Synthetic Crystals Research Articles

Autonomous materials systems from active liquid crystals

Liquid crystals (LCs) are ubiquitous in display technologies. The orientational ordering in the nematic phase of LCs gives rise to structural anisotropy, the ability to form topological defects and extraordinary sensitivity to interfacial events — three features that are not found in traditional, isotropic liquids. Active LC systems represent a particular class of active materials, in which some form of energy is transformed and used to generate motion, providing opportunities for new technologies and offering a platform to investigate matter far from equilibrium. In this Review, we discuss recent advances in the field of active LC systems, including natural systems, such as cell colonies, biopolymers and bacteria, and synthetic systems, which mimic the adaptive and autonomous behaviours found in nature. We investigate the properties of defects and flows, examine LC interfaces and emulsions, and discuss active LC colloids and composites. Finally, we highlight future possibilities and applications of active LC systems. Active liquid crystals are a particular type of active materials in which an inherent structural anisotropy leads to long-range order and topological defects. This Review discusses natural and synthetic active liquid crystals, and explores their autonomous behaviour as well as potential applications.

Limitations of dual-energy CT in the detection of monosodium urate deposition in dense liquid tophi and calcified tophi

Dual-energy CT (DECT) detection of monosodium urate (MSU) crystal deposition has demonstrated good sensitivity and specificity in patients with established gout. However, limitations have been reported with early disease and with low urate burden. We aimed to study the performance of DECT in the detection and quantification of MSU deposition in solid and liquid tophi. Patient-derived solid and liquid tophi, suspensions of commercial synthetic, and in-house synthetic MSU crystals were prepared at varying concentrations.DECT was performed at 80 kVp and 150 kVp, and post-processed using Syngo Via gout software (Siemens) that color-coded urate and cortical bone as green and purple, respectively.DECT findings were correlated with ultrasound and microscopic findings. The protocol was reviewed by IRB and considered a non-human subject research. DECT did not detect urate deposition in either patient-derived liquid tophi or in-house synthetic crystals at any concentration. Lowering the post-processing minimum threshold increased the detection of in-house synthetic crystals but did not change the detection of patient-derived liquid tophi. Areas of calcium-rich purple color-coded regions, masking detection of urate, within the solid tophi and surrounding liquid tophi were noted on DECT. Histology showed co-presence of calcium along with MSU deposition in these. This study illustrates important limitations of DECT for liquid tophi due to subthreshold CT attenuation and for calcified tophi due to the obscuration of urate by calcium. Urate may be either undetectable or underestimated by DECT when these conditions are present.

Are the thermodynamic properties of natural and synthetic Mg2SiO4-Fe2SiO4 olivines the same?

Abstract It is not known if the thermodynamic behavior of some minerals and their synthetic analogues are quantitatively the same. Olivine is an important rock-forming substitutional solid solution consisting of the two end-members forsterite, Mg2SiO4, and fayalite, Fe2SiO4. We undertook the first heat capacity, CP, measurements on two natural olivines between 2 and 300 K; nearly end-member fayalite and a forsterite-rich crystal Fo0.904Fa0.096. Their CP(T) behavior is compared to that of synthetic crystals of similar composition, as found in the literature. The two natural olivines are characterized by X-ray powder diffraction and 57Fe Mössbauer spectroscopy. The X-ray results show that the crystals are well crystalline. The Mössbauer hyperfine parameters, obtained from a fit with two Fe2+ quadrupole split doublets, are similar to published values measured on synthetic olivines. There are slight differences in the absorption line widths (i.e., FWHM) between the natural and synthetic crystals. CP (2 to 300 K) is measured by relaxation calorimetry. The CP results of the natural nearly end-member fayalite and published values for two different synthetic Fa100 samples are in excellent agreement. Even CP resulting from a Schottky anomaly and a paramagnetic-antiferromagnetic phase transition with both arising from Fe2+ are similar. There are slight differences in the Néel temperature between the natural 63 K and synthetic ~65 K fayalites. This is probably related to the presence of certain minor elements (e.g., Mn2+) in the natural crystal. The third-law entropy, S°, value is 151.6 ± 1.1 J/(mol·K). CP behavior of the natural forsterite, Fo0.904Fa0.096, and a synthetic olivine, Fo90Fa10, are in excellent agreement between about 7 and 300 K. The only difference lies at T < 7 K, as the former does not show Debye T3 behavior, but, instead, a plateauing of CP values. The S° value for the natural forsterite is 99.1 ± 0.7 J/(mol·K).

