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Texturally and chemically sector-zoned garnet crystals in two contiguous metapelitic rocks from the Danba dome, eastern Tibetan Plateau (SW China) were investigated. A petrographic boundary in one of the rocks (sample 21DB103) separates a thin section into two zones. Whereas one zone containing sector-zoned garnet and fined-grained matrix is enriched in graphite and quartz, the other zone encompasses garnets with relatively regular habit in a coarse-grained matrix poor in graphite and quartz. The two zones are distinct with regards to the chemical compositions of biotite and plagioclase, as well as the major and trace element zoning patterns of garnet. Electron back-scattered diffraction analysis shows that all the investigated garnet crystals in this sample are single crystals. Relatively higher P-T conditions are estimated for the initial growth of sector-zoned garnet (~ 5.0 kbar / ~540 ℃) compared to the regular garnet (~ 3.8 kbar / ~510 ℃) in this rock, possibly indicating that growth of the sector-zoned garnet postdates growth of the regular garnet. Texturally and chemically radial sectors with garnet-quartz intergrowths and irregular sectors of garnet are preserved in the other graphite-rich rock (sample 21DB104). Isopleth thermobarometry applied to the core of the largest garnet crystal exhibiting sector zoning in this sample reveals P-T conditions of initial garnet crystallization (~ 4.4 kbar / ~512 ℃) that deviate far (~ 0.8 kbar/~45 ℃) from equilibrium, potentially indicating significant overstepping required for garnet nucleation. Plagioclase inclusions in garnet display varying trace element abundances, indicating their replacements of different preexisting phases. These results suggest that abundant graphite may play a pivotal role in changing fluid conditions and reducing the solubility of SiO2 to grow sector-zoned garnet, as well as impeding matrix coarsening. Development of sector-zoned core and dodecahedral faces of garnet may be related to rapid growth with changes in crystal morphology. Irregular sectors may have developed through fluid infiltration and local chemical adjustments. [ABSTRACT FROM AUTHOR] more...

Gold in Carlin-type gold ores is commonly hosted in the arsenian pyrite rim, but the formation of arsenian pyrite and its contribution to Au adsorption are poorly understood. Based on our previous NanoSIMS Au mapping, we conducted SEM and HR-TEM analyses to examine the Au deportment and nanoscale texture of individual auriferous arsenian pyrite grains from the giant Carlin-type Lannigou gold deposit, SW China. The results indicate that the arsenian pyrite rim is composed of numerous nanoparticulate pyrite grains (rather than a single crystal), and gold nanoparticles (Au0) occur mainly in sub-rim with the highest Au content, which are porous and have lower degrees of order. We propose that nanoparticulate arsenian pyrite attachment and aggregation is the main mechanism for the arsenian pyrite rim growth, and such mechanism is crucial for the Au efficient enrichment for this giant gold deposit. [ABSTRACT FROM AUTHOR] more...

Inspired by 'Hufu' in ancient China, we manufactured semiflexible micro crystallizer with two aspectant sessile platforms by 3D-printing technique that can construct a series of heteromorphic droplets (HDs) via stretching droplet height. By coordinating the gas–liquid interface and flow intensity (i.e., Ra/Ma), central-converging micro-flows were generated, which dominated solute and particle motion towards droplet center. Efficient harvest of single cubic NaCl crystal was achieved at platform center under wide volume and concentration ranges. [Display omitted] Droplet crystallization behavior held great potential in crystal preparation, micromaterial engineering, and molecular assembly. However, restricted by natural surface tension, the intrinsic crystallization regulation and efficient harvest of high quality crystal in diverse droplet features were still a great challenge. Herein, we developed a 3D printed semiflexible micro crystallizer with two aspectant sessile platforms that could simultaneously construct a series of heteromorphic droplets (HDs) and controllable HD shape. By shaping HD on the interface of the platform, central-converging micro-flows were generated by coordinating the gas–liquid interface and flow intensity (i.e., Ra/Ma) during HD crystallization from 'barrel', 'can', to 'sand clock' shape, which was validated via simulative and experimental research. Therefore, HDs, constructed in semiflexible micro crystallizer, exhibited efficient screening (>70 %) of single cubic crystal just at the center zone of platform, even under wide ranges of concentration and volume, manifesting excellent repeatability on high quality crystal harvest and relevant interfacial science research. [ABSTRACT FROM AUTHOR] more...

