Quartz Phase Research Articles

Comparative Study Of The Variability In The Compositions And The Effect Of Milling Time On Coal Fly Ash And Wood Fly Ash Nanoparticles

Abstract Industrial and domestic fly ashes (FA) also known as coal fly ash (CFA) and wood fly ash (WFA) respectively has been causing environmental menaces but in recent times they are gaining potential applications in various industries varying from Construction, processing, activated carbon, filler and reinforcement, agriculture to water purifications, to mention but a few due to its availability and low cost. There is every need to place these two fly ashes and weigh their compositions. In this study, the chemical and elemental compositions of both coal fly ash and wood fly ash are compared. The physiochemical and Morphological Characteristics of the milled and unmilled nano fly ashes were determined using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF) analyses. The milling times were taken at 0, 20, 40 and 60 mins and 0 min taken when sieved with 75µm size ASTM standard before milling. The crystal phases detected by the XRD in WFA are rhombohedral, hexagonal, cubic and tetragonal while that of CFA are hexagonal, orthorhombic, rhombohedral and anorthic. XRD analysis shown that the most dominant crystalline in wood fly ash were calcite (CaC03), quartz (SiO2), Sylvite (KCl), Lime (CaO), maghemite-Q (γ-Fe2O3), nitratetine (Na(NO3)) and magnetite (Fe3O4) phases; while in coal fly ash were Quartz (SiO2), Mullite (Al2.32Si0.68O4.84), Sillimanite (Al2(SiO4)O, Calcite high (CaCO3), Hematite (Fe2O3), Microcline (KAlSi3O8). The particles size got increased from 75µm to average diameter of 200nm. Morphological characteristics revealed that the surface of nano obtained shows that wood fly ash nanoparticles (WFA-NPs) has more irregular shape, rough and uneven compared to coal fly ash nanoparticles (CFA-NPs). As revealed by EDX the elemental composition that are present in Wood fly ash nanoparticles are Ca, K, Mg, Si, Al and Fe while that of coal fly ash nanoparticles are Si, Al, Ca, Fe, Ti and Mg. The overall effects of the grinding process showed that there are tremendous reductions in both the particle and crystallite size of CFA-NPs and WFA-NPs as well as great improvement in the metallurgical and mechanical properties of the two samples with respect to milling time when compared to unmilled samples.

Chemical and Mineralogical Studies of Gold-bearing Rock in Iperindo, Ilesha Goldfield, Southwest Nigeria

This paper provides chemical and mineralogical studies on Gold-bearing rock ore. The samples used was sourced from Iperindo at Ilesha Local Government Area of Osun state, Nigeria. 500g of the ore was weighed using digital weighing balance. The samples were crushed and ground until 80% passing of 75 μm sieve. The ground ore was blended homogeneously before the analysis while for the ore microscopic study, true fraction representative gold-bearing rock samples were prepared as polished mounts and characterized using Scanning Electron Microscope–Energy Dispersive X-ray (SEM/EDX). X-ray Fluorescence (XRF) was used to determine the chemical composition while identification of the associate mineral phase was done using X-ray Diffraction (XRD) technique. From the optical microscopy and SEM/EDX study, the gold grain was found embedded in the quartz and spotted interlocked in feldspar within a microscopic size level while a fracture type of surface morphology was observed which shows a protuberant quartz-feldspar veins texture. XRD shows the mineral phases of quartz, dolomite, sylvite, annite. The traces of K, Ba and Rb, in this compound shows that the ore is a typical mesothermal gold deposit. Hence, the gold is finely disseminated on the silicate mineral and this characteristic is unsuitable to be processed by physical separation as the microscopic gold will tend to be lost during processing. However, a sustainable processing method such as froth flotation can be proposed to overcome this problem.

