Amorphous Arsenic Sulfide Research Articles

Chemical composition of early mediaeval arsenic sulphide glass’ beads as an indicator of the origin of the raw material

In the early mediaeval cemetery in Bodzia (Poland) a unique large collection of 85 small red beads in a rich burial of an adult woman were found. Analysis of the chemical composition and structure of the selected artefacts was made by use of electron microprobe (EMPA), X-ray fluorescence analysis (XRF) and Raman spectroscopy (RMS). These archaeometric tests showed that they are made of amorphous arsenic sulphide glass (ASG). This glass was obtained by melting natural arsenic sulphide (orpiment). The artefacts were formed at a temperature of about 350 °C. Increased content of Sb, Pb, Cu, Te and Se may indicate that the arsenic sulphide used in the production of ASG co-occurred with stibnite and other sulphides and sulphosalts of copper and lead. This mineral assemblage is typical of low-temperature hydrothermal polymetallic deposits from Maramuresh region in Romania.

A multidisciplinary approach to investigate the peculiar artistic technique of Scagliola: Modern age decorations in Hadrian’s Villa (Tivoli, Italy)

In the present work, a multi-technique approach was adopted to study and characterize six polychrome decorated elements found in the storerooms of the archaeological site of Hadrian's Villa in Tivoli (Rome). In particular, preliminary microscope observations along with μ-Raman and FT-IR spectroscopies and FESEM-EDS analyses were adopted to identify the used materials and the execution technique. This information could allow placing the artefacts in a chronological context, in particular by evaluating possible coherences with the modern phases of the archaeological site. At first visual observation, both stylistic and technical details suggested that the artefacts had been performed by using Scagliola, a particular and not deeply investigated artistic technique developed in Europe at the end of the XVI century for interior decorations. The acquired information has been compared with data obtained by similar in-situ decorations, found on the vault of the Casino Fede, an XVIII century building of the Villa. The characterization of the constituent materials revealed a rich palette, based on both inorganic and organic pigments, some alteration products, and a massive presence of gypsum in the matrix. These results led to confirm the use of Scagliola technique in the realization of all the artefacts, even though this information is not sufficient to confirm if they belong to the same building. Furthermore, a peculiar result was the identification of arsenic-based pigments as pararealgar and amorphous arsenic sulphide as an orange pigment. In particular, pararealgar was identified as the initial material used for the synthesis of the amorphous pigment, a very rare identification in artworks.

The Matter from Which an Orange Colour Is Made: On the Arsenic Pigment Used in a Portuguese Mannerist Painting

The painting The Descent from the Cross, painted in 1620 by Pedro Nunes (1586–1637), presents two large figures with orange-coloured fabrics with conservation problems. Through the analysis of two samples with several analytical techniques, especially scanning electron microscopy combined with X-ray spectroscopy and Raman microscopy, it was possible to conclude that the orange colour is due to a complex artificial pigment made of amorphous arsenic sulphide. It essentially consists of spherical particles obtained by sublimation and condensation, possibly from orpiment, which ended up being joined with irregularly shaped particles resulting from crushing of the residual fraction obtained by solidification and fusion. This is a rare documented case of the extensive use of artificial arsenic sulphides in European easel painting, especially outside Italy. The conservation problems can be explained by the great sensitivity of the arsenic sulphides to photodegradation and the formation of powdery compounds.

The Application of Surface Plasmon Resonance with As2S3 Waveguide for Alcohols Identification

AbstractIn a composite structure, which contains dielectric‐metal interface, waves of electric charge densities can be initiated. The wave intensity decreases exponentially in adjacent media meaning that the wave closely localized at the interface does exist. Label‐free chemical sensors are realized as the propagation constant of the wave is highly sensitive to the refractive index. Surface plasmons can be excited by incident light flow directed at some specific angle (surface plasmon resonance) with a very sharp shape. In the present paper the possibility of identification of several most common alcohols such as methanol, ethanol, propanol, butanol, or pentanol, which have different refractive indices, has been studied. The structure is composed of a coupling prism made of rutile (TiO2), a thin gold film, and an amorphous arsenic sulfide (As2S3) thin film.

