Boron thin films

Pure boron in the form of a thin film can also be obtained by heating diborane to 1000 K ... 

A thin layer of dark green beryl had been grown by a hydrothermal technique over the surface of a pale beryl to imitate emerald. It has been suggested that such stones should be called synthetic emerald-beryl doublets (16). The abiHty to grow thin, but not thick, single-crystal diamond on the surface of natural diamond (17) leads to the possibiHty of growing such a thin film colored blue with boron this has been done experimentally (18). 

NAA cannot be used for some important elements, such as aluminum (in a Si or Si02 matrix) and boron. The radioactivity produced from silicon directly interferes with that ftom aluminum, while boron does not produce any radioisotope following neutron irradiation. (However, an in-beam neutron method known as neutron depth profiling C3J be used to obtain boron depth profiles in thin films. ) Another limitation of NAA is the long turn-around time necessary to complete the experiment. A typical survey measurement of all impurities in a sample may take 2-4 weeks. 

Couto et al. [11] developed a flow injection system with potentiometric detection for determination of TC, OTC, and CTC in pharmaceutical products. A homogeneous crystalline CuS/Ag2S double membrane tubular electrode was used to monitor the Cu(II) decrease due to its complexation with OTC. The system allows OTC determination within a 49.1 1.9 x 103 ppm and a precision better than 0.4%. A flow injection method for the assay of OTC, TC, and CTC in pharmaceutical formulations was also developed by Wangfuengkanagul et al. [12] using electrochemical detection at anodized boron-doped diamond thin-film electrode. The detection limit was found to be 10 nM (signal-to-noise ratio = 3). 

Wangfuengkanagul and Chailapakul [9] described the electroanalysis of ( -penicillamine at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, and provided a linear dynamic range from 0.5 to 10 mM with a detection limit of 25 pM in voltammetric measurement. In addition, penicillamine has been studied by hydrodynamic voltammetry and flow injection analysis with amperometric detection using the BDD electrode. 

J. Stotter, J. Zak, Z. Behier, Y. Show, G.M. Swain, Optical and electrochemical properties of optically transparent, boron-doped diamond thin films deposited on quartz, Anal. Chem., vol. 74, p.5924, 2002. 

The boron-doped diamond (BDD) thin films are particifiarly attractive for electro analytical applications due to their unique characteristics, including... 

Boron-doped chemical-vapor-deposited diamond is an exceptionally inert carbon electrode with a very wide potential window and very low voltammetric background current. [A. E. Fischer, Y. Show, and G. M. Swain, Electrochemical Performance of Diamond Thin-Film Electrodes from Different Commercial Sources, Anal. Chem. 2004, 76, 2553.]... 

A recent innovation in thin-film detectors has appeared on the commercial market in which a standard Si(Li) detector is protected by an apparently strong, X-ray transparent and radiation insensitive thin-film. The exact nature and composition of this thin-film is yet to be disclosed in the open literature. However, according to manufacturer s reports [13] this detector window allows transmission of boron X-rays (0.185kv for Ka) and can be operated at atmospheric pressure. In a typical spectrum from this type of detector provided by the manufacturer, a strong oxygen Ka line as well as well-defined Si, Al and Na peaks can be observed for albite (NaAlSi Og). Since these detectors have only recently been installed in the field, details of performance have yet to be reported by users. 

Hach CT, Jones LE, Crossland C, Thrower PA. An investigation of vapor deposited boron rich carbon—a novel graphite-like material—part I The structure of BCj (C6B) thin films. Carbon 1999 37 221-230. 

Okino P, Shibata H, Kawasaki S, Touhara H, Momota K, Nishitani-Gamo M, Sakaguchi I, Ando T (1999) Electrochemical fluorination of 1, 4-difluorobenzene using boron-doped diamond thin-film electrodes. Electochem Solid-State Lett 2 382-384... 

In addition to thin-film electrodes, compact diamond single crystals grown at high temperature and high pressure have become the object of electrochemical study in recent years. These so-called HTHP crystals can be obtained by crystallization from a carbon solution in a metal melt (e.g., based on the Ni-Fe-Mn system) at /arranges that correspond to the conditions of thermodynamic stability of diamond. These crystals can be also doped with boron in the course of growth. 

Fig. 28. Anodic O3 evolution plots for polycrystalline diamond thin-film electrodes (top) and PbC>2 electrodes exposed to 10 vol. % H2SO4 solution. The boron/carbon ratio in the source gas during the films growth shown on the figure [119]. Reproduced by permission of The Electrochemical Society, Inc.

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