Beryl Crystals Research Articles

Polarized Raman spectra of beryl and bazzite

The polarized Raman spectra of four different beryl crystals were studied at room temperature in the range from 30 to 4000 cm-1. The spectra show significant differences between the samples studied, and corrections are proposed for the reference Raman spectra of beryl previously reported by Adams and Gardner (1974). Type II water is observed in two crystals; the corresponding symmetric Raman stretching band at 3595 cm-1 is extremely strong for an impurity (about 20% of the strongest beryl lattice mode). Another, sharper, band of similar intensity at 3605 cm-1 could possibly originate from a hydroxyl stretching mode. Additional weaker bands are observed around 1600 cm-1 and 3600–3750 cm-1. The first polarized Raman spectra of bazzite are presented and discussed.

Habit modifications of Beryl grown by the flux method

Single crystals of beryl grown by slow cooling from an impurity doped flux without a seed crystal have been grown and their habit modifications studied by SEM and optical microscopic observation. Transition metal doping using Fe 2O 3, Cr 2O 3, Mn 2O 3 and alkali metal doping experiments were also carried out. Two characteristics, (1) the ratio (H/W), height to width of the crystals and (2) combination and relative development of crystal faces, were used as a measure of habit modifications. In general, as impurity doping increased, the crystals became slender and the second order prism disappeared. The ratio H/W was less in the larger crystals. This tendency can be attributed to the selective incorporation of impurity atoms on certain faces.

Properties of beryl single crystals grown by a high pressure hydrothermal method

Beryl crystals were grown under high pressure hydrothermal condition of 1 GPa. The optimum crystal growth was observed at 600°C and from 0.1N NaOH solution. The beryl crystals from 0.1–0.3N NaOH solutions incorporated water molecules and alkali cations in the channels of the beryl structure. The crystals showed same refractive indices and density as those of natural emerald crystals. These physical properties were very similar to natural emeralds.

Soft x-ray beamline and a double-crystal monochromator of UVSOR (abstract)

The UVSOR is a 750-MeV dedicated electron storage ring in the Institute for Molecular Science at Okazaki, Japan. The ring was constructed mainly for the use of VUV photons. However, the intensity of the soft x-ray region around 10 Å region is not negligible. The ring is also equipped with a 4 T superconducting three-pole horizontal wiggler. We have constructed a beamline equipped with a monochromator in order to utilize the soft and normal x-ray photons from the ring. In order to separate the vacuum of the ring from that of the monochromator, a light tight Be foil of 10 μm in thickness is placed in the upstream of the monochromator in the beamline. The monochromator constructed is a high vacuum compatible with double crystal which provides constant offset of the output beam. The constant offset during the rotation of crystal plane was realized by a simple linkage of linear motions of the two crystals with two linear guides placed on both input and output beam levels. The mechanical movement was found to be very smooth through a full rotation of 60° (between 15° and 75° of Bragg angle). Monochromator crystals such as beryl (101̄0), quartz (101̄0), InSb(111), Ge(111), and Ge(220) whose 2d value is 15.965, 8.512, 7.481, 6.532, and 4.00 Å, respectively, are being used with a reasonable intensity and signal-to-noise ratio of output signal. The range of photon energy which can be used with this line is from 850 eV to 4 keV in the bending magnet section, and from 850 eV to 6 keV with a wiggler. Because of the comparatively low energy of 750 MeV of the electron, the heat load is not a severe problem, and no radiation damage was observed for the first beryl crystal during an exposure to the beam for several months. We have measured the Na K-edge XANES spectrum of a thin film of NaCl which was evaporated in situ on a collodion film in the sample chamber at room temperature by using beryl as monochromator crystal. From the doublet separation of the spectrum, we can estimate the resolution better than 1 eV, which is sufficient for this energy range. With Ge(220) as monochromator crystal, K edge of potassium has been measured with a reasonable signal-to-noise ratio. Therefore, the practical limit of the energy attainable in this beamline of bending magnet section is about 4 keV.

