Tabular Grains Research Articles

Olivine Morphology and Fabric During Diffusion Creep: Pure Shear Experiments

AbstractWe deformed aggregates of Fe‐free olivine +20 vol% diopside in pure shear to study olivine grain morphology and fabric during diffusion creep. Samples were each deformed to a strain of around 0.7 at different temperatures and experimental durations, which resulted in different grain sizes among the samples due to grain growth. The sample microstructures were observed from each of the three principal stress directions, which revealed various 3D grain morphologies among the samples. Samples with tabular grains displayed a crystallographic preferred orientation (CPO) in olivine, while samples with weakly anisotropic grains had uniform CPOs. The CPO patterns vary from AG‐type (i.e., a uniaxial [010] concentration in the direction of sample shortening) to A‐type (i.e [010] and [100] concentrations in the directions of sample shortening and stretching, respectively), with intermediate types being the most common. The transition from AG‐ to A‐type fabrics is accompanied by a change from oblate to prolate grain morphologies. We explain the direct correlation between the olivine morphology and fabrics based on preferential grain‐boundary sliding (GBS) at boundaries with fewer steps (ledges). Oblate morphologies with well‐developed grain boundaries oriented parallel to (010) provide easy GBS along (010) and [h0l] planes and directions, respectively, while relatively prolate morphologies with boundaries parallel to (010) that are elongated along [100] provide easy GBS along (010) and [100] planes and directions, respectively. Boundaries form parallel to a particular crystallographic plane through differential grain growth in the directions of the crystallographic axes. Such grain growth causes fabric transitions during diffusion creep.

Potential application of Bayer alumina with high Na2O content

Bayer alumina with high Na2O content is hardly used. In this paper, Bayer alumina with a pseudomorphic structure was used as raw material, which is pressed and sintered at high temperatures without any sintering aid. The effects of Na2O content on the densification behavior, microstructure, and physical properties of the pseudomorphic structure were studied. Bayer alumina with high Na2O content is often used as a low-grade raw material because Na2O inhibits the densification process of spherical Bayer alumina particles. However, the sintering mechanism of Bayer alumina particles with pseudomorphic structure is significantly different from that of spherical Bayer alumina particles. With the increase of Na2O doping amount, the linear shrinkage increases, and the degree of densification decreases. Tabular grains grow in the pseudomorphic structure, forming an interlocking network structure, inhibiting pore shrinkage and significantly improving mechanical properties. This study provides a theoretical basis for the rational application of low-grade Bayer alumina with high Na2O content and realizes the high-value utilization of low-cost materials.

Eleomelanite, (K2Pb)Cu4O2(SO4)4, a new mineral species from the Tolbachik Volcano, Kamchatka, Russia

ABSTRACT The new mineral eleomelanite, (K2Pb)Cu4O2(SO4)4, was found in the Arsenatnaya fumarole on the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik Volcano, Kamchatka, Russia. It is associated with euchlorine, fedotovite, wulffite, chalcocyanite, dolerophanite, dravertite, hermannjahnite, alumoklyuchevskite, klyuchevskite, piypite, cryptochalcite, cesiodymite, anglesite, langbeinite, calciolangbeinite, metathénardite, belomarinaite, aphthitalite, krasheninnikovite, steklite, anhydrite, hematite, tenorite, sanidine, sylvite, halite, lammerite, urusovite, and gold. Eleomelanite occurs as interrupted crusts up to 6 mm across and up to 0.3 mm thick consisting of equant, prismatic, or tabular crystals or grains up to 0.3 mm. It is translucent and black. The luster is oleaginous on crystal faces and vitreous on a cleavage surface. Dcalc is 3.790 g/cm3. Eleomelanite is optically biaxial (–), α 1.646(3), β 1.715(6), γ 1.734(6), 2Vmeas. = 60(15)°. The chemical composition (wt.%, electron-microprobe) is K2O 9.62, Rb2O 0.49, Cs2O 0.24, CaO 1.23, CuO 35.28, PbO 19.25, SO3 34.78, total 100.89. The empirical formula calculated based on 18 O apfu is (K1.88Pb0.79Ca0.20Rb0.05Cs0.02)Σ2.94Cu4.07S3.99O18. Eleomelanite is monoclinic, P21/n, a 9.3986(3), b 4.8911(1), c 18.2293(5) Å, β 104.409(3)°, V 811.63(4) Å3, and Z = 2. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 7.38(44)(101), 3.699(78)(112), , 3.173(40)(211), 2.915(35)(114), 2.838(35)(204), , and . The crystal structure was solved using single-crystal XRD data, R1 = 4.78%. It is based on heteropolyhedral Cu–S–O chains composed of Cu-centered polyhedra with [4+1+1] Cu2+ coordination and SO4 tetrahedra. Adjacent Cu–S–O chains are connected via chains of (K,Pb)O8 and KO10 polyhedra. Eleomelanite belongs to a novel structure type but has common structural features with klyuchevskite, alumoklyuchevskite, wulffite, parawulffite, and piypite. The name is derived from the Greek ελαιν (eleon), oil, and μλας (melas), black, due to its black color and oleaginous luster on crystal faces that are uncommon for sulfate minerals.

