Characterisation of baroque tin amalgam mirrors of the historical Green Vault in Dresden

The historical Green Vault, one of Europe’s most sumptuous treasure chambers, has reopened in September 2006 in the Dresden Royal Palace. For the baroque presentation of the artworks the special properties of tin amalgam mirrors are of great importance. A comprehensive analytic characterisation was necessary for restoration and reconstruction. The different original casting glasses were analysed in respect of chemical composition, roughness, waviness and optical properties like chromaticity coordinates and transmittance. The microstructure of the tin amalgam layers were investigated on metallographic cross-sections and by X-ray diffraction. The investigations reveal that the tin amalgam layers are composed of γ-HgSn_6-10 phase with a grain size between 5 and 50 μm surrounded by a thin mercury phase with about 2 wt. % tin. However the most important property of the baroque tin amalgam mirrors is a relative low reflectivity of about 59% which is drastically lower than for silver mirrors with a reflectivity of about 96%. According to the characterisation results a suitable glass for reconstruction was selected. The mirror layers were produced by historical tin amalgam technology for the rooms not destroyed by bombarding of Dresden in February 1945. For the completely destroyed Jewel Room pure tin layers were deposited by magnetron sputtering. The results show that this new technology enables an adequate substitute for the original tin amalgam layers. PACS  61.66.-f; 74.25.Gz; 61.10.Nz; 68.37.Hk     

Study of tin amalgam mirrors by 119Sn Mössbauer spectroscopy and other analytical methods

From the beginning of the 16 ^th until the end of the 19 ^th century the most widely used mirrors consisted of a pane of glass backed with a reflecting layer of tin-mercury amalgam. They were made by sliding the glass pane over a tin foil covered with liquid mercury. After removal of the superfluous mercury, tin amalgam formed slowly at ambient temperature and yielded a reflecting layer adhering to the surface of the glass. Such mirrors often deteriorate in the course of time by oxidation of the tin in the amalgam to stannous or stannic oxide. ¹¹⁹Sn Mössbauer spectroscopy, scanning electron microscopy, micro-XRF and X-ray diffraction have been used to study this deterioration process. The studied specimens were a modern mirror made for the reconstruction of the Green Vault in Dresden in the early 2000s, two rather well preserved German mirrors from the 17 ^th and 19 ^th centuries and several strongly deteriorated specimens of Baroque mirrors from the south of Spain. The modern mirror consists mainly of a Sn_0.9Hg_0.1 amalgam with only 2 % of SnO₂. The older German mirrors showed more pronounced oxidation, containing 12 and 15 % of SnO₂, which did not noticeably impair their reflectivity. In the samples from the Spanish mirrors at best a few percent of metallic phase was left. The majority of the tin had oxidised to SnO₂, but between 8 and 20 % of the tin was present as SnO. X-ray diffraction yielded similar results and micro-XRF mapping using synchrotron radiation for excitation gave information on the distribution of Sn and Hg in the reflecting layer of the mirrors.     

Electrochemical deposition of silver nanoparticles on TiO2/FTO thin films

Silver nanoparticles were deposited on titanium oxide^IV (TiO₂) thin films supported on FTO (fluorine-doped tin oxide^IV) glass using a double pulse electrochemical deposition method. A systematic study of particle nucleation and growth is presented as a function of applied potential and time. Samples were analyzed by grazing-angle X-ray diffraction (GIXRD) technique and morphology was observed using Scanning Electron Microscopy and Energy Dispersive Spectroscopy device (SEM-EDS). Our results confirm the possibility of controlled electrochemical homogeneous deposition of metallic silver particles over TiO₂ surface, which exhibit a potential application in catalytic processes.     

加热过程中古代铜镜表面"锡汞齐"相变分析

利用可在常温至1 200℃下,对样品进行边加热边检测的θ-θ扫描(立式测角仪)密封陶瓷X射线管全自动衍射仪及X射线荧光,再结合表面形貌特征等对涂抹"锡汞齐"的高锡铜镜样品进行了检测分析,证明在加热到高于Hg的沸点时含汞物相会逐渐消失;说明铜镜或青铜器表层中有无Hg不能作为判断其是否采用过"锡汞齐"工艺的依据,并且从使用角度来看,铜镜涂抹"锡求齐"也没有必要.     

