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Laser-excited N and R fluorescence lines of heavily doped ruby have been studied up to 26 GPa at low temperatures. While the intensity of the R lines at ambient pressure significantly decreases with decreasing temperature, the intensity of N lines originating from exchange-coupled Cr ion pairs is enhanced at low temperatures. The pressure induced wavelength shift of the N lines at 19 K is well fitted with an empirical formula similar to the equation for the R1 line, showing that the intense N line could be used as an alternative pressure scale at low temperatures. We also observe continuous increase in non-hydrostaticity with increasing pressure at low temperatures when silicone oil and 4:1 mixture of methanol and ethanol are used as pressure media. [ABSTRACT FROM AUTHOR]

Crystal growth methods that do not require high temperatures are highly needed for the facile growth of oxide single crystals with melting points of several thousand degrees Celsius. This paper represents the first report of a method for the low-temperature growth of ruby crystals (chromium-doped Al 2 O 3 ) at 750 °C, which is one-third of the conventionally required temperature (2050 °C). In solution-based crystal growth, the target crystal is grown at a temperature considerably lower than its melting point. However, conventional crystal growth processes involving solvent evaporation and cooling require high temperatures to completely liquefy the material, with previously reported solution growth temperatures of ≈1100 °C. Supersaturation based on the decomposition of crystal-solvent intermediates eliminates the need to completely liquefy the material, enabling low-temperature crystal growth. The combination of computational and experimental investigations helps determine the optimum conditions for low-temperature crystal growth. The proposed method is a novel green process that breaks the conventional frontiers of crystal growth while ensuring eco-friendliness and low energy consumption. In addition, its scope can potentially be expanded to the synthesis of various crystals and direct growth on substrates with low melting points., (© 2024 Wiley‐VCH GmbH.)

Presents information on a study of the use of stimulated emission for measuring R-line shifts in shocked ruby crystals. Use of Euler's method; Generation of a plane shock wave; Concluding remarks.

Significant uncertainty surrounds the processes involved in the formation of basalt-hosted corundum, particularly the role that the mantle plays in corundum generation. Some previous studies have suggested that trace-element ratios (namely, Cr/Ga and Ga/Mg) are useful for distinguishing two types of corundum: 'magmatic' and 'metamorphic', designations that include mantle and crustal processes. However, recent studies, including this one, have discovered transitional groups between these end-members that are difficult to classify. We used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to measure trace-element concentrations in sapphire and ruby crystals from eight alluvial deposits that span a significant length of the eastern Australian gemstone belt. Additionally, we collected LA-ICP-MS U-Pb and traceelement data from zircon megacrysts atWeldborough, Tasmania, which is also within the gemstone belt. Our sapphire and ruby results reveal a continuum in trace-element compositions, an observation that raises questions regarding previous classifications that ascribe corundum from basalt-hosted gemfields to either 'magmatic' or 'metamorphic' sources. The spatial association of basalt-related gemfields in eastern Australia with a long-lived convergent margin suggests a link between corundum formation and Al-enrichment of the mantle wedge during periods of subduction. [ABSTRACT FROM AUTHOR]

The article offers news briefs in the gemstone industry as of September 2017. New Era Gems has introduced the blue-green pyrope-spessartine garnet with high vanadium from Tanzania and Kenya. Also cited are the Montana sapphires mined by Potentiate Mining, and the developments in ruby mining and trading in Mozambique.

Rare ruby crystals appear among prevailing sapphire crystals mined from placers within basaltic areas in the New England gem-field, New South Wales, Australia. New England ruby (NER) has distinctive trace element features compared to those from ruby elsewhere in Australia and indeed most ruby from across the world. The NER suite includes ruby (up to 3370 ppm Cr), pink sapphire (up to 1520 ppm Cr), white sapphire (up to 910 ppm) and violet, mauve, purple, or bluish sapphire (up to 1410 ppm Cr). Some crystals show outward growth banding in this respective colour sequence. All four colour zones are notably high in Ga (up to 310 ppm) and Si (up to 1820 ppm). High Ga and Ga/Mg values are unusual in ruby and its trace element plots (laser ablation-inductively coupled plasma—mass spectrometry) and suggests that magmatic–metasomatic inputs were involved in the NER suite genesis. In situ oxygen isotope analyses (secondary ion mass spectrometry) across the NER suite colour range showed little variation (n = 22; δ 18 O = 4.4 ± 0.4, 2σ error), and are values typical for corundum associated with ultramafic/mafic rocks. The isolated NER xenocryst suite, corroded by basalt transport and with few internal inclusions, presents a challenge in deciphering its exact origin. Detailed consideration of its high Ga chemistry in relation to the known geology of the surrounding region was used to narrow down potential sources. These include Late Palaeozoic–Triassic fractionated I-type granitoid magmas or Mesozoic–Cenozoic felsic fractionates from basaltic magmas that interacted with early Palaeozoic Cr-bearing ophiolite bodies in the New England Orogen. Other potential sources may lie deeper within lower crust–mantle metamorphic assemblages, but need to match the anomalous high-Ga geochemistry of the New England ruby suite. [ABSTRACT FROM AUTHOR]