Origin of corundum within anorthite megacrysts from anorthositic amphibolites, Granulite Terrane, Southern India

Abstract Growth of corundum in metamorphosed anorthosites and related basic-ultra-basic rocks is an exceptional feature, and its origin remains elusive. We describe the occurrence of and offer an explanation for the genesis of corundum in anorthositic amphibolites from ~2.5 Ga old basement of the Granulite Terrane of Southern India (GTSI). The studied amphibolites from two localities, Manavadi (MvAm) and Ayyarmalai (AyAm), contain anorthite lenses (An90–99) with euhedral to elliptical outline set in a finer-grained matrix of calcic plagioclase (An85–90) and aluminous amphibole (pargasite-magnesiohastingsite). The lenses, interpreted as primary magmatic megacrysts, and the matrix are both recrystallized under static condition presumably during the regional high pressure (HP) metamorphism (~800 °C, 8–11 kbar) at ~2.45 Ga. Corundum occurs in the core of some of the recrystallized anorthite lenses (An95–99) in two modes: (1) Dominantly, it forms aggregates with magnetite (with rare inclusion of hercynite; in MvAm) or spinel (and occasionally hematite-ilmenite; in AyAm). The aggregates cut across the polygonal grain boundaries of the anorthite and contain inclusions of anorthite. (2) Corundum also occurs along the grain boundaries or at the triple junctions of the polygonal anorthite grains, where it forms euhedral tabular grains, sieved with inclusions of anorthite or forms skeletal rims around the recrystallized anorthite, such that it seems to be intergrown with anorthite. Combined petrological data and computed phase relations are consistent with growth of corundum in an open system during regional metamorphism in the presence of intergranular fluids. Two mechanisms are proposed to explain the formation of the corundum in the amphibolites: (1) corundum + magnetite/spinel aggregates formed dominantly by oxy-exsolution of pre-existing Al-Fe-Mg-(Ti)-spinel. This pre-existing spinel may be primary magmatic inclusions within the anorthite phenocrysts or could have formed due to reaction of primary magmatic inclusions of olivine with the host anorthite. Pseudosections of fO2-nH2O-T-P in the CaO–FeO–MgO–Al2O3–SiO2–H2O (CFMASH) system indicate that fO2 and H2O strongly influence the formation of corundum + amphibole from the initial magmatic assemblage of anorthite (phenocrysts) + spinel ± olivine (inclusions). (2) The corundum with anorthite presumably formed through desilification and decalcification of anorthite, as is indicated by computed phase relations in isobaric-isothermal chemical potential diagrams (µSiO2-µCaO) in parts of the CASH system. Growth of corundum in this mode is augmented by high activity of anorthite in plagioclase, high pressure, and low-to-medium temperature of metamorphism. This study thus presents a new viable mechanism for the origin of corundum in anorthositic amphibolites, and basic-ultra-basic rocks in general, which should provide new insight into lower crustal processes like high-pressure metamorphism.