原位土培秸秆育苗容器的降解特性光谱分析

为研究新型可降解育苗容器降解行为,以改性大豆胶为基体树脂,秸秆为增强材料热压制备的秸秆育苗容器为研究对象,利用原位土培降解秸秆育苗容器,采用纤维素测定仪、傅里叶红外光谱(FTIR spectra)、扫描电镜-X能谱(scanning electron microscopy-energy dispersive X-ray spectroscopy,SEM-EDS)以及热重(thermo-gravimetry,TG)等分析手段,对秸秆育苗容器土培降解前后物理、化学组分和结构变化进行表征。研究结果表明:与土培前秸秆育苗容器相比,土培降解秸秆容器中纤维素、半纤维素和木质素相对含量从29.03%,30.44%和12.52%降低至21.43%,21.41%和9.54%;FTIR分析表明土培降解后秸秆育苗容器中酯键和脂肪键发生断裂,且芳香族特征峰明显减弱;SEM-EDS谱图结果证明秸秆容器中微纤丝链段、基体树脂溶解,材料表面发生氧化降解;TGA结果分析表明土培秸秆容器内部存在大量小分子物质,分解后残余物耐热性提高。     

Synthesis,deposition and characterization of tin selenide thin films by thermal evaporation technique

Tin selenide alloy was synthesized by following simple chemical reaction method, at comparatively lower temperature of 100 °C, from alkaline medium using SnCl₂.2H₂O and selenium as source materials. Powder X-ray diffraction analysis reveals that the particle size of the synthesized product is in nanometer scale. Using the reaction product as source material, the SnSe films were deposited on glass substrates at room temperature, 150 °C, 250 °C, 350 °C and 450 °C. Structural, elemental, optical, surface morphological and electrical properties of the as deposited films were studied by X-ray diffraction, Energy Dispersive X-ray Analysis, UV-Vis-NIR, Scanning Electron Microscopy and Hall effect measurement techniques and the relevant details have been obtained.     

Bronze roman mirrors: the secret of brightness

The surface microchemical structure of high tin leaded bronze Roman mirrors has been studied by means of scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and optical microscopy (OM) techniques. The results allowed understanding of the origin of their high chemical stability and silvery-lustrous appearance. Indeed, some areas of the selected Roman mirrors are still characterised by a highly reflective and silver coloured surface even though they have been buried in the soil for about 2000 years. The micro-chemical results obtained from these areas have revealed that the mirror surface was tin enriched via inverse-segregation phenomenon by tailoring the cooling parameters. Furthermore, the presence of tin could be likely enhanced via cycles of oxidation and selective copper corrosion processes, thus resulting in a tin surface enrichment as a semi-transparent amorphous-like tin oxide (SnO₂) film, as well as a copper depletion at the outer surfaces.     

Production of reference alloys for the conservation of archaeological silver-based artifacts

In the framework of the EC PROMET project, the chemical composition and metallurgical features of a large number of archaeological artifacts were investigated by different analytical surface and bulk techniques, such as Optical Microscopy (OM), Scanning Electron Microscopy coupled with energy dispersive X-ray micro-analysis (SEM-EDS), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The study of the corrosion products grown on the archaeological Ag-based artifacts revealed a quite ubiquitous and nearly constant presence of chlorine from the soil as the main corroding agent, mainly producing chlorargyrite (AgCl). Results of this extensive chemical, physical and metallurgical characterization were used to produce modern reference Ag-based alloys with a chemical composition and micro-chemical structure similar to that of ancient alloys. Furthermore, these reference Ag-based alloys were submitted to an accelerated degradation method in order to produce corroded samples to be used as sacrificial materials for testing corrosion inhibiting products. The production of artificial “patinas” and corrosion layers was made by a chemical and soil-induced degradation procedure. The comparison of the micro-chemical structures of natural and artificial corrosion layers shows that the selected degradation method produces “patinas” resembling those grown on archaeological artifacts from a chemical, structural and micro-morphological point of view.     