Provides information on a study that focused on the measurement of the temperature dependence of the ruby R1 and R2 lines for several ruby samples. Reason for measuring the temperature dependence of the ruby; Findings with regard to the error in pressure; Use of the ruby fluorescence scale.

Focuses on a study which compared the pressure-induced wavelength shift of a laser-excited fluorescence in samarium-doped yttrium aluminum garnet (SM:YAG) with that of ruby. Analysis of fluorescence spectra; Pressure dependence of the amount of the splitting of the fluorescence lines for both Sm: YAG and ruby; Relationship of pressure with wavelength shift for Sm:YAG fluorescence.

Measures the lifetime τ of the R[sub1] fluorescence line of ruby under high-pressure conditions using a modulation fluorometry technique. Application of standard pressure measurement system; Overview of experimental results for lifetime measurements at high pressure; Difference between nonradiative decay probability and radiative decay probability.

Thermal emission spectra of ruby single crystals in the range 400-800 nm were studied experimentally as functions of the intensity at 10.6 μm of exciting pulses (~0.5 s) from a continuous-wave electrical-discharge CO laser. Spectra at excitation intensity 1-20 kW/cm were superpositions of the thermal emission continuum of the sapphire crystal lattice in the range 600-800 nm and selective emission spectra of Cr that were observed for the first time for ruby and consisted of R-lines at 695 nm; N-lines at 715 nm; T , T → A transition bands at ~672 and 643 nm; and T , T → A transition bands at ~530 and 490 nm that were not observed in the luminescence spectrum. Time dependences of the shapes of selective emission spectra, quenching and shifts of the R line, and the temperature dependence of ruby luminescence spectra were investigated. [ABSTRACT FROM AUTHOR]

Particularly in hot climates, various pigments are used to formulate desired non-white colors that stay cooler in the sun than alternatives. These cool pigments provide a high near-infrared (NIR) reflectance in the solar infrared range of 700–2500 nm, and also a color specified by a reflectance spectrum in the 400–700 nm visible range. Still cooler materials can be formulated by also utilizing the phenomenon of fluorescence (photoluminescence). Ruby, Al 2 O 3 :Cr, is a prime example, with efficient emission in the deep red (~694 nm) and near infrared (700–800 nm). A layer of synthetic ruby crystals on a white surface having an attractive red color can remain cooler in the sun than conventional red materials. Ruby particles can also be used as a red/pink pigment. Increasing the Cr:Al ratio produces a stronger (darker) pigment but doping above ~3 wt% Cr 2 O 3 causes concentration quenching of the fluorescence. The system quantum efficiency for lightly doped ruby-pigmented coatings over white is high, 0.83±0.10. [ABSTRACT FROM AUTHOR]

A luminescent trace has been observed in a ruby crystal (AlO: Cr) that rotates at a frequency of 2 to 200 Hz and is irradiated by 532-nm coherent electromagnetic radiation. A method has been proposed to determine the lifetime of the excited electronic state of chromium ions from the measurement of the length of an arc of the trajectory of a light spot on the surface of a rotating ruby single crystal. A 'comet trace' formed at the passage of radiation through the rotating crystal near the absorption band of the material has been detected inside the ruby crystal. It has been shown that the theory based on the analysis of the motion of polaritons in the rotating reference frame is in satisfactory agreement with experimental results. [ABSTRACT FROM AUTHOR]

