BaCuSi2O6 Research Articles

Development of Chinese barium copper silicate pigments during the Qin Empire based on Raman and polarized light microscopy studies

Ancient Chinese objects dating from the Warring States period (475–221BC) to the Han dynasty (206BC–220AD), including faience beads, wall paintings, polychrome decoration on pottery, stone and bronze objects, were studied using Raman microscopy and polarized light microscopy (PLM). Chinese Blue (BaCuSi4O10) and Chinese Purple (BaCuSi2O6) were identified, and additionally dark blue particles of a new pigment BaCu2Si2O7 were also detected in purple decoration. Based on PLM observation, Chinese Blue, Chinese Purple and BaCu2Si2O7 frequently coexist in single polychrome samples and cannot be individually identified using other analytical methods because of the minute amount that these chemicals present: sometimes comprising just one or two particles. The use of Raman spectroscopy can identify such small presences. This paper illustrates the man-made barium copper silicate pigments along the Qin historical development and shows the advantage of PLM combined with Raman spectroscopy to analyses pigments giving us an overall picture of the dates and the places where barium copper silicate pigments were used in ancient China. Their origin, decline and manufacturing techniques are also discussed.

Exfoliation of Egyptian Blue and Han Blue, two alkali earth copper silicate-based pigments.

In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi4O10 and BaCuSi4O10, the colored components of the historic Egyptian blue and Han blue pigments. The bulk forms of these materials are synthesized by both melt flux and solid-state routes, which provide some control over the crystallite size of the product. The melt flux process is time intensive, but it produces relatively large crystals at lower reaction temperatures. In comparison, the solid-state method is quicker yet requires higher reaction temperatures and yields smaller crystallites. Upon stirring in hot water, CaCuSi4O10 spontaneously exfoliates into monolayer nanosheets, which are characterized by TEM and PXRD. BaCuSi4O10 on the other hand requires ultrasonication in organic solvents to achieve exfoliation. Near infrared imaging illustrates that both the bulk and nanosheet forms of CaCuSi4O10 and BaCuSi4O10 are strong near infrared emitters. Aqueous CaCuSi4O10 and BaCuSi4O10 nanosheet dispersions are useful because they provide a new way to handle, characterize, and process these materials in colloidal form.

Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments

In a visualized example of the ancient past connecting with modern times, we describe the preparation and exfoliation of CaCuSi4O10 and BaCuSi4O10, the colored components of the historic Egyptian blue and Han blue pigments. The bulk forms of these materials are synthesized by both melt flux and solid-state routes, which provide some control over the crystallite size of the product. The melt flux process is time intensive, but it produces relatively large crystals at lower reaction temperatures. In comparison, the solid-state method is quicker yet requires higher reaction temperatures and yields smaller crystallites. Upon stirring in hot water, CaCuSi4O10 spontaneously exfoliates into monolayer nanosheets, which are characterized by TEM and PXRD. BaCuSi4O10 on the other hand requires ultrasonication in organic solvents to achieve exfoliation. Near infrared imaging illustrates that both the bulk and nanosheet forms of CaCuSi4O10 and BaCuSi4O10 are strong near infrared emitters. Aqueous CaCuSi4O10 and BaCuSi4O10 nanosheet dispersions are useful because they provide a new way to handle, characterize, and process these materials in colloidal form.

April 2014: This Month in JoVE - Bioengineering for ACL Tears, Neuroscience behind Insect Locomotion, Improved Genetic Engineering of Crops, and Synthesizing Secret Ink