Anisotropic thermal transport properties of quartz: from −120 °C through the <i>α</i>–<i>β</i> phase transition

Abstract. Thermal diffusivities of synthetic quartz single crystals have been measured between −120 and 800 ∘C using a laser flash method. At −120 ∘C, the lattice thermal diffusivities are D[001]=15.7(8) mm2 s−1 and D[100]=8.0(4) mm2 s−1 in the [001] and [100] directions, respectively. Between −80 and 560 ∘C, the temperature dependence is well approximated by a D(T)=1/Tn dependency (with n=1.824(29) and n=1.590(21) for the [001] and [100] directions), whereas for lower temperatures measured thermal diffusivities show smaller values. The anisotropy of the thermal diffusivity D[001]∕D[100] decreases linearly over T in α- and β-quartz, with a discontinuity at the α–β phase transition at Tα,β=573 ∘C. In the measured signal–time curves of α-quartz, an unusual radiative heat transfer is observed, which can be linked to the phase transition. However, the effect is already observed far below the actual transition temperature. The standard evaluation procedure insufficiently describes the behaviour and leads to an underestimation of the thermal diffusivity of ≥20 %. Applying a new semi-empirical model of radiation absorption and re-emission reproduces well the observed radiative heat transfer originating in the phase transition. In the β-quartz region, the radiative heat transfer is not influenced by the phase transition effect observed in α-quartz and for the thermal diffusivity evaluation common models for (semi)transparent samples can be used.

Dual-Energy Computed Tomography for Detection and Characterization of Monosodium Urate, Calcium Pyrophosphate, and Hydroxyapatite: A Phantom Study on Diagnostic Performance.

The aim of this study was to determine the diagnostic performance of dual-energy computed tomography (DECT) to detect and distinguish crystal deposits in a phantom. The primary objective was to determine the cutoff DECT ratio and the cross-sectional area (CSA) of a crystal deposit necessary to differentiate monosodium urate (MSU), calcium pyrophosphate (CPP), and calcium hydroxyapatite (HA) using DECT. Our secondary objective was to determine the concentration for limit of detection for MSU, CPP, and HA crystal deposits. Exploratory objectives included the comparison between 2 generations of DECT scanners from the same manufacturer as well as different scanner settings. We used a cylindrical soft tissue phantom with synthetic MSU, CPP, and HA crystals suspended in resin. Crystal suspension concentration increased with similar attenuation between MSU, CPP, and HA in conventional CT. The phantom was scanned on 2 dual-source DECT scanners, at 2 dose levels and all available tube voltage combinations. Both scanners had a tin (Sn) filter at the high-energy spectra. Dual-energy CT ratios were calculated for a given tube voltage combination by dividing linear regression lines of CT numbers against concentration. Dual-energy CT ratios were compared using an analysis of covariance. Receiver operating characteristic curves and corresponding areas under the curve (AUCs) were calculated for individual crystal suspension comparisons (HA vs CPP, MSU vs CPP, and MSU vs HA). At standard clinical scan settings with 8 mGy and 80/Sn150 kV, the DECT ratios were as follows: CPP, 2.02 (95% confidence interval [CI], 1.98-2.07); HA, 2.00 (95% CI, 1.96-2.05); and MSU, 1.09 (95% CI, 1.06-1.11). Ratios varied numerically depending on the scanner and tube voltage combination. Monosodium urate crystal DECT ratios were significantly different from HA and CPP (P < 0.001), whereas DECT ratios for HA and CPP crystals did not differ significantly (P = 0.99). The differentiation of MSU crystals from both calcium crystals (HA and CPP) was excellent with an AUC of 1.00 (95% CI, 1.00-1.00) and an optimal cutoff DECT ratio of 1.43:1.40 depending on the scanner. In addition, differentiation of MSU and calcium-containing crystals (HA and CPP) required a CSA of minimum 4 pixels of crystal at standard clinical scan conditions. In contrast, differentiation between CPP and HA crystals was moderate with AUCs ranging from 0.66 (95% CI, 0.52-0.80) to 0.80 (95% CI, 0.69-0.91) and an optimal cutoff DECT ratio of 2.02:2.06 depending on the scanner. Furthermore, differentiation between CPP and HA crystals required a CSA of minimum 87 pixels of crystal at standard clinical scan conditions, corresponding to a region of interest of 3.7 mm diameter. When scanning at highest possible spectral separation and maximum dose of 50 mGy, the limit of detection for crystals within a region of interest of 50 pixels was 14 mg/cm3 for MSU and 2 mg/cm3 for both CPP and HA. This phantom study shows that DECT can be used to detect MSU, CPP, and HA crystal deposits. Differentiation of CPP and HA was not possible in crystals deposits less than 3.7 mm in diameter, but MSU could accurately be differentiated from CPP and HA crystal deposits at standard clinical scan conditions.

