Synthesis and properties of BxCyNz coatings

Some of the most interesting compounds from both technological and a scientific viewpoint can be found within the B–C–N composition triangle. Despite all the attention that some phases on the vertices and sides of the triangle have attracted, few works have focused inside the triangle itself. A laser-assisted chemical vapor deposition system was used to deposit B–C–N phases over fused quartz substrates. Two sets of gaseous precursors were used, namely B2H6 + NH3 + C2H4 and B2H6 + (CH3)2NH. The coatings were characterized regarding chemical composition, structure, and morphology. Hardness measurements were also carried out with a depth-sensing indentation instrument. It was found that depending on the gas phase, different regions of the BCN solid composition triangle are accessed. Coatings ranging from pure h-BN to pure B4C were obtained, as well as mixtures of these with BxCyNz compounds.

Sol-gel Lithium Borophosphates

In this paper we present sol-gel synthesis and thermal and structural characterization of some lithium borophosphates. The as-prepared samples are mostly partially crystalline, and densification heat treatments at 500 °C cause samples to crystallize. In the phosphorus-rich part of the composition triangle we have lithium excess with respect to the nominal composition, which is likely due to the low reactivity of the phosphorus precursor. On the boron-rich side, in contrast, lithium losses are found which probably occur during syneresis.