A largely overlooked form of asterism consisting of dual-color double stars is found in natural sapphire, in diffusion-treated and non-diffusion-treated synthetic rubies and sapphires, and in natural quartz. To characterize and explain this phenomenon, examples of these materials were examined. In transparent or translucent samples, an optical pattern of a white six-rayed star and a bodycolored (e.g., red, orange, yellow, green, blue) six-rayed star was frequently observed. Grinding and repolishing experiments showed that the asterism of part of the synthetic samples was produced or enhanced by diffusion treatment. The mechanism responsible for the formation of the dual-color double stars is discussed. To produce the pattern, acicular inclusions must either be present in relatively thin layers confined to the dome and the base of diffusion-treated ruby or sapphire cabochons, or be distributed throughout the complete corundum (natural or synthetic) or quartz samples. The white star is caused by interaction of light with the upper layer of the cabochon's dome. The bodycolored star, in contrast, is generated by light that enters the cabochon, is reflected and scattered at the base layer of the cabochon, and then travels a second time back through the body of the sample. As further prerequisites for observation of the phenomenon, the gemstones must be transparent or translucent, with polished base and dome. A historical summary of the manufacture and improvement of synthetic asteriated corundum by diffusion treatment offers additional insight into dual-color double-star stones. According to firsthand accounts and patent documents, diffusion has been used to produce or enhance asterism in synthetic and natural corundum since the 1950s. The treated material has been released commercially since at least the 1970s, and it is still produced and found on the international market. [ABSTRACT FROM AUTHOR]

Polycrystalline ruby (α-AlO:Cr), a widely used pressure calibrant in high-pressure experiments, was compressed to 68.1 GPa at room temperature under non-hydrostatic conditions in a diamond anvil cell. Angle-dispersive X-ray diffraction experiments in a radial geometry were conducted at beamline X17C of the National Synchrotron Light Source. The stress state of ruby at high pressure and room temperature was analyzed based on the measured lattice strain. The differential stress of ruby increases with pressure from ~3.4 % of the shear modulus at 18.5 GPa to ~6.5 % at 68.1 GPa. The polycrystalline ruby sample can support a maximum differential stress of ~16 GPa at 68.1 GPa under non-hydrostatic compression. The results of this study provide a better understanding of the mechanical properties of this important material for high-pressure science. From a synthesis of existing data for strong ceramic materials, we find that the high-pressure yield strength correlates well with the ambient pressure Vickers hardness. [ABSTRACT FROM AUTHOR]

The article focuses on the field expedition of a ruby and spinel deposit located east of the Namya jade mine at Hpakant in Kachin, Myanmar, by author. It mentions that the author was hired by Bangkok-based gem merchant and spinel connoisseur Henry Ho to find a bright 10 caret spinel from Namya. It discusses several sources of red spinels including Badakhshan, Afghanistan, Myanmar and Vietnam. It also offers information on Mogok, Myanmar which produces gems like rubies, sapphires and spinels.

An introduction is presented in which the editor discusses various topics within the issue including novel application of ruby, production of polymer nanoparticles and bioprobes.

We report the first numerical observation of composite fermion (CF) states in fractional Chern insulators (FCI) using exact diagonalization. The ruby lattice Chern insulator model for both fermions and bosons exhibits a clear signature of CF states at filling factors 2/5 and 3/7 (2/3 and 3/4 for bosons). The topological properties of these states are studied through several approaches. Quasihole and quasielectron excitations in FCI display similar features as their fractional quantum hall (FQH) counterparts. The entanglement spectrum of FCI ground states shows an identical fingerprint to its FQH partner. We show that the correspondence between FCI and FQH obeys the emergent symmetry already established, proving the validity of this approach beyond the clustered states. We investigate other Chern insulator models and find similar signatures of CF states. However, some of these systems exhibit strong finite size effects. [ABSTRACT FROM AUTHOR]