Growth of Beryl Single Crystals by Internal Heating Hydrothermal Apparatus

An internal heating hydrothermal apparatus which can be used up to 1000°C and 300MPa, was designed to realize high temperature hydrothermal conditions. Transparent beryl crystals were grown in 0.025-0.05N NaOH solutions on the seed above 600°C and 160MPa. Step and pyramidal growth patterns were observed on the surfaces of the crystals grown on the seed crystals with a (1120) and s (1121) faces. Relatively high growth rate (30-40μm/day) was attained for the both seed crystals. Water molecules and alkali cations were incorporated into the channels of the beryl structure as in natural emeralds.

Investigation of excess 4He and 40Ar in beryl by laser extraction technique

We have investigated the distribution of 4He and 40Ar in a beryl crystal using a laser gas-extraction system. 4He is distributed almost homogeneously in the crystal, but 40Ar is concentrated both near a beryl-quartz boundary and near a large crack. This fact suggests that noble gases diffused into the beryl from the outside. From numerical simulation we infer that Ar in this beryl had two origins: one type had been trapped at the time of crystallization (“trapped”) and the other diffused into the mineral from the outside (“diffuse-in”). Stepwise heating experiments revealed that beryl has two kinds of sites which trap Ar. The amounts of Ar trapped in these sites were comparable to each other for all samples irrespective of their localities within a crystal. These observations suggest that both kinds of sites trapped Ar atoms not only at the time of crystallization but also by “diffuse-in” after crystallization. The present study showed that we should consider two origins, “diffuse-in” and “trapped”, in explaining excess 4He and 40Ar in beryl.

Soft x-ray beam line for surface EXAFS studies in the energy range 60≤hν≤11 100 eV at the Daresbury SRS

The characteristics of the beam line used for surface EXAFS (extended x-ray absorption fine structure) studies at the Daresbury Synchrotron Radiation Source (SRS) are described. Monochromatic photons are available in the energy range 60≤hν≤11 100 eV. This has been achieved using a monochromator with a combination of crystal and grating optics. The radiation is focused through the monochromator by a toroidal premirror at 0.5° grazing angle. Three pairs of crystals and a plane grating with focusing mirror are available which can be interchanged under ultrahigh vacuum (UHV). The plane grating/mirror monochromator has two ranges of zero-order angles, 6.4° and 2°, giving photon energy ranges of 60–550 eV and 600–2000 eV, respectively, with a 1200 l mm−1 grating. The crystals in use are InSb(111), Ge(111), and Ge(220) having photon energy ranges of 1745–7360 eV, 2000–8430 eV, and 3260–11 100 eV. The performance of the gratings and crystals in respect to intensity, resolution, scattered light, and higher orders is discussed, and some representative results from the beam line are given. Detailed consideration has been given to thermal effects on the crystal and grating optics. The grating can be exposed to a maximum power density of 9 W cm−2 and has so far withstood the intense radiation. The Ge crystals, which can see power densities of up to 150 W cm−2, have survived, but exit beam movement and energy scale shifts are observed. Efforts to reduce these beam movement effects have been successful inasmuch as the instrument is usable. InSb crystals suffered some radiation damage, and eventually surface melted. Beryl and quartz crystals have been tried but did not survive. The crystal part of the monochromator is in routine use, but the grating part has yet to be proved successful for surface EXAFS experiments.

Comparative efficiency of natural crystals and multilayers as dispersing devices in the copper L_2,3 range

Recent sputtering techniques have been used to produce layered synthetic microstructures (LSMs) as dispersing devices for varied applications in x-ray optics and spectroscopy. These analyzers, specially suited for synchrotron radiation, have been mounted in a two-parallel crystal monochromator. In this paper we show the first experimental results obtained with beryl crystals and multilayers for analyzing x-ray spectral distributions transmitted through screens or reflected on mirrors of copper near the L(2) and L(3) absorption edges. The significance of these findings is discussed in terms of comparison with natural and synthetic crystals and of designing a useful dispersing device for x-ray spectroscopy.

A high energy resolution X-ray spectroscopy synchrotron radiation beamline for the energy range 800–5000 eV

A beamline for X-ray spectroscopy of atomic and molecular gases and condensed matter has been designed and installed at the National Synchrotron Light Source. The beamline is UHV compatible to allow windowless operation for improved flux at low photon energies. A double axis crystal monochromator is employed with a collimating premirror and a focusing postmirror. Paris of beryl, quartz or silicon crystals define an energy band width of <0.4 eV at an arbitrary energy above 0.8 keV. The premirror acts as a tuneable low-pass filter to minimize heat loading on the first monochromator crystal. At the present operating parameters of NSLS, a flux of 10 9–10 13 photons/s of highly monochromatic X-rays can be focused onto a 1 mm diameter spot. Initial experimental results are presented.

