Improvement of Boron-Rich Boronitride Adhesion through Titanium Boronitride on Glass Surfaces and Optical Fibers by Diammonium Hexafluorotitanate(IV) and Borazine

Titanium boronitride (Ti−B−N) films have been produced by solid−gas reaction in the temperature range 600−700 °C using [(NH 4 ) 2 TiF 6 ] and B 3 N 3 H 6 (borazine) as precursors. The resulting material is deposited on SiO 2 substrates and on optical fibers, respectively. Films with thicknesses ranging from 0.3 to 1 μm possess a characteristic black color. They are stable over a wide temperature range, exhibit strong adhesion to glass and quartz glass and show resistance to mechanical deformation (i.e., fracture toughness). Furthermore, the ceramic films are not oxidized at room temperature even by strong oxidizing acids such as concentrated HNO 3 . Auger electron spectroscopy (AES) depth profile analyses indicate that the Ti concentration decreases progressively from the interface to the surface of the film. Results obtained by Rutherford backscattering spectroscopy (RBS) studies agree well with those of AES. Moreover, the decomposition products of [(NH 4 ) 2 TiF 6 ] are involved in the reactions at the surface of the substrate, enhancing the adhesion of the film. AFM analyses show a columnar type film growth with grain sizes ranging from 200 to 700 nm. The films possess electrical resistivity and hardness on the order of 6000 μΩcm and 22 Gpa (Vickers), respectively.