Abstract: Based on the modified formalism of Dorogokupets and Oganov (2007), we calculated the equation of state for diamond, MgO, Ag, Al, Au, Cu, Mo, Nb, Pt, Ta, and W by simultaneous optimization of the data of shock-wave experiments and ultrasonic, X-ray diffraction, dilatometric, and thermochemical measurements in the temperature range from ~100 K to the melting points and pressures of up to several Mbar, depending on the material. The obtained room-temperature isotherms were adjusted with a shift of the R1 luminescence line of ruby, which was measured simultaneously with the unit cell parameters of metals in the helium and argon pressure media. The new ruby scale is expressed as P(GPa) = 1870⋅Δλ / λ0(1 + 6⋅Δλ / λ0). It can be used for correction of room-pressure isotherms of metals, diamond, and periclase. New simultaneous measurements of the volumes of Au, Pt, MgO, and B2-NaCl were used for interrelated test of obtained equations of state and calculation of the room-pressure isotherm for B2-NaCl. Therefore, the constructed equations of state for nine metals, diamond, periclase, and B2-NaCl can be considered self-consistent and consistent with the ruby scale and are close to a thermodynamic equilibrium. The calculated PVT relations can be used as self-consistent pressure scales in the study of the PVT properties of minerals using diamond anvil cell in a wide range of temperatures and pressures. [Copyright &y& Elsevier]

Abstract: The ruby thin films were deposited by pulsed laser deposition (PLD) technique in an atmosphere of oxygen using ruby pellet, indigenously prepared by mixing Al2O3 and Cr2O3 in appropriate proportion. The characteristics R 1 and R 2 lines at 694.2nm and 692.7nm in the photoluminescence spectra of target pellet as well as that of PLD thin films, confirmed the ruby phase in both. The XRD and Raman spectra confirmed deposition of c-axis oriented crystalline ruby thin film on sapphire substrate. Effect of deposition time, substrate and deposition temperature on PLD grown thin films of ruby are reported. The intensity of R 1 and R 2 lines of PLD ruby thin films increased enormously after annealing the film at 1000°C for 2h. The film deposited on sapphire substrate for 2h was 260nm thick and the corresponding deposition rate was 2.16nm/min. This film was subjected to temperature dependent photoluminescence studies. The peak positions of R 1 and R 2 lines and corresponding line width of PLD ruby thin film were observed to be blue shifted with decrease in temperature. R 1 line position sensitivity, , cm−1/K in the range 138–368K was very well fitted to linear fit and hence can be used as temperature sensor in this range. [Copyright &y& Elsevier]

We present a comprehensive numerical model that accounts for non-uniform pumping and a related thermal and electronic lensing effects in Q-switched unstable laser cavities. We study the influence of these effects on the output beam profile in Nd:YAG and ruby laser systems with side-pumped crystal rods. We also constructed both lasers to experimentally validate the numerical results and found very good agreement. The results show that both types of lensing effects are particularly detrimental in ruby, while they are insignificant in Nd:YAG. [ABSTRACT FROM AUTHOR]

We have developed the glass ceramics containing ruby crystals by heat treatment of a Cr3+-doped SiO2-Al2O3-Y2O3 glass at 1550°C. The shape of precipitated crystals in the glass matrix was rod type whose average width and length were around 10 and 200 μm, respectively. From an X-ray diffraction measurement and an electron probe X-ray microanalysis, it was confirmed that the rod crystals were α-Al2O3. Intense emission bands of Cr3+ at 694 nm, called the R-lines, were observed in the glass ceramics heat treated above 1300°C. In addition, the intense red luminescence was observed only in the α-Al2O3 rod crystals by a photoluminescence mapping image. [ABSTRACT FROM AUTHOR]

Abstract: Fine-grained and transparent polycrystalline ruby ceramics (Cr2O3-doped Al2O3) were successfully prepared by spark plasma sintering (SPS). The effect of Cr2O3 concentration on the grain size, hardness, fracture toughness and thermal conductivity of ruby ceramics was investigated systematically. For 0.05wt.% Cr2O3, high in-line transmittance of 85% at 2000nm can be reached, further increase of Cr2O3 concentration leads to the decrease in transmittance. High hardness of 23.95–25.05GPa can be achieved due to the fine grain size in all ruby ceramics. The fracture toughness of 1.9–2.29MPam1/2 indicates that no improvement in fracture toughness over pure Al2O3 can be obtained by Cr2O3 doping in these submicron grained ruby ceramics. High thermal conductivity of 28–29.8W/(mK) at room temperature, close to that of single crystal sapphire, can be achieved. The change in grain size for different Cr2O3 concentrations is the major reason for the change in mechanical and thermal properties, but not for the change in optical properties. [ABSTRACT FROM AUTHOR]