Isodon amethystoides (Lamiaceae) is a popular plant in folk medicine in the southern provinces of China. Our phytochemical investigation of the twigs and leaves of this plant led to the discovery of five new diterpenoids with isopimarane and 3,4-seco isopimarane scaffolds [isoamethinols A–E (1–5)], along with the known compound 3,4-seco isopimara-4(18),7,15-triene-3-oic acid methylester (6). The chemical structures of these compounds, including the absolute configurations of the new diterpenoids, were determined by comprehensive spectroscopic analyses and single crystal X-ray diffraction measurements. These compounds were evaluated for their biological activities against a panel of human cancer cell lines, gram-positive bacterial strains and HIV. Notably, the 3,4-seco-isopimarane isoamethinol D (4) showed toxicity to the cervical Hela cancer (Hela) cells with an IC50 value of 27.21 μM and the lung (A549) cancer cells with an IC50 value of 21.47 μM. Compound 4 also exhibited mild antimicrobial activity against the oral bacterial strain Streptococcus mutans. These findings suggested that the diterpenoids with a 3,4-seco-isopimarane diterpenoids isolated from I. amethystoides could provide a novel structure scaffold for the discovery of anticancer and antimicrobial compounds. [ABSTRACT FROM AUTHOR] more...

The p-type 4H-SiC are ideal materials of substrate for high-power electronic devices. However, p-type 4H-SiC single crystal substrates with high quality, large size and low resistance could not be produced in China due to technological constraints. In this paper, Al doped p-type 4H-SiC single crystal substrates with a diameter of 4-inch were prepared by physical vapor transport (PVT). Dislocation defects were tested by the corrosion of KOH on the substrate. The crystal quality was characterized by high resolution X-ray diffraction (HRXRD), the crystal polytype was determined by Raman spectrum scanning, and the resistivity was measured by non-contact resistivity tester, respectively. It suggest that as-prepared substrates with low overall dislocation density and total resistivity (less than 0.5 Ω·cm) are prepared, meanwhile their crystal quality are good and crystal polytype is stable. Furthermore, the energy band structure and density of states of pristine 4H-SiC and Al doped p-type 4H-SiC were calculated via the first-principles plane wave ultra-soft pseudopotential method. The results show that the gap width decreases and the Fermi level passes through the valence band after the introduction of Al, which is considered as the characteristics of a p-type semiconductor. This elaborate study pave the way for the large-scale production of the p-type 4H-SiC substrate with high quality and low resistance. [ABSTRACT FROM AUTHOR] more...

In accordance with the second phase construction blueprint for the China Spallation Neutron Source (CSNS-II), the proposal includes the establishment of a single crystal neutron diffractometer. This apparatus necessitates a neutron detector array spanning over 1 m2 and capable of covering neutron diffraction angles from 20° to 160°. Additionally, the detector's position resolution must better than 1 mm × 1 mm. To meet such requirements, a scintillator neutron detector based on the Anger-Camera principle was designed. The detector is composed of a 6LiF/ZnS (Ag) scintillation screen, optical guide, silicon photomultipliers (SiPMs) array and self-design composite compression readout electronic systems. A detector prototype, featuring a detection area of 50 mm × 50 mm, was fabricated and subjected to testing at the BL20 neutron test line in the China Spallation Neutron Source (CSNS). The detector system achieved an optimal position resolution of 0.6 mm, while the maximum count rate was approximately 20 kHz. Moreover, the detector's Bragg edge imaging capability was preliminarily investigated using stainless steel samples, demonstrating its future potential for Bragg edge transmission imaging. The proposed detector demonstrates promising potential as a candidate for the single crystal diffractometer in CSNS-II. • Development of a novel position-sensitive scintillator neutron detector utilizing the Anger-Camera principle. • Composition includes a 300 μm thick 6LiF/ZnS (Ag) scintillation screen, 5 mm air light guide, SiPM array, and advanced compression circuit readout electronics. • Demonstrated performance with a high position resolution of 0.6 mm and maximum counting rate of 20 Kcps in neutron beam experiments. • Successful application in acquiring the Bragg edge transmission spectrum of 316L stainless steel, suggesting potential for preliminary crystal structure identification in metals. • Outperforms traditional 3He PSD tubes in position resolution, enhancing capabilities for neutron scattering applications. • Meets crucial specifications for various diffractometers, poised to facilitate future neutron instrument development and research. [ABSTRACT FROM AUTHOR] more...