锡汞齐工艺中Hg对铜镜的影响

采用X射线衍射、扫描电镜等实验手段,对涂抹锡汞齐的青铜样品进行分析,讨论Hg在铜镜表面处理过程中可能会产生的作用,证明铜镜中Hg并不能完全挥发,残留的Hg在铜镜中会不断扩散,最终使铜镜表面逐渐模糊,不能用于映照。     

Spontaneous alloying of tin atoms into nanometer-sized gold clusters and phase stability in the resultant alloy clusters

Alloying behavior and phase stability has been studied in situ by transmission electron microscopy using clusters in the Au-Sn system. When tin atoms are vapor-deposited onto nm-sized gold clusters, rapid dissolution of tin atoms into gold clusters takes place and as a result Au-rich solid solution, amorphous-like Au-Sn alloy and AuSn compound clusters are formed depending upon the concentration of tin. The remarkable enhancement of solubility has been observed in Au-rich solid solution and AuSn compound. It becomes more difficult to form two phases in the interior of individual clusters even if the composition of alloy clusters falls in the two-phase region in the phase diagram for the bulk alloy and as a result amorphous-like phase is stabilized in nm-sized Au-Sn alloy clusters. Received 2 August 1999 and Received in final form 8 November 1999     

Composition distributions in FePt(Au) nanoparticles

Ternary alloy FePt(Au) nanoparticles were prepared by the co-reduction of platinum(II) acetylacetonate and gold(III) acetate and the thermal decomposition of iron pentacarbonyl in hot phenyl ether in the presence of oleic acid and oleylamine ligands. This gave spherical particles with an average diameter of 4.4 nm with a range of diameters from approximately 1.6–9 nm. The as-synthesized particles had a solid solution, face-centered-cubic structure. Though the average composition of the particles was Fe₄₄Pt₄₅Au₁₁, individual particle analysis by Scanning Transmission Electron Microscopy–X-ray Energy Dispersive Spectroscopy showed a broad distribution in composition. In general, smaller-sized particles tended to have a lower amount of Au as compared to larger-sized particles. As the Au content increased, the ratio of Fe/Pt widened.     

三门峡虢国墓地M2009出土铁刃铜器的科学分析及其相关问题

三门峡虢国墓地出土铁刃铜器是中原地区较早的用铁证据。利用金相显微镜、扫描电子显微镜-能谱仪（SEM-EDS）、电子探针（EPMA）等多种方法,对三门峡虢国墓地M2009出土的3件铁刃铜器进行了科学检测分析。结果显示,铜骹铁叶矛（STG001）铁质部分可见硅酸盐与氧化亚铁共生夹杂,且沿着加工方向拉长,其材质为块炼铁。铁刃铜削（SGT002）和铜内铁援戈（SGT003）残留铁金属颗粒中均检测出较为显著的Ni和少量Co,SEM-EDS线扫描分析显示Ni和Co在各相之间存在高低交错的分布特征,判断其材质为陨铁,其Ni含量处于铁陨石ⅢC和ⅢD之间,原始结构应属极细粒八面体铁陨石（Off）或无纹铁陨石（Ataxite）类型。样品STG001和SGT002铜质部分均保留较为典型的锡青铜铸造组织形态,基体为已腐蚀的α固溶体,残余（α+δ）固溶体均匀分布,铜铁结合处无明显的晶粒变形和再结晶现象,显示该区域未经历铸后的冷热加工。由此推断,铁刃部分应是先锻打加工成形后,嵌入铸造铜质部分的组合陶范,通过铸接的方式与铜质部分紧密结合而形成铜铁复合器物。简要梳理了中国早期铁金属的使用证据,指出陨铁和人工冶铁制品在虢国墓地的同时出现,显示了该时期在研究中国铁冶金技术起源和传播中的重要地位。西北地区在早期块炼铁技术传播中扮演了重要角色,而生铁技术在中原地区的产生则与商周青铜铸造技术传统关系密切。     

The photodegradation of cadmium yellow paints in Henri Matisse’s Le Bonheur de vivre (1905–1906)

