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The operation characteristics of an ac plasma display panel (PDP) with Si-doped MgO protecting layer are examined. Lower static operation voltages, higher luminous efficacy and shorter statistical delay time are observed.

The reactivity, or rate of consumption, of magnesium oxide (MgO) powder used in forming magnesium oxychloride (MOC) cement is largely affected by its thermal history and particle size. That, in turn, influences both reaction rate and properties of the reaction products of MOC cement. It is believed that the traditional measurements of properties of MgO powder itself are not able to reflect the actual consumption rate of MgO during chemical reaction, which is the key information needed for the appropriate proportions of starting materials to ensure the formation of Phase 5 crystals for better strength and physical properties. The experimental results show that X-ray diffractograms and phase diagram of a ternary MOC system can be utilized to evaluate the reactivity of MgO, and to optimize the formulation of MOC cement as well. Consequently, the apparent molar ratios of MgO over magnesium chloride (Mg[Cl.sub.2]) are adopted and recommended. The equivalent weight ratios between MgO and Mg[Cl.sub.2] are also given for the convenience of normal applications. DOI: 10.1061/(ASCE)0899-1561(2008)20:3(239) CE Database subject headings: Cements; Portland cements; Particle size; Chemicals.

Optical spectra of Cu, Ag, and Au monomers and dimers at regular sites and oxygen vacancies of the MgO(001) surface were studied by time-dependent density functional study. The embedded cluster model was used which provided an accurate description of substrate relaxation and long-range electrostatic interaction.

The process of dual ion assist beam deposition (DIBAD) of Magnesium Oxide (MgO) template layers for the second (2nd) generation coated conductors is explained. An increase in the MgO thickness also leads to an increase in the chemical stability of the templates.

A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase) and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a brief introduction in using powder X-ray diffraction to identify a solid and to measure lattice parameters could also be used for an integrated physical chemistry and instrumental analysis laboratory or an advanced materials science laboratory.

Density functional theory calculations were used to explore N[O.sub.2] adsorbed on MgO(100) supported by Ag or Pt. Analysis revealed that the oxide/metal interface is modified upon N[O.sub.2] adsorption and its effect is electron abstraction from the oxide, yielding an increased oxide/metal adhesion indicating a marked shift of the asymmetric N-O stretch vibration when supporting MgO on Ag(100).

Minimizing the reset discharge produced under an MgO-cathode condition and eliminating the wall charges accumulated on the address electrode prior to the reset period are the key factors involved in reducing temporal dark image sticking. Thus, based on the perceived luminance, new driving waveforms that can prohibit an MgO-cathode induced reset discharge or erase the wall charges accumulated on the address electrode prior to the reset period are examined for the complete elimination of temporal dark image sticking without deteriorating the address discharge characteristics. As a result of monitoring the difference in the infrared emission and perceived luminance between the cells with and without image sticking, the proposed driving waveform was shown to effectively remove temporal dark image sticking without deteriorating the address discharge characteristics. Index Terms--Perceived luminance, prereset waveform, reset discharge under an MgO-cathode condition, temporal dark image sticking.

The pure synthetic end-member of antigorite was studied by in-situ Raman spectroscopy in a diamond anvil cell. It can be metastably compressed up to 10 GPa at room temperature without occurrence of phase transition or amorphization. The spectrum in the OH region is simpler than in natural antigorite, allowing identification and assignment of the two observed bands at 3672 and 3698 [cm.sup.-1] to the in-phase stretching modes of the outer O3-H3 bonds (brucite-like) and to the stretching mode of the inner O4-H4 bonds (talc-like), respectively. A broad weak shoulder on the low frequency side of the OH bands near 3650 [cm.sup.-1] is better resolved above 7 GPa and assigned to the out-of-phase stretching mode of the outer OH. The two strong OH peaks have small positive pressure dependences (average of 2.3 [cm.sup.-1]/GPa), indicating no enhancement of hydrogen bonding at high pressure. One broad OH band at about 3670 [+ or -] 20 [cm.sup.-1] has a large pressure-induced shift (10 [+ or -] 2 [cm.sup.-1]). It could be related to structural defects. The specific behavior of OH bands in serpentines can influence the high pressure D/H partitioning with respect to other hydrated minerals. Keywords: Antigorite, serpentines, hydroxyl in serpentine, stability of antigorite, Raman spectroscopy, high-pressure studies