The potential of La-containing spent catalysts from fluid catalytic cracking as feedstock of mullite based refractories

The potential of La-containing spent FCC catalysts as feedstock of mullite refractories is discussed. A simple methodology to determine the maximum use temperatures is proposed. It combines the analysis of the microstructural evolution with temperature with strain-controlled (2 × 10−4s-1 to 3% maximum strain) and constant stress compressive creep tests at high stresses (15−30 MPa) at 1100–1200 °C. Complete reaction was assured by milling the waste before processing mullite materials. Phase and microstructural evolutions with temperature were established combining dynamic techniques (DTA-TG and dilatometry) with quenching experiments. Isothermal treatments at 1300 and 1400 °C allowed selecting the optimum thermal treatment: 1400 °C-3 h.The formation of a La2O3 rich Al2O3-SiO2 liquid at low temperatures ≈1200 °C leads to the development of a microstructure constituted by a skeleton of mullite tabular grains trapping the remaining glass. Such microstructure endows the material with sufficient creep resistance at temperatures 1100−1200 °C to be used as constituent of refractories for temperatures ≤1200 °C.

Relationship between magnetic nucleation and the microstructure of a hot-deformed permanent magnet: micromagnetic simulation

The grains initiating magnetization reversal in the microstructure of a hot-deformed permanent magnet have been identified in this study by performing micromagnetic simulations based on the Landau–Lifshitz–Gilbert equation. Hot-deformed permanent magnets comprise tabular grains, the easy-axis orientations of which are inclined with respect to the nominal easy axis of the permanent magnet. In the simulation model, the grains complexly overlap, similar to in actual permanent magnets. We analyze the simulation results considering grain overlap and the easy-axis tilt angles of the grains. The initiation of magnetic nucleation requires a high concentration of grains with large easy-axis tilt angles. We clarify the magnetic-nucleation process and provide a method to enhance the performance of permanent magnets by avoiding a high concentration of grains with large easy-axis tilt angles.

Ta-Nb mineralization in rare-metal pegmatite from north-western frame of Lypniazhka granite-migmatite structure

The three type of rare-metal pegmatites are know in Stankuvatske ore field (Ingul megablock, the Ukraianian Shield), such as: Li-bearing, Bi-As-U and Ta-Nb pegmatites. For the first time Ta-Nb mineralisation from Ta-Nb bearing albite-K-Feldspar rare metal pegmatite have been described. Investigated pegmatite is located on the Norh-West frame of the Lypnazky granitemigmatite massive among hosted amphibolites. Rare-metal pegmatite doesn’t have obvious zonality and consist of alkaline feldspar, biotite, muscovite, dark to black colour quartz, blue-greenish apatite, nigerite, gachnite, tourmaline, monazite. The primary ferrocolumbite and Nb-rutile-II have undergone strong hydrothermal alteration. Thus primary rutile-II decomposed with formation of skeletal intergrowths of secondary cassiterite and rutile-III with a much lower volume of Nb and Ta under the influence of hydrothermal fluid. Primary homogenous Nb-rutile-I (Nb2O5+Ta2O5 from 33,5 to 42,9 wt.%) exsolved a fine trellis-like pattern and lamellar of Nb-pure rutile-III, cassiterite and Mn-rich ilmenite. The Nb-rutile-II is occurred in tabular grains with unclear internal zonation. Primary ferrcolumbite breakdown to Ti-ixiolite and Nb-rutile-III. Primary oscillatory zonality is transformed into irregularly patchy and veinlety. Recrystallized ferrotantalite is secondary and uncommon mineral. Ferrocolumbite contains 2.93 to 4.74 wt.%TiO2, and titanian ixiolite 7,33-10,76 wt.%. The (Ti,Nb)>Ta mineral assemblages, and compositional trend of columbite with very low Ta/(Ta+Nb) and Mn/ (Mn+Fe) imply a general low level of fractionation in comparison with typical beryl-columbite rare-metal pegmatites.

