XRD and Raman analysis reveal a single phase for BNBK93, BNBK91 and BNBK93 samples.
Rietveld refinements showed coexistence of three phases for BNBK88 and BNBK86 samples.
BNBK88 and BNBK86 samples showed a not previously reported additional P4bm phase.
Raman analysis confirmed the coexistence of phases for BNBK88 and BNBK86 samples.
BNBK86 and BNBK88 compositions are located in the MPB region of the BNBK system.