We describe here the synthesis of amphiboles along the nominal Na(NaMg) [Mg.sub.5][Si.sub.8][O.sub.22][(OH).sub.2]-Na(LiMg)[Mg.sub.5][Si.sub.8] [O.sub.22][(OH).sub.2] join, at 800 [degrees]C, 0.4 GPa. High amphibole yields (>90%) plus minor quartz and enstatite have been obtained at all compositions; amphibole crystals are acicular and their size rarely exceeds 20-30 x 0.5-3 [micro]m. TEM analysis shows the presence of h+k odd reflections in all samples, indicative of a P-lattice. By similarity with closely related amphiboles from the literature (e.g., Oberti et al. 2000; Camara et al. 2003) a P[2.sub.1]/m space group was assigned to the amphiboles synthesized here. Refined cell-parameters from X-ray powder-patterns show a linear decrease as a function of increasing Li at M4, a and [beta] being the most affected parameters. The four infrared OH-stretching spectra all show two main bands at 3741-3748 and 3712-3716 [cm.sup.-1], respectively. They are assigned to two independent O-H groups in the P[2.sub.1]/m structure, interacting with a strongly delocalized [sup.A]Na. The spectra show in addition two minor absorptions at about 3688 and 3667 [cm.sup.-1], respectively; these bands are assigned to vacant A-sites in the structure and indicate slight departure of the nominal composition toward cummingtonite. The present work shows that one apfu of [sup.B]Na can also be completely replaced by one apfu of [sup.B]Li ([M.sup.+]), in synthetic Na([M.sup.+]Mg)[Mg.sub.5][Si.sub.8][O.sub.22] [(OH).sub.2], and that all compositions have P[2.sub.1]/m symmetry at ambient conditions. Keywords: amphibole synthesis, FTIR spectroscopy, TEM, XRPD, amphibole symmetry

Impregnation is used for the calcination of a Fe/MgO catalyst to result in a solid solution with the growth of single- and double-walled carbon nanotubes. The formation of iron layers on the catalyst surface is caused due to the hydrogen reduction resulting in a high yield of impurity-free nanotubes.

A detailed investigation of the Fe/Co alloys' formation and composition is reported. It appears that the presence of Co(super +2) ions hinders the dissolution of iron in the MgO lattice, so that an increasing fraction of cobalt in the oxide powders favors the formation and clustering of Fe(super 3+) ions.

A comparative quantum chemical cluster study is done on CO(sub 2) adsorption on MgO and CaO, where theoretical infrared (IR) frequencies are calculated and compared with IR experiments. It is observed that CO(sub 2) adsorbs as monodentate on edge sites and bidentate on corner sites on MgO, whereas on CaO, CO(sub 2) adsorbs as monodentate on both edge and corner sites.

Single d-metal atoms on oxygen defects F(sub S) and F(sub S)(super +) of the MgO(001) surface are studied using density functional method combined with cluster models, embedded in an elastic polarizable environment. The implication for an experimental detection of metal atoms on oxide supports based on computed core-level energies are discussed.

Findings suggest that a Ni-Cu-MgO catalyst maintained its activity for the decomposition of methane at high levels for substantially long periods of time at 665-725 degree Celsius, being capable of generating large amounts of CO-free H2 and solid carbon. Transmission electron microscopy (TEM) studies revealed that the solid carbon consisted exclusively of nanofibers possessing a 'platelet' structure, in which the graphite layers are aligned in a direction perpendicular to the axis of the fiber.

The photogeneration of hydroxyl radicals OH(super .) in photosystem II membrane was studied using EPR spin-trapping spectroscopy. Evidence is given indicating that OH(super .) is produced by two reaction pathways, the reduction of peroxide bound to PSII metal center and the reduction of free H(sub 2)O(sub 2) mediated by free metal ions, the most likely being Mn(super 2+) and Fe(super 2+).

