Highly sensitive optical thermometer of Sm3+, Mn4+ activated LaGaO3 phosphor for the regulated thermal behavior

Sm3+, Mn4+ co‐activated LaGaO3 phosphors, giving the characteristic emissions of orange and red emission simultaneously, were prepared by a solid‐state reaction. Their luminescence properties, energy transfer behavior, thermal stability, and ratiometric temperature sensing performance were investigated. Thanks to the inhibition of energy transfer between Sm3+ and Mn4+ ions at high temperature and the reconstruction of the traps, the distinct optical behavior of the involved activators dependent on the ambient temperature was evaluated. Anti‐thermal quenching performance of Sm3+ ions along with the emission declination of Mn4+ ions was observed. Hence, the optical thermometry characteristics of the resultant phosphor based on the fluorescent intensity ratio (orange/red) realize a recorded temperature sensitivity of 4.19% K−1 and 2.09% K−1. Moreover, the as‐explored film combined with the LaGaO3: Sm3+, Mn4+ phosphor is demonstrated to be a promising multi‐color optical thermometer.