Synthetic ruby

Aluminium oxide occurs naturally as emery (an impure form) and as corundum. Corundum is a crystalline form which may be coloured by traces of impurity, for example as ruby (red) and sapphire (blue). Small synthetic rubies and sapphires have been made by heating alumina with the colouring oxide in an oxy-hydrogen flame. 

The compounds of greatest importance are aluminum oxide, the sulfate, and the soluble sulfate with potassium (alum). The oxide, alumina, occurs naturally as ruby, sapphire, corundum, and emery, and is used in glassmaking and refractories. Synthetic ruby and sapphire are used in lasers for producing coherent light. 

Aluminum oxide is used to make synthetic rubies and sapphires for lasers beams. It has many pharmaceutical uses, including ointments, toothpaste, deodorants, and shaving creams. 

The red color of the ruby is also caused by the presence in it of a trace of chromic oxide, which distinguishes this costly gem from common crystalline corundum (alumina). Thus chromic oxide, according to F. H. Pough, is the most valuable commodity in the world when purchased in the form of a ruby (84). A beautifully illustrated article on synthetic rubies appeared in the Journal of Chemical Education for June, 1931 (85). 

See Fig), because it used a synthetic ruby crystal rod for emission of light (instead of gas used in MASERS). The color of light was red and it was shot in bursts. 

These are some of the most important lasers used in photochemical research. As they are rather similar only the ruby laser is described here in detail. The active material of the ruby laser is a dispersion of Cr3+ ions in alumina, A1203, in the form of a glass rod. This is in fact a synthetic ruby , not the natural half-precious stone which would not have the required degree of purity the details of the synthetic process are outside the scope of this book. 

Synthetic gemstone materials often have multiple uses. Synthetic ruby and colorless sapphire are used for watch bearings, unscralchablc watch crystals, and bar-code reader windows. Synthetic quartz oscillators are used for precision timekeeping, citizen s band radio (CB) crystals, and filters. Synthetic ruby, emerald, and garnets are used for masers and lasers. 

Simoes, M. L. (2005). Study of hydrophobic interactions in humic substances and soil components using spectroscopic methodologies. Ph.D. thesis, University of Sao Paulo-USP, Brazil. Singer, L. S. (1959). Synthetic ruby as a secondary standard for the measurement of intensities in electron paramagnetic resonance. J. Appl. Phys. 30,1463-1464. 

Verneuil A process for growing single crystals of refractory compounds. The powdered material is dropped through an oxy-hydrogen flame and the product, consisting of microscopic molten droplets, is collected on a seed crystal. As the liquid mass reaches a cooler zone, it crystallizes in the form of a single crystal, known as a boule. Invented by A.V.L. Verneuil at the Museum of Natural History, Paris, who made synthetic rubies and sapphires in this way. 

Aluminum, gallium, and thallium form mixed oxides with other metals. First, there are aluminum oxides containing only traces of other metal ions. These include ruby (Cr3+) and blue sapphire (Fe2+, Fe3+, and Ti4+). Synthetic ruby, blue sapphire, and gem-quality corundum are now produced synthetically in large quantities. Second, there are mixed oxides containing macroscopic proportions of other elements, such as spinel (MgAl204) and crysoberyl (BeAl204). 

August Verneuil develops a process for making synthetic rubies... 

The bathophenanthroline method was used for determining iron in blood plasma [157], in plant materials [158], in waters [159], in niobium, tantalum, molybdenum, and tungsten [42,160], in molybdenum compounds [161], in cobalt [162], in cadmium and cadmium telluride [5], platinum [163], synthetic rubies and sapphires [164], silicon tetrachloride [165], and in boiler water [166]. 

Minerals are inorganic compounds that are found in nature and have both a well-defined composition and crystalline arrangement of atoms. Coal and petroleum hydrocarbons are organic and thus not minerals. Obsidian is not a mineral because it has neither crystalline structure nor a specific composition. Stones such as chert and flint, which are mainly silica, SiO, have a relatively precise composition but lack crystalline structure, so are not minerals. While copper is a mineral, brass and bronze do not occur in nature and do not have a fixed elemental composition, so they are not minerals. A synthetic material can be a mineral, however, as long as it is also found in nature. Hematite can be produced artificially by firing ceramics in an oxidizing environment, but it is still considered mineral because hematite can be found in nature. A synthetic ruby is likewise a mineral because rubies do occur in nature, but modem cubic zirconia is not. 

A common check valve design is to have a small synthetic ruby bead contained in a small cylinder that composes the check valve. On one end of the cylinder there is a centrally perforated funnel-like ceramic disk on which the bead can seat and block liquid flow. At the other end of the check valve, the ball can seat on a small ceramic highly porous disk (Figure 11.11). In the inlet check valve, as the piston enters the chamber and pressurizes the mobile phase, the bead will seat on the funnel-like disk and prevent any back-flow while the outlet check valve will open and allow the mobile phase to be forced through the column. As the piston is withdrawn from the chamber, backpressure will cause the outlet check valve to close and allow fluid to enter the piston chamber from the solvent reservoir via the inlet check valve. The cycle then repeats. 

Figure 11.11 Schematic representation of a piston-driven HPLC pump. Check valves are designed to open and close in response to pressure. They do so by having fluid flow move a small ball, usually of synthetic ruby, from a place where it is firmly seated on a ceramic funnel-like cylindrical element that blocks fluid flow, to a position where it can rest against a highly porous screen-like ceramic element. During the intake phase of the pump stroke, as the piston withdraws from the piston chamber, back pressure (i.e., fluid pressure between the outlet check valve and the ultimate outlet of the detector(s)) forces the outlet check valve to close and allow mobile phase to enter the piston chamber. During the delivery phase, the piston enters the piston chamber and pressurizes it. This causes the inlet check valve to close and allows the outlet check valve to open once the back pressure in the system is exceeded by the fluid pressure in the piston chamber. This allows the mobile phase to be driven through the system. The piston seais prevent fluid from ieaking past the piston into the piston drive motor mechanism.

Synthetic ruby 2 %Ct20 in a-Al203) for lasers is made industrially by the Verneuil method as are single crystals of corund itself, sapphire, rutile, spinels, and strontium titanate. In this method the oxide particles are dropped through a flame,... 

When aluminum oxide is fused (melted) at high temperature (2045°C), it forms corundum, one of the hardest materials known. Corundum is used as an abrasive for grinding tools. When aluminum oxide is fused with small quantities of other metal oxides, synthetic sapphires and rubies are obtained. Synthetic ruby, for example, contains about 2.5% chromium oxide, Cr203. Ruby is used in fine instrument bearings ( jewel bearings) and to make lasers. ... 

Figure 17 shows a relatively economical micropinch valve fabricated by Piccini and Towe [20]. The system consists of a microbore silicone tube, a Ni — Ti SMA wire, a miniaturized synthetic ruby ball and a thermocouple. All of the components are off-the-shelf components. As shown in Fig. 17, the ruby ball blocks the tubing in a nor-... 

---