Fabrication and microstructure of liquid sintered porous SiC ceramics through spark plasma sintering

6H-SiC porous SiC ceramics accompanied by the formation of large clubbed and tabular grains were successfully fabricated at 1800 °C under an applied pressure of 50 MPa for 5 min by spark plasma sintering technique without introducing any pore-creating agent. The phase composition, microstructure and properties of porous SiC ceramics were investigated. The measured porosity of the specimens was 35.7% and the mean pore size varied in the range of 0.3–3 μm. The sintered specimen had a strength of 103 MPa, a fracture toughness of 2.89 MPam1/2, and a density of 1.85 g/cm3. The mechanisms of porous structure and grain growth were elucidated.

Air Jet Mill 공법과 PMMA의 단분산성이 프레스드 파우더의 밀착성 및 발림성 향상에 대한 연구

베이스메이크업 중의 하나인 프레스드 파우더는 주요 품질 속성으로 밀착성과 발림성이다. 일반적으로 메이크업 화장료에서 밀착성을 향상시키면 반대속성인 발림성이 저하되기 때문에 밀착성과 발림성을 동시에 충족시키는데 한계가 있었다. 본 연구에서는 두 가지 주요 속성을 만족시키기 위해서 air jet mill 공정을 시도하였고, lauroyl lysine (LL)과 sodium cocoyl glutamate (SCG)의 혼합물로 습식 코팅 처리한 sericite를 적용하여 밀착성을 향상시켰다. 또한, 분산성이 단분산성을 이루고 있는 polymethyl methacrylate (PMMA)와 diphenyl dimethicone/ vinyl diphenyl dimethicone/ silsesquioxane crosspolymer (DDVDDSC)를 적용하여 발림성을 향상시켜 서로 양립하기 어려운 두 가지 품질 속성을 모두 만족시켰다. air jet mill 공정은 제약, 식품 산업에서 주로 적용되고 있으며 화장품 분야에서는 파우더 소재 가공을 위해 사용되고 있는 공법이다. 본 연구에서는 air jet mill 공정을 제조 공정단계에서 접목시켜 최적의 입경인 <TEX>$6.8{\mu}m$</TEX>의 화장료를 완성할 수 있었다. 그리고, EDS 매핑으로 Ti 원소가 화장료에서 전체적으로 고르게 분포하고 있음을 확인하였고, SEM 분석을 통하여 판상 입자의 모서리 부분이 둥글게 가공처리 됨을 확인하였다. 이는 화장 도구를 이용하여 화장료를 취하여 피부에 도포할 때, 발림성이 향상되는 효과를 줄 수 있다고 판단된다. 피부 친화성이 우수한 LL과 저자극이면서 코코넛에서 유래한 SCG를 습식 코팅하여 sericite의 밀착성을 더욱 향상시켰다. 그리고, PMMA의 분산성과 형태가 발림성에 미치는 영향을 평가하기 위해서 SEM을 분석하였다. 유사한 형태를 갖는 구형 및 진구형에서도 분포도가 균일하고 단분산상일 때 발림성 효과가 더욱 증가하는 것으로 나타났다. PMMA의 단분산성과 입경에 따른 발림성을 동마찰계수 측정으로 확인하였고, 최적의 함량을 결정하였다. 그리고, 실리콘 러버 파우더 종류에 따른 발림성과 경도, 낙하안정성 등을 확인하여 DDVDDSC를 결정하였다. 최종적으로 PMMA의 단분산성과 실리콘 러버 파우더가 발림성에 영향을 끼치는 것을 알 수 있었다. 이와 같은 화장료는 적정한 경도를 갖으면서도 낙하안정성이 우수하며, 경시에 따른 안정성도 우수하였다. 본 연구 결과를 통해 본 논문에서 제시하는 프레스드 파우더의 밀착성과 발림성을 향상시킬 수 있는 한 가지 방법으로 활용될 수 있을 것이라 판단된다. The key quality attributes of the pressed powder, one of base makeup products, are skin-affinity and spreadability. In general, there was a limit to meet skin-affinity and spreadability simultaneously, which are opposite attributes each other. In this study, air jet mill process was tried to satisfy two main properties. Skin-affinity was improved by a wet coating of sericite with a mixture of lauroyl lysine (LL) and sodium cocoyl glutamate (SCG). The application of mono-dispersed polymethyl methacrylate (PMMA) and diphenyl dimethicone/vinyl diphenyl dimethicone/silsesquioxane crosspolymer (DDVDDSC) improved both qualities. Air jet mill process has been mainly applied in the pharmaceutical and food industries, and is a method used for processing powder materials in cosmetic field. In this study, we were able to complete makeup cosmetics with an optimum particle size <TEX>$6.8{\mu}m$</TEX> by combining the air jet mill process at the manufacturing stage. It was confirmed that the Ti element was uniformly distributed throughout the cosmetics by EDS mapping, and that the corners of the tabular grains were rounded by SEM analysis. It is considered that this can provide an effect of improving the spreadability when the cosmetic is applied to the skin by using a makeup tool. LL with excellent skin compatibility and SCG derived from coconut with little skin irritation were wet coated to further enhance the adhesion of sericite. SEM images were analyzed to evaluate effect of the dispersion and uniformity of PMMA on spreadability. With the spherical shapes of similar size, it was found that the spreading effect was further increased when the distribution was homogeneously mono-dispersed. The dispersion and spreadability of PMMA were confirmed by measuring the kinetic friction and optimal content was determined. The silicone rubber powder, DDVDDSC, was confirmed by evaluating the hardness, spreading value, and drop test. Finally, it was found that the dispersion of PMMA and silicone rubber powder affected spreadability. Such makeup cosmetics have excellent stability in drop test while having appropriate hardness, and good stability over time. Taken together, it is concluded that air jet mill process can be utilized as a method to improve skin-affinity and spreadability of the pressed powder.

