Tunable emission color and anti-thermal-quenching behaviors in niobates for high-sensitive optical thermometry

•The tunable multi-color emission is realized via the energy transfer from Bi3+ to Eu3+ ions.•An anti-thermal-quenching behavior of Eu3+ ion and a great emission loss of Bi3+ ion can be achieved.•The maximum Sa and Sr reach as high as 0.318 K−1 and 1.62%K−1.•The surrounding temperature can be qualitatively estimated by observing the thermochromic behaviors.•The designed phosphor presents a multiplicity of applications in non-contact temperature measurement and white LED.