Physicochemical and environmental properties of arsenic sulfide sludge from copper and lead−zinc smelter

Abstract Physicochemical properties of arsenic sulfide sludge (ASS) from copper smelter (ASS-I) and lead−zinc smelter (ASS-II) were examined by XRD, Raman spectroscopy, SEM−EDS, TG−DTA, XPS and chemical phase analysis method. The toxicity characteristic leaching procedure (TCLP), Chinese standard leaching tests (CSLT), three-stage sequential extraction procedure (BCR) and batch leaching experiments (BLE) were used to investigate the environmental stability. The ASSs from different smelters had obviously different physicochemical and environmental properties. The phase composition and micrograph analysis indicate that ASS-I mainly consists of super refined flocculent particles including amorphous arsenic sulfide adhered with amorphous sulfur and that ASS-II mainly consists of amorphous arsenic sulfide. The valence state of arsenic in both sludges is trivalent, but the valence composition of sulfur is quite different. The ASSs have thermal instability properties. The results of TCLP and CSLT indicate that the concentrations of As and Pd in the leaching solution exceed the standard limits. More than 5% and 90% of arsenic are in the form of acid soluble and oxidizable fractions, respectively, which explains the high arsenic leaching toxicity and environmental activity of ASS. This research provides comprehensive information for the disposal of ASS from copper and lead−zinc smelter.

Evidence of early amorphous arsenic sulfide production and use in Edo period Japanese woodblock prints by Hokusai and Kunisada

This study explores the evolution of the manufacturing process of artificial arsenic sulfide pigments in Edo-period Japan through the analysis of three impressions of the same print dated from the 1830s and attributed to Katsushika Hokusai (1760–1849), and one from 1852 and attributed to Utagawa Kunisada (1786–1865). Colorants in the yellow and green areas of the four prints were investigated by means of non-invasive and microanalytical techniques such as optical microscopy, fiber optic reflectance spectroscopy and Raman spectroscopy. While the pigments in the green and yellow areas are similar throughout the set of prints—Prussian blue, indigo (for the Hokusai prints) and orpiment were identified—optical microscopy and Raman spectroscopy highlighted some variations in the orpiment used in the green areas of the prints. Two of the Hokusai prints present bright yellow particles of larger size and lamellar morphology, identified by Raman spectroscopy as natural orpiment. The third print presents an admixture of bright yellow natural orpiment particles with a smaller number of orange-yellow particles shown by Raman to be partially amorphous arsenic sulfide. Small bright yellow particles identified as fully amorphous arsenic sulfide pigments by Raman were found throughout the green areas of the Kunisada print. Although supported by Japanese historical sources, local production of artificial arsenic sulfide in the early nineteenth century was not previously documented. The simultaneous presence of both crystalline and amorphous domains in a single pigment particle in some of the Hokusai prints suggests that natural orpiment was used as primary source of arsenic for the production of a low grade artificial pigment. The pigment found in the Kunisada print, by contrast, was obtained from arsenic oxide (or arsenolite) and sulfur though a dry-process synthesis, as shown by the sulfur excess, signs of heat treatments and fully amorphous nature of the pigment. These findings set the earliest dates for both the ore sublimation process and the arsenolite dry process, and are of foremost importance to understand the evolution of the amorphous arsenic sulfide production in Edo-period Japan and its introduction in the palette of Japanese woodblock prints.