Here's a look at what's coming up in the April 2014 issue of JoVE: The Journal of Visualized Experiments. In the Bioengineering section we have a video article that examines the anterior cruciate ligament (ACL), which is critical for keeping the knee stable when pivoting or planting. Torn or ruptured ACLs are among the most common of all serious knee injuries, especially in athletes, and even partial tears can hurt knee stability and function. Because they can't heal on their own, torn ACLs are often treated surgically, sometimes by reconstructing the ligament with a tendon grafted from the patient's own body or from a cadaver. Every year, over 100,000 ACL reconstructions are performed in the United States. The torn ligaments are usually discarded as surgical waste, but Gupta et al. see them as a valuable source of cells for potentially repairing ACLs. They developed a method for harvesting and expanding human ACL-derived cells then growing them on scaffolds to form tissue-engineered patches. Under scanning electron microscopy, the engineered matrix demonstrates good cellular adherence and growth. This technique could lead to methods for strengthening damaged ligaments and enhancing ACL repair, especially for those wishing to maintain an athletic lifestyle. In the Neuroscience section we examine motor control in insects, which are among the most athletic creatures on Earth. They are especially good at adapting to sudden changes in terrain, so scientists are interested in correlating neural activity with behavior in insects. Guo et al. have developed a method for recording brain activity in the discoid cockroach, also known as the tropical cockroach, as they explore an arena or as they encounter obstacles that cause them to change course. The authors also demonstrate how to collect the data for subsequent analysis, which may yield insight into the neural control of behavior. In JoVE Environment we feature a technique for transient gene expression in plants. To express gene products in specific parts of the cell, plants often have several copies of a gene and express them separately in different organelles (such as the chloroplast and peroxisome) or in the cytosol. Therefore, genetic engineers may have to target multiple duplicated genes to manipulate expression in different cell parts. To get around this problem, Mattozzi et al. use a novel method for multiple-organelle targeting that takes advantage of alternatively spliced mRNAs, which are sent to different locations in the cell. The targeting constructs are designed using Gibson assembly, a one-step cloning method, and then delivered using a gene gun. This technique offers great flexibility in terms of genetic design, and can be applied to large-scale selective genetic engineering in agriculture or the environment. In the Chemistry section we feature an article that uses modern chemical techniques to examine two bright blue pigments that were synthesized in ancient societies. Calcium copper tetrasilicate, commonly known as Egyptian blue, is thought to be the first synthetic pigment and used in Egypt as early the 4th Dynasty (ca. 2500 BC), the height of the pyramid-building era. Barium copper tetrasilicate, also known as Han blue, was later developed in China during the beginning of the Zhou Dynasty, or the height of the bronze age (1045-771 BC). Nowadays, scientists are interested in the strong near infrared (NIR) emission properties of these two pigments, which can be utilized for optical sensors. Related to this application is the ability to exfoliate copper tetrasilicates into 2D monolayers, or nanosheets. Johnson-McDaniel and Salguero demonstrate how to synthesize these two copper tetrasilicate pigments and exfoliate them into monolayer nanosheets. Egyptian blue spontaneously exfoliates into monolayers when stirred in hot water, whereas Han blue requires ultrasonication in organic solvents. Our authors show that both the bulk and nanosheet forms of the two pigments are strong near infrared emitters with potential applications ranging from security inks to biomedical imaging. You've just had a sneak peek of the April 2014 issue of JoVE. Visit the website to see the full-length articles, plus many more, in JoVE: The Journal of Visualized Experiments.

Nonfrustrated Interlayer Order and its Relevance to the Bose-Einstein Condensation of Magnons inBaCuSi2O6

Han purple (${\mathrm{BaCuSi}}_{2}{\mathrm{O}}_{6}$) is not only an ancient pigment, but also a valuable model material for studying Bose-Einstein condensation of magnons in high magnetic fields. Using precise low-temperature structural data and extensive density-functional calculations, we elucidate magnetic couplings in this compound. The resulting magnetic model comprises two types of nonequivalent spin dimers, in excellent agreement with the $^{63,65}\mathrm{Cu}$ nuclear magnetic resonance data. We further argue that leading interdimer couplings connect the upper site of one dimer to the bottom site of the contiguous dimer, and not the upper-to-upper and bottom-to-bottom sites, as assumed previously. This finding is verified by inelastic neutron scattering data and implies the lack of frustration between the layers of spin dimers in ${\mathrm{BaCuSi}}_{2}{\mathrm{O}}_{6}$, thus challenging existing theories of the two-dimensional-like Bose-Einstein condensation of magnons in this compound.