Abstract: Theoretical and experimental EELS studies have been performed to optimize the chromium (Cr) quantification in natural ruby, featuring low concentrations of Cr in alumina (Al2O3). First, the noise performance of the detection system was determined (MTF, DQE), having been vastly underestimated in literature, as there was hardly any consideration of the dose dependence on the DQE. The superiority of the MLLS fit technique over conventional background subtraction for quantitating low Cr concentrations has been proven, and could be further supported by numerical signal-to-noise analysis of simulated noise free and Poisson-noisy EEL spectra. MLLS fitted ruby spectra by using appropriate standard specimens have also been investigated from an experimental point of view, by studying the influence of different instrumental configurations on the quantification results (monochromator/non-monochromator). The detection limits could be re-established within a novel mathematical expression based on MLLS fit parameters, avoiding the need of using factors that are hard to estimate otherwise. It is possible to detect atomic concentrations of Cr in Al2O3 down to 0.03% for a given optimal determined set of analysis parameters at a particular microscope setting. [ABSTRACT FROM AUTHOR]

In this review article, we summarized the study of the weak light nonlinear properties associated with group velocity change in the ruby. The ruby could be reduced to a two-level system, in which population oscillations could lead to a subluminal result. With the modulated TEM00 beam introduced into the ruby, self-phase modulation together with Fraunhofer diffractions and nondegenerate two-wave coupling between different spatial frequency components of the beam occurs at the same time. Population oscillations, self-phase modulation together with Fraunhofer diffractions and nondegenerate two-wave coupling mechanism competes with each other, which brings a new phenomenon of self-superluminal group velocity propagation in the ruby. [ABSTRACT FROM AUTHOR]

We have investigated the deformation mechanism of ruby in a microscopic area using a femtosecond laser having a pulse width, wavelength, and repetition rate of 238 fs, 780 nm, and 1 kHz, respectively. Transmission electron microscope observation revealed that a specific oblique pattern originating from cracks having a width of approximately 10 nm formed at the focal point. The peak shift of ruby fluorescence indicated the existence of a residual stress of 0.11 GPa at the irradiated area. Considering the pattern and magnitude of the residual stress at the focal point, we suggest that the crack propagated along the rhombohedral planes and the planes by laser irradiation. [ABSTRACT FROM AUTHOR]

Differentiation of treated and non-treated gemstones is a chief concern for major jewellery import companies. Low-quality corundum specimens coming from Asia appear to be often treated with heat, BeO or flux in order to enhance their properties as precious minerals. A set of corundum samples, rubies and sapphires from different origins, both treated and non-treated has been analysed at the Centre Européen d’Archéométrie, with ion-beam-induced luminescence (IBIL) and other complementary techniques such as Raman, proton-induced X-ray emission (PIXE), and proton-induced gamma-ray emission (PIGE). IBIL, also known as ionoluminescence, has been used before to detect impurities or defects inside synthetic materials and natural minerals; its use for the discrimination of gemstone simulants or synthetic analogues has been elsewhere discussed (Cavenago-Bignami Moneta, Gemología, Tomo I Piedras preciosas, perlas, corales, marfil. Ediciones Omega, Barcelona, 1991). PIXE has been frequently applied in the archaeometric field for material characterisation and provenance studies of minerals (Hughes, Ruby & sapphire. RWH Publishing, Fallbrook, 1997; Calvo del Castillo et al., Anal Bioanal Chem 387:869–878, 2007; Calligaro et al., NIM-B 189:320–327, 2002) and PIGE complements the elemental analysis by detecting light elements in these materials such as—and lighter than—sodium that cannot be identified with the PIXE technique (Sanchez et al., NIM-B 130:682–686, 1997; Emmett et al., Gems Gemology 39:84–135, 2003). The micro-Raman technique has also been used complementarily to ion beam analysis techniques for mineral characterisation (Novak et al., Appl Surf Sci 231–232:917–920, 2004). The aim of this study is to provide new means for systematic analysis of corundum gemstone-quality mineral, alternative to the traditional gemmologic methods; for this purpose, a Spanish jewellery import company supplied us with a number of natural corundum samples coming from different places (part of them treated as explained above). The PIXE elemental concentrations of the samples showed large quantities of calcium and lead in some cases that can be linked to treatment with fluxes or lead oxide. The plot of the chromium and iron concentration grouped the samples in various aggregates that corresponded to the different types of corundum analysed. Micro-Raman complemented the PIXE analysis corroborating the presence of lead oxides but the use of the PIGE technique was not successful for the detection of beryllium due to the low cross section of the nuclear reaction chosen for its identification. IBIL was capable of distinguishing between treated and non-treated samples of the same type based on the luminescent features of the materials. [ABSTRACT FROM AUTHOR]

