Tantalum pentoxide, thickness

Antireflection coatings are used over the silicon surface which, without the coating, reflects ca 35% of incident sunlight. A typical coating consists of a single layer of a transparent dielectric material with a refractive index of ca 2, which is between the index of siUcon and ait or cover material. Materials such as titanium dioxide, tantalum pentoxide, Ta20, or siUcon nitride, Si N, ca 0.08-p.m thick are common. The coating and a physically textured... 

The scheme of such a metal-arch capacitance transducer is shown in Fig. 50. The transducer is about 3 mm thick and has a diameter between 6 and 10 mm. The fixed electrode consists of a sputtered tantalum film on a glass substrate, the dielectric is a reactively sputtered tantalum pentoxide film, and the variable electrode consists of phosphor bronze and is either an arch shaped 15 pm thin foil obtained from a metal strip or a spherical dome shaped foil made by sputtering [245]. A maximum capacitance value of 340 pF could be obtained and short time and long time stability s were better than 0.2 pF min 1 and 0.05 pF hour 1 respectively. The sensitivity of such transducers was between 2000 and 8000 pF mm 1. Q factors have been obtained in... 

A quarter wave stack on a glass substrate ( = 1.545), in air, is required to reflect light of 650 nm from a laser. The materials chosen have refractive indices of 2.15 (tantalum pentoxide, Ta20s) and 1.35 (cryolite, Na3AlF6). What are the real (physical) thicknesses of the layers ... 

Table 9.16 Titanium oxide thickness (nm), relative to tantalum pentoxide (Ong et aL, 1993)...

Chemical Properties.6—Tantalum is not affected by air or moisture at ordinary temperatures and does not rust. When the metal is heated in the form of sheet or thick wire in air it becomes yellow at about 400° C.,7 and with increasing temperature blue, and finally black. Above a dull red heat a film of the white pentoxide is produced, which to a large extent prevents further oxidation. Very thin tantalum wire can, however, be ignited in air by a match. In oxygen tantalum wire glows without flame at a white heat, and yields the pentoxide if the pressure of oxygen is greater than 20 mm. The reaction,... 

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