Micromagnetic simulation for the magnetization reversal process of Nd-Fe-B hot-deformed nanocrystalline permanent magnets

We numerically demonstrated the magnetization reversal process inside a hot-deformed nanocrystalline permanent magnet. We performed large-scale micromagnetics simulation based on the Landau–Lifshitz–Gilbert equation with 0.1 billion calculation cells. The simulation model for the hot-deformed nanocrystalline permanent magnet consists of 2622 tabular grains that interact with each other by inter-grain exchange and dipole interactions. When the strength of the external field approached a coercive force, nucleation cores were created at the grain surface. The magnetization reversal was propagated by the inter-grain and dipole interactions. When the grains had overlapping regions parallel to the external field, the magnetization reversal propagated quickly between the grains due to the dipole interaction. In contrast, the motion of the magnetic domain wall was inhibited at interfaces between the grains perpendicular to the external field. Reversal magnetic domains had a pillar-shaped structure that is parallel to the external field. In the perpendicular direction, the reversal magnetic domain expanded gradually because of the inhibition of the domain wall motion.

Evolution of textured Ca0.85(LiCe)0.075Bi4Ti4O15 ceramics via templated grain growth using a rolling-extended method

The textured Ca0.85(LiCe)0.075Bi4Ti4O15 (LCCBT) ceramics were fabricated by templated grain growth method, with the piezoelectric constant (d 33) around 29.5 pC/N. Owning to the orientation of the grains, the properties of the textured ceramics have been improved. The mechanism of texture development was explored for textured LCCBT ceramics. The factors contributing to the texture evolution include the templates growth, the morphological change of the matrix grains and the grains group formation. The change of the matrix grains goes through four stages: the equiaxed grains, the square tabular grains, the pyramid-like terraces, the platelike sheets.

Effect of Adding Y&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; on Synthesis of Al&lt;sub&gt;4&lt;/sub&gt;SiC&lt;sub&gt;4&lt;/sub&gt; Powders

The reaction process of synthesis of Al4SiC4from Al, Si and graphite powders and the effects of Y2O3on synthesis and microstructure of Al4SiC4were investigated in this paper. The results show that no substantial changes in the formation of Al4SiC4content with or without addition of Y2O3. The addition of Y2O3to Al, Si and carbon powder mixtures was found to be effective for obtaining tabular grains of Al4SiC4. Conversely, Al4SiC4grains existed as irregular granules without addition of Y2O3.

