Process‐Structure‐Reflectance Correlations for TiB₂ Films Prepared by Chemical Vapor Deposition

Abstract

The process‐structure‐reflectance interrelationships for TiB2 films prepared by CVD were determined using statistically designed experiments. A hot wall CVD reactor employing graphite substrates and the TiCl4+ BCl3+ H2 reagent system were used at pressures of 2.7 and 6.7 kPa. Single‐phase polycrystalline TiB2 films were obtained. An increasing percentage of the grains were oriented with their (001) planes parallel to the substrate as the deposition temperature was increased and as the BCl3:TiCl4 ratio decreased. Grain size increased from ∼0.5 to 3 µm as the deposition temperature was increased from 900° to 1100°C and as the coating rate was decreased from 0.6 to 0.1 µm/min. Fine‐grained, smooth, highly reflective films were obtained at low deposition temperatures and high BCl3:TiCl4 ratios.

Hafnium diboride thin films by chemical vapor deposition from a single source precursor

“…19 Chemical vapor deposition ͑CVD͒ can afford stoichiometric MB 2 films if the surface reactions during growth remove excess atoms as volatile by-products. Several CVD studies have used halogen-based precursors, [20][21][22] but the incorporation of residual halogen atoms has proven to be detrimental to film properties. 23,24 The single source precursor tetrakis͑tetrahydroborato͒hafnium, Hf͓BH 4 ͔ 4 , and its zirconium analog Zr͓BH 4 ͔ 4 , were reported as viable CVD precursors in 1988, but the growth kinetics were not studied in detail.…”

A New Approach to the Deposition of Elemental Boron and Boron-Based Coatings by Pulsed Magnetron Sputtering of Loosely Packed Boron Powder Targets

“…Other boron‐based materials (e.g. AlMgB 14 ,5 boron suboxides (BO x ),6–12 c‐BN,13–18 metal diborides,19–31 etc.) widen the potential application areas further.…”

Titanium diboride ceramics for solar thermal absorbers

“…Despite the high interest in TiB2, its optical properties are, to the best of our knowledge, totally unexplored, as far as bulk materials are concerned. Indeed, the only literature source is limited to the spectral range from 0.4 to 1.0μm and is referred to thin films [52].The present investigation is first aimed to the optimization of the SPS conditions for the full densification of additive free TiB2 powders synthesized by SHS. In this regard, it should be noted that the combination of the SHS and the SPS techniques was recently exploited for the fabrication of other UHTC systems, both in monolithic [11,53,54] and composite forms [55][56][57][58][59].Subsequently, in the present work we report on microstructure, topological characterization, and hemispherical reflectance spectra in the wavelength range 0.3-15 μm of TiB2 produced by the twosteps SHS-SPS technique, with the aim to evaluate the material potential for solar absorber applications.…”

“…Despite the high interest in TiB2, its optical properties are, to the best of our knowledge, totally unexplored, as far as bulk materials are concerned. Indeed, the only literature source is limited to the spectral range from 0.4 to 1.0μm and is referred to thin films [52].…”