Amorphous arsenic sulfide nanoparticles in a shallow water hydrothermal system

Hydrothermal fluids can contain trace elements such as arsenic (As), which are toxic to surrounding biota. In these kind of fluids, the bioavailability and biotransformation of As have been investigated but so far the ratio of total soluble As (<200 nm) versus the amount of As contained in a nanoparticulate phase has not been reported. Here, for the first time, the presence of As in the nanoparticulate fraction (between 200 and 20 nm) is described for arsenic-rich hydrothermal fluids in a marine shallow-water hydrothermal system. Samples of diffusively venting hydrothermal fluids, pore-water and seawater were collected in the hydrothermal system located in Paleochori Bay, Milos Island (Greece), and the fraction between 200 and 20 nm (As200-20) was studied. Up to 38% of the soluble arsenic was present within the As200-20 fraction in pore fluids, 10 to 20% in hydrothermal fluids and 5% in seawater. Identification and characterization of particles in hydrothermal fluid, pore-water and seawater was performed by scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) with selected area electron diffraction (SAED) and dynamic light scattering (DLS). The particles are of spherical morphology with a polydisperse size distribution (PDI: 0.37) and diameters close to 100 nm. EDX studies confirmed a chemical composition rich in As and S. The SAED pattern revealed absence of a crystal phase indicating the presence of an amorphous arsenic sulfide material. These results bring into discussion the role of the nanoparticulate fraction for As dispersion, bioavailability, and potentially harmful effects in marine coastal ecosystems.

Physical Mechanism and Response Characteristics of Unsaturated Optical Stopping-Based Amorphous Arsenic Sulfide Thin-Film Waveguides

Optical stopping can serve as a light-controlled solution to implementing photonic components. In contrast to saturated optical stopping that provides enough excited electrons to entirely absorb signal lights, unsaturated optical stopping introduces a photon competition mechanism for signal lights and pump lights due to insufficient excited electrons. This photon competition mechanism produces a kind of regular signals, which is very similar to the signals applied in pulse-coupled neural network. However, due to its unclear physical mechanism, it is impossible to further improve performances of the unsaturated optical stopping-based components. Here, we propose a kinetic model to reveal physical mechanism of the unsaturated optical stopping and establish a corresponding formalism that enables calculation of time response of the unsaturated optical stopping-based amorphous arsenic sulfide thin-film waveguides. Our work provides a new insight into the physical phenomenon of unsaturated optical stopping and builds a theoretical foundation for further research on response characteristics of amorphous arsenic sulfide thin-film waveguides.

Study of dry‐ and wet‐process amorphous arsenic sulfides: Synthesis, Raman reference spectra, and identification in historical art materials

AbstractThis paper reports the dry and wet synthetic procedures and characterization by Raman spectroscopy of amorphous arsenic sulfide reference pigments. Reference spectra of two amorphous materials obtained by wet process methods and four dry process references of amorphous arsenic sulfide pigments of known composition are presented and discussed.While all materials present a main band characteristic for the amorphous pigment centered on 341 cm−1, additional small contributions indicate the presence of sulfur, arsenic oxide, and crystalline nano phases embedded in the amorphous matrix. Although only the broad 341‐cm−1 peak is necessary to identify the arsenic sulfide as an amorphous material, the smaller additional features allow for the characterization of the various manufacturing processes and initial materials used. In ideal conditions, these small features also enable to assess the As/S ratio of the studied amorphous arsenic sulfide pigments based on their relative intensity. In this context, the latter reference spectra were used to characterize the amorphous arsenic sulfide pigments and their arsenic to sulfur elemental composition in four 18th‐ to 20th‐century historical samples and compared with scanning electron microscopy with energy dispersive X‐ray semiquantitative analyses. The identification of the amorphous arsenic sulfide used in these historical samples was compared with the description of the manufacturing processes reported in historical sources of the time, allowing for a better understanding of the evolution of the amorphous arsenic sulfide pigments manufacturing methods.

Characteristics of Amorphous As2S3 Semiconductor Films Obtained via Spin Coating

Centrifugation is used in fabricating, e.g., films with large areas and/or thicknesses of several micrometers. However, it has yet to be widely employed for chalcogenide compounds, due to their relatively weak solubility in most solvents. Determining the optimum conditions for preparing solutions of chalcogenide compounds and obtaining films via centrifugation is therefore of great interest. Specific features of amorphous arsenic sulfide (As2S3) films prepared via the centrifugation of solutions in n-butylamine have been studied. These films were characterized by means of X-ray diffraction analysis, IR spectroscopy, atomic-force microscopy and Raman spectroscopy. It was shown that amorphous As2S3 films have a greater elasticity modulus than those of analogous composition produced via thermal evaporation in vacuum, or As2S3 glass. A structural model based on arsenic sulfide clusters whose surfaces are bound by negatively and positively charged ions is used to explain the experimental results obtained in this work. DC measurements show that the amorphous films exhibit semiconductor-type conductivity. Their room temperature conductivity is ~10−15 S/cm, which indicates good dielectric properties. The films are optically transparent starting from the yellow spectral range, making them promising functional materials for engineering applications in optics and photonics.

