Application of ICP-MS trace element analysis in study of ancient Chinese ceramics

Thirty-nine trace elements of the Song-Yuan period (960-1368 AD) porcelain bodies from Cizhou, Jizhou and Longquanwu kilns were analyzed with ICP-MS, a technique rarely used in Chinese archaeometry, to investigate its potential application in such studies. Trace element compositions clearly reflect the distinctive raw materials and their mineralogy at the three kilns and allow their products to be distinguished. Significant chemical variations are also observed between Yuan and Song-Jing dynasties samples from Cizhou as well as fine and coarse porcelain bodies from Longquanwu. In Cizhou, porcelains of better quality which imitate the famous Ding kiln have trace element features distinctive from ordinary Cizhou products, that indicates geochemically distinctive raw materials were used and which possibly also underwent extra refining prior to use. The distinct trace element features of different kilns and the various types of porcelains from an individual kiln can be interpreted from a geochemical perspective. ICP-MS can provide a large amount of valuable information about ancient Chinese ceramics as it is capable of analyzing >40 elements with a typical of precision < 2%.

Transparent boundary conditions for wave propagation on unbounded domains

The numerical solution of the time dependent wave equation in an unbounded domain generally leads to a truncation of this domain, which requires the introduction of an artificial boundary with associated boundary conditions. Such nonreflecting conditions ensure the equivalence between the solution of the original problem in the unbounded region and the solution inside the artificial boundary. We consider the acoustic wave equation and derive exact transparent boundary conditions that are local in time and can be directly used in explicit methods. These conditions annihilate wave harmonics up to a given order on a spherical artificial boundary, and we show how to combine the derived boundary condition with a finite difference method. The analysis is complemented by a numerical example in two spatial dimensions that illustrates the usefulness and accuracy of transparent boundary conditions.

Synthesis, characterization, and electrical conduction of 10 mol% Dy2O3 doped CeO2 ceramics

Well-densified 10 mol% Dy2O3-doped CeO2 (20DDC) ceramics with average grain sizes of similar to 0.12-1.5 mu m were fabricated by pressureless sintering at 950-1550 degrees C using a reactive powder thermally decomposed from a carbonate precursor, which was synthesized via a carbonate coprecipitation method employing nitrates as the starting salts and ammonium carbonate as the precipitant. Electrical conductivity of the ceramics, measured by the dc three-point impedance method, shows a V-shape curve against the average grain size. The sample with the smallest grain size of 0.12 mu m exhibits a high conductivity of similar to 10(-1.74) S/cm at the measurement temperature of 700 degrees C, which is about the same conduction level of the micro-grained 10 mol% Sm2O3- or Gd2O3-doped CeO2, two leading electrolyte materials. (c) 2004 Elsevier Ltd. All rights reserved.

Experimental and theoretical investigation of the structural, chemical, electronic, and high frequency dielectric properties of barium cadmium tantalate-based ceramics

Single-phase Ba(Cd1/3Ta2/3)O-3 powder was produced using conventional solid state reaction methods. Ba(Cd1/3Ta2/3)O-3 ceramics with 2 wt % ZnO as sintering additive sintered at 1550 degreesC exhibited a dielectric constant of similar to32 and loss tangent of 5x10(-5) at 2 GHz. X-ray diffraction and thermogravimetric measurements were used to characterize the structural and thermodynamic properties of the material. Ab initio electronic structure calculations were used to give insight into the unusual properties of Ba(Cd1/3Ta2/3)O-3, as well as a similar and more widely used material Ba(Zn1/3Ta2/3)O-3. While both compounds have a hexagonal Bravais lattice, the P321 space group of Ba(Cd1/3Ta2/3)O-3 is reduced from P (3) under bar m1 of Ba(Zn1/3Ta2/3)O-3 as a result of a distortion of oxygen away from the symmetric position between the Ta and Cd ions. Both of the compounds have a conduction band minimum and valence band maximum composed of mostly weakly itinerant Ta 5d and Zn 3d/Cd 4d levels, respectively. The covalent nature of the directional d-electron bonding in these high-Z oxides plays an important role in producing a more rigid lattice with higher melting points and enhanced phonon energies, and is suggested to play an important role in producing materials with a high dielectric constant and low microwave loss. (C) 2005 American Institute of Physics.

Local structures around Y and Ce cations in 10 mol% Y2O3 doped ceria ceramics by EXAFS spectroscopy

Local structures around host Ce and dopant Y cations in 10 mol% Y2O3 doped ceria solid solutions have been investigated by room and high temperature EXAFS spectroscopy. The results show that the local structures around the Cc cation in doped ceria samples are similar to that in the fluorite CeO2 structure though the coordination numbers of Ce-O tend to be smaller than 8. The local structures around Y cation, however, are significantly different from those around Ce cation, and show more resemblance to that around Y cation in the C-type Y2O3 Structure. A more accurate description of the local structures around Y cation in doped ceria was given by analyzing Y-K edge EXAFS spectra based on the C-type Y2O3 structure. (c) 2006 Elsevier B.V. All rights reserved.