2) and HER (98 mV @ 20 mA/cm2) in 1.0 M KOH electrolyte medium. The proclaimed efficiencies are attributed to the enhanced oxygen vacancies, interfacial bonds and surface sulfur sites in the heterostructure as evident from electrochemical and X-ray photoelectron spectroscopy (XPS) studies. Apart from that, the proposed heterostructure electrode attained a current density of 10 mA/cm2 with a very low cell voltage of 1.60 V when employed as a dual electrode in an electrolyser cell. The Sn–O bond at the interface of CuCo2O4 and SnS stabilizes the heterostructure that helped in maintaining the lower current degradation rate (CDR) in Chronoamperometry (CA) test.

The Effect of substrate Nature on the properties of Tin Sulfide Nanostructured films Prepared by chemical bath deposition

The substrate's nature plays an important role in the characteristics of semiconductor films because of the thermal and lattice mismatching between the film and the substrate. In this study, tin sulfide (SnS) nanostructured thin films were grown on different substrates (polyester, glass, and silicon) using a simple and low-cost chemical bath deposition technique. The structural, morphological, and optical properties of the grown thin films were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. The XRD and FESEM results of the prepared films revealed that each film is polycrystalline and exhibits both orthorhombic and cubic structure types. In addition, the deposited films on polyester and glass showed good absorption in the UV-Vis-NIR range.

Deposition of Thin Electroconductive Layers of Tin (II) Sulfide on the Copper Surface Using the Hydrometallurgical Method: Electrical and Optical Studies.

Thin films of tin (II) sulfide (SnS) were deposited onto a 500 µm thick copper substrate by a chemical bath method. The effect of sodium (Na) doping in these films was studied. The synthesis of the films was performed at temperatures of 60, 70, and 80 °C for 5 min. The microstructure of the SnS films analyzed by scanning electron microscopy (SEM) showed a compact morphology of the films deposited at 80 °C. The edges of the SnS grains were rounded off with the addition of a commercial surfactant. The thickness of different SnS layers deposited on the copper substrate was found to be 230 nm from spectroscopic ellipsometry and cross-section analysis using SEM. The deposition parameters such as temperature, surfactant addition, and sodium doping time did not affect the thickness of the layers. From the X-ray diffraction (XRD) analysis, the size of the SnS crystallites was found to be around 44 nm. Depending on the process conditions, Na doping affects the size of the crystallites in different ways. A study of the conductivity of SnS films provides a specific conductivity value of 0.3 S. The energy dispersive analysis of X-rays (EDAX) equipped with the SEM revealed the Sn:S stoichiometry of the film to be 1:1, which was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. The determined band-gap of SnS is equal to 1.27 eV and is in good agreement with the literature data.

Mixed phase formation of SnS-SnO2 on air-annealed thermally evaporated SnS thin films

The present study examined the influence of annealing temperature on structural, morphological, electrical, and optical properties of thermally evaporated tin sulfide (SnS) thin films. The annealing of the prepared thin films has been carried out in the ambient atmosphere at a temperature between 100 and 300 °C. Structural, Optical, and compositional investigation has been performed using various characterization techniques. The X-ray diffraction pattern exhibits the mixed phase of SnS-SnO2 for the annealed films, ascribed to the reaction of SnS with atmospheric oxygen. A band gap in the 1.7–1.94 eV range was estimated from the Tauc-plots for all the films under investigation. The stoichiometric composition ratio of Sn/S=1.0 was obtained for the as-evaporated films. However, it deviates from the air-annealed SnS thin films. The air-annealed SnS thin films exhibit resistivity, carrier concentration and mobility in the range of 5.03–17.7 Ω-cm, 1.48 × 1018 – 2.18 × 1018 cm−3, and 0.04–1.05 cm2/V-s, respectively. The acquired results from this study elucidate the phase conversion of SnS thin films annealed in an ambient atmosphere. The current study aims to find an optimal absorber layer to enhance photovoltaic device performance.

Discovery of Ge-bearing mineral in a Carboniferous coal from the Yuzhou Coalfield, southern part of the North China Basin

This work describes a Ge-bearing mineral in the Carboniferous medium-ash, high-sulfur and low-volatile bituminous coal of the Yuzhou Coalfield, southern part of the North China Basin. Germanium (Ge) in the investigated coals ranges from 10.4 to 57.6 μg/g, with an average of 32.8 μg/g. Average concentrations of Ge in coal samples are about 16 times higher than that of world hard coals (2.4 μg/g). Ge-bearing mineral was found in the coal sample. It occurs as a vein and is closely associated with copper zinc tin sulfide, and illite. To the best of our knowledge, this is the first record of this mineral in coal. The average chemical composition based on the electron microprobe analyses is (in wt. %): Al 23.42, Ge 32.92, O 35.24, F 7.82, total 99.39, corresponding to (Al1.97Ge0.03)2GeO4(F0.93, OH)1.93. Krieselite has the ideal chemical formula Al2GeO4(F, OH)2, and is most likely the Ge-bearing mineral found in the investigated coal sample. The appearance of Ge-bearing mineral indicates an origin later than peat deposition and also demonstrates that Ge mineralization could take place during coalification.