High-efficiency V-shaped phase gratings to suppress high order diffractions

We propose a V-shaped phase grating to simultaneously improve the diffraction efficiency of the 1st order diffraction mode and suppression of high order modes. An analytic description is given that indicates the 0th, 2nd, 3rd, and 4th order diffractions can be completely suppressed while the 1st order absolute diffraction efficiency can reach a theoretical maximum of 27.72%, which is much higher than that reported from single order gratings, such as sinusoidal amplitude transmission gratings. The dependencies of the 1st order diffraction efficiency on the wavelength and depth deviations are also discussed. The experimental results show that the absolute efficiency of the 1st order diffraction is 25.85% while the 2nd, 3rd, and 4th order diffractions disappear completely, confirming the theoretical predictions. The diffraction patterns of a xenon lamp demonstrate the suppression of the high order diffractions from our quartz phase grating. The unique dispersive properties of the V-shaped phase grating make it attractive for broad spectroscopy and high-accuracy monochromatization applications.

Dynamic tensile and shear storage moduli of PEG/silica‐polymorph composites

ABSTRACTThe effect of silica polymorphs on the thermomechanical properties of 0, 5, 10, and 20 wt % silica particles‐reinforced‐based poly(ethylene glycol) (PEG) composites have been studied as a function of temperature using dynamic mechanical analysis (DMA). The silica polymorphs exhibited quartz (Q), cristobalite (C), and amorphous (A) phases, which were obtained by processing natural silica sand. The DMA thermomechanical properties were determined in tensile (E) and shear (G) modes. The maximum storage moduli (E′ and G′) were achieved by samples with 20 wt % silica for all type of fillers. These values increased approximately 12 times for PEG/Q, 10 times for PEG/A, and 11 times for PEG/C composites compared to the pure PEG. Furthermore, the Poisson's ratio values of the composites were filler phase dependent, that is, 0.39–0.47 for PEG/Q, 0.15–0.18 for PEG/A, and somewhat anomalous for PEG/C composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47372.

Upper crustal fluids in a large fault system: microstructural, trace element and oxygen isotope study on multi-phase vein quartz at the Bavarian Pfahl, SE Germany

Fault systems are zones of crustal weakness and are used as pathways for ascending hydrothermal fluids. One impressive example is the more than 150 km long Bavarian Pfahl system at the SW boundary of the Bohemian Massif. Dextral ductile shearing of Moldanubian basement has shaped a several hundred meter wide zone of mylonites and ultramylonites. This setting was reactivated under brittle conditions and infiltrated by fluids resulting in a multi-phase quartz lode. Structural analysis using scanning electron microscopy cathodoluminescence (SEM–CL) images has been carried out in combination with trace element and oxygen isotope analysis on quartz along the system. Three successive quartz phases have been distinguished due to their structural details and trace element contents. Cryptocrystalline quartz fabric in the first quartz phase results from crystallization from a silica gel, whereas in phases II and III, quartz precipitation is characterized by repeated fragmentation and sealing, visible due to strongly varying CL intensities. The δ18O of Bavarian Pfahl quartz decreases from 13.8‰ in the NW to 8.5‰ in the SE, whereas quartz from the close-by-situated Wölsendorf fluorite deposit shows δ18O between 15.9 and 18.5‰ (vs. SMOW). Flat shale-normalized rare earth element patterns point towards an upper crustal origin of the hydrothermal fluids. The southeastern part of the Bavarian Pfahl is interpreted to represent a deeper crustal level with higher mineralization temperatures (about 350 °C) compared to the rest of the Pfahl (< 250 °C).