The effect of pressure on synthetic diamond crystals at high temperatures and pressures in an Fe/Ni catalyst system

Pressure is a necessary condition for the growth of natural diamond.

Comprehensive Density Functional Theory Studies of Vibrational Spectra of Carbonates.

Within the framework of the density functional theory (DFT) and the hybrid functional B3LYP by means of the CRYSTAL17 program code, the wavenumbers and intensities of normal oscillations of MgCO3, CaCO3, ZnCO3, CdCO3 in the structure of calcite; CaMg(CO3)2, CdMg(CO3)2, CaMn(CO3)2, CaZn(CO3)2 in the structure of dolomite; BaMg(CO3)2 in the structure of the norsethite type; and CaCO3, SrCO3, BaCO3, and PbCO3 in the structure of aragonite were calculated. Infrared absorption and Raman spectra were compared with the known experimental data of synthetic and natural crystals. For lattice and intramolecular modes, linear dependences on the radius and mass of the metal cation are established. The obtained dependences have predictive power and can be used to study solid carbonate solutions. For trigonal and orthorhombic carbonates, the linear dependence of wavenumbers on the cation radius RM (or M–O distance) is established for the infrared in-plane bending mode: 786.2–65.88·RM and Raman in-plane stretching mode: 768.5–53.24·RM, with a correlation coefficient of 0.87.

Gaussian Thermionic Emission Model for Analysis of Au/MoS2 Schottky-Barrier Devices

