The near-infrared luminescence of Ca6Ba(PO4)4O∶Mn5+is demonstrated and explained.When excited into the broad and strong absorption band that spans the 500-1000 nm spectral range,this phosphor provides an ultranarrow(FWHM=5 nm)emission centered at 1140 nm that originates from a spin-forbidden 1E → 3A2 transition with a 37.5％internal quantum efficiency and an excited-state lifetime of about 350 μs.We derived the crystal field and Racah parameters and calculated the appropriate Tanabe-Sugano diagram for this phosphor.We found that 1E emission quenches due to the thermally-assisted cross-over with the 3T2 state and that the relatively high Debye temperature of 783 K of Ca6Ba(PO4)4O facilitates efficient emission.Since Ca6Ba(PO4)4O also provides efficient yellow emission of the Eu2+dopant,we calculated and explained its electronic band structure,the partial and total density of states,effective Mulliken charges of all ions,elastic constants,Debye temperature,and vibrational spectra.Finally,we demonstrated the application of phosphor in a luminescence intensity ratio thermometry and obtained a relative sensitivity of 1.92％K-1 and a temperature resolution of 0.2 K in the range of physiological temperatures.

Miroslav D.Drami?anin;?ukasz Marciniak;Sanja Kuzman;Wojciech Piotrowski;Zoran Risti?;Jovana Peri?a;Ivana Evans;Jelena Mitri?;Vesna Dor?evi?;Neboj?a Rom?evi?;Mikhail G.Brik;Chong-Geng Ma

School of Optoelectronic Engineering&CQUPT-BUL Innovation Institute,Chongqing University of Posts and Telecommunications,Chongqing 400065,PR China;Centre of Excellence for Photoconversion,Vinca Institute of Nuclear Sciences-National Institute of the Republic of Serbia,University of Belgrade,P.O.Box 522,Belgrade 11001,Serbia;Institute of Low Temperature and Structure Research,Polish Academy of Sciences,Okólna 2,50-422 Wroclaw,Poland;Department of Chemistry,Durham University,Durham DH1 3LE,UK;Institute of Physics,University of Belgrade,Pregrevica 118,11080 Belgrade,Serbia;Institute of Physics,University of Tartu,Tartu 50411,Estonia;Department of Theoretical Physics,Jan D?ugosz University,Czestochowa PL 42200,Poland;Academy of Romanian Scientists,Ilfov Str.No.3,050044 Bucharest,Romania

光：科学与应用（英文版）

[1]Miroslav D.Drami?anin;?ukasz Marciniak;Sanja Kuzman;Wojciech Piotrowski;Zoran Risti?;Jovana Peri?a;Ivana Evans;Jelena Mitri?;Vesna Dor?evi?;Neboj?a Rom?evi?;Mikhail G.Brik;Chong-Geng Ma-.Mn5+-activated Ca6Ba(PO4)4O near-infrared phosphor and its application in luminescence thermometry)[J].光：科学与应用（英文版）,2022(10):2463-2475

Mn5+,Ca6Ba,4O,Mn5+is,Racah,Sugano,3T2,Eu2+dopant

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