TheCambrian strata at the northwesternmargin of the NorthChina Platform in InnerMongolia hold thick oolitic-grain bank deposits. Generally, the strata are dominated by calcareous mudstone of shelf facies in the lower part, micritic limestone consisting of deep to middle ramp facies in the middle part, and oolitic limestone encompassing shallow ramp to grain bank facies in the upper part of each formation. The shelf and deep ramp facies are the result of relative sea-level rise, while oolitic limestones developed in response to relative sea-level fall. Microscopically, the studied ooids are represented by radial crystal structures and concentric laminations with or without cores, single crystal or neomorphosed ooids, and highly bored ooids. The size andmorphology of the ooids indicate a two-fold mechanical influence of microbes; constructive in the Miaolingian and destructive in the Furongian ooids. Based on these observations, it can be inferred that microbes (predominantly composed of filamentous fossils of cyanobacteria) excreted extracellular polymeric substances (EPS) to develop multiple bacterial biofilms microbial mats. The subsequent decay of the EPS through sulfate reducing bacteria most likely caused precipitation around these ooids. The depositional style of ooids occupying the upper parts of the formations, and their possible genesis from microbes provide clue for regional correlation, as well as affirm biological control in the formation of ooids. [ABSTRACT FROM AUTHOR] more...

Low-dimensional perovskite materials and their derivatives with excellent optical performance are promising candidates for light-emission applications. Herein, centimeter lead-halide Cs4</subscript>PbBr6 single crystals (SCs), which have been used for radiation detection with the indirect conversion method, were synthesized by a facile solution process. The Cs4PbBr6 scintillator exhibits bright green emission peaking at 525 nm and a high photoluminescence quantum yield (up to 86.7%) under 375 nm laser excitation. The Cs4PbBr6 SCs exhibit high sensitivity to 40 keV X-rays, with a favorable linearity with the X-ray exposure dose rate, and the detection limit is as low as 64.4 nGyair/s. The scintillation time-response performance of the Cs4PbBr6 SCs was acquired by a time-correlated single-photon counting system under alpha-particle excitation. The Cs4PbBr6 SCs exhibit a very fast time response (τav = 1.46 ns) to alpha particles from a 241Am radiation source. This value is comparable to that of the commercial plastic scintillator EJ-228 (τav = 1.31 ns) and much faster than that of the LYSO(Ce) scintillator (τav = 36.17 ns). Conceptual X-ray imaging and alpha-particle pulse height spectroscopy experiments were also performed. These results demonstrated the potential of Cs4PbBr6 SCs for radiation detection applications, including X-ray imaging and charged particle detection with fast scintillation decay time and high sensitivity. Medical imaging: Scintillating crystals reduce radiation risks An improved technique for producing scintillators, materials that light up in the presence of ionizing radiation, shows promise for low-dose X-ray imaging applications. Commercial scintillators typically need to be fabricated through a series of high-temperature purification steps to become sufficiently sensitive to radiation. Qiang Xu and Xiaoping Ouyang from the Nanjing University of Aeronautics and Astronautics in China and co-workers now demonstrate that cesium–lead–bromide scintillators with ideal single-crystal structures can be synthesized through an inexpensive process involving the slow cooling of liquefied precursors. The team's experiments revealed that these crystals could be produced at centimeter scales with favorable characteristics for radiation detection, including nanosecond-quick response times. Clear X-ray images were obtained at dosages much lower than those in standard chest computed tomography (CT) scans. We investigated the scintillation performance of centimeter lead-halide Cs4PbBr6 single crystal synthesized by a facile solution process. Cs4PbBr6 single crystal have been demonstrated with fast scintillation decay time, low detection limit, and without hygroscopic, which makes it ideal for indirection radiation detection applications. The alpha pulse height spectroscopy deconvoluted into two Gaussian functions were obtained. The clear X-ray imaging of a standard pattern plate with 600 μm interval width under a low dose rate below 3.3 μGyair/s was collected. All these results indicate that this low-cost Cs4PbBr6 SCs scintillator is expected to be a promising low-dose X-ray imaging material. [ABSTRACT FROM AUTHOR] more...