Laser‐Induced Formation of CdS Crystallites in Cd‐Doped Amorphous Arsenic Sulfide Thin Films

As2S3:Cd films with nominal Cd content x up to 4 at.% were prepared by thermal evaporation. Their amorphous structure is confirmed by Raman spectroscopy. The film surface roughness estimated from atomic force microscopy does not exceed 1 nm. Energy‐dispersive X‐ray spectroscopy and X‐ray photoelectron spectroscopy show a strong decrease of Cd content with the film depth. Peaks of CdS longitudinal optical phonon and its overtones emerging in the Raman spectra of films with x ≥ 2 at.% Cd are the evidence for the laser irradiation‐induced formation of CdS crystallites in the As2S3:Cd films. The downward shift of the CdS Raman peak frequencies is mainly explained by tensile strain undergone by the CdS crystallites in the films caused by material transfer from the laser spot due to the photoplastic effect.

Optical properties of As2S3 layers deposited from solutions obtained by chemical reaction

This paper deals with three approaches for the preparation of arsenic sulfide layers from solutions. First approach employs arsenic sulfide solutions obtained by dissolving powder of arsenic sulfide glass in n-propylamine. Second approach, a novel one, employs amorphous arsenic sulfide precipitated by chemical reaction of arsenic trichloride and ammonium sulfide. The precipitate was dissolved in n-propylamine. Third original approach relays on the same chemical reaction carried out in a mixture of n-propylamine and water that prevents the precipitation. By using all the approaches input arsenic sulfide solutions with a concentration of 0.33 mol/l were fabricated and applied onto glass slides by dip-coating method with withdrawing velocities of 50, 100, 200, and 250 mm/min. Applied layers dried in vacuum at 60 °C for 1 h and thermally treated at 180 °C for 30 s were characterized by optical and atomic force microscopy as well as by transmission spectroscopy in a wavelength range of 300–2500 nm. Refractive indices, thicknesses and band gaps were estimated from measured spectra. A maximum refractive index of about 2.15 at 600 nm and thicknesses up to 220 nm were determined on layers fabricated from input solutions obtained by dissolving of arsenic sulfide glass. Arsenic sulfide layers prepared on the basis of the arsenic sulfide precipitation exhibit refractive indices up around 1.90 and thicknesses up to 410 nm. Photonic band gap values on a level of 2.2 eV have been determined on these layers. On the other hands, composite layers prepared by reaction of arsenic trichloride and ammonium sulfide in the solution of n-propylamine and water exhibited low transparencies, refractive indices around 1.7 and thicknesses of about 2 µm.

Russoite, NH4ClAs23+O3(H2O)0.5, a new phylloarsenite mineral from Solfatara Di Pozzuoli, Napoli, Italy

