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CaMoO 4 :Pr3+ thermochromic phosphors with diverse thermal responses for temperature sensing were prepared by the traditional solid-phase reaction method. The typical CaMoO 4 :Pr3+ had scheelite structure belonging to tetragonal crystal system and space group of I 4 1 / a (88). Pr3+ ions can be easily substituted for Ca2+ ions of host CaMoO 4 because of similar ionic radius. CaMoO 4 : 1.5% Pr3+ have the block structure with mean size of 6.84 μm. The E g (∼3.93 eV) value of pure CaMoO 4 is bigger than that (∼3.65 eV) of CaMoO 4 : 1.5%Pr3+, attributing to the existence of intermediate defect energy levels. Appropriate Pr3+ doping concentration is 1.5%, and the concentration quenching phenomenon can be explained by the concrete electric multipole type of d-d interaction. The emission peak at ∼605 nm from 1D 2 →3H 4 transition have a good thermal stability of 99.452%@423 K, while the wide band centered at ∼490 nm from 3T 1,2 → 1A 1 transition in the MoO 4 2− complex and 3P 0 →3H 4 transition in Pr3+ have a poor thermal stability of 27.572%@423 K. Calculated activation energy is 0.239 eV. Temperature-dependent FIR for optical thermometry was constructed due to their diverse thermal responses. CaMoO 4 : Pr3+ phosphor had good relative sensitivities of 2.216%, 0.969% and 0.932% based on FIR of I 605 nm /I 490 nm with Boltzmann distribution, modified Boltzmann distribution and exponential equation fitting. Thermochromic behavior and thermal quenching mechanism are investigated. The obtained relative sensitivity is better than that of most phosphors, implying that CaMoO 4 : Pr3+ has a potential for application in optical thermometry. [ABSTRACT FROM AUTHOR]

The photoluminescence and temperature sensitivities of Ca 3 Y 2 Si 3 O 12 :Pr3+ thermo-phosphors with silico-carnotite structure obtained by solid state reaction method were investigated. Pr3+ ions were accommodated in the A sites having coordination number of 9 in AB 2 C 2 (SiO 4) 3 to replace Y3+ ions. The typical sample consisted of microcrystals with an irregular structure and the surface of particles was smooth, which could enhance the luminescence due to reducing the scattering and non-radiation produced by rough surfaces. The band gap value of typical sample was about 4.01 eV. Dipole-dipole interaction could account for concentration quenching. The two thermometry strategies including normalized intensities from 3P 0 →3H 4 transition and Fluorescence intensity ration (FIR) of 3P 0 →3H 4 /3P 1 →3H 5 transitions were employed for temperature sensing in 298–573 K. The results revealed that Ca 3 Y 2 Si 3 O 12 :Pr3+ thermo-phosphors had good temperature sensitivity performance with maximum S r of 0.59% K−1@573 K and 0.762% K−1@298 K in the above two methods, respectively. Hence, Ca 3 Y 2 Si 3 O 12 :Pr3+ would be a promising candidate in the field of optical thermometry. [ABSTRACT FROM AUTHOR]