Studying the influence of oxygen on the growth and properties of diamond has research significance. In this paper, we created an oxygen-rich environment by adding Ni2O3 to the Fe–Ni–C system. Large single crystals of oxygen-containing diamond were successfully synthesized using the temperature gradient method (TGM) in a China-type large volume cubic high-pressure apparatus (CHPA) at 5.5–6.0 GPa and 1360–1600 °C. The results show that with the increase of the Ni2O3 content in the Fe–Ni–C system, the rate of diamond growth decreased while the conditions for diamond growth were enhanced. The morphology of the diamonds changed from {111}, {110} and {113} mixed faces to {111} dominant face. The IR results show that the presence of Ni2O3 increased the nitrogen content in diamonds from 237 ppm to 543 ppm. When 3.5 wt% Ni2O3 was added, A-centre nitrogen began to appear in the diamonds. The XPS results confirmed that oxygen successfully entered the diamond lattice in the form of C–O, C＝O, O–C＝O and N–O with a high concentration of Ni2O3 additives. Meanwhile, there were no obvious impurity inclusions and cracks in the diamond crystals. In addition, the Raman peak position of the diamond appeared to red shift, and the FWHM increased from 4.93 cm−1 to 5.52 cm−1. [ABSTRACT FROM AUTHOR] more...

Herein, the characteristics of heavy FeS-doped diamond crystals were studied using a China-type large volume cubic high-pressure apparatus (CHPA) with FeNi alloy as the catalyst at 6.0–6.5 GPa and 1350–1400 °C. The crystals were characterized via optical microscopy (OM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman). OM of the crystal showed that the crystals cracked when the doping ratio was increased, and an increase in pressure was beneficial to alleviate the phenomenon of cracking. The XPS spectrum of the crystal showed that S successfully enters the diamond lattice in three bonding modes, C–SO2–C6H5, C–S–SO2–C and C–S, under high concentration doping conditions. The infrared spectrum showed that the content of N in the crystal decreased with an increase in the doping ratio. The Raman spectroscopy analysis showed that the heavy FeS-doped Ib-type diamond single crystal has a high quality sp3 structure, and the full width at half maximum (FWHM) of the crystal gradually broadened as the doping ratio increased. Additionally, it showed that increasing the pressure under the same doping concentration is beneficial to increase the crystallinity of the crystal. [ABSTRACT FROM AUTHOR] more...

Large amounts of perfect crystals were excavated from ancient coffins dating 2510 (±50) bp, in Jing'an County, Jiangxi Province, China. The coffins were wrapped by multiple bamboo mats and sealed highly by waterproof soil layers. In this study, crystals, wooden coffins, surrounding water and clay materials of several buried wooden coffins were subject to various analyses, and the crystals were identified to be vivianite by single crystal X‐ray diffraction, X‐ray fluorescence (XRF) and infrared (IR) spectroscopy. Spatial distribution of the vivianite crystals, which was consistent with first Fick's diffusion principle, indicated that the phosphate (PO43−) of the vivianite was originated from human bone that was demineralized under an acidic clay condition. Spatial distributions of iron(III) oxide (Fe2O3) and iron(II) oxide (FeO) indicated that iron(II) cations (Fe2+) of the vivianite originated from clay outside the coffins. Perfect vivianite crystals were formed at an extremely slow rate within the highly sealed coffins, in which Fe2+ and PO43− concentrations were of such a low level that the rapid precipitation of imperfect vivianite crystals was prevented, as the clay colloid could infiltrate only along the limited passageways of jointed seams between two halved timbers of the coffins. [ABSTRACT FROM AUTHOR] more...