The effect of the support on the adsorbate/metal bond and the effect of the adsorbates on the metal/metal oxide interface are studied. The underlying mechanism for bond strengthening is due to CO-metal and metal-metaloxide bond characteristics.

The DOS is downshifted when the substrate coverage is increased for all the interface models. The interfacial interaction arises from a charge redistribution within the components of the interface.

The adsorption properties of magnesium oxide in two different physical types - large micron-sized crystals (CM-MgO) and nanoscale crystals (AP-MgO) are reported. The enhanced reactivities of the nanoscale MgO, halogen adducts as halogenating agents of organic molecules and their noticeable biocidal activity are explained.

Mg(001) terrace cluster models and density functional theory (DFT) are used to characterize the adsorption properties of neutral and charged NO, NO2, and NO3. Results provide a new framework for understanding the formation of chemisorbed surface NOx on all oxide surfaces in terms of adsorbate oxidizing strength, acid-base pair formation, and redox processes.

The adsorption of NO on MgO ulthratin films grown on a Mo(100) substrate results in the formation of N2O at low temperature (120 K). The isotope exchange experiments show that the reaction does not involve lattice oxygens.

The simultaneous presence of Au(I) and zerovalent goldclusters with an average diameter of about 30 Angstorm in MgO-supported catalysts is demonstrated by X-ray absorption near edge spectroscopy (XANES) of the functioning catalysts during steady-state CO oxidation. The initial dispersion and oxidation state of the gold in the catalyst were found not to affect the properties of the catalyst functioning at steady state.

The simultaneous presence of Au(I) and zerovalent goldclusters with an average diameter of about 30 Angstorm in MgO-supported catalysts is demonstrated by X-ray absorption near edge spectroscopy (XANES) of the functioning catalysts during steady-state CO oxidation. The initial dispersion and oxidation state of the gold in the catalyst were found not to affect the properties of the catalyst functioning at steady state.

The calorimetrically measured heats of adsorption of Cu, Ag, and Pb on MgO(100) are correlated with bulk properties of the metals and their sticking probabilities and film morphologies. The low-coverage heats of adsorption are used to estimate meta-MgO(100) bond energies within a pairwise bond addivity model.

A study of the heterogeneous uptake of SO2 on alpha-Al2O3 and MgO particles at 296K, where transmission FT-IR experiments reveal that under dry conditions SO2 reacts with alpha-Al2O3 and sulfite on MgO to form strongly absorbed bisulfite, HSO3- (aq) and sulfite, SO3-2 (aq).

The interaction of H2S and So2 with Cr2O3(0001), MgO(100), and Cr(sub x)Mg(sub 1-x)O(100) surfaces are studied using synchrotron-based high-resolution photoemission. The behavior of the Cr(sub x)Mg(sub 1-x)O system shows a fundamental principle for the design of mixed-metal oxide catalysts.

The growth mode of layered, binary mixed oxides consisting of NiO, MgO, and CaO with the use of low-energy electron diffraction (LEED), ion scattering spectroscopy (ISS), and NO temperature-programmed desorption (NO-TPD) is studied. A greater long-range order relative to NiO/CaO is seen in the NiO/MgO layered system.

Structural analyses are carried out in the near surface and bulk phase of MgO in Li-doped MgO, by means of XRD, XPS, Mg K-edge XANES, and SEM techniques to characterize active defect sites. The defect species containing Li(super +)-O(super -) in both surface and bulk can act as the active species for producing C(sub 2) compounds with high selectivity is concluded.

A combination of scanning tunneling microscopy and infrared spectroscopy techniques is employed to explain the charge-mediated adsorption behavior of CO observed on the MgO-supported Au clusters. The correlations existing between charge and adsorption properties of different confined metal systems are also discussed.

Several spectroscopic analyses are conducted to determine the charge state of the various point defects observed on MgO films that are deposited on the Ag(001) complex. The morphology and other properties of the single color centers found in such systems are also explained.

