Yttrium aluminium garnet

Laser action can be induced in Nd ions embedded in a suitable solid matrix. Several matrices, including some special glasses, are suitable but one of the most frequently used is yttrium aluminium garnet (Y3AI5O12), which is referred to as YAG. 

Lasers produce spatially narrow and very intense beams of radiation, and lately have become very important sources for use in the UV/VIS and IR regions of the spectrum. Dye lasers (with a fluorescent organic dye as the active substance) can be tuned over a wavelength range of, for instance, 20-50 nm. Typical solid-state lasers are the ruby laser (0.05% Cr/Al203 694.3 nm) and the Nd YAG laser (Nd3+ in an yttrium aluminium garnet host 1.06 pm). 

TEHTM Tris(2-ethylhexyl)trimellitate YAG Yttrium aluminium garnet... 

Solid-state lasers, such as the ruby laser, neodymium doped yttrium aluminium garnet (Nd-YAG) laser and the titanium doped sapphire laser. 

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The preparation of yttrium aluminium garnet (Y3AI5O12, YAG) illustrates a variation of the hydrothermal method used if the starting materials have very different solubilities from each other. In this case, yttrium oxide (Y2O3) was placed in a cooler section of the autoclave and aluminium oxide as sapphire in a hotter section to increase its solubility (Figure 3.8). YAG forms where the two zones meet. 

Figure 8.16 illustrates the energy levels of Nd in yttrium aluminium garnet (Y3AI5O12), which are involved in the laser action of this crystal (known as the neodymium YAG laser). Describe the processes that occur when the laser is working. 

NBTC NC ND Nd YAG ndc NDR NEST NEXAFS Nanobiotechnology Center (Cornell University) nanocrystal nanodiamond neodymium-doped yttrium aluminium garnet (laser) 2,6-naphthalenedicarboxylate 2-nitro-jV-methyl-4-diazonium-formaldehyde resin New and Emerging Science and Technology near-edge x-ray absorption fine structure (spectroscopy)... 

A 30-year-old man, a cocaine sniffer, who had used cocaine more than five times a month for 4 years, complained of shortness of breath and acute chest pain. He had episodic cough and bloody sputum. A chest X-ray showed an 80% pneumothorax on the left side. On thoracoscopy the entire lung visceral pleura seemed to be covered by fibrinous exudate. After yttrium aluminium garnet (YAG) laser pleurodesis surgery, which abrades the pleura, he made a full recovery within 4 days. 

Figure 5.20. Changes in the Al MAS spectra and A1 site occupancy of yttrium aluminium garnet gel during thermal transformation to crystalline Y3AI5O12. After MacKenzie and Kemmitt (1999).

Laser Ablation [7]. The modern method for quantitative solid analyses is carried out using a laser ablation technique (Figure 2.16). The laser, usually in the form of Nd YAG (Neodymium - Doped Yttrium Aluminium Garnet), is focused on to the surface of a sample which, by continuous pulsing, leads to vaporisation at that point and the vapour is transported directly to the plasma with argon for detection and quantification. Detection limits are... 

Laser ablation can be carried out on any material without special sample preparation. The laser beam can be directed onto a defined spot of the sample or moved to different parts to analyse over a defined area. It can be moved in an XYZ plane using a stepper motor and driven in translational motions on which the cell is mounted and with more expensive models can be turned for analysis in other parts of the sample. Lasers can operate in UV, visible, and IR regions of the spectrum and a recent development in laser technology uses neodymium yttrium aluminium garnet (Nd YAG) which gives high repetition rate at a comparatively low power. This method of analysis is suited to bulk analysis of solid materials and the amount of volatility varies from sample to sample. The size of the laser spot can vary from 10 to 250 pm and little or no sample preparation is required. Errors are greatly reduced because of the simple sample preparation, and the fact that no solvents are required reduces interferences. 

Ceramics in aluminate systems are usually formed from cubic crystal systems and this includes spinel and garnet. Rare earth aluminate garnets include the phase YAG (yttrium aluminium garnet), which is an important laser host when doped with Nd(III) and more recently Yb(III). Associated applications include applications as scintillators and phosphors. 

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