[1] [1] HUANG W H, HE S, HAO A Z, et al. Structural phase transition, electrical and photoluminescent properties of Pr3+-doped (1-x)Na0.5Bi0.5TiO3-xSrTiO3 lead-free ferroelectric thin films［J］. Journal of the European Ceramic Society, 2018, 38(5): 2328-2334.

[2] [2] DU P, LUO L H, LI W P, et al. Photoluminescence and electrical performance of smart material: Pr-doped (1-x)(Na0.5Bi0.5)TiO3-xCaTiO3 ceramics［J］. Journal of Alloys and Compounds, 2013, 551: 219-223.

[3] [3] MISHRA A, KHATUA D K, DE A, et al. Off-stoichiometry, structural-polar disorder and piezoelectricity enhancement in pre-MPB lead-free Na0.5 Bi0.5TiO3-BaTiO3 piezoceramic［J］. Journal of Applied Physics, 2019, 125(21): 214101.

[4] [4] ADHIKARY G D, KHATUA D K, SENYSHYN A, et al. Long-period structural modulation on the global length scale as the characteristic feature of the morphotropic phase boundaries in the Na0.5Bi0.5TiO3 based lead-free piezoelectrics［J］. Acta Materialia, 2019, 164: 749-760.

[5] [5] XIA X, JIANG X P, CHEN C, et al. Enhanced piezoelectric performance and orange-red emission of Sm3+ doped (Na1/2Bi1/2)TiO3 based lead-free ceramics［J］. Ceramics International, 2017, 43(1): 376-384.

[6] [6] ZHANG Q W, CHEN K, WANG L L, et al. A highly efficient, orange light-emitting (K0.5Na0.5)NbO3∶Sm3+/Zr4+ lead-free piezoelectric material with superior water resistance behavior［J］. Journal of Materials Chemistry C, 2015, 3(20): 5275-5284.

[7] [7] CHEN S, WU M J, AN L Q, et al. Strong green and red upconversion emission in Er3+-doped Na1/2Bi1/2TiO3 ceramics［J］. Journal of the American Ceramic Society, 2007, 90(2): 664-666.

[8] [8] LIU M L, LEI F Y, JIANG N, et al. Enhanced piezoelectricity, bright up-conversion and down-conversion photoluminescence in Er3+ doped 0.94(BiNa)0.5TiO3-0.06BaTiO3 multifunctional ceramics［J］. Materials Research Bulletin, 2016, 74: 62-69.

[9] [9] Ma C L, Wang X Y, Tan W S, et al. Enhanced photoluminescence and ferro/piezoelectric performance in piezo-luminescent materials with outstanding water resistance and thermal stability［J］. Dalton transactions, 2020, 49 (17): 5581-5589.

[10] [10] REN Y T, YANG Z W, LI M J, et al. Upconversion luminescence modification induced near infrared luminescence enhancement of Bi2Ti2O7∶Yb3+, Er3+ inverse opals［J］. Journal of Luminescence, 2019, 208: 150-154.

[11] [11] LIN C, WU X, LIN M, et al. Optical, luminescent and optical temperature sensing properties of (K0.5Na0.5)NbO3-ErBiO3 transparent ceramics［J］. Journal of Alloys and Compounds, 2017, 706: 156-163.

[12] [12] KHATUA D K, AGARWAL A, KUMAR N, et al. Probing local structure of the morphotropic phase boundary composition of Na0.5Bi0.5TiO3-BaTiO3 using rare-earth photoluminescence as a technique［J］. Acta Materialia, 2018, 145: 429-436.

[13] [13] SCHLAGHECKEN G, GOTTMANN J, KREUTZ E W, et al. Pulsed laser deposition of Er∶BaTiO3 for planar waveguides［J］. Applied Physics A, 2004, 79(4/5/6): 1255-1257.

[14] [14] AUZEL F. Upconversion and anti-stokes processes with f and d ions in solids［J］. ChemInform, 2004, 35(16): no.

[15] [15] YU X C, SONG F, WANG W T, et al. Comparison of optical parameters and luminescence between Er3+/Yb3+ codoped phosphate glass ceramics and precursor glasses［J］. Journal of Applied Physics, 2009, 104(11): 113105.

[16] [16] SHANNON R D. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides［J］. Acta Crystallographica Section A, 1976, 32(5): 751-767.

[18] [18] ZHAO J, LU Z, YIN Y, et al. Upconversion luminescence with tunable lifetime in NaYF4∶Yb, Er nanocrystals: role of nanocrystal size［J］. Nanoscale, 2013, 5(3): 944-952.