Hydrothermal synthesis and properties of pigments Chinese purple BaCuSi2O6 and dark blue BaCu2Si2O7

A green chemistry strategy was developed to prepare two barium copper silicate pigments. Chinese purple BaCuSi2O6 and dark blue BaCu2Si2O7 are synthesized through mild hydrothermal treatment in narrow pH range. The compounds are characterized by powder X-ray diffraction techniques, infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive spectroscopy, luminance and magnetic measurements. When excited by a visible laser, hydrothermally synthetic BaCuSi2O6 exhibits a broad emission in the near-infrared region with an excited state lifetime 6.4 μs due to the square-planar Cu2+ ions as the chromophores. Magnetic analysis of BaCuSi2O6 indicates the spin gapped antiferromagnetic property due the presence of the Cu–Cu dimers in the structure. BaCu2Si2O7 shows interesting quasi-one-dimensional antiferromagnetic property.

The spatially resolved characterisation of Egyptian blue, Han blue and Han purple by photo-induced luminescence digital imaging

The photo-induced luminescence properties of Egyptian blue, Han blue and Han purple were investigated by means of near-infrared digital imaging. These pigments emit infrared radiation when excited in the visible range. The emission can be recorded by means of a modified commercial digital camera equipped with suitable glass filters. A variety of visible light sources were investigated to test their ability to excite luminescence in the pigments. Light-emitting diodes, which do not emit stray infrared radiation, proved an excellent source for the excitation of luminescence in all three compounds. In general, the use of visible radiation emitters with low emission in the infrared range allowed the presence of the pigments to be determined and their distribution to be spatially resolved. This qualitative imaging technique can be easily applied in situ for a rapid characterisation of materials. The results were compared to those for Egyptian green and for historical and modern blue pigments. Examples of the application of the technique on polychrome works of art are presented.

Three fabricated pigments (Han purple, indigo and emerald green) in ancient Chinese artifacts studied by Raman microscopy, energy‐dispersive X‐ray spectrometry and polarized light microscopy

AbstractIn this study, we analyzed three fabricated pigments from ancient artifacts in China. The purple pigment was obtained from a painted pottery figurine unearthed from the Chu Tombs group of the Western Han dynasty in Xuzhou, Jiangsu Province. The dark blue dye was from silk textiles in the Palace Museum. The green pigment was from decorative paintings on ancient architectures in the Palace Museum. These pigments were analyzed with Raman microscopy (RM), energy‐dispersive X‐ray (EDX) analytic spectroscopy and polarized light microscopy (PLM). By comparing their Raman spectra with standard samples, the primary ingredients of the purple pigment and the dark blue dye were found to be Han purple and indigo, respectively. However, the green pigment could not be identified by RM because of strong fluorescence. It was then confirmed to be emerald green by using EDX analytic microscopy and PLM. We also describe the traditional manufacturing methods of these pigments and their applications on artifacts in Chinese history. Copyright © 2007 John Wiley & Sons, Ltd.

The invention of blue and purple pigments in ancient times

This tutorial review examines manmade blue and purple pigments appearing in antiquity. They were obtained by chemical synthesis from mineral starting materials and refer to chemical compounds: Egyptian Blue (CaCuSi4O10), Han Blue (BaCuSi4O10) and Han Purple (BaCuSi2O6), Maya Blue (x.indigo.(Mg,Al)4Si8(O,OH,H2O)24) and Ultramarine Blue (Na,Ca)8(AlSiO12)(S, SO4,Cl). The Egyptian and Chinese copper-based pigments are assumed to have been developed independently and are presumably an outcome of the historical developments in glazing techniques. A technology transfer from Egypt into China cannot be fully excluded but, based on the facts acquired up to now, looks less probable.

