Size-Dependent Persistent Luminescence of YAGG:Cr3+ Nanophosphors

In the current work, YAGG:Cr3+ nanophosphors were synthesized by the Pechini method and then annealed at different temperatures in the range 800–1300 °C. The structure and morphology of the samples were characterized by X-ray Powder Diffraction (XRPD). The lattice parameters and average crystalline sizes as site occupation by Al3+ and Ga3+ ions were calculated from the Rietveld refinement data. To investigate the effect of crystalline size of the materials on their optical properties: excitation and emission spectra were recorded and analyzed. Finally, the effect of crystalline size on the probability of carrier recombination leading to PersL was determined experimentally with thermoluminescence analyses. The Tmax-Tstop method was applied to determine the trap type and particle size (calcination temperature) effect on their redistribution. A correlation between structural changes and trap redistribution was found. In particular, the extinction of high-temperature TL maximum with increasing annealing temperatures is observed, while low-temperature TL maximum increases and reaches a maximum when the lattice parameter reaches saturation

Terbium (III) Oxide (Tb₂O₃) Transparent Ceramics by Two-Step Sintering from Precipitated Powder

As a result of preliminary air calcination and subsequent reduction in a flowing NH3 atmosphere of the precursor from the liquid precipitation method for the first time, pure-phase Tb2O3 powder with an average particle size of 135 nm was prepared. The Tb2O3 magneto-optical transparent ceramics with the average grain size of 1.3 μm were successfully fabricated by vacuum pre-sintering and hot isostatic pressing post-treatment from the as-synthesized Tb2O3 powder. In-line transmittance values of Tb2O3 ceramics reach 70.3% at 633 nm, 78.1% at 1064 nm, and 79.4% at 1400 nm, respectively. Thanks to the high intrinsic concentration of Tb3+, Tb2O3 ceramics present high Verdet constants of −427.3 and −123.7 rad·T−1·m−1 at 633 and 1064 nm, which are about 3.1 and 3.4 times higher than those of commercial Tb3Ga5O12 crystals, respectively. Due to the excellent magneto-optical properties, Tb2O3 ceramics are promising candidates for the development of Faraday isolator toward compaction used in visible and near-infrared bands

Fine-Grained Tb₃Al₅O₁₂ Transparent Ceramics Prepared by Co-Precipitation Synthesis and Two-Step Sintering

In recent years, transparent terbium aluminum garnet (TAG) ceramics have attracted much attention for use in high-power Faraday isolators. Fine-grained ceramics usually possess better mechanical properties and accordingly better service performance. In this work, transparent TAG ceramics with fine grains were prepared using a two-step sintering procedure based on the low-temperature sintering process to suppress grain growth. The composition of TAG precursor and powders calcined at different temperatures was studied in detail. The microstructure and relative density of air pre-sintered TAG ceramics were studied to meet the requirements of hot isostatic pressing (HIP) post-treatment. Driven by the low pre-sintering temperature in air, the average grain sizes of the obtained TAG ceramics after HIP treatment are about 2.9–5.3 μm. The TAG ceramics (1.2 mm thick) pre-sintered at 1450 °C with HIP post-treatment at 1550 °C for 3 h under a 176 MPa Ar atmosphere possess the highest in-line transmittance of 80.3% at 1064 nm. The Verdet constant of the TAG ceramics at 632.8 nm is −180.5 rad·T−1·m−1 at room temperature, which is about 1.3 times larger than that of the commercial Tb3Ga5O12 single crystals

Measurement of the neutron capture cross sections of rhenium up to stellar s- and r-process temperatures at the China Spallation Neutron Source Back-n facility

The neutron capture measurement of natural rhenium was performed with the time-of-flight technique at the Back-n facility of the China Spallation Neutron Source in the energy range from 1 to 500 eV of the resolved resonance region (RRR) and from 5 to 400 keV in the unresolved resonance region (URR). Prompt γ-rays originating from neutron-induced capture events were detected by four C_{6}D_{6} detectors. The pulse height weighting technique and the double-bunch unfolding method based on the Bayesian theory were used in the data analysis. To obtain reliable measurement results, background subtraction, normalization, and corrections were carefully considered. The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the RRR. An absence of resonance near 392 eV is observed in our measurement, which has been observed in previous works. The average cross sections in the URR of natural rhenium relative to ^{197}Au were obtained in logarithmical equidistant energy bins with 20 bins per energy decade. The talys code was used to describe the average cross sections in the URR; the Maxwellian-averaged cross sections (MACSs) of ^{185}Re and ^{187}Re are given from kT=5 to 100 keV. At a thermal energy of kT=30 keV, the MACS value for ^{185}Re (1469±127 mb) is in good agreement with the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNIS) recommended value (1535±62 mb) within the error bars. By contrast, the value of 1361±118 mb for ^{187}Re shows a discrepancy with the KADoNiS recommended value (1160±57 mb)

Measurement of the

In nuclear astrophysics, the nuclides $$^{151}$$Eu and $$^{153}$$Eu are both in the path of the s-process, and their (n, $$\gamma$$) cross sections are important input parameters for the calculation of the nuclear astrophysics network. According to the EXFOR database, the neutron capture cross section of natural europium in the resonance region has not been fully measured. The (n,$$\gamma$$) cross section of $$^{nat}$$Eu was measured using the time-of-flight (TOF) technique at the Back-n white neutron source facility of the China Spallation Neutron Source (CSNS) in the 1 eV–to 500 keV range. Four C$$_{6}$$D$$_{6}$$ liquid scintillator detectors and pulse height weighting techniques were used to measure prompt $$\gamma$$ rays and analyze the data. The results of the analysis were compared with the evaluated data of ENDF/B-VIII.0 and JENDL-5.0. It shows that there are some differences between the measurement results and different evaluated data libraries. The resonance parameters of $$^{151}$$Eu and $$^{153}$$Eu were extracted in the 1  eV–150 eV region using the R-Matrix code SAMMY. The accurate Maxwellian-averaged capture cross section (MACS) is derived over the temperature range of the s-process nucleosynthesis model. The result shows that at kT=30 keV, the MACS value of $$^{151}$$Eu is 3417 ± 297 mb and the value of $$^{153}$$Eu is 2718 ± 237 mb