The modification of aluminium content of natural zeolites with different composition

A series of natural zeolites with different compositions were modified by formation of hydrated aluminium oxide onto the zeolite structure after NaOH treatment of the natural zeolites. Natural and modified zeolites were characterized by XRD, SEM, N2 adsorption-desorption, FTIR, zeta potential and temperature-programmed desorption of ammonia (NH3-TPD). The treatment with NaOH and then aluminium loading significantly alter zeolite characteristics depending on zeolite composition and structure. The treatment with NaOH causes significant desilication and partial dealumination of the zeolites irrespective of their compositions. The presence of quartz and feldspar phases in the zeolites increases their stability towards alkali treatment. Aluminium introduction into the zeolites treated with NaOH leads to reorganisation of zeolite structure and surface characteristics. The introduction amount of aluminium is strongly related with zeolite composition that aluminium oxide phase is detected on zeolites undergone highly desilication with NaOH treatment. Both alkali treatment and aluminium loading dramatically alter distribution of acid sites in the zeolites that while alkali treatment increases mostly strong acid sites of zeolites, aluminium loading enhances weak and medium acid sites. Enhanced aluminium content of zeolites improved its manganese adsorption capacity depending on their composition.

Investigation of the firing temperature effects on clay brick sample; Part-I: Mineralogical phase characterization

Present research work was focused to investigate the firing temperature effects on mineralogical phase composition of nine clay bricks collected from the brick factory of Kathmandu valley using X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra analyses. Main mineralogical phases of quartz, feldspars, spinel, mullite and hematite in the brick specimens fired at different firing temperatures including muscovite type of mica mineral in the sun-dried brick specimen are identified from XRD and FTIR analyses. Disappearance of the muscovite type of mica clay mineral with feldspars enhanced to form alumina rich spinel phase at firing 900° to 1000° C, and finally the primary mullite phase in the fired clay brick samples is clearly observed at 1100° C firing temperature.BIBECHANA 16 (2019) 122-130

Diversity and origin of quartz cements in continental carbonates: Example from the Lower Cretaceous rift deposits of the South Atlantic margin

Silica precipitation in continental carbonates is a common process occurring during sedimentation and diagenesis. The Lower Cretaceous rift deposits of the South Atlantic equatorial margin, which are intensively explored by petroleum companies, provide good examples of such silicifications in carbonates, exhibiting a wide diversity of petrographic habit of early to late quartz cements. In order to understand the palaeoenvironmental and diagenetic conditions leading to this diversity, we integrated detailed petrography of diagenetic sequences and quartz habit with δ18Oquartz measurements (by SIMS) of individual cements observed in samples from the offshore and onshore basins of the West African margin. The petrographic description highlights the omnipresence of early fibrous microquartz cements exhibiting either length-fast or length-slow habit, in addition to laminated microquartz and micro- or mega-quartz forms. Amongst the isotopic analysis, the δ18Oquartz data show that length-slow cements are generally strongly enriched in 18O (δ18Oquartz ranging from 31 to 37‰ SMOW), whereas length-fast forms show less elevated values (<32‰ SMOW). The highest δ18Oquartz values for fibrous microquartz are interpreted to reflect precipitation from evaporated meteoric fluids at temperatures >25 °C and <100 °C. The alkalinity required to favor the precipitation of length-slow fibrous microquartz cements is probably related to fluid/rock interactions with underlying mantel-related or basic volcanic rocks. Such interactions would be in agreement with the recent geodynamic models of the South Atlantic passive margin. The length-fast fibrous microquartz associated with δ18Oquartz values ranging from 27 to 32‰ SMOW, probably reflect precipitation from moderately to non evaporated, fairly neutral to acid, fluids. The partial dissolution of carbonate cements prior to quartz cementations represents the signature of those acidic conditions. We therefore suggest that acidic pH was obtained through fluid/rock interactions with the intermediate to acid volcanic rocks encountered along the palaeohydrological pathway. Other quartz phases, such as the megaquartz cement, exhibit highly variable δ18Oquartz values ranging from 20 to 40‰. This variation may reflect significant variation in temperature conditions (between 100 and 200 °C) or changes in fluid δ18O at the small scale. For these populations of non-fibrous quartz cement, the very high δ18Oquartz values may reflect a contribution of fluids that have either suffered strong evaporation or strong water/rock interaction.

