Reaction Process of Titanium Tetrachloride with Ammonia in the Vapor Phase and Properties of the Titanium Nitride Formed

Abstract

The reaction products of gaseous TiCl4 with ammonia were TiCl4·5NH3 at 200 °C, TiCl4·5NH3, TiClN, and NH4Cl at 250–400 °C, TiCl4·5NH3, TiClN, TiNx, and NH4Cl at 450–650 °C, TiNx and NH4Cl at 700–1000 °C, and TiNx, NH4Cl, and HCl at 1100–1400 °C. The N/Ti atomic ratio, x, of the TiNx formed was 1.21 at 700 °C, 1.16 at 800 °C, 1.13 at 900 °C, and 1.10 above 1000 °C. The lattice constants of the TiNx formed are shown. The reaction process can be represented as follows: The reaction of gaseous TiCl4 with ammonia occurs first to form TiCl4·5NH3. Above ca. 220 °C, the TiCl4·5NH3 decomposes to TiClN. Above ca. 430 °C, the TiClN reacts with ammonia to form TiNx. Above ca. 1100 °C, in addition to these reactions, the reaction of TiCl2, formed by the reduction of TiCl4 with hydrogen resulting from the thermal dissociation of ammonia, with ammonia occurs to form TiNx. On heating the TiNx, formed by the vapor-phase reaction, at temperatures higher than 500 °C in an argon atmosphere, the value of x decreased and became close to that of the stoichiometric nitride, being 1.02 at 900–1100 °C.

Superconducting nitride halides MNX (M = Ti, Zr, Hf; X = Cl, Br, I)

“…In both cases the by-products ammonium halides, amide halides like M(NH 2 ) 3 X (M ¼ Ti, Zr; X ¼ Cl, Br) [14,17,18], different ammonia adducts such as MX 4 Á n NH 3 (M ¼ Ti, Zr; X ¼ Cl, Br, I; n ¼ 2, 4,5,6,8) [12,13,17,19,20] and (NH 4 ) 2 [MCl 6 ] (M ¼ Ti, Zr) [21,22] necessitate a purification step, which comprises sublimation or thermal treatment in an ammonia stream at the synthesis temperature (see Table 1). Especially the ammonia adducts and amides were observed as main products at low temperatures (<400 C) [20], while at higher temperatures (>750 C) binary nitrides with several compositions (Zr 3 N 4 , Zr 3 N, ZrN, MN x with M ¼ Ti, Zr) are obtained [19,20,22]. For higher crystallinity of the product the purified nitride halides were annealed at synthesis temperatures for the a-polymorph (180-400 C) and at higher temperatures for the b-phase (900-1000 C) [16].…”

Theoretical ab initio Study of TiCl4 Ammonolysis: Gas Phase Reactions of TiN Chemical Vapor Deposition

“…Trimethylamine reduces Ti (IV) to Ti(III) and forms a complex with resulting titanium trichlorideTiCl 3 :2NH 3 . Saeki et al [9 ] observed TiCl 4 :5NH 3 as a product of the gas phase reaction between TiCl 4 and NH 3 at a temperature below 220°C, which presumably consists of a mixture of NH 4 Cl with an ammonia adduct of the partially aminolyzed TiCl 4 . In the temperature range between 220 o C and 430 o C TiCl 4 :5NH 3 decomposes to ClTiN, which at higher temperatures reacts with ammonia forming TiN x powder [9].…”

“…Saeki et al [9 ] observed TiCl 4 :5NH 3 as a product of the gas phase reaction between TiCl 4 and NH 3 at a temperature below 220°C, which presumably consists of a mixture of NH 4 Cl with an ammonia adduct of the partially aminolyzed TiCl 4 . In the temperature range between 220 o C and 430 o C TiCl 4 :5NH 3 decomposes to ClTiN, which at higher temperatures reacts with ammonia forming TiN x powder [9]. The thermochemistry of gas-phase species relevant to TiN CVD has been studied theoretically by Allendorf et al [10 ] who reported a 17 kcal mol -1 exothermic enthalpy of the 1:1 complex formation between TiCl 4 and NH 3 and a 20 kcal mol -1 endothermic decomposition energy of this complex toward Cl 3 TiNH 2 and HCl.…”

Vapor Phase Synthesis of Multicomponent Si‐N‐Ti Powders

“…Thermal cracking is only of importance at temperatures above 1000 C. [10,11] In all cases, post-treatment is necessary to remove the by-product NH 4 Cl, as well as to destroy formed chlorine-containing intermediates. Post-treatment at 900 C in an ammonia atmosphere leads to mainly chlorine-free powders with a particle size < 1 lm, and a spherical morphology.…”