We describe a simple, reliable, and inexpensive experiment for teaching the basic features of slow light propagation using a solid saturable absorber at room temperature. The experiment is accessible to undergraduate and graduate students. We provide an explanation and analysis based on the coherent population oscillations model, which describes the propagation of light across a ruby crystal. [ABSTRACT FROM AUTHOR]

The main aim of this work is a precise experimental assessment of the local stress fields developed at the notch-root in a ruby crystal, selected as a paradigm brittle material, by means of photo- and electron-stimulated luminescence techniques. Our approach takes advantage of the piezo-spectroscopic (PS) effect, which consists of a spectral shift of the luminescence emitted by the material due to lattice strain. Highly spatially resolved stress maps were extensively collected at the notch-root and spectral shifts monitored for the chromophoric ( R-lines) fluorescence observed in a single-crystalline ruby sample. Experimental data were analyzed and compared to the theoretical solutions of notch-root stress fields given by Filippi and by Creager-Paris. Due to its inherent simplifications, the Creager–Paris solution was found leading to underestimation of the maximum stress value piled up in the material, while the Filippi’s solution represented a more suitable approximation for the stress field developed at the notch-root. [ABSTRACT FROM AUTHOR]

Abstract: Two examples are treated of nonequilibrium phonons in ruby as studied with optical pumping for generation and luminescence for detection. The first example concerns nonequilibrium and near-zone-boundary phonons generated in the nonradiative decay from higher multiplets to and . The second example shows that coherent phonons are produced by stimulated emission over the Zeeman transition within the metastable doublet. [Copyright &y& Elsevier]

Abstract: A full understanding of the complicated spectra of the “N lines” in ruby that result from exchange-coupled pairs of chromium ions has remained a challenging but daunting task, especially for the nearest neighbour pair. Various inventive techniques were employed by spectroscopists in their studies of the problem. A major advance was made in 1962 by Kaplyanskii and Przhevuskii where they showed how the piezospectroscopic technique (stressing the ruby crystal in various directions) could be employed to help associate specific N lines with specific types of pair centres. In this work, using the methods of selective excitation combined with phase-sensitive detection of luminescence, we have succeeded in identifying all four transitions between the lowest level of the excited state of the nearest neighbour pair centre and the ground state, thereby confirming the energy level structure in the ground state. The low-temperature emission from this centre is found to be dominated by an exchange-induced electric dipole process, but the emission is almost all contained in the vibrational sideband. A similar behaviour is found for second nearest neighbour pair centres. [Copyright &y& Elsevier]

Abstract: After some recollections of phonon and photon trapping in ruby, a critical review of this effect of renewed interest in trivalent lanthanide-doped materials is presented showing that the two independent derivations taking their roots in the work of Milne for gases and of Birks for organic scintillators are practically described by an analogous phenomenological equation when re-absorption is weak. The problem of obtaining “extrinsic” quantum efficiency larger than one is briefly discussed. [Copyright &y& Elsevier]

Abstract: We have made the XANES measurements at the Cr–K edge on natural Burma ruby single crystals (corundum) and its two irradiated samples with fluence 1×1012 Fe3+ and 1×1013 Fe3+ions/cm2. XANES measurements show progressive increase in the intensity of pre-edge features (1s→3d), while intensity of 1s→4p transition Cr reduces with Fe fluence. Crystal field-splitting energy is found to be a 2.2eV and unchanged in irradiated samples. [Copyright &y& Elsevier]

Incorporation of silver ions into undoped and doped lead crystal glass was performed by ion exchange. Polyvalent arsenic, antimony, cerium and tin oxides, used as thermoreducing agents, were added in different weight percentages to the starting lead crystal glass. Thus, several doped lead crystal glasses were obtained by conventional melting. The role of the polyvalent oxides as reducing agents of silver ions introduced by ion exchange was studied by focussing on analysis of diffusion depth profiles obtained by SEM-EDX and direct observations performed by TEM. The optical absorption behaviour of the samples was studied to clarify the influence of the parameters involved in the ion exchange process. Chromatic coordinates were calculated from the corresponding transmission visible spectra. The influence of the nature and concentration of the polyvalent oxide dopants on the formation, size and aggregation of silver colloids is discussed Experimental parameters affecting the ion exchange treatment were varied and optimised to obtain silver colloids suitable to produce yellow and red ruby colouring in the undoped and doped lead crystal glasses, respectively. The most intense red ruby colouring was obtained with antimony doped lead crystal glasses, which were the most efficient at reducing silver ions and forming nanosized metallic colloids. Temperature, silver nitrate concentration in the molten salt bath and duration of the ion exchange treatment affect the size, aggregation and distribution of the silver colloids generated It has been demonstrated that ion exchange is a suitable process to obtain superficial ruby lead crystal glasses. In such glasses the synergic presence of both silver and a polyvalent oxide dopant favours the formation of metallic particles responsible for the ruby colouring. [ABSTRACT FROM AUTHOR]