Investigation of sintering behavior of sanitaryware ceramics by controlling glassy phase

The focus of this study was to investigate the effects of glassy and crystalline phases in sintering behavior of the sanitaryware body. To achieve this aim, two different phase analysis methods, the ratio of slopes and Rietveld methods, were compared. This research was carried out in three steps by using X-ray analysis values. In the first step, different amounts of metallic Si were added to pure mullite and quartz materials and their reference analysis lines were drawn. Secondly, sanitaryware samples were analyzed and their analysis lines were also drawn and compared with references. Therefore, a comparison between the slopes of the reference and analysis lines was allowed for the determination of the amount of quartz, mullite, and amorphous phases as 22.1, 18.8, and 59.1 wt.%, respectively. These results were used to estimate the chemical composition of the glassy phase that formed in standard sanitaryware microstructure. In the last step of research, new glassy phase compositions were prepared based on a standard sanitaryware glassy phase composition. Different mixture ratios of alkaline and earth alkaline oxides (Na2O/K2O, Na2O + K2O, SiO2/Al2O3, and MgO/CaO) were used to modify the glassy phase compositions. Results show that softening point and viscosity of the glassy phase can be controlled by controlling these certain parameters, and this helps to consume energy in the sintering process.

Preparation of high porosity bricks by utilizing red mud and mine tailing

Due to tremendous size and environmental concerns, management and utilization of red mud and gold tailing have received attention for the last few decades. In the present study, the novel process for utilization of red mud and gold tailing for high porosity brick was proposed and its physical properties were evaluated. By adopting the gelation of slurry method, above 75% apparent porosity; that is hardly obtainable by traditional method, was successfully achieved. Morphologies investigation including pore size distribution revealed that the increasing mixing ratio of gold tailing results in the increasing pore diameter along with changing into closed cell structure. In addition, effect of crystalline phase on thermal conductivity was evaluated and found the dominant effect of quartz phase on thermal conductivity. As a result, increasing of gold tailing leads to increasing of thermal conductivity. Finally, the thermal conductivity of present system was successfully estimated by using Ashby-Glicksman model considering the different type of cell structure.

Deciphering Silicification Pathways of Fossil Forests: Case Studies from the Late Paleozoic of Central Europe

The occurrence and formation of silicified wood from five late Paleozoic basins in Central Europe was investigated. Fossil wood from diverse geological settings was studied using field observations, taphonomic determinations as well as mineralogical analyses (polarizing microscopy, cathodoluminescence (CL) microscopy and spectroscopy). The results indicate that silicification is either a monophase or multiphase process under varying physico-chemical conditions. In particular, CL studies revealed complex processes of silica accumulation and crystallization. The CL characteristics of quartz phases in silicified wood can mostly be related to blue (390 and 440 nm), yellow (580 nm), and red (650 nm) emission bands, which may appear in different combinations and varying intensity ratios. Yellow CL is typical for initial silicification, reflecting quick precipitation under oxygen-deficient conditions caused by initial decay of the organic material. Blue CL is predominantly of secondary origin, resulting from replacement of precursor phases by a secondary hydrothermal quartz generation or subsequent silicification of wood. The red CL can be related to a lattice defect (non-bridging oxygen hole center—NBOHC).

Mineralogical Analysis of Sand Roses and Sand Dunes Samples from Two Regions of South Algeria

In this work, it is found that the important minerals in sand dunes and sand roses samples from Anqousa in the south-east of Algeria in Ouargla region and from Charouin in the south-west in Adrar area are the quartz and Gypsum phases. The aim of this study is a qualitative and quantitative minerals evaluations of two areas samples using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Granulometric classification and size distribution were carried out using Laser scattering particle size analyser. Numerous observed diffraction peaks confirm the presence of polycrystalline quartz phase in sand dunes samples as principal mineral. In the case of sand roses samples, the diffraction spectra show that the basic mineral is Gypsum. The sand dunes samples infrared absorption spectrum show the characteristic vibration bond peaks for quartz as 460, 695, 779 and 1082 cm− 1, also these analysis reveal the Gypsum characteristic peaks at 1616 and 1620 cm− 1. FTIR spectra enregistred on sand roses samples showed the absorption peaks at 3552, 3492, 3404, 1685, 1620, 669 and 602 cm− 1 indicate the presence of gypsum. Through combination between the results of DRX, FTIR and EDS, it appears that the concentration of quartz in ouargla sand samples is greater than that in Adrar sand, contrariwise the concentration of Gypsum in Adrar sand dunes is the most important. It was deduced that Adrar sand roses have the higher concentration of Gypsum. The grain size varies between 58.953 and 777.141μm with an average value ≈ 213.386 μm for ouargla sand and between 74.219 and 198.531μm with an average value ≈ 132.684 μm for Adrar sand dunes. The obtained results confirm that the two regions can be important sources of quartz and Gypsum as primary materials for many industry applications.

