Fluorescent Material Of Mn Ions Doped YAG And YAP:Synthesis,Luminescent Tunability

In this work,phosphors of Mn²⁺and Mn⁴⁺doped yttrium aluminum garnet and yttrium orthoaluminate were synthesized by a traditional solid-state reaction method.The composition,morphology and luminescence properties of samples were investigated by XRD,SEM and spectrofluorometer.The excitation wavelength,emission wavelength,fluorescence decay etc of Mn²⁺and Mn⁴⁺dopant ions in the host were studied as well as luminescent tunability has been investigated.Furthermore,the effective application in white light LED,temperature sensor and so on were explored.（1）The Ce³⁺/Mn²⁺/Si⁴⁺:Y₃Al₅O₁₂2 phosphors were synthesized by a traditional solid-state reaction and they have intense red luminescence attributed to Mn²⁺:⁴T₁→⁶A₁ spin-forbidden transition under the excitation of blue light via efficient energy transfer from Ce³⁺to Mn²⁺.Temperature-dependent emission spectra and luminescent decay curves evidenced that Mn²⁺activators partitioned into both the Al³⁺octahedral site and Y³⁺dodecahedral one while Si⁴⁺ones located in the Al³⁺tetrahedral site as charge compensators.Furthermore,inorganic Ce³⁺:Y₃Al₅O₁₂and Ce³⁺/Mn²⁺/Si⁴⁺:Y₃Al₅O₁₂2 dual-phase transparent glass ceramics were successfully fabricated by a low-temperature co-sintering technique to replace phosphor in organic silicone as color converter,and the red to yellow tunable luminescence can be easily achieved via controlling the content of red phosphor in glass matrix.Notably,by combining the fabricated dual-phase glass ceramics with InGaN blue chip,warm white light-emitting diodes with superior optical performance and excellent heat-resistance stability were successfully constructed.（2）A series of Mn⁴⁺doped Y_3-y（Gd/Lu）_yAl_5-xGa_xO₁₂（x=0⁵;y=0³）phosphors were fabricated by a conventional high-temperature solid-state reaction technique.In this work,taking Y₃Al₅O₁₂as the Mn⁴⁺doped host,we demonstrate the tunability of excitation and emission of Mn⁴⁺activator via cation substitution.X-ray diffraction patterns confirm that Y³⁺and Al³⁺in the host can be completely replaced by Gd³⁺/Lu³⁺and Ga³⁺,respectively.Impressively,the substitution of Al³⁺ions by Ga³⁺ones is beneficial to significantly enhance Mn⁴⁺⁴A₂→⁴T₂ blue excitation band and shift ²E→⁴A₂ red emission band toward low-energy region.the replacement of Y³⁺by Gd³⁺induces red-shifting of both Mn⁴⁺excitation and emission bands while Lu³⁺doping leads to the opposite result.Finally,inorganic Ce³⁺:Y₃Al₅O₁₂and Mn⁴⁺:Y₃Al₅O₁₂2 dual-phase embedded glass ceramic is prepared by a low-temperature co-sintering route to replace phosphors in organic silicone as color converter,and by combiningthe synthesized glass ceramic with InGaN blue chip,warm white light-emitting diode with superior optical performance is successfully realized.（3）A novel Yb³⁺/Ln³⁺/Mn⁴⁺（Ln=Er,Ho,Tm）:YAlO₃ phosphors were fabricated by a conventional high temperature solid-state reaction.In the present work,a strategy to achieve Mn⁴⁺room-temperature near-infrared upconversion luminescence with the aid of efficient energy transfer of Yb³⁺→Ln³⁺→Mn⁴⁺in the specially prepared Yb³⁺/Ln³⁺/Mn⁴⁺（Ln=Er,Ho,Tm）:YAlO₃ products is reported for the first time.Steady-state and time-resolved upconversion emission spectra are adopted to systematically clarify the related energy transfer mechanisms and determine energy transfer efficiencies.Benefited from completely different thermal-quenching mechanisms of Mn⁴⁺and Ln³⁺as well as intermediate crystal field environment of Mn⁴⁺in YAlO₃ host,the possibility using Mn⁴⁺/Ln³⁺dual-emitting based upconversion fluorescence intensity ratio and Mn⁴⁺upconversion lifetime as dual-modal temperature signals for accurate temperature sensing is demonstrated.It is believed that this preliminary study will offer a significant advance in exploring novel transitional metal based upconversion materials as well as self-calibrated optical thermometric media.