Evidence for the alteration of the yellow paints in Henri Matisse’s Le Bonheur de vivre (1905–1906, The Barnes Foundation) has been observed since the 1990s. The changes in this iconic work of Matisse’s Fauvist period include lightening, darkening, and flaking of the yellow paints. Handheld X-ray fluorescence (XRF) and multispectral imaging surveys reveal that the degradation is confined to cadmium yellow (CdS) paints. The discoloration of cadmium yellow paints in Impressionist, Post-Impressionist and early modernist work from the 1880s through the 1920s has been ascribed to the photo-oxidative degradation of CdS. Preliminary investigations of the degraded yellow paints in this work involved Cd L_III-edge X-ray Absorption Near Edge Spectroscopy (XANES) at the Stanford Synchrotron Radiation Light Source (SSRL Menlo Park, California) and Scanning Electron Microscopy-energy dispersive X-ray analysis (SEM-EDS) at the Winterthur Museum Scientific Research and Analysis Laboratory. To determine if the visual changes in the paints did in fact indicate photo-oxidative degradation and if different chemistries could be observed for the lightened versus darkened regions, synchrotron radiation-micro Fourier Transform InfraRed (SR-μFTIR) spectroscopy, X-ray Fluorescence (SR-μXRF) mapping and micro X-ray Absorption Near Edge Spectroscopy (μXANES) mapping at the Cd L_III-edge of the altered paint cross-sections were carried out at the European synchrotron radiation facility (ESRF, Grenoble, France) beamline ID-21. The goal is to elucidate the discoloration mechanisms observed in the paint using elemental and speciation mapping. The μXANES mapping and SR-FTIR imaging showed a substantial enrichment of CdCO₃ in the off-white surface crust of the faded/discolored CdS paint. This suggests that the CdCO₃ is present as an insoluble photodegradation product rather than solely a paint filler or starting reagent. Additionally, oxalates and sulfates were found to be concentrated at the alteration surface.     

Iron oxide nanoparticles and VOx/Hexadecylamine nanotubes composite

In this work, we present the synthesis and characterization of a hybrid nanocomposite constituted by iron oxide nanoparticles and vanadium oxide/Hexadecylamine (VO_x/Hexa) nanotubes. Transmission Electron Microscopy (TEM) images show small particles (around 20 nm) in contact with the external wall of the multiwall tubes, which consist of alternate layers of VO_x and Hexa. By Energy Dispersive Spectroscopy (EDS), we detected iron ions within the tube walls and we have also established that the nanoparticles are composed of segregated iron oxide. The samples were studied by Electron Paramagnetic Resonances (EPR) and dc-magnetization as a function of the magnetic field. The analysis of the magnetization and EPR data confirms that a fraction of the V atoms are in the V⁴⁺ electronic state and that the nanoparticles exhibit a superparamagnetic behavior. The percentage of V and Fe present in the nanocomposite was determined using Instrumental Neutron Activation Analysis (INAA).     

Diffusion barrier performance of TiVCr alloy film in Cu metallization

In this study, 15 nm-thick sputter-deposited TiVCr alloy thin films were developed as diffusion barrier layers for Cu interconnects. The TiVCr alloy film tends to form a solid solution and a simple crystal structure from the constituted elements. Under TEM, the 15 nm-thick as-deposited TiVCr alloy film was observed to have a dense semi-amorphous or nanocrystalline structure. In conjunction with X-ray diffraction, transmission electron microscopy, and energy-dispersive spectroscopy analyses, the Si/TiVCr/Cu film stack remained stable at a high temperature of 700 °C for 30 min. The electrical resistance of Si/TiVCr/Cu film stack remained as low as the as-deposited value. These indicated that the mixed TiVCr refractory elements’ alloy barrier layer is very beneficial to prevent Cu diffusion.     

A new large – Scale synthesis of magnesium oxide nanowires: Structural and antibacterial properties

Large-scale one-dimensional magnesium oxide (MgO) nanowires with diameters of 6 nm and lengths of 10 μm have been successfully synthesized by a new facile and simple reaction. This production was performed via a microwave hydrothermal approach at low temperature growth of 180 °C for 30 min. The structure of as synthesized MgO nanowires were investigated by means of X-ray diffraction (X-ray), Fourier Transformation Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED) and Energy Dispersive X-ray (EDS). The antibacterial behavior of MgO nanowires concentration in solid media against Gram negative and Gram positive for different bacteria has been tested in details. The results show that the MgO nanowires have bacteriostatic activity against Escherichia coli and Bacillus sp. The antibacterial activity increases with increasing MgO nanowires concentration. Furthermore, the presence of one-dimensional MgO nanowires has high antibacterial efficacy and damages the membrane wall of bacteria. Finally, this study offered the prospect of developing ultrafine nanoscale devices utilizing MgO nanowires and implementing their useful potential in biological control.     