Raman and SEM Studies of Man-made Barium Copper Silicate Pigments in Ancient Chinese Artifacts

Ancient Chinese objects from the eighth to the third centuries BC were studied by Raman microscopy and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX). They included blue glassy faience beads, blue or purple beads of vitreous sinter material high in lead and barium, earrings and octagonal sticks. Man-made Han blue (BaCuSi4O10) and Han purple (BaCuSi2O6 ) were identified by Raman microscopy, as was ultramarine blue in two faience beads. SEM-EDX studies on the compact bodies of one bead and one octagonal stick revealed vitreous and crystalline phases, the latter with the approximate composition (BaO)n·(CuO)m·2SiO2, n, m = 1 or 2. All objects were found to contain varying amounts of lead.

High-Field NMR Insights into Quantum Spin Systems

Possibilities of NMR technique will be illustrated by a selection of high-field NMR results on antiferromagnetic quantum spin systems, obtained at the Grenoble High Magnetic Field Laboratory. We present results for two well known systems, doped Haldane spin chain Y2BaNi1-xMgxO5 and spin-Peierls compound CuGeO3, as well as two newly studied compounds, the NaCU2O2 chain (or zigzag ladder) and the 2D dimer compound BaCuSi2O6 (Han purple).

Photoluminescence of the inorganic pigments Egyptian blue, Han blue and Han purple

The room-temperature photoluminescence spectra of various samples of Egyptian blue (CaCuSi 4O 10) are presented, discussed and compared with those of recently synthesized compounds corresponding to the ancient pigments Han blue (BaCuSi 4O 10) and Han purple (BaCuSi 2O 6). All the samples of Egyptian blue show identical spectra, in spite of their very different origin. The spectra of Han blue and Han purple are significantly different. Since the Cu 2+ ion may be considered the only luminescent centre in the spectral range under investigation, the differences between the spectra of the various pigments are ascribed to a ligand-field change. This can be related to the larger size of the Ba 2+ ion with respect to Ca 2+. The use of PL spectra for the identification of these pigments in works of art is proposed.

A purple barium copper silicate pigment from early China

AbstractA purple barium copper silicate, BaCuSi206, an artificial inorganic pigment, has been identified, sometimes mixed with the known blue barium copper silicate, BaCuSi4O10. It occurs on- painted objects and in octagonal sticks from China attributed to the Han dynasty (208 Be-AD 220). This man-made pigment, for which the name Han purple is proposed, has not been previously characterized.

A Purple Barium Copper Silicate Pigment from Early China

A Purple Barium Copper Silicate Pigment from Early China

Refinement of the structure of barium copper silicate BaCu[Si4O10] at 300 K

Cristallisation dans P4/ncc avec a = 7,447 et c = 16,138 A, Z = 4; affinement jusqu'a R = 0,023. La structure est du type BaFe[Si 4 O 10 ]. Elle contient des tetraedres SiO 4 qui partagent des sommets pour former des cycles a 4 membres qui a leur tour forment des couches Si 8 O 20 . Les cations Ba et Cu sont localises entre les couches. Coordination carree autour de Cu et antiprisme carre autour de Ba.

Structure of the cyclic barium copper silicate Ba2Cu2[Si4O12] at 300 K

Cristallisation dans I4/mmm avec a=7.0515, c=11.1503A, Z=2; affinement jusqu'a R=0.0300. La structure contient des groupements cycliques [Si 4 O 12 ] 8- isoles avec Si-O(1)=1.570 et Si-O(2)=1.602A. La coordination carree du cuivre s'effectue avec quatre atomes O(1) et Cu-O(1)=1.925A. L'ion baryum est environne de huit atomes O(1) formant un antiprisme carre.

An early man-made blue pigment from China—barium copper silicate

Barium copper silicate, BaCuSi4O10, an artificially produced mineral, has been identified on Chinese painted ceramic objects attributed to the Han dynasty (208 Bc–220 AD). The mineral has also been observed as an important component in octagonal sticks probably dating to the Warring States period (475–221 BC) or to the Han dynasty. This man-made mineral has been hitherto unreported as a pigment in the ancient Chinese palette.