AbstractThe new mineral russoite (IMA2015-105), NH4ClAs23+O3(H2O)0.5, was found at the Solfatara di Pozzuoli, Pozzuoli, Napoli, Italy, as a fumarolic phase associated with alacránite, dimorphite, realgar, mascagnite, salammoniac and an amorphous arsenic sulfide. It occurs as hexagonal plates up to ~300 µm in diameter and 15 µm thick, in rosette-like intergrowths. On the basis of powder X-ray diffraction measurements and chemical analysis, the mineral was recognised to be identical to the corresponding synthetic phase NH4ClAs2O3(H2O)0.5. Crystals are transparent and colourless, with vitreous lustre and white streak. Tenacity is brittle and fracture is irregular. Cleavage is perfect on {001}. The measured density is 2.89(1) g/cm3; the calculated density is 2.911 g/cm3. The empirical formula, (based on 4.5 anions per formula unit) is [(NH4)0.94,K0.06]Σ1.00(Cl0.91,Br0.01)Σ0.92As2.02O3(H2O)0.5. Russoite is hexagonal, space group P622, with a = 5.2411(7), c = 12.5948(25) Å, V = 299.62(8) Å3 and Z = 2. The eight strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 12.63(19)(001), 6.32(100)(002), 4.547(75)(100), 4.218(47)(003), 3.094(45)(103), 2.627(46)(110), 2.428(31)(112) and 1.820(28)(115). The structure, was refined to R = 0.0518 for 311 reflections with I &gt; 2σ(I) and shows a different location of the ammonium cation and water molecules with respect to that reported for the synthetic analogue. The mineral belongs to a small group of phylloarsenite minerals (lucabindiite, torrecillasite and gajardoite). It contains electrically neutral As2O3 layers, topologically identical to those found in lucabindiite and gajardoite between which are ammonium cations and outside of which Cl– anions. Water molecules and additional ammonium cations are located in a layer between two levels of chloride anions.

Assessing the stability of arsenic sulfide pigments and influence of the binding media on their degradation by means of spectroscopic and electrochemical techniques

In this paper, we used the semiconducting and lightfastness properties of synthetic and mineral arsenic sulfide pigments to study their stability by means of electrochemical and microfadometric techniques. A combination of these techniques shows that in the early stage of the degradation process, amorphous arsenic sulfides are more stable than both crystalline forms, while upon longer exposure time, amorphous pigments will fade more than both mineral pigments, making it less suitable. While the stability study was carried out on unbound pigments, the influence of the organic binder on the relative degradation of the arsenic sulfide pigments was investigated through a multi-analytical approach on pigment/binder mock-up paint samples. For this purpose, the formation of arsenic trioxide was assessed by micro Fourier transform infrared (μ-FTIR) spectroscopy while the influence of the binder on the formation of sulfates was studied by means of synchrotron radiation X-ray near edge structure (μ-XANES). Both techniques elucidate a higher stability of all pigments in gum arabic while the use of egg yolk as binder leads to the most degradation, most likely due to its sulfur-rich composition. In the context of the degradation of arsenic sulfide pigments, other binders such as animal glue, egg white or linseed oil show an intermediate impact.

Identification by Raman spectroscopy of pararealgar as a starting material in the synthesis of amorphous arsenic sulfide pigments

In this study, a combination of elemental analytical techniques (MA-XRF and SEM-EDX) were used to localize arsenic sulfide pigments within a 17th-century Dutch painting and in the stratigraphy of an 18th-century Flemish polychrome sculpture. Once located, Raman spectroscopy was used to obtain the vibrational signature of the arsenic sulfide pigments employed. By means of the latter analytical technique and due to the very distinctive Raman scattering signal of the various arsenic sulfide compounds, it was possible to identify the arsenic-based pigments as natural orpiment and amorphous arsenic sulfide. In the latter case, based on the minor bands observed and the good condition of the paint layers, it was possible to identify pararealgar, the orangey-yellow to yellow degradation product of realgar, as the initial arsenic sulfide material used for the synthesis of the amorphous pigment. To the best of our knowledge, this is the first time that combined pararealgar/amorphous arsenic sulfide Raman spectra are reported in historical samples. Therefore, this would be the first identification of pararealgar as the starting material to produce amorphous arsenic sulfide pigments used in artworks.