Schottky-barrier inhomogeneities are expected at the metal--transition-metal-dichalcogenide (TMDC) interface and this can impact device performance. However, it is difficult to account for the distribution of interface inhomogeneity as most techniques average over the spot area of the analytical tool (e.g., few hundred micrometers squared for photoelectron-based techniques), or the entire device measured for electrical current-voltage (I-V) measurements. Commonly used models to extract Schottky-barrier heights neglect or fail to account for such inhomogeneities, which can lead to the extraction of incorrect Schottky-barrier heights and Richardson constants that are orders of magnitude away from theoretically expected values. Here, we show that a Gaussian-modified thermionic emission model gives the best fit to experimental temperature-dependent current-voltage (I-V-T) data of van der Waals $\mathrm{Au}$/p-${\mathrm{Mo}\mathrm{S}}_{2}$ interfaces and allow the deconvolution of the Schottky-barrier heights of the defective regions from the pristine region. By the inclusion of a Gaussian-distributed Schottky-barrier height in the macroscopic I-V-T analysis, we demonstrate that interface inhomogeneities due to defects are deconvoluted and well correlated to the impact on the device behavior across a wide temperature range from a room temperature of 300 K down to 120 K. We verify the Gaussian thermionic model across two different types of p-${\mathrm{Mo}\mathrm{S}}_{2}$ (geological bulk crystals and synthetic flux-grown crystals), and finally compare the macroscopic Schottky-barrier heights with the results of a nanoscopic technique, ballistic hole emission microscopy (BHEM). The results obtained using BHEM are consistent with the pristine $\mathrm{Au}$/p-${\mathrm{Mo}\mathrm{S}}_{2}$ Schottky-barrier height extracted from the Gaussian-modified thermionic emission model over hundreds of nanometers. Our findings show that the inclusion of Schottky-barrier inhomogeneities in the analysis of I-V-T data is useful to elucidate the impact of defects (e.g., grain boundaries, metallic impurities, etc.) and hence their influence on device behavior. We also find that the effective Richardson constant, a material-specific constant typically treated as merely a fitting constant, is a useful parameter to check for the validity of the transport model.

Barium Titanate Nanostructures and Thin Films for Photonics

AbstractBarium titanate (BaTiO3) is a synthetic crystal used in electromechanical transducers and multilayer ceramic capacitors. Since it is not available in nature, a variety of growth methods has been employed to produce in large scale, with high quality and low‐cost. BaTiO3, as a metal oxide meets practical requirements such as physical hardness, stability and tunable optoelectronic properties. The plethora of characteristics renders it functional in diverse fields of applications from energy harvesting to biophotonics. Related to optical properties, it is a dielectric material from the near ultraviolet to the near‐infrared part of the spectrum with low optical losses and relatively high refractive index. The strong second‐order nonlinear response has resulted in several breakthroughs in bioimaging, while its intrinsic electrooptic response is among the highest within the existing materials. The properties of the BaTiO3 may also be modified by doping or hybridization with other materials. This review presents the basic optoelectronic properties of BaTiO3, reports on the recent advances in BaTiO3 nanostructures and thin films related to photonic applications, and oversees photonic technologies that may benefit from this material platform in the near future.

Hard to Soft: Biogenic Absorbent Sponge-like Material from Waste Mussel Shells

Summary Mussel shells are a source of renewable CaCO3 and can be obtained from aquaculture waste streams. Valorization of waste shells relieves strain on landfills and aligns with the goals of a circular economy. Here, we present the preparation of an absorbent CaCO3 material, soft calcite (SC), prepared from waste blue mussel shells under mild conditions. Calcite is the only polymorph present in SC, despite the presence of aragonite in the shell. SC has a nest-like morphology, unlike the highly ordered calcite in the shell. SC is formed by the reassembly of calcite prisms and may be held together by the organic matrix “glue” from the original shell as evidenced by NMR spectroscopy. This inorganic sponge adsorbs dyes from aqueous solution and absorbs crude oil from seawater with good recyclability. Our results demonstrate how a natural structure can be modified in a sustainable fashion to yield a higher-value material.

Double-Crystal X-Ray Diffractometry and Topography Methods in the Analysis of the Real Structure of Crystals

The high efficiency of double-crystal X-ray diffractometry and topography methods in the characterization of crystals during refinement of the crystal-growth technology is demonstrated for the example of diamond bulk crystals and films obtained by the high pressure, high temperature method and by chemical vapor deposition, respectively. Techniques and study schemes for analysis of the real crystal structure, assessment of the chemical composition and the period of the crystal lattice, and analysis of the distinctive features of the deformation and thickness of thin films are described. Major structural defects (dislocations, stacking defects, inclusions of a different phase, and others) that emerge during the production of synthetic diamond crystals are identified.

