https://www.intechopen.com/books/physical-and-chemical-properties-of-carbon-nanotubes/synthesis-atomic-structures-and-properties-of-boron-nitride-nanotubes

https://www.intechopen.com/books/physical-and-chemical-properties-of-carbon-nanotubes/synthesis-atomic-structures-and-properties-of-boron-nitride-nanotubes

Dear Atif Suhail, please find below a reference describing the preparation of boron nitride nanoparticles and boron nitride nanotubes. However, it does not exactly answer your question as the interconversion of the two BN materials is not described.

Article Synthesis and Characterization of Nanoparticles, Nanotubes, ...

Dear Atif Suhail

Please read the below article. It has detail discussion and information about the synthesis of boron nitride nanotubes:

Synthesis of boron nitride nanotubes via chemical vapour deposition: a comprehensive review

https://pubs.rsc.org/en/content/articlehtml/2015/ra/c5ra01594d