Aluminum borate

EXAMPLE 1.7 The fluorescence lifetime measured from the metastable state Ej/2 ofNd + ions in the laser crystal yttrium aluminum borate (YAl3(B03)4) is 56 lus. If the quantum efficiency from this state is 0.26, determine the radiative lifetime and the radiative and nonradiative rates. 

Yttrium aluminum borate, YAlj (603)4 (abbreviated to YAB), is a nonlinear crystal that is very attractive for laser applications when doped with rare earth ions (Jaque et al, 2003). Figure 7.9 shows the low-temperature emission spectrum of Sm + ions in this crystal. The use of the Dieke diagram (see Figure 6.1) allows to assign this spectrum to the " Gs/2 Hg/2 transitions. The polarization character of these emission bands, which can be clearly appreciated in Figure 7.9, is related to the D3 local symmetry of the Y + lattice ions, in which the Sm + ions are incorporated. The purpose of this example is to use group theory in order to determine the Stark energy-level structure responsible for this spectrum. 

It forms aluminum nitride, AIN when heated with coal in a stream of nitrogen and aluminum borate, AI2O3 B203 when heated with B2O3 at 1000°C. 

Aluminum borate whiskers are produced commercially by an external flux method. Chlorides, sulfates, or carbonates of alkali metals are added to alumina and boric oxide (or boric acid) and the mixture is heated to 800°C-1000°C to produce aluminum borate whisker (length 10-30 pm and diameter 0.5-1.0 pm). It has a melting point of 1440°C, a very low coefficient of thermal expansion, and an excellent chemical resistance toward acids. The aluminum borate whisker was reported to be effective in improving not only the thermal degradation but also the glass transition temperature of epoxy76... 

Both hydrated and anhydrous metal borates have numerous industrial uses. Some of the major uses of hydrated metal borates are the manufacture of glasses, ceramics, and industrial fluids, and as micronutrient fertilizers, fire retardants, and biostats. Anhydrous borates find use as heterogeneous catalysts, scintillation hosts, and in the fabrication of optoelectronic devices. Anhydrous aluminum borates are used as additives in oxide ceramics to promote the formation of desirable phases. Also, aluminum borate whiskers are used as reinforcing additives in composite materials. Specific nses of sodium, calcium, zinc, and barium borates are discussed in sections below. 

Aluminum borate (AIBO2) Aluminum bromide (AlBr) Alianinum bromide (AlBr ) Aluminum bromide (AlBr ) Aluminum bromide (AlBr ) Aluminum bromide (AlBr ) Aluminum bromide ((AlBr )2) Aluminum carbide (AlC)... 

When aluminum borate whiskers were incorporated in SAN/PA-6 blends, the whisker, due to acid/based interaction had a better affinity to PA-6 than to SAN and for this reason they ended up in residence in the polyamide phase. A similar principle was used to obtain a conductive blend by compounding PA, PP and carbon black. Carbon black has a better affinity to polyamide and thus it prefers to reside in the polyamide phase or in the interphase formed between two immiscible polymers. Even when carbon black is added initially to polypropylene, it still transfers to the polyamide phase. This migration and preferential location of carbon black is not only an interesting scientific principle but it also has important practical implications. For the purpose of conductivity, a certain threshold concentration of carbon black is required to enable percolation and this threshold concentration is substantially lower if the carbon black settles in only one phase. This phase be-... 

Typical fillers glass fiber, PTFE, aluminum borate whiskers... 

It is not only the blend morphology which is affected by filler presence filler orientation might be affected by its surface treatment, as was observed in the works on PC/ABS blends containing aluminum borate whisker. When the whisker surface was treated with epoxy silane, its reaction to flow in injection and compression molding processes changed, resulting in a different orientation even though all other parameters of process and composition were the same. ... 

Shikoku Chemical Corp. aluminum borate whiskers 19... 

Aluminum Borate, Occurs in nature as the mineral eremeyeviu or Jeremejevite, AljOj-BjO. Prepd by heating AljOj with B2Oy when heated to 100CT 2AI2GJ.BJOJ is... 

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