In situ imaging of two-dimensional surface growth reveals the prevalence and role of defects in zeolite crystallization

Zeolite crystallization predominantly occurs by nonclassical pathways involving the attachment of complex (alumino)silicate precursors to crystal surfaces, yet recurrent images of fully crystalline materials with layered surfaces are evidence of classical growth by molecule attachment. Here we use in situ atomic force microscopy to monitor three distinct mechanisms of two-dimensional (2D) growth of zeolite A where we show that layer nucleation from surface defects is the most common pathway. Direct observation of defects was made possible by the identification of conditions promoting layered growth, which correlates to the use of sodium as an inorganic structure-directing agent, whereas its replacement with an organic results in a nonclassical mode of growth that obscures 2D layers and markedly slows the rate of crystallization. In situ measurements of layered growth reveal that undissolved silica nanoparticles in the synthesis medium can incorporate into advancing steps on crystal surfaces to generate defects (i.e., amorphous silica occlusions) that largely go undetected in literature. Nanoparticle occlusion in natural and synthetic crystals is a topic of wide-ranging interest owing to its relevance in fields spanning from biomineralization to the rational design of functional nanocomposites. In this study, we provide unprecedented insight into zeolite surface growth by molecule addition through time-resolved microscopy that directly captures the occlusion of silica nanoparticles and highlights the prevalent role of defects in zeolite crystallization.

Small Bragg-plane slope errors revealed in synthetic diamond crystals.

Wavefront-preserving X-ray diamond crystal optics are essential for numerous applications in X-ray science. Perfect crystals with flat Bragg planes are a prerequisite for wavefront preservation in Bragg diffraction. However, this condition is difficult to realize in practice because of inevitable crystal imperfections. Here, X-ray rocking curve imaging is used to study the smallest achievable Bragg-plane slope errors in the best presently available synthetic diamond crystals and how they compare with those of perfect silicon crystals. It is shown that the smallest specific slope errors in the best diamond crystals are about 0.08 (3) µrad mm-2. These errors are only 50% larger than the 0.05 (2) µrad mm-2 specific slope errors measured in perfect silicon crystals. High-temperature annealing at 1450°C of almost flawless diamond crystals reduces the slope errors very close to those of silicon. Further investigations are in progress to establish the wavefront-preservation properties of these crystals.

Dynamic and reversible shape response of red blood cells in synthetic liquid crystals

Mammalian cells are soft, and correct functioning requires that cells undergo dynamic shape changes in vivo. Although a range of diseases are associated with stiffening of red blood cells (RBCs; e.g., sickle cell anemia or malaria), the mechanical properties and thus shape responses of cells to complex viscoelastic environments are poorly understood. We use vapor pressure measurements to identify aqueous liquid crystals (LCs) that are in osmotic equilibrium with RBCs and explore mechanical coupling between RBCs and LCs. When transferred from an isotropic aqueous phase into a LC, RBCs exhibit complex yet reversible shape transformations, from initially biconcave disks to elongated and folded geometries with noncircular cross-sections. Importantly, whereas the shapes of RBCs are similar in isotropic fluids, when strained by LC, a large variance in shape response is measured, thus unmasking cell-to-cell variation in mechanical properties. Numerical modeling of LC and cell mechanics reveals that RBC shape responses occur at constant cell membrane area but with membrane shear moduli that vary between cells from 2 to 16 × 10-6 N/m. Temperature-dependent LC elasticity permits continuous tuning of RBC strains, and chemical cross-linking of RBCs, a model for diseased cells, leads to striking changes in shape responses of the RBCs. Overall, these results provide insight into the coupling of strain between soft mammalian cells and synthetic LCs, and hint at new methods for rapidly characterizing mechanical properties of single mammalian cells in a population and thus cell-to-cell variance.