Direct evidence for reversible diffusional phase change in nanometer-sized alloy particles

Solid solubility in isolated nanometer-sized particles has been studied by in situ transmission electron microscopy using alloy particles in the Pb-Sn binary system. In approximately 17-nm-sized particles of a lead-56 at. % Sn solid solution, a phase change from a single phase of the lead solid solution to two phases, a lead solid solution and a tin-solid solution, takes place when the temperature is reduced from 110 degrees C to room temperature (RT). Furthermore, it is confirmed that this phase change could occur rather reversibly when the temperature is cyclically changed between 110 degrees C and RT. This observation provides direct evidence for reversible diffusional phase change in nanometer-sized alloy particles. It seems safe to conclude that the solubility limit of tin in lead is higher than 56 at. % at 110 degrees C, which is almost 5 times higher than the solubility limit of tin in bulk lead (i.e., 10 at. %).     

Micro-chemical and micro-structural investigation of archaeological bronze weapons from the Ayanis fortress (lake Van, Eastern Anatolia, Turkey)

Bronze weapons (VII cen BC) found during the archaeological excavation of the Ayanis fortress (lake Van, eastern Anatolia, Turkey) are investigated in order to determine their chemical composition and metallurgical features as well as to identify the micro-chemical and micro-structural nature of the corrosion products grown during long-term burial. Small fragments were sampled from the artefacts and analysed by means of the combined use of optical microscopy (OM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show that the bronze artefacts have been manufactured by using alloys with a controlled and refined chemical composition demonstrating the high level metallurgical competence and skill of the Urartian craftsmen and artists. Furthermore, the micro-structural and metallurgical investigations evidence the presence of equiaxed grains in the matrix, indicating that the artefact were produced by repeated cycles of mechanical shaping and thermal annealing treatments to restore the alloy ductility. From the degradation point of view, the results show the structures and the chemical composition of the stratified corrosion layers (i.e. the patina) where the copper or tin depletion phenomenon is commonly observed with the surface enrichment of some elements coming from the burial soil, mainly Cl, which is related to the high concentration of chlorides in the Ayanis soil. The results reveal also that another source of degradation is the inter-granular corrosion phenomenon likely increased by the metallurgical features of the alloys caused by the high temperature manufacturing process that induces crystallisation and segregation phenomena along the grain boundaries.     

Interaction of a low-pressure mercury discharge with the discharge tube wall

The darkening of soda-lime glass envelopes of low-pressure mercury discharge tubes has nothing to do with the formation of sodium amalgam on the inner surface of the tube. It is, however, connected with the diffusion of mercury ions into the glass of the tube. By applying a high negative voltage to part of the outer surface of a burning tube a sodium depleted region is created at the corresponding part of the inner surface. After removal of the high-voltage electrode and continued normal operation the rate of darkening of the sodium-depleted part of the tube is about 50 times larger than the rate observed for the normal parts of the same tube.     

Formation region of amorphous thin CoZr and CuZr films prepared by cocondensation on hot substrates

The glass formation ranges of thin CoZr and CuZr films condensed on cold and hot substrates (10–800 K) are experimentally determined by X-ray diffraction. The maximum substrate temperatures allowed to condense amorphous films are only slightly below the crystallization temperatures of the amorphous phases. These experimental results are compared with predictions of the glass formation ranges from thermodynamic calculations and instability models. At low substrate temperatures, where no phase separation is possible due to kinetic restrictions, the amorphous phase is favoured in the range between theT _o lines which are the stability limits of the extended solid solutions on both sides of a metastable binary phase diagram. For high substrate temperatures, where at least one species of the binary alloy is able to move, the amorphous state can be described to be in a metastable equilibrium with the extended solid solutions neglecting the intermetallic compounds. Therefore, the single-phase amorphous state is restricted to the range between theT _ml lines which are the metastable liquidus temperatures.