Photoluminescence spectra measured for pristine ruby and its two irradiated samples with Fe 3+ ion show R 1 , R 2 , N lines and a broad band. Decrease in intensities of these features is observed with irradiation of Fe 3+ ion in ruby. Progressive structural changes and modifications on surface of irradiated rubies with Fe 3+ ion have been observed by atomic force microscopy. Decrease in intensities is discussed in terms of pair formation. [ABSTRACT FROM AUTHOR]

We have made the PL measurements on ruby at room temperature and 4.2 K. The characteristic R[SUB1] and R[SUB2] lines of chromium in ruby are found to be absent in the spectra recorded at 4.2 K. Instead of these characteristic lines a band centered on 1.6 eV is observed. A possible explanation has been discussed in terms of co-existence of the two electronic states due to presence of Cr[SUP3+] and Cr[SUP4+] ions in the ruby lattice. [ABSTRACT FROM AUTHOR]

Single-crystal ruby fibers with nominal diameters in the range from 80 to 500 μm and lengths up to 170 mm have been produced using the laser heated miniature pedestal growth technique. These fibers were tested for use as the basis of fiber optic temperature sensors. Characterization of the fiber fluorescence properties and comparison to bulk samples together with their high melting point indicate their potential for fluorescence-based sensing at extremely elevated temperatures. Good geometrical matching with current fiber optic technology and the use of phase-locked detection techniques also allow high resolution measurements to be obtained. [Copyright &y& Elsevier]

The fiber-optic thermometer probe, in which the sapphire fiber was connected mechanically with the ruby sensor head, has been fabricated and the performances of the probes are evaluated as compared with those using the silica fiber. The value of photoluminescence (PL) lifetime and its temperature coefficients for the ruby sensor head with sapphire fiber (t=3.9 ms and −9.9 μs/K) were slightly different from those using the silica fiber (τ=4.2 ms and −10.9 μs/K), even if the same ruby sensor head was used. These differences are found to be caused by the background PL due to residual impurities and/or defects in the sapphire fibers, which vary with the growth techniques of the fibers. The influence of the PL from the sapphire fiber on the temperature measurements can be reduced successfully using a modified lifetime calculation based on the curve fitting of the PL decay with double exponential equation. By using a modified lifetime calculation, the ruby sensor head with sapphire fiber can be used in the temperature measurement ranging from 270 to 670 K with ±1.5 K accuracy. [Copyright &y& Elsevier]

Ruby growth in phlogopite-bearing marbles has been indirectly dated using the 40Ar/39Ar laser stepwise heating technique on purified syngenetic phlogopite and other micas from ruby deposits in Yen Bai, Luc Yen and Quy Chau mining districts, in northern Vietnam. The principal results indicate the following.(1) Across the Red River shear zone, the phlogopites from the Yen Bai deposits yielded Miocene cooling ages between 23.2 and 24.4 Ma identical to those previously published using the same dating method on magmatic and metamorphic rocks from the Day Nui Con Voi range.(2) Luc Yen ruby deposits in the Lo Gam zone, on the eastern flank of the Red River shear zone, yielded Oligocene cooling 40Ar/39Ar mica ages between 30.8 and 34.0 Ma. Regarding the age of ruby crystallisation itself, the most plausible hypothesis is that all rubies in both zones formed during the period 40 to 35 Ma. Diachronism of cooling in adjacent zones leads to the conclusion that around 35 Ma, the ductile deformation in the Lo Gam zone ended and the ruby-bearing marbles cooled rapidly while the high-temperature deformation remained in the Red River shear zone, resulting in cooling through blocking temperature, some 15 Ma later.(3) The Quy Chau ruby deposit is restricted to the Quy Chau shear zone that bounds the eastern part of the Oligocene–Miocene Bu Khang dome. Phlogopite and biotite samples reveal Miocene cooling ages between 21 and 22.5 Ma which are minimum ages for ruby formation. These ages could be linked with the end of the extension of the Bu Khang dome.Vietnamese ruby formation is linked to Cenozoic tectonics resulting from continental collision between the Asian and Eurasian plates as for other marble-hosted ruby deposits in Central and Southeast Asia. [Copyright &y& Elsevier]