Metasurfaces as Artificial Crystals for Electromagnetic Polarization Handling

Metasurfaces acting on electromagnetic fields have emerged as powerful tools that can address all the wave’s degrees of freedom: amplitude, phase and polarization. It is especially with respect to polarization that their role is steadily growing: metasurfaces can indeed perform, by design, operations that would usually require very specific, delicate and expensive natural or synthetic ordinary crystals. Here, I will first briefly review the history of light polarization, and its connection with ordinary crystals. Subsequently, I will highlight in which sense metasurfaces are artificial quasi-two-dimensional crystals, evidencing their potential as future polarization-handling (meta) materials.

Realization of high-dimensional frequency crystals in electro-optic microcombs

Crystals are ubiquitous in nature and are at the heart of material research, solid-state science, and quantum physics. Unfortunately, the controllability of solid-state crystals is limited by the complexity of many-body dynamics and the presence of defects. In contrast, synthetic crystal structures, realized by, e.g., optical lattices, have recently enabled the investigation of various physical processes in a controllable manner, and even the study of new phenomena. Past realizations of synthetic optical crystals were, however, limited in size and dimensionality. Here we theoretically propose and experimentally demonstrate optical frequency crystal of arbitrary dimensions, formed by hundreds of coupled spectral modes within an on-chip electro-optic frequency comb. We show a direct link between the measured optical transmission spectrum and the density of states of frequency crystals in one, two, three, and four dimensions, with no restrictions to further expanding the dimensionality. We demonstrate that the generation of classical electro-optic frequency comb can be modeled as a process described by random walks in a tight-binding model, and we have verified this by measuring the coherent distribution of optical steady states. We believe that our platform is a promising candidate for exploration of topological and quantum photonics in the frequency domain.

Simultaneous δ2 H and δ18 O analyses of water inclusions in halite with off-axis integrated cavity output spectroscopy.

Stable isotope compositions of ancient halite fluid inclusions have been recognized to be valuable tools for reconstructing past environments. Nevertheless, in order to better understand the genesis of halite deposits, it could be of great interest to combine both δ2 H and δ18 O measurements of the water trapped as inclusions in the defects of the mineral lattice. We developed a method combining off-axis integrated cavity output spectroscopy (OA-ICOS) connected on line with a modified elemental analyzer (EA-OA-ICOS) to perform those measurements. The first step was to test the method with synthetic halite crystals precipitated in the laboratory from isotopically calibrated waters. Water isotopic signatures have been measured with conventional techniques, equilibration for δ18 O and chromium reduction for δ2 H. Then, we modified and optimized a conventional EA to connect it online with an OA-ICOS instrument for H2 O measurements. The technique is first evaluated for calibrated free water samples. The technique is also evaluated for salt matrix effect, accuracy, and linearity for both isotopic signatures. Then, the technique is used to measure simultaneously δ2 H and δ18 O values of halite water inclusions precipitated from the evaporation experiments. Data generated with this new technique appeared to be comparable with those inferred from prior off-line technique studies. The advantages offered by the OA-ICOS technique are the simultaneous acquisition of both isotopic ratios and the substantial reduction of data acquisition time and sample aliquot size. Natural halite samples have been analyzed with this method. Natural halite samples as old as Precambrian have also been analyzed with this method.

Thermoelastic properties of synthetic single crystal portlandite Ca(OH)2 - Temperature-dependent thermal diffusivity with derived thermal conductivity and elastic constants at ambient conditions

Synthetic portlandite single crystals were used to measure thermal diffusivity and elastic constants. The full tensor of elastic constants cijkl is derived by Brillouin spectroscopy at ambient conditions. The resultant aggregate bulk and shear moduli are KS, VRH= 32.2(3) GPa and GVRH= 21.2(2) GPa, respectively. The thermal diffusivity D was measured from −100 ∘C to 700 ∘C parallel [001] and perpendicular [100] to the crystallographic c-axis using laser flash method. The dehydration of the crystals influences the thermal diffusivity determination depending on sample size, orientation and heating rate. Thermal diffusivity and the derived thermal conductivity show a pronounced anisotropy with a maximum perpendicular to the c-axis, i.e. in the plane of the [CaO6] octahedral layers. In the same direction the highest sound velocities (vP and vmean) and longest mean free path length of phonons are determined. The thermal diffusivity as well as the derived thermal conductivity show a distinct temperature dependence.