Crystal growth and characterization of beryl doped with transition metal ions

Beryl crystals containing transition metal ions (Cr 3+ , Fe 3+ , Fe 2+ and Mn 2+ ) have been grown from Li 2 Mo 2 O 7 mineralizing flux. The crystal growth procedure, X-ray examination and optical characterization of the crystals are described.

An X-ray topographic study of the growth textures of natural beryl crystals

Many Brazilian natural crystals of beryl have been studied by X-ray topography from the interest in crystal growth. This study has shown that the crystals can be classified into two groups with respect to the growth-sectorial structure, although the size and perfection vary with the crystals. Each of these two types of growth texture has a peculiar structure that the whole crystal volume is composed of the inner and the outer concentric zones in its characteristic manner. Furthermore some systematic minor differences in the growth texture are found among the crystals of one group. The interpretations of these growth-texture differences are described in connection with the growth mechanism or condition.

Lithium in NaBe-cordierites from El Pe��n, Sierra de C�rdoba, Argentina

NaBe-cordierites (Fe/(Fe+Mn+Mg)=0.49–0.57) with BeO contents up to 1.16 weight % and additional Li2O contents up to 0.21 wt.% occur in cordierite-apatite-uraninite-muscovite-biotite-chlorite-feldspar-quartz nodules within pegmatites penetrating gneissic roof pendants of a lower Palaeozoic granite batholith. Occasional small crystals of beryl are interpreted to coexist stably with unaltered cordierite. Be and Li are incorporated in cordieriteaccording to the substitutions Na[Channel] + Be[4]→ Al[4] and Na[Ch]+Li[6]→R2+[6], respectively. The coexisting phyllosilicates do apparently not contain appreciable amounts of Li. According to powder IR-data, the analyzed water contents of the cordierites are dominantly of type II, and there is also little CO2. Their distortion indices Δ are rather low (0.121–0.145) and so are their optic angles (2Vα=50-51°). Considering all eleven NaBeLi-cordierites known thus far there is a strong positive correlation between Na and (Be+Li) with a slope close to 1.0. However, there is virtually no correlation between Be and Li, their incorporation into cordierite depending on the local geochemical environment. A strong negative correlation exists between the distortion indices Δ of the NaBeLi-cordierites and their Be contents. Li has a disturbing influence on this relationship, and the Δ versus Na correlation is also statistically worse than Δ versus Be.

10 Be in commercial beryllium

10Be has been observed at a level of about 10 −14 in four commercially available beryllium compounds. The possibility that this 10Be arises from cross-talk in the ion source has been eliminated. On the other hand, beryllium oxide extracted from beryl crystals found at a depth of 30–40 feet in a lithium mine in South Dakota shows no indication of containing 10Be. An upper limit on its 10 Be: 9 Be ratio is 1.7 × 10 −15 at the 95% confidence level.

X-ray topographic study of Brazilian natural beryl crystals

X-ray topographic study of Brazilian natural beryl crystals

The Formation of Chrysoberyl in Metamorphosed Pegmatites

The Formation of Chrysoberyl in Metamorphosed Pegmatites

Reflective properties of beryl and gypsum crystals in the 1 keV photon energy region

AbstractReflexion Curves from gypsum and beryl crystals have been calculated using the dynamic theory of x‐ray diffraction, assuming that the crystal is perfect, and taking into account the photoabsorption of incident photons by the crystal. The calculations were performed for two values of photon energy: 851 eV (Ni Lα emission) and 1098 eV (Ga Lα emission). The results are discussed comparatively.