Effect of ZrO2 additions on densification and mechanical properties of modified resistant porcelains using economic raw materials

The aim of this work was to determine the effect of temperature and ZrO2 addition on sintering and mechanical properties of porcelain prepared from local Algerian raw materials. Based on a preliminary work, the new selected composition was 25 wt.% feldspar, 25 wt.% quartz, and 50 wt.% kaolin (25 wt% kaolin Algerian nano-sized halloysite type + 25 wt% kaolin Tamazart) and containing different contents of ZrO2 (5 and 8 wt%). It should be noticed here that all these used native raw materials are not against the environment. Samples were prepared by sintering the mixture at different temperatures (1000–1250 °C). Subsequently, the obtained phases in the elaborated samples were investigated by X-ray diffraction, Fourier transform infrared spectroscopy analyses, Raman spectroscopy, and SEM analysis. The optimum sintering conditions gave a relatively high density (2.47 g/cm3) and relatively excellent mechanical properties for these samples. The obtained porcelains were mainly constituted of quartz, mullite, and amorphous phases. The three-point flexural strength (3PFS), Vickers microhardness (VMH), and apparent porosity (PA) of porcelains sintered at 1200 °C were 132 MPa, 13.08 GPa, and 1.6%, respectively. The flexural strength value of this specimen is significantly higher than those reported for conventional porcelains (ranged between 60 and 80 MPa) even though for certain commercialized dental porcelains.

Mineralogical and thermal characterization of soft rock from Campinas, Brazil

In this study, the main purpose was the mineralogical and thermal characterization of clayey siltites sampled in a quarry located near Viracopos Airport, Campinas city, Sao Paulo State, Brazil. The sedimentary rocks are fissile and expansive and are therefore easily disaggregated. These characteristics make the rock of difficult geomechanical characterization, because it undergoes defragmentation very easily. Mineralogical considerations about the composition of this rock were carried out by petrography analysis, scanning electronic microscopy (SEM), X-ray diffraction pattern and energy-dispersive spectroscopy. Thermal characterization of powdered rock was carried out by thermogravimetry (TG/DTG) under synthetic air and nitrogen purge gases. The dehydration kinetics of this rock was studied by a non-isothermal method. The mineralogical results show that this rock had quartz, feldspar and kaolinite as the major components and pyrite and chlorite as the minor constituents. The presence of organic matter was verified as fragments present in the rock and seen by SEM. The amount of organic matter was also determined by the gravimetric method, and the results showed a loss of 3.27%. The differential thermal analysis results under nitrogen purge gas exhibit the transition phase of quartz at 575 °C. The kinetic evaluation was made with two dehydration stages obtained from DTG curves, which show that the dehydration stage occurs with two behavior patterns.

