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Searching for new low-dimensional organic–inorganic hybrid phosphors is of great significance due to their unique optical properties and wide applications in the optoelectronic field. In this work, we report a Mn4+ doped zero-dimensional organic–inorganic hybrid phosphor [N(CH3)4]2ZrF6, which was synthesized by a wet chemical method. The crystal structure, thermal stability, and optical properties were systemically investigated by means of XRD, SEM, TG-DTA, FTIR, DRS, emission spectra, excitation spectra, as well as decay curves. Narrow red emission with high color purity can be observed from [N(CH3)4]2ZrF6:Mn4+ phosphor, which maintains effective emission intensity even at room temperature, indicating its potential practical application in WLEDs. In the temperature range of 13–295 K, anti-Stokes and Stokes sidebands of Mn4+ ions exhibit different temperature responses. By applying the emission intensity ratio of anti-Stokes vs. Stokes sidebands as temperature readout, an optical thermometer with a maximum absolute sensitivity of 2.13% K−1 and relative sensitivity of 2.47% K−1 can be obtained. Meanwhile, the lifetime Mn4+ ions can also be used for temperature sensing with a maximum relative sensitivity of 0.41% K−1, demonstrating its potential application in optical thermometry. [ABSTRACT FROM AUTHOR]

Highlights: [•] Dy3+:Li3Ba2La3(MoO4)8 crystal was grown by the top seeded solution growth method. [•] The morphology, structure and spectral properties of the crystal were studied. [•] The main spectroscopic parameters were calculated by J–O theory and F–L formula. [•] The fluorescence dynamics was analyzed based on the Inokuti–Hirayama (I–H) model. [•] Comparisons with other reported crystals were made and the prospect was concluded. [ABSTRACT FROM AUTHOR]

Abstract: Nd3+:Li3Ba2Gd3(MoO4)8 crystal has been grown from a Li2MoO4 flux by the top seed solution growth method (TSSG). The structure of the crystal was confirmed by X-ray powder diffraction. The principal coefficients of thermal expansion along a, b and c-axes were precisely measured to be 1.62×10−5, 1.73×10−5 and 2.15×10−5 K−1, respectively. The specific heat value was 0.42J/gK at 50°C. The polarized spectral properties of Nd3+:Li3Ba2Gd3(MoO4)8 crystal were investigated and the spectroscopic parameters were calculated and analyzed based on the Judd–Ofelt theory. The absorption cross-sections around 805nm were determined to be 15.13, 3.84 and 5.27×10−20 cm2 for E//b, E//D1 and E//D2, respectively. The emission cross-sections σ em were determined to be 9.5×10−20 cm2 for E//b, 8.2×10−20 cm2 for E//D1, and 7.9×10−20 cm2 for E//D2, respectively. The fluorescence lifetime was measured to be 130μs and the quantum efficiency was calculated to be 93%. [ABSTRACT FROM AUTHOR]

Abstract: Dy3+:Li2Gd4(MoO4)7 crystal with dimensions of ∅20×25mm3 has been grown by the Czochralski method. The spectroscopic properties of Dy3+:Li2Gd4(MoO4)7 crystal have been investigated. Based on the analysis of polarized absorption spectra in the framework of the Judd–Ofelt theory, the main spectroscopic characteristics, including the phenomenological intensity parameters, spontaneous transition probabilities, fluorescence branching ratios and radiative lifetimes of Dy3+ in the crystal, have been determined. The emission cross-sections for the 4F9/2 → 6H13/2 transition of special interest for laser application have been calculated using the Füchtbauer–Ladenburg (F–L) equation. The fluorescence and radiative lifetimes of 4F9/2 manifold are equal to 126.5μs and 201.1μs, respectively, which mean the quantum efficiency is 62.9%. The results propose the possibility of Dy3+:Li2Gd4(MoO4)7 crystal for solid-state yellow laser pumped by commercially available blue laser diodes. [Copyright &y& Elsevier]

Abstract: The Cr3+:KAl(MoO4)2 single crystal was grown by top seeding solution growth method (TSSG). Based on the absorption and emission spectra, the crystal field strength Dq, the Racah parameters B and C, the effective phonon energy ℏω and the Huang–Rhys factor S were calculated: Dq=1494.8 cm− 1, B =585.5 cm− 1 and C =3049 cm− 1, ħω =373.8 cm− 1 and the Huang–Rhys factor S =3.74, respectively. The value Dq/B =2.55 indicates that Cr3+ ion occupies the strong crystal field site in KAl(MoO4)2 crystal. A comparison of crystal field parameters for Cr3+:KAl(MoO4)2 with other Cr3+-doped crystals was presented. The results of spectral measurement show that Cr3+:KAl(MoO4)2 may be a potential candidate for broadband laser applications. [Copyright &y& Elsevier]

Abstract: (Ba0.32Sr0.68)5Nb4O15 crystal with sizes of Ø 17×35 mm was grown successfully by Czochralski technique method. The thermal anisotropy was discussed. The principal coefficients of thermal expansion along (100), (010), (001) directions were precisely measured to be 1.308×10−5, 1.288×10−5, 1.478×10−5 K−1, respectively. Its optical transparency range has been measured and found to span from 323 to 5500 nm. The bands present in the IR spectra were identified and assigned to the corresponding vibration modes of NbO6 anions. [Copyright &y& Elsevier]

Abstract: The Ho3+:NaGd(MoO4)2 crystal with dimensions of Ф12×42mm2 has been grown by Czochralski (CZ) method. Polarized absorption and fluorescence spectra at room temperature were investigated. The largest absorption cross-sections, corresponding to 5I8 → 5G6 + 5F1 absorption bands, are 31.0×10−20 cm2 and 23.8×10−20 cm2 for π- and σ-polarization, respectively. The strongest emission corresponding to the 5S2 + 5F4 → 5I8 transition can be induced by populating any higher energy level of Ho3+ ion. The fluorescence lifetimes at room temperature are 3.4μs at 550nm, 3.5μs at 754nm and 46.4μs at 1193nm, corresponding to transitions 5S2 + 5F4 → 5I8, 5S2 + 5F4 → 5I7, 5I4 → 5I8, and 5I6 → 5I8, respectively. Due to the influence of fluorescence trapping, the measured fluorescence lifetimes of 550 and 1193nm should be longer than their actual values. Based on the Judd–Ofelt (J–O) theory and polarized absorption spectrum, the spontaneous transition probabilities, the fluorescent branching ratios and the radiative lifetimes were calculated. [Copyright &y& Elsevier]

Abstract: The Tm3+/Er3+:NaGd(MoO4)2 crystal with dimensions of Φ22×30mm3 was grown by Czochralski method. Polarized spectra and fluorescence lifetime for the 4I13/2(Er3+)→4I15/2(Er3+) transition at room temperature were investigated. Based on the Judd–Ofelt theory, the spontaneous transition probabilities, the fluorescent branching ratios and the radiative lifetimes were calculated. The fluorescence lifetime was measured to be 1.81ms. The detailed excited-transition mechanism with 800nm radiation is also discussed. [Copyright &y& Elsevier]