Reports that cavities formed in ruby by the healing and annealing of indentation cracks at 1600 degrees Celsius are more equiaxed than similar cavities in sapphire. Surface energies for the observed facet planes relative to the surface energy of the basal plane; Indistinguishability of the surface energies of observed facets.

The article presents the examination of a flower shaped ruby called Trapiche Ruby found from the region of Mong Hsu township, Myanmar which was examined on the basis of its hexagonal cores, crystallization growth and colour appearances.

A design study of a proposed fiber-optic flow sensor is presented. The concept used is that the temperature-dependent fluorescent decay time of a ruby crystal may be measured to determine the temperature of the crystal. The heat induced by light from a laser shone on the crystal is dissipated through it and may be conducted away by a flowing fluid. The measurement of crystal temperature can therefore be used as a means of measurement of fluid flow. In this work, the transient heat distribution in the crystal is modeled; as the basis of the design study, the results produced by the model indicate that this is a method that has potential as a practical system [ABSTRACT FROM AUTHOR]

In this article, a fluorescence decay-time thermometer using ruby crystal as the transducer material and carefully designed signal processing, with a light-emitting diode source and solidstate optical detection is reported. Results over a range to 170°C are discussed with a standard deviation irt the measurement, at best, corresponding to ± 0.04 K, in laboratory tests. [ABSTRACT FROM AUTHOR]

Predicts the occurrence of a phase transition at high pressure from the corundum structure to that of Rh2O3(II). Application of first-principles calculations with linearized, augmentized plane-wave method; Existence of free Al2O3 in deep lower mantle; Effect of transition on fluorescence of ruby and shock resistance tests of Al2O3 as window material.

Abstract: Ruby single crystals were synthesized from Mo- or Pb-based fluxes. The specific surface free energy of crystal was experimentally obtained using contact angle of liquid droplets on the crystal surface, and compared with the equilibrium grown length of each face. The proportion of the specific surface free energy and the equilibrium grown length was constant for the different faces of each individual ruby crystal, which looks to satisfy Wulff’s relationship. The relationship between specific surface free energy of the faces of the individual crystal with the same index and the equilibrium grown length of the face was linier. The difference in the specific surface free energy for the face of the same index can be explained by the difference in step length. [Copyright &y& Elsevier]

Paraxial energy transport of an intensity-modulated and focused Gaussian beam is studied in ruby. Deformations of the temporal profiles are observed under different conditions and explained by the interplay among a nondegenerate two-wave couplinglike mechanism, the population oscillations, and the Fraunhofer diffraction. Experimental evidence is provided for the existence of a nondegenerate two-wave couplinglike mechanism. The self-superluminal can be observed under proper conditions. A group velocity of -83 m/s is achieved with a Gaussian-like-modulated pulse of 30 ms with background illumination. Based on these results, a method to control the group velocity of a single beam in such media is proposed. [ABSTRACT FROM AUTHOR]

Ruby single crystals have been grown successfully from the melt droplet on the sapphire crystal fibers as the sensor head directly coupled with optical fiber for the thermometer applications using fluorescence decay. In this fabrication process, droplets of slurry of ruby powders are formed on the end of the sapphire crystal fiber and are dried, sintered, and then melted and solidified in a floating-zone furnace. The photoluminescence (PL) lifetime of the ruby sensor head varies from &tao;=3.8 to 2.5 ms with the Cr[SUP3+] concentrations from 0.07 to 1.0 at. %. The ruby crystal with a Cr[SUB3+] concentration of 0.35 at. % is found to be the most suitable sensor head having the longest PL lifetime. The temperature coefficient of the fiber-optic thermometer equipment using the directly coupled ruby sensor head with a Cr[SUP3+] concentration of 0.35 at.% is -12.4 μs/K. [ABSTRACT FROM AUTHOR]