SrMoO 4 : Sm3+ orange red-emitting phosphors for novel application in temperature measurement were prepared by solid-phase synthesis method. SrMoO 4 : Sm3+ phosphor with scheelite structure was assigned to tetragonal system and I 4 1 /a space group. Sm3+ ions could occupy Sr2+ lattice sites of SrMoO 4. SrMoO 4 : Sm3+ consisted of irregular microparticle with well-crystallized pomegranate seed-like morphology and Sm3+ ions can be evenly distributed in the SrMoO 4 matrix. The band gap value of SrMoO 4 : 1.0%Sm3+ (∼4.228 eV) is less than that of SrMoO 4 (∼4.267 eV), which is due to generation of defective energy levels in band gap. The appropriate quenching concentration of Sm3+ was 1.0%, the critical distance is ∼25.57 Å and θ is 7.1, close to 8, which was attributed to dipole−quadrupole interaction type of electric multipolar interaction. SrMoO 4 :1.0%Sm3+ had excellent thermal stability of the PL peak at 598 nm and 644 nm and anti-thermal quenching property of the PL peak at 530 nm and 563 nm. The activation energy based on the intensity of the PL peak at 598 nm is 0.318 eV. The new dual-model thermometry strategy base on exponential function and modified Boltzmann population distribution would be proposed. SrMoO 4 :Sm3+ phosphor had the absolute sensitivities of 0.108 K−1 based on exponential function and the relative sensitivities of 0.601% K−1 based on modified Boltzmann population distribution. The excellent anti-thermal quenching and good thermal stability of SrMoO 4 : Sm3+ phosphors indicate that it has a potential for applications as pc-WLEDs and optical thermometry. [Display omitted] • SrMoO 4 : Sm 3+ thermometric phosphors were prepared by solid state reaction method. • The excellent anti-thermal quenching and good thermal stability of SMO: Sm3+ phosphors. • The new dual-model thermometry strategy would be proposed. • SrMoO 4 : Sm3+ has a potential for application as optical thermometry. [ABSTRACT FROM AUTHOR]

SrSnO 3 : Pr3+ phosphors with red long afterglow (LAG)and temperature sensing were prepared by albumin assisted sol-gel method. The typical sample had cubic structure. The mean particle size was about 2.02 μm. The band gap values of samples were in the range of about 4.06–4.09 eV. The luminescent properties and LAG behaviors of SrSnO 3 : Pr3+ phosphors were investigated and the luminescence mechanism of red LAG was discussed. Albumin assisted SrSnO 3 : Pr3+ phosphor with a red long afterglow had an average decay time of 74.25 s. Pr3+ ions not only act as an activator, emitting red long afterglow, but also act as a trap provider. Moreover, the temperature sensing property was studied based on the non-thermal coupling FIR of TE and 3P 0 →3H 4 transition emission. The relative sensitivity was as high as 3580.89/T2. The absolute sensitivity (S a) and relative sensitivity (S r) of SrSnO 3 : 0.5%Pr3+ were 0.0374 K-1 and 4.03% K−1, respectively. Its optical thermometry performance is better than that of most phosphors. It has the potential to be applied in the field of temperature sensing. [Display omitted] • Albumin assisted SrSnO 3 : Pr3+ phosphors with red long afterglow (LAG)and temperature sensing were prepared. • Pr3+ ions not only act as an activator, but also act as a trap provider, emitting red long afterglow. • The relative sensitivity was as high as 3580.89/T2. • It has the potential to be applied in the field of temperature sensing. [ABSTRACT FROM AUTHOR]

CaSnO 3 : Pr3+ phosphor for new application in temperature sensing was investigated. CaSnO 3 : 0.3%Pr3+ had distorted orthorhombic perovskite structure and Pr3+ occupied Ca2+ sites due to their similar ionic radii. CaSnO 3 : 0.3%Pr3+ had spherical particles with mean size of 0.816 μm. The electric dipole−dipole interaction could explain the concentration quenching mechanism. The chromaticity coordinates were (0.1324, 0.3847), located in greenish-blue region and the average afterglow decay time was 60.2 s for CaSnO 3 : 0.15%Pr3+, which had potential applications for LED and emergency lighting. CaSnO 3 : 0.3%Pr3+ had the activated energy of 0.380 eV. The maximum relative temperature sensitivity for CaSnO 3 : 0.3%Pr3+ was 7.57% K−1 at 298 K and relative sensitivity was as high as 6722.76/T2 K−1, which was better than that of most Pr3+ doped phosphors and had potential application in temperature sensing. Moreover, the possible luminescence and long afterglow mechanisms and thermal quenching process of 3P 0 level through IVCT state were proposed. Unlabelled Image • Pr3+ doped CaSnO 3 phosphor for new application in temperature sensing. • S r value of 6722.7557/T2 K−1 was better than that of most Pr3+ doped phosphors. • CaSnO 3 : 0.3%Pr3+ had spherical particles with mean particle size of 0.816 μm. • τ avg is 60.2 s for CaSnO 3 : 0.15%Pr3+, potential application in emergency lighting. • Possible luminescence and long afterglow mechanisms were proposed. [ABSTRACT FROM AUTHOR]