X-ray spectral line coincidences between fluorine K- and transition-metal L-series lines

X-ray spectroscopy was performed in the 12–15-Å region, recording L-series lines from selected laser-irradiated transition metals. Line coincidences and near coincidences were identified between Cr, Mn, Fe, and Ni L spectra, and F viii and F ix K-shell lines. Wavelengths were determined to accuracies of 1–3 mÅ and will be utilized in selecting potential pumping candidates in future x-ray lasing schemes. High-resolution x-ray spectra were collected under controlled illumination and target conditions, using 1.05- and 0.527-μm laser excitation with the KMS CHROMA laser. Laser intensity varied from 1.2–2.5×1014 W/cm2 in 200-ps pulses. Three groups of x-ray spectra were collected with highly dispersive x-ray crystals at wave bands centered at 12.643, 13.781, and 14.458 Å, corresponding to H- and He-like lines from fluorine. Two specially designed flat crystal spectrographs employing camera shutters were used with pairs of beryl and thallium acid phthalate (TAP) crystals. The spectra from potential lasant and pump candidates could be recorded on the same spectrogram to aid in identifying x-ray line coincidences. In cases where wavelengths were measured in both the 1.05- and 0.527-μm laser work, agreement within 1–3 mÅ was obtained for the L-series x-ray lines. Within this accuracy range, some five L-series x-ray lines, mostly 2p-3d transitions from the metals Cr, Mn, and Ni, had wavelength values coincident with K-series lines in fluorine.

Optical absorption and electron spin resonance in blue and green natural beryl: A reply

A comparative study of blue and green beryl crystals (from the region of Governador Valadares, Minas Gerais, Brazil) using electron paramagnetic resonance (EPR) and optical absorption (OA) spectroscopy is reported. The EPR spectra show that Fe3+ in blue beryl occupies a substitutional Al3+ site and in green beryl is localized in the structural channels between two O6 planes. On the other hand the infrared spectra show that the alkali content in the blue beryl is mostly at substitutional and/or interstitial sites and in green beryl is mostly in the structural channels. The OA spectra show two types of Fe2+. Thermal treatments above 200° C in green beryl cause the reduction of Fe3+ into Fe2+ accompanied by a change of color to blue. The blue beryl color does not change on heating. The kinetics of the thermal conversion of Fe3+ into Fe2+ is composed of two first order processes; the first one has an activation energy ΔE 1=0.30 eV and the second one has an activation energy ΔE 2=0.46 eV.

Performance and application of a double crystal monochromator in the energy region [formula omitted] eV

The performance and application of an ultrahigh vacuum compatible constant-deviation double-crystal monochromator (JUMBO) in operation at SSRL is demonstrated. The monochromator can be operated with any of four pairs of crystals interchangeable in situ. An electronic maximum search feedback loop optimizes the intensity of the spatially fixed outgoing beam as the photon energy is scanned. The monochromatic beam is focused (∼1.5 mm × 5 mm) onto the sample by a toroidal mirror. Monochromator crystals of beryl(10 1 0), InSb(111) and Ge(111) have been tested in the energy regions 800−1540 eV, 1690–4000 eV and 1930–4500 eV, respectively. The performance of these crystals with regard to the resolution, the intensity, the level of scattered light, and the contribution of higher orders have been determined. Various effects arising from a radiation-induced temperature gradient in the monochromator crystals are discussed. Novel studies of bulk and surface properties of materials by angle-resolved photoemission, X-ray induced Auger spectroscopy, photon-stimulated ion desorption, bulk and surface extended X-ray absorption fine structure (EXAFS and SEXAFS) measurements in this previously inaccessible energy region of the electromagnetic spectrum are also discussed.

The surface preparation of beryl crystals for X-ray spectroscopy

One of the few crystals available for X-ray spectroscopy in the 1.0 to 1.5 nm band is natural beryl. This report describes work carried out to measure and improve the X-ray characteristics of four samples of the pink form of beryl (morganite) to establish the suitability of its use in the X-ray polychromator (XRP) instrument flown in the NASA Solar Maximum Mission satellite. Surface preparation of beryl crystals by etching in hydrofluoric acid followed by polishing in X-30 syton is shown to bring the rocking curve widths (FWHM) as measured on a two-crystal spectrometer to the near perfect values of 5 arc sec at Cu K alpha (0.154 nm) and 3.3 arc min at Cu L alpha (1.331 nm). In addition the crystals peak reflectivity can be enhanced by a factor eight times that of flat and ground but otherwise untreated crystals.