Significant of Gold Mineralogical Study for The Chemical Separation of Weathered Ore in Malaysia

This paper provides a mineralogical study on the gold ore sample obtained from a local gold mine in Malaysia that underwent the lateritisation process. The mineralogical characteristic of the secondary gold was investigated using the optical microscope study. Then, the presence of other minerals was identified by X-ray fluorescence, X-ray diffraction and scanning electron microscope / energy dispersive X-ray. X-ray mapping was also employed for the determination of the elemental distribution in the gold ore samples. From the optical microscopy and SEM/EDX study, the gold grain was found embedded in the quartz and also was spotted interlocked in iron oxide and arsenopyrite as well within size from sub-microscopic (1<μm) to microscopic (≤10μm) with a flaky type of surface morphology as well as the presence of element of Si, O and Fe. XRD shows the mineral phases of quartz, muscovite and magnetite. In XRM, the gold was also found disseminated on the silicate minerals surface like quartz (SiO2), chlorite ((Mg5Al)(AlSi3)O10(OH)8) and clay minerals, as also confirmed by the chemical composition presents in the XRF analysis. Hence, from this mineralogical studies, the characteristic of the gold is unsuitable to be processed by physical separation as the submicroscopic gold will tend to be lost during processing and a sustainable processing method such as non-cyanide leaching can be proposed to overcome the problem.

Mineralogical Characterization and Determination of Refractoriness of Malaysian Gold Ore

This study aims to conduct mineralogical characterization and determine the refractoriness of gold ore from Eastern Coast of Peninsular Malaysia. Elements presence in the sample were investigated using X-ray fluorescence (XRF) analysis while X-ray diffraction (XRD) method was used for the identification of mineral phases. Polished sections samples were studied by optical microscopy (OM), scanning electron microscopy and energy-dispersive X-ray (SEM/EDX). XRD phase analysis showed the presence of mineral phases of quartz, iron sulphide and silicate minerals, which were confirmed by XRF with the elements detected as Si, O, Al, Fe, As and S. From SEM/EDX analysis, gold was found mostly interlocked in sulphide minerals such as arsenopyrite, galena and others. Fire assay and cyanide bottle roll test were employed on the bulk samples to assay the gold content and free gold, respectively. Atomic Absorption Spectrometry (AAS) revealed the gold content to be 31 gram per tonne in the sample. The cyanide bottle roll test determined the free gold assay of 16 gram per tonne. These findings imply that the samples contained free gold of about 52% along with gold present interlocked with minerals unfavourable to cyanidation, which further provide valuable information in terms of the refractoriness of the gold for further processing.

Cadmium isotope fractionation during coal combustion: Insights from two U.S. coal-fired power plants

Coal combustion, one of the principal energy sources of electricity in the United States, produces over 100 million tons of coal combustion products (CCPs) per year in the U.S. The reuse and disposal of CCPs has the potential to release toxic trace elements, including cadmium (Cd), into the environment. In this study, we investigated CCPs, including bottom ash (BA), economizer fly ash (EFA), and fly ash (FA), as well as feed coal (FC) and pulverized coal (PC) collected from two U.S. coal-fired power plants in New Mexico and Ohio with different coal supplies. The New Mexico plant uses high volatile C bituminous, low-sulfur coals mined from the San Juan Basin (Cretaceous Fruitland Formation) and the Ohio plant uses high volatile A bituminous, high-sulfur central Appalachian Basin coals (Upper Pennsylvanian Monongahela Formation). Mineralogical and elemental analysis showed that these CCP samples consist of ∼70% amorphous Al-Si-rich glasses and ∼30% mineral phases of quartz (SiO2) and mullite (Ai6Si2O13). The Cd isotope compositions (δ114Cd, normalized to NIST Cd standard 3108) of FA and EFA samples (ranging from −0.51 to +0.47‰) are distinctively heavier than those of BA samples (−0.75 to −0.52‰) in both power plants. We interpret this Cd isotope difference as a result of Cd condensation from the gas phase during flue gas cooling, instead of evaporation of Cd phase during coal combustion. Cd condensation is the main process to generate the isotopically heavy Cd signatures that preferentially partition on the fine FA particles. We also investigated Cd isotope compositions in different leachate products from a series of batch-leaching experiments with these CCPs, using diluted acetic acid, hydroxyl ammonium chloride, hydrogen peroxide followed by ammonium acetate, and 5% nitric acid, as a possible means to identify CCP-released Cd in the environment. Unusually and significantly heavier Cd isotope compositions were observed in each leachate of FA samples (+1.10 to +7.09‰), which fall far outside from the range of Cd isotope ratios observed in natural soils and rocks, but less so for the EFA samples (−0.43 to +1.18‰). Such an observation is consistent with the interpretation that isotopically heavy Cd preferentially partitions on the fine FA particles after coal combustion and is readily to be released during these leaching experiments. This study demonstrates that high-temperature coal combustion can lead to a very large degree of fractionation of Cd isotopes that can be used as a unique tracer for identifying anthropogenic metal inputs in the environment. The major Cd isotope fractionation process occurs as the Cd gas phase condenses on fine FA particles during the flue gas cooling stage after coal combustion.