THE PRESENCE OF PLUMBOAN INGODITE AND A RARE Bi-Pb TELLUROSULFIDE, Pb3Bi4Te4S5, IN THE LIMARINHO GOLD DEPOSIT, NORTHERN PORTUGAL

A rare Bi-Pb tellurosulfide (the unnamed Pb3Bi4Te4S5) has been found in samples from the Au-bearing quartz-arsenopyrite veins of the Limarinho deposit (northern Portugal), along with other Pb-Bi sulfotellurides, such as aleksite and plumboan ingodite [(Bi0.93Pb0.11)S0.52Te0.42]. This is the first occurrence of these minerals in the Iberian Peninsula. The optical and BSE images of the unnamed Pb3Bi4Te4S5 are the first ever obtained for this mineral. The mineral is anisotropic, pale grey in color, and occurs as tabular grains with perfect cleavage. Electron microprobe compositions of the Limarinho samples confirm the presence of this mineral in nature.

New type of shock twinning in potassium feldspar

Peculiar deformations were observed in potassium feldspar grains from the glass-poor suevites of the Zeleni Gay astrobleme on the Ukrainian shield. In cross-polarized light, they resemble kink bands in mica. We investigated the composition of the potassium feldspar and the optical orientation of the deformation features, which appeared to be in a twin relation to the crystal matrix. Twin laws and other characteristics of the deformations were determined. The origin of such textures was attributed to a combination of relatively low-pressure shock loading (possibly, under the conditions of impactor ricochet) of a block of target granites with a subparallel orientation of tabular microcline grains.

U-Pb zircon age of the gold-bearing Seredovina Massif, Middle Urals

The Seredovina gold-bearing massif is located in the Middle Urals, 2 km southeast of Nev’yansk in the well-known Nev’yansk gold district and is confined to the outer contact of the large Verkhisetsk tonalite‐granodiorite batholith (Fig. 1). The massif is a typical minor granitoid intrusion localized in the apical part of batholith-shaped bodies, which usually contains dike fields with gold-bearing quartz veins and wallrocks composed of listwaenite‐beresite metasomatites [1‐3]. The massif hosts the Nev’yansk Seredovina quartz‐sulfide gold deposit. The Seredovina Massif is composed of hornblende‐ biotite granodiorites crosscut by thin (up to 0.5 m thick) aplite dikes. The hornblende‐biotite granodiorites are light gray medium-grained rocks with a vague gneissic structure and porphyritic hypidiomorphic texture. The rock contains plagioclase, quartz, biotite, hornblende, and K-feldspar. Epidote, titanite, apatite, allanite, and zircon are accessory minerals. Plagioclase forms elongated prismatic and tabular grains with distinct rhythmic zoning. Potassium feldspar occurs as irregularly shaped interstitial grains of a cross-hatched microcline containing oikocrysts of tabular plagioclase and occasional amphibole. Quartz is observed as irregular grains. Amphibole is represented by common hornblende with brownish green pleochroism along Np and Nm to dark green along Ng . Biotite forms tabular and elongated plates with brownish green pleochroism. Biotite flakes often contain inclusions of apatite, zircon, and titanite, and often grow together with epidote. Zircons for isotope dating were extracted by the routine procedure: crushing of typical granodiorite sample (30 kg) of the massif to a fraction of ‐0.5 mm; extraction of the heavy fraction using the Wifley table and heavy liquid technique; and separation of zircon grains under binocular microscope. U‐Pb analyses were performed on a SHRIMP-II ion microprobe at the Center of Isotope Research, Karpinskii All-Russia Research Institute of Geology, using the standard technique [4, 5].

