Tantalum diboride

C14B tetrachromium boride [12006-81-4] ">1680 TaB2 tantalum diboride [12007-35-1] 3100... 

It was also announced that tantalum diboride can be successfully synthesized from chloride - fluoride melts using the electrochemical method [560]. 

Chemical vapor deposition processes are complex. Chemical thermodynamics, mass transfer, reaction kinetics and crystal growth all play important roles. Equilibrium thermodynamic analysis is the first step in understanding any CVD process. Thermodynamic calculations are useful in predicting limiting deposition rates and condensed phases in the systems which can deposit under the limiting equilibrium state. These calculations are made for CVD of titanium - - and tantalum diborides, but in dynamic CVD systems equilibrium is rarely achieved and kinetic factors often govern the deposition rate behavior. 

Single-phase tantalum diboride of composition TaB, <,o-TaB, 5 is deposited using reaction (e) on a quartz substrate when the B/Ta ratio in the source gas is higher than 1.5, and T > 1000°C. At lower T and B/Ta ratios, deposition of metallic Ta is predominant. On substrates containing Ni or Pd impurities, woolly crystals up to 100 m in length can be grown in 30 min at 1050°C. As in the case of NbBj, a tip-VLS mechanism of growth is presumed . 

The system (LiF-NaF-KF)eut-KBF4-B203 is a part of the (LiF-NaF-KF)eut-K2TaFy-KBF4-B203-Ta205 system, where melts were proposed as electrolytes in the electrochemical synthesis of tantalum diboride by Polyakova et al (1998, 1999). 

Tantalum Diboride (TaB2) hexagonal, AIB2 structure (C-32 type) isomorphous with other transition metal diborides a=3.078-3.088A c=3.241-3.265A c/a= 1.06-1.074... 

Borides Chromium Diboride (CrB2) Hafnium Diboride (HfB2) Tantalum Diboride (TaB2) ZlxlO 10-12 X 10 oaxio room temp. 

Zirconium Oxide (Zr02) — tetragonal Mullite (3AI2O3 2Si02) Tantalum Diboride (TaB2) Silicon Carbide (SiC) 5.0x10 for 0 to 1400 C 5.0x 10 for25to800 C 5.1 x 10 at room temp. 5.12 x 10 for 25-1000"C... 

Zirconium Mononitride (ZrN) Titanium mononitride (TiN) Tantalum Diboride (TaB2) Titanium Diboride (TiB2) Knoop 30g 1983 kg/mm Knoop 30g 2160 kg/mm Knoop 30g 2537 kg/mm Knoop 30g 3370 kg/mm ... 

Aluminum Oxide (AI2O3) Titanium Monocarbide (TiC) Silicon Carbide (SiC) Tantalum Diboride (TaB2) Knoop lOOg 2000-2050 kg/mm Knoop lOOg 2470 kg/mm Knoop lOOg 2500-2550 kg/mm Knoop lOOg 2615 120 kg/mm ... 

HM > 8) Gray metallic powder. Severe oxidation in air above 800 °C. Corroded by the following molten metals Nb, Mo, Ta, and Re. Tantalum diboride... 

Deviatkin, S.V., Taranenko, V.I., Kushkhov, Kh.B., and Shapoval V.I. (1992) High-temperature electrochemical synthesis of tantalum diboride in chloride-fluoride melts, Rasplavy (Russ.), 2, 70-73. 

The structures of vanadium and niobium diboride crystals (161) resemble those of tantalum diboride grown by the floating-zone method (162). Widmanstatten-type precipitates found in... 

K Nakano, Y Kumashiro, E Sakuma. Single-crystal growth of tantalum diboride. J Less Common Met 65 27, 1979. 

The development of (Zr,Mo)B2 solid solution, confirms a discrete solubility of Mo in ZrB. On the other hand, the detection of Mo traces in HfB and TaB grains suggests that molybdenum is also partially soluble in the hafnium and tantalum diboride matrix phase, although to a lower extent. 

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