Effect of phase separation on the Jian ware blue colored glaze with iron oxide

This study was aimed to explore the effect of phase separation on the Jian ware blue colored glaze with iron oxide. In order to analyze the forming cause of glaze patterns and their coloring mechanism, the phase, microstructure and chemical state of the samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectrum. The results indicated that the addition of calcium phosphate introduced highly-active Ca2+ and P5+ into the glaze. Since Ca2+ with high ionic potential had a greater ability to appeal O2− than Si4+, the glaze melt was separated into calcium-rich phase and silicon-rich phase. The difference of viscosity caused the non-uniform distribution of quartz and glass phase, and then affected the distribution of iron ions in two phases, which formed glaze patterns. Adding P5+ that had a strong effect of reversed polarization on the Fe-O increased the contents of Fe2+ and Fe3+-O-Fe2+, and thus deepened the blue-green of glaze surface. In addition, it promoted the formation of worm-like phase-separated structures and the existence of structural color. Therefore, phase separation enriched not only patterns but also glaze colors of the Jian ware blue colored glaze.

High-precision calibration method for shear ratio based on the shearing wavefront feature extraction of a phase plate.

A new method based on the shearing wavefront feature extraction (SWFE) of a phase plate is proposed to accurately estimate the shear ratio of the system. The relationship between the shear ratio of a quadriwave lateral shearing interferometer based on a randomly encoded hybrid grating (REHG) and the measurement sensitivity, dynamic range, and wavefront retrieval accuracy is analyzed to provide a theoretical guidance for practical application. The simulation result of the SWFE method shows that the relative error of the shear ratio value is about 1.8×10-3, within the acceptable range of the system. In the experiment, two fused quartz phase plates etched with step change edge grooves were introduced to calibrate the shear ratio of the REHG wavefront diagnosis system. Then, the etching depths of these two phase plates and the figure error of a spherical surface were characterized by the REHG. A comparison with a ZYGO GPI interferometer exhibits that the testing results by the REHG are highly precise, which further confirms the effectiveness of the SWFE method in the shear ratio calibration. This shear ratio calibration method is available for similar kind of shearing interferometric wavefront sensor.

Mapping uncharted territory in ice\xa0from zeolite networks to ice structures

Ice is one of the most extensively studied condensed matter systems. Yet, both experimentally and theoretically several new phases have been discovered over the last years. Here we report a large-scale density-functional-theory study of the configuration space of water ice. We geometry optimise 74,963 ice structures, which are selected and constructed from over five million tetrahedral networks listed in the databases of Treacy, Deem, and the International Zeolite Association. All prior knowledge of ice is set aside and we introduce “generalised convex hulls” to identify configurations stabilised by appropriate thermodynamic constraints. We thereby rediscover all known phases (I–XVII, i, 0 and the quartz phase) except the metastable ice IV. Crucially, we also find promising candidates for ices XVIII through LI. Using the “sketch-map” dimensionality-reduction algorithm we construct an a priori, navigable map of configuration space, which reproduces similarity relations between structures and highlights the novel candidates. By relating the known phases to the tractably small, yet structurally diverse set of synthesisable candidate structures, we provide an excellent starting point for identifying formation pathways.