Polycrystalline diamond films and coatings are widely used in optical components

thermal management

and cutting tools. Chemical vapor deposition (CVD) is widely used for their synthesis

while the initial nucleation stage largely determines the continuity and morphology of the diamond layer. Conventional nucleation is achieved by surface seeding with nanodiamond particles. An alternative approach is chemical nucleation

extensively studied for carbon-containing precursors and polymers

whereas nucleation on non-carbon particles remains comparatively unexplored. Here

lithium fluoride (LiF) particles were used as a model non-carbon system to study diamond nucleation and subsequent growth in CH

4

–H

2

microwave plasma CVD. Surface morphology and Raman spectroscopy showed that LiF promotes localized formation of well-faceted diamond crystallites without conventional nanodiamond seeding. Increasing the substrate temperature to 900°C produced a nearly linear increase in nucleation density and enabled the formation of nearly continuous polycrystalline films

whereas further heating to 950°C promoted island-like growth despite increasing growth rate. Methane concentration mainly affected the growth regime: at CH

4

contents of 10% and higher

secondary nucleation became pronounced

suppressing crystallite enlargement and promoting the transition from microcrystalline to nanocrystalline

diamond. Raman analysis showed that substrate temperature had little effect on the sp

3

/sp

2

ratio

although the diamond Raman line broadened at higher temperatures

whereas elevated methane concentrations increased the contribution of non-diamond carbon phases. These findings suggest that non-carbon chemical nucleation can provide a new perspective on diamond formation during CVD

including the emergence of diamond nuclei under conditions where diamond remains thermodynamically metastable.