Amorphous As-sulfide precipitates from the shallow-water hydrothermal vents off Milos Island (Greece)

Amorphous orpiment-like As-sulfides (As2S3) are the most common As phases precipitating in hydrothermal systems, yet there is a lack of information regarding their solid-state characterization. Using a combination of optical, SEM–EDS, micro-Raman and XANES/EXAFS applications, we investigated yellow-orange As- and S-rich sediments occurring in the shallow-water hydrothermal system off the coast of Milos Island, Greece. The precipitates have several morphologies, but are dominantly colloidal. Intriguing “biological” morphologies also exist (e.g., cell-like (~10μm), spirals (~20μm), and rounded “cinnamon bun” shapes (~20μm)). SEM–EDS data indicated that the precipitates have an As:S ratio similar to orpiment (average=0.58, range 0.51–0.63; n=8). Micro-Raman spectra indicated that orange colored precipitates appear to be dominated by poorly crystalline and/or amorphous arsenic sulfides with micro-amounts of more crystalline orpiment and impure sulfur. The yellow sediments also contained crystalline elemental sulfur in the form S8. Bulk As K-edge XANES spectra of the As-sulfide precipitates proved a valence of As corresponding to orpiment-type (As2S3) compounds (−1 to +3). EXAFS fitting results indicated that the studied material exhibits an amorphous orpiment-like structure with As ions coordinated by 3 sulfur atoms (CN=3.0). The As–S interatomic distance of the first shell is calculated at 2.279Å and the Debye–Waller factor (σ2) is 0.00427. These data suggest that the modeled structure of the studied precipitates is slightly S-deficient and ordered only in the first shell around As, resembling an orpiment-type structure, whereas higher shells are not present and must be disordered. The disorder phenomenon may be strictly produced either by the existence of occasional As–S–As bridges with As–As bonds or by the occurrence of As–O–As bridges, causing twisting of the AsS3 pyramids in the initial orpiment structure. This distortion in the higher coordination shells of the structural sheets creates the amorphous orpiment.

Identification of artificial orpiment in the interior decorations of the Japanese tower in Laeken, Brussels, Belgium

In this paper, we used a multi-technique approach in order to identify the arsenic sulfide pigment used in the decorative panels of the Japanese tower in Laeken, Belgium. Our attention was drawn to this particular pigment because of its relatively good conservation state, despite its known tendency to fade over time when exposed to light. The pigment was used with different painting techniques, bound with oil and urushi in the lacquers and with an aqueous binder in the mat relief panels. In the latter case it is always applied as an underlayer mixed with ultramarine blue. This quite unusual pigment mixture also shows a good state of preservation. In this study, the orpiment used for the Japanese tower has been identified as an amorphous arsenic sulfide glass (AsxSx) with the aid of light microscopy, PLM, SEM-EDX and Raman microscopy. The pigment features different degrees of As4S4 monomer units in its structure, also known as realgar-like nano-phases. This most likely indicates different synthesis processes as the formation of these As4S4 monomers is dependent of the quenching temperature (Tq) to which the artificial pigment is exposed during the preparation phase.

Characterization of radiation-induced effects in amorphous arsenic sulfides by positron annihilation lifetime spectroscopy

Abstract

Pore formation and removal in solution-processed amorphous arsenic sulfide films

This paper studies the formation of nanopores in solution-processed amorphous arsenic sulfide films and provides an effective method to remove such pores. Nanopores are observed mainly in the bulk of the film after being annealed above 120°C, and pore sizes are determined to increase with both baking temperature and duration. These observations are explained by a vacancy coalescence mechanism in the context of propylamine solvent. By adding a second solvent, ethylenediamine (EDA), to the original solution, we can essentially modify the material dissolution and annealing chemistry. Most pores are removed when 10% EDA is added, rendering a homogeneous film. The work presented here has great implications for improving the quality of optical chalcogenide components processed with solution methods. It also reinforces the pore formation mechanism that has been relevant to many solution-processed materials.

Recovery process of optical stopping effect in tin or phosphorus-doped amorphous As2S8thin-film waveguide

In this research, the recovery process of the optical stopping effect on an amorphous arsenic sulfide thin-film waveguide is studied, both on the net As(2)S(8) and doping As(2)S(8) waveguide. Based on the experimental results, we analyzed the chemical bond structure of the samples. The hybrid orbital theory and electron energy bandgap theory are applied in order to establish the model of optical stopping and the recovery process. The numerical analysis results are well matched with the experiment data, which indicates that the model properly explains the optical stopping effect phenomenon. The model also can be applied to predict the recovery process of the optical stopping effect.