Density functional theory is used for examining CO oxidation over an ultrathin MgO film supported on Ag(100). [O.sub.2] is activated on MgO/Ag(100) whereas CO is weakly bonded to the surface and these absorption properties together with a low activation barrier have given the MgO/Ag system an efficient catalyst for CO oxidation at low temperatures.

The reaction of excess electrons at the surface of MgO with ammonia has led to surface ammoniated electrons analogous to those formed when alkali metals are dissolved in anhydrous ammonia. HYSCORE spectra has helped in obtaining the full hyperfine interaction of the solvated electron with the ammonia protons, which is consistent with a small and negative spin density in the [super 1]H 1s orbital.

Calorimetric measurements of Ca and Li adsorption energies on MgO(100) and ion-damaged Mgo(100) along with density functional theory (DFT) calculations and kinetic modeling are used for assessing the nature of the defect sites on oxide surfaces and their lateral distributions. The model has reproduced the measured Li and Ca film morphology observed by ion scattering spectroscopy.

Experiments are conducted for laser induced production of magnesium (Mg) from magnesium oxide (MgO) by using reducing agents (R). The utilization of solar-pumped laser in Mg production with reducing agent has reduced C[O.sub.2] emission and produced magnesium with high-energy efficiency and large throughput.

The control and tunability of the catalytic oxidation of CO by gold clusters deposited on MgO surfaces grown by molybdenum, Mo(100), to various thicknesses are analyzed by using temperature-programmed reaction measurements on mass-selected 20-atom gold clusters and via first-principles density functional theory calculations. The reactions catalyzed by [Au.sub.20] nanoclusters adsorbed on relatively thick defect-poor MgO films supported on Mo and on defect-rich thick MgO surfaces containing oxygen vacancy defects are studied.

The crystallization process of an amorphous [C.sub.40][Fe.sub.40][B.sub.20] ribbon and a MgO/amorphous-[Co.sub.40][Fe.sub.40][B.sub.20] thin film is examined to simulate the segregation of B in the magnetic tunneling junctions that use CoFeB ferromagnetic electrodes and a MgO tunneling barrier. Electron filtering transmission electron microscopy has displayed strong boron segregation at the MgO/FeCo interface after the crystallization of the MgO/amorphous-[Co.sub.40][Fe.sub.40][B.sub.20] bilayer film.

Density functional theory (DFT) calculations are used for describing a viable method for stabilizing and chemically activate gold nanoclusters on MgO. The calculations have shown that the ([H.sup.+])([e.sup.-]) centers have acted both as nucleation and activation sites.

The critical size effect of a Au catalyst on MgO nanowire vapor-liquid-solid (VLS) growth by pulsed laser deposition (PLD) is described. The mechanism of the critical phenomenon is described in terms of the catalyst size dependence on the amount of adatoms diffused from surroundings into the catalyst.

The low temperature scanning tunneling microscopy (STM) technique is employed to study the adsorption behavior of Au dimers on thin MgO(001) films. The upright dimers are shown to be neutral, as compared to the charged flat ones.

A triblock copolymer pluronic (P123)-assisted hydrothermal dissolution-crystallization method was employed to characterize the rectangular parallelepiped and hexagonal prism MgO single crystallites. The MgO crystallites are found to exhibit three-dimensional wormholelike mesoporous architectures and have a high surface area of 298 [m.sup.2]/g even after calcination at 550 degree Celsius for 3 hours.

The temperature dependence of the heterogeneous reaction of carbonyl sulfide (COS) on magnesium oxide (MgO) is examined by using a Knudsen cell reactor and a temperature-programmed reaction apparatus. The results have shown that the initial uptake of COS on MgO is contributed by an absorption process and the steady state uptake is due to a catalytic reaction.

Chemically ordered [L1.sub.0] FePt is obtained at temperature as low as 280 degree centigrade by in situ heating by using MgO buffer layer on CrRu underlayer. The studies have shown that the change in the out-of-plane coercivity is due to the improved chemical ordering and hence higher magnetocrystalline anisotropy.