The structure of trigonal ferrinatrite, Na3Fe(SO4)3⋅3H2O, from the Hongshan Cu-Au deposit, Eastern Tianshan, NW China was refined in space group P 3 ¯ based on single crystal X-ray diffraction data [a = 15.553(2), c = 8.6616(17) Å, V = 1814.4(5) Å3, Z = 6; R1 = 0.0535]. All hydrogen atoms were located by difference Fourier methods and refined with soft restrictions for distances, but with fixed thermal isotropic displacement parameters. The atomic arrangement in ferrinatrite is based on chains along [001] consisting of isolated FeO6-octahedra corner-linked with sulfate groups. All vertices of octahedra link to tetrahedra, and half the tetrahedron vertices link to octahedra. These chains are linked by interstitial Na-ions and H2O groups. All Na atoms are coordinated to four oxygen atoms of sulfate groups and to two oxygen atoms of H2O molecules within 2.33–2.71 Å; next oxygens are at distances of 2.85–3.00 Å. Among six hydrogen bonds, three acceptor O-atoms of sulfate groups belong to the nearest octahedral-tetrahedral chains, and three acceptor sulfate O-atoms from the neighboring chains, which further strengthen the linkages between octahedral-tetrahedral chains. The O–H···O distances are in the range 2.86–3.13 Å. The O–H stretching frequencies derived from structural data are in good consistence with the known Infrared spectra. [ABSTRACT FROM AUTHOR] more...

Pressure is a vital condition in the synthesis of diamond crystals via the temperature gradient method. Exploring the effect of pressure on the growth of diamond crystals is vital. In this study, we investigated the synthesis of diamond crystals using iron–nickel alloy catalysts and analyzed the properties of the synthesized diamonds in the pressure gradient using a China-type large-volume cubic high-pressure apparatus. The synthesis temperature of 1600 K and pressure range of 5.5–6.5 GPa were used. The results of Raman spectra showed that increasing the pressure would increase the crystallinity of diamond crystals. The FTIR spectra of diamond samples featured peaks at 1332 (N+ ions), 1130, and 1344 cm−1, indicating that with increasing pressure, the concentration of nitrogen atoms and ions in diamonds significantly decreased. The photoluminescence spectra of nitrogen ions in diamond samples displayed a peak at 40–100 ppm. The 692 and 694 nm peaks and the phonon bands of NV-chromophores gradually weakened with increasing pressure, indicating that the 692 and 694 nm peaks are attributable to the NV-color center and phonon displacement energy of 165 meV occurred. The Electron paramagnetic resonance spectra displayed a phonon bands of the NV-color center phonon are expressed in EPR through the g-value of NV-.These test results indicated that the pressure featured a significant effect on the nitrogen concentration and the nitrogen-related defects in diamonds. • It is proved that pressure cannot effectively improve the quality of the surface morphology of diamond crystals. • The residual stress and half-peak width by Raman spectroscopy verified that pressure can improve the crystal quality of diamond crystals. • It was demonstrated that the increase in pressure can reduce the growth rate of diamond crystals and thus the nitrogen content and related defects, and N+ ions were found in diamond crystals with lower nitrogen content. • PL spectra and EPR spectra illustrate that phonon boundaries of NV-color centers are produced at 40–100 ppm of nitrogen in diamond crystals. [ABSTRACT FROM AUTHOR] more...

It was not possible to carry out a complete analyses of crystal, as the experiment by Ding and Shi et al. It's analysis precision R=0.25 or more big than this, which value are not satisfied for single crystal study, but we through many test and found the best: [ R(int)=14.5%]. The final full-matix least-squares refinement on F2 converged to R1=0.0791 and w R2=0.1864 for 704 observed reflections [I3 2s(I)]. Daomanite is orthorhombic system, space group Cmc21 a=3.7520(8))Å, b=15.844 (4) Å, c=5.8516(12) Å, α=β=γ=90°. V=347.86(14)Å3, Z=4. Daomanite chemical formula is CuPtAsS2. Idealized composition Me+M2+M2+S2=CuS·PtAsS. There is no other similar mineral in the world. [ABSTRACT FROM AUTHOR] more...

[Display omitted] β-Elemene is the major constituent of the antitumor drugs elemene extract approved in China. By incorporating macrocyclization strategy into the β-elemene skeleton, we designed a series of novel macrocycles retaining three key carbon–carbon double bonds. Four different methods have been successfully developed for these challenging ring systems. A total of twenty-eight 14- to 24-membered macrocycles were synthesized. Most of these macrocycles exhibited good antitumor activity against several cancer cell lines (PC-3, A549, U87MG, U251 and HCT116), with up to 40 folds improvement of activity comparing to β-elemene. Additionally, X-ray single crystal structures of compounds Ic , Ip , and IIh were successfully solved as the proof of macrocycle formation. The results warrant the further investigation of this novel class macrocycles in pharmacokinetic and pharmacodynamics studies, which will be reported in due course. [ABSTRACT FROM AUTHOR] more...