Growth of Tabular α‐Al2O3 Grains on Porous Alumina Substrate

Gradient, porous alumina ceramics were prepared with the characteristics of microsized tabular α‐Al2O3 grains grown on a surface with a fine interlocking feature. The samples were formed by spin‐coating diphasic aluminosilicate sol on porous alumina substrates. The sol consisted of nano‐sized pseudo‐boehmite (AlOOH) and hydrolyzed tetraethyl orthosilicate [Si(OC2H5)4]. After drying and sintering at 1150°–1450°C, the crystallographic and chemical properties of the porous structures were investigated by analytical electron microscopy. The results show that the formation of tabular α‐Al2O3 grains is controlled by the dissolution of fine Al2O3 in the diphasic material at the interface. The nucleation and growth of tabular α‐Al2O3 grains proceeds heterogeneously at the Al2O3/glass interface by ripening nano‐sized Al2O3 particles.

Photothermographic Materials with Tabular Silver Iodide Grains

It has been revealed in this study that the sensitivity of newly developed composite grains with tabular silver iodide grains as hosts and epitaxially formed silver bromide microcrystals as guests is high enough in photothermographic materials to realize a blue medical x-ray film-screen system in combination with BaFBr:Eu fluorescent radiographic intensifying screen. Beside the fact that the quality of the system image is comparable with that of conventional ones, the image stability as well as the haze of the new system is satisfactory, in spite of the fact that the new system uses photothermographic materials, since the grains used as photosensors are fixed during thermal development.

Kinetics study of ultrafast electron transfer from sensitized dyes to silver halide microcrystals

Spectral sensitization micromechanism of cyanine dyes J-aggregate adsorbed on the tabular and cubic AgBr microcrystals with different dye concentrations is studied by using picosecond time-resolved fluorescence spectroscopy and the dependences of electron transfer and spectral efficiency sensitization on different conditions are analysed in detail. With the steady spectroscopy, the wavelengths of absorption and fluorescence of J-aggregate adsorbed on AgBr microcrystals are found to shift to red relative to dye monomer. The spectrum of fluorescence has a red shift relative to the absorption peak. With the time-resolved fluorescence spectroscopy, the fluorescence decay curves of cyanine dyes J-aggregate adsorbed on the tabular and cubic AgBr grains are found to be fitted well by a double-exponential decay function. The fitting curves consist of a fast and a slow component. Because of the large amplitude of the fast component, this fast decay should be attributable mainly to the electron transfer from J-aggregate of dye to a conduction band of AgBr.

New Mineral Names

Other| August 01, 2005 New Mineral Names* Paula C. Piilonen; Paula C. Piilonen † Research Division, Canadian Museum of Nature, P.O. Box 3443, Stn. D, Ottawa, Ontario K1P6P4, Canada †E-mail: ppiilonen@mus-nature.ca Search for other works by this author on: GSW Google Scholar T. Scott Ercit T. Scott Ercit Research Division, Canadian Museum of Nature, P.O. Box 3443, Stn. D, Ottawa, Ontario K1P6P4, Canada ‡English translations of articles are available upon request from T.S.E. (sercit@mus-nature.ca). Search for other works by this author on: GSW Google Scholar American Mineralogist (2005) 90 (8-9): 1466–1469. https://doi.org/10.2138/am.2005.448 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Paula C. Piilonen, T. Scott Ercit; New Mineral Names. American Mineralogist 2005;; 90 (8-9): 1466–1469. doi: https://doi.org/10.2138/am.2005.448 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search K.A. Rosenberg, R.K. Rastsvetayeva, N.V. Chukanov, I.A. Verin (2004) Centrosymmetric modular structure of an analogue of labyrinthite. Dokl. Akad. Nauk, 399, 791–794 (in Russian); Dokl. Chem., 399, 253–256 (in English). An apparently new member of the eudialyte group has been found in the central zone of an alkaline pegmatite at Mt. Koashva, Khibiny massif, Kola Peninsula, Russia. The mineral occurs in tabular grains intimately intergrown with villiaumite, in associations with lomonosovite, barytolamprophyllite, aegirine, and microcline. The authors infer from this assemblage that the formational conditions included relatively high temperature and high sodium and fluorine activity. The mineral is dichroic brown-gray... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Study on Formation Mechanism of AgCl Twinned Tabular Grains

Study on Formation Mechanism of AgCl Twinned Tabular Grains