Potentially Probiotic Lactobacillus Strains Derived from Food Intensify Crystallization Caused by Proteus mirabilis in Urine

Proteus mirabilis is a common cause of infectious urolithiasis. The first stage in the formation of urinary stones is the crystallization of mineral salts in the urine induced by urease activity of this microorganism. Lactobacillus spp. are an important component of the human microbiota and in large quantities occur in foods. Regardless of their origin, those with probiotic properties are proposed as an alternative to antibiotic therapy in the treatment of urinary tract infections. The aim of the study was to check the effect of selected Lactobacillus plantarum and Lactobacillus brevis strains on crystallization caused by P. mirabilis in an in vitro experiment. It has been confirmed that selected Lactobacillus strains have antibacterial properties and colonize the urinary tract epithelium. During 24-h incubation of bacterial cultures, containing P. mirabilis and individual Lactobacillus strains, in synthetic urine, bacterial viability (CFU/mL), pH, and crystallization were determined. Crystallization was assessed quantitatively and qualitatively using AAS and XRD techniques as well as phase-contrast microscopy. It has been shown that in the presence of selected Lactobacillus strains, the culture pH increases faster, especially after 8 h of incubation, compared with the pure P. mirabilis culture. An increase in pH reduces the viability of P. mirabilis; however, in the presence of some lactobacilli, the uropathogen grows more intensively. The presence of Lactobacillus also affected crystallization by increasing its intensity, and the resulting crystals were larger in size. Tested L. plantarum and L. brevis strains could therefore accelerate the formation of urinary stones and development of infection.

The State of Trace Elements (In, Cu, Ag) in Sphalerite Studied by X-Ray Absorption Spectroscopy of Synthetic Minerals

The oxidation state and local atomic environment of admixtures of In, Cu, and Ag in synthetic sphalerite crystals were determined by X-ray absorption spectroscopy (XAS). The sphalerite crystals doped with In, Cu, Ag, In–Cu, and In–Ag were synthesized utilizing gas transport, salt flux, and dry synthesis techniques. Oxidation states of dopants were determined using X-ray absorption near edge structure (XANES) technique. The local atomic structure was studied by X-ray absorption fine structure spectroscopy (EXAFS). The spectra were recorded at Zn, In, Ag, and Cu K-edges. In all studied samples, In was in the 3+ oxidation state and replaced Zn in the structure of sphalerite, which occurs with the expansion of the nearest coordination shells due to the large In ionic radius. In the presence of In, the oxidation state of Cu and Ag is 1+, and both metals can form an isomorphous solid solution where they substitute for Zn according to the coupled substitution scheme 2Zn2+ ↔ Me+ + In3+. Moreover, Ag K-edges EXAFS spectra fitting, combined with the results obtained for In- and Au-bearing sphalerite shows that the Me-S distances in the first coordination shell in the solid solution state are correlated with the ionic radii and increase in the order of Cu &lt; Ag &lt; Au. The distortion of the atomic structure increases in the same order. The distant (second and third) coordination shells of Cu and Ag in sphalerite are split into two subshells, and the splitting is more pronounced for Ag. Analysis of the EXAFS spectra, coupled with the results of DFT (Density Function Theory) simulations, showed that the In–In and Me+–In3+ clustering is absent when the metals are present in the sphalerite solid solution. Therefore, all studied admixtures (In, Cu, Ag), as well as Au, are randomly distributed in the matrix of sphalerite, where the concentration of the elements in the “invisible” form can reach a few tens wt.%.