In Liaoning Province, Northeastern China, the Early Cretaceous Jehol Biota records significant evolution and radiation of fauna in terms of diversity, abundance and complexity. The alluvial-to-fluvial Lujiatun and lacustrine Jianshangou beds of the lower Yixian Formation yield exceptionally well-preserved three-dimensional and articulated dinosaur and mammal fossils, and two-dimensional primitive birds/feathered dinosaurs, respectively. Published 40Ar/39Ar ages for the two fossil beds have uncertainties of ± 0.4 to 1.0 Ma (± 2 σ analytical uncertainty), and these reflect the measurement of large, and potentially heterogeneous, populations of feldspar crystals. More precise constraints on the timing and duration of biological radiation recorded by this sequence can further quantify evolutionary patterns and rates of diversification of important Early Cretaceous animals and plants. Single crystal 40Ar/39Ar fusion experiments on sanidine from intercalated ash beds yield dates that constrain the deposition of the Jianshangou and Lujiatun fossil beds to between 125.374 ± 0.085 and 125.572 ± 0.120 Ma, and 125.541 ± 0.099 and 125.793 ± 0.127 Ma, respectively. These ages indicate that the lower part of Jianshangou fossil bed was deposited nearly contemporaneously with the Lujiatun fossil bed. Thus, mass mortality events reflected by dinosaur fossil concentrations in the Lujiatun fossil bed and feathered dinosaur/primitive bird fossils in the Jianshangou fossil bed were nearly coeval and short-lived. These 40Ar/39Ar ages, combined with astrochronologic and paleomagnetic results from the lacustrine sediments in the Jianshangou fossil bed, not only refine the duration and rapid radiation of primitive birds and feathered dinosaurs in the deposit, but also suggest that the distribution of magnetic polarity chron boundaries within the Barremian stage in the current geologic time scale (GTS 2020) requires a revision. • The lower part of JSG and LJT fossil member deposited nearly contemporaneously. • Strata preserving primitive birds/feathered dinosaurs paced by short eccentricity. • Duration of biological radiations recorded by the 11 m strata is ∼460 to 610 kyr. • Timing of magnetic boundaries within Barremian stage in GTS 2020 requires revision. [ABSTRACT FROM AUTHOR] more...

A new generation electron–positron collider, the Super Tau-Charm Facility (STCF), has been proposed in China. As a critical part of the STCF Linac, the positron source will use a 10 nC/50 Hz 1.5 GeV electron beam to bombard a single crystal tungsten target. To obtain a stable and reliable positron source with a long lifetime, this paper presents a molecular dynamics model to simulate the anisotropy of thermal conduction for single crystal tungsten. A series of electron beam bombardment experiments were performed, which confirmed that the anisotropy of thermal conductivity and the highest thermal conductivity for single-crystal tungsten is the close-packed crystallographic orientation of [111]. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were used to study the recrystallization of the single crystal tungsten target. Finally, a new oscillation motional target system was designed for the STCF, and thermal simulation and moving speed optimization were performed. [ABSTRACT FROM AUTHOR] more...

• High-quality gem diamond were successfully synthesized in the pure Fe-C system. • There are no NV0, NV− center in diamond synthesized in pure Fe-C system. • Our findings are greatly helpful for the synthetic high-purity diamond crystal. In this paper, the diamond large single crystals were successfully synthesized in the pure Fe-C system by temperature gradient growth (TGG) method in China-type cubic anvil high-pressure apparatus (CHPA) at 5.8 GPa and 1550 °C. The synthesized diamonds were characterized by Optical microscopy, Infrared spectroscopy, Raman spectroscopy and Photoluminescence (PL) spectroscopy. The results show that the nitrogen concentration of type Ib diamonds synthesized in pure Fe-C system is about 80 ppm, which is much lower than diamonds synthesized by Ni-based and Fe-based alloys. PL spectra result indicated that there were no peaks related to the NV centers in diamonds synthesized by Fe-C system. In addition, high-quality type IIa gem diamond can be synthesized by adding a small amount of nitrogen getter in the pure Fe-C system. We believe that this work is of great significance for the synthesis of high-purity large single type IIa diamonds without impurities such as nitrogen and metals. [ABSTRACT FROM AUTHOR] more...