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In this investigation, BaAl 2 Si 2 O 8 (BAS):Eu2+ (BaF 2 -derived BAS:Eu and BaCO 3 -derived BAS:Eu) series of blue phosphor samples were synthesized through high-temperature solid-phase method, and their structure and luminescence properties were examined. In the case of BaF 2 -derived BAS:Eu, hexagonal feldspar (BaAl 2 Si 2 O 8) was obtained, which exhibited a UV region (λ em = 372 nm) fluorescence at 300 nm excitation. In the case of BaCO 3 -derived BAS:Eu, a monoclinic feldspar (BaAl 2 Si 2 O 8) was obtained, which exhibited a blue region (λ em = 428 nm) fluorescence at 300 nm excitation. The luminescence mechanism was the f-d transition of Eu2+, and the Eu2+ underwent different degrees of 5 d energy level splitting in different crystal field environments. This accounted for the UV region and blue region fluorescence. Considering that the phase transition between the hexagonal and monocline phases is a slow process, fluorescence emissions in UV and blue regions were generated during the two-phase transition period. As a result, phosphor exhibited a controllable spectrum from UV region (λ em = 372 nm) to blue region (λ em = 428 nm). Furthermore, based on the crystal field splitting formula, the blue-shift phenomenon of the spectrum was shown to occur in the monoclinic phase. Finally, the crystal distortion index of the environment of Eu2+ was calculated. Image 1 • Route for BaAl 2 Si 2 O 8 :Eu phase transition and fluorescence regulation via Ba source. •Samples were fabricated by high temperature solid-phase method. •BaF 2 - derived BaAl 2 Si 2 O 8 :Eu reveled hexagonal feldspar. •BaCO 3 -derived BaAl 2 Si 2 O 8 :Eu provided monoclinic feldspar. •The phosphor exhibited a controllable spectrum from UV region (λ em =372 nm) to blue region (λ em =428 nm). [ABSTRACT FROM AUTHOR]