Enhanced photoluminescence and high temperature sensitivity of a novel Pr3+ doped SrSnO 3 /SnO 2 composite phosphor was investigated. The typical samples had SrSnO 3 and SnO 2 phases and spherical morphology with mean particle size of 421 nm. The presence of SnO 2 phase could contribute to improving crystallinity of SrSnO 3. The optical bandgap values of Pr3+ doped SrSnO 3 /SnO 2 composite phosphors were in the range of ~3.85–~3.88 eV. Enhanced photoluminescence intensity of the typical Pr3+ doped SrSnO 3 /SnO 2 composite phosphor was attributed to the effective energy transfer from host material to Pr3+ ions. The typical samples had the greenish-blue emission. The d-d or d-p interaction could explain the Pr3+–Pr3+ energy transfer mechanism. The activated energy value was 0.206 eV for SrSnO 3 : 0.6%Pr3+ phosphor and 0.429 eV for SrSnO 3 /SnO 2 : 0.16%Pr3+ composite phosphor. The maximum relative sensitivity of SrSnO 3 /SnO 2 : 0.16%Pr3+ was estimated to be 5.727% K−1 at 303 K (5257.83/T2), which was very prominent and excellent, compared with that of SrSnO 3 : 0.6%Pr3+, for temperature sensitivity application. The possible mechanism for the greenish-blue emission and the thermal quenching process of 3P 0 level through IVCT state were proposed from the configurational coordinate diagram. Enhanced photoluminescence and high temperature sensitivity of Pr3+-doped SrSnO 3 /SnO 2 composite phosphor was investigated. Excessive SnO 2 did not quench the Pr3+ luminescence, but enhanced its photoluminescence. The possible mechanism for the greenish-blue emission and the thermal quenching process of 3P 0 level through IVCT state were proposed from the configurational coordinate diagram. The high S r of 5257.83/T2 was obtained. Our work expands the design thought on the optical thermometric material, which may provide a promising pathway to develop high optical temperature sensing. Image 1 • High temperature sensing and enhanced PL of Pr3+ doped SrSnO 3 /SnO 2 composite phosphor. • The CIE chromaticity coordinates are in the region of greenish-blue light. • IVCT state interfered thermometers with the high S r of 5.727% K−1 at 303 K (5257.83/T2). • Ranking among the highest ones for inorganic optical thermometric materials reported before. • Providing a promising pathway to develop high optical temperature sensing. [ABSTRACT FROM AUTHOR]

High temperature sensitivity phosphor based on an old material red emitting CaTiO 3 : Pr3+ phosphor prepared via H 3 BO 3 flux assisted solid-state reaction is reported. The typical sample possesses the orthorhombic perovskite phase and no impurity is found. The optical bandgap value is ~3.59 eV. There exists a single red emission with ideal color purity. The average long-afterglow decay time is 87.7s, the average trap depth is 0.76 eV. The maximum absolute sensitivity at 473 K is equal to ~0.0258 K-1 and the maximum relative sensitivity is estimated to be 7.69% K−1 at 298 K with the resolution of 0.26–0.65 K, indicating the suitability of the material for temperature sensitivity application. A possible mechanism for the quenching of 3P j emission at room temperature and the thermal quenching process of 1D 2 level through intervalence charge transfer state are proposed from the configurational coordinate diagram. Image 1 • High temperature sensitivity phosphor based on H 3 BO 3 flux assisted CaTiO 3 : Pr3+. • The CIE chromaticity coordinates are very close to that of the ideal red light. • IVCT state interfered thermometers with maximal S a and S r is ~~0.0258 K-1 and~ 7.69% K−1. • Ranking among the highest ones for inorganic optical thermometric materials reported before. • Providing a promising pathway to develop high optical temperature sensitivity. [ABSTRACT FROM AUTHOR]