•The size and crystallinity of γ-CuI crystal are larger and better with addition of ZnI2 cosolute.•Adding ZnI2 cosolute improves the X-ray excited luminescence of the γ-CuI crystal.•The decay time of the emission at 435 nm is first reported less than 1 ns.γ-CuI single crystal was grown via evaporation method in ZnI2 acetonitrile solvent. The ZnI2 plays a unique role which can not only increase the solubility of CuI in acetonitrile but also introduce the Zn and I ions in the crystal. The γ-CuI crystal grown in ZnI2 acetonitrile is regular and transparent. Its size reaches up to 18 × 11 × 2 mm3 which is larger than that of the crystal grown in pure acetonitrile. In terms of the photoluminescence, the intensity of the emission at 411 nm of the crystal grown with ZnI2 as a cosolute is much higher than that of the crystal grown without ZnI2, which implies that the crystallinity of the crystal can be improved by ZnI2 doping. The X-ray excited luminescence of the crystal shows that the emission at 435 nm can be significantly enhanced and the emission near 680 nm can be suppressed by introducing Zn and I in the natural non-stoichiometry γ-CuI crystal. The nature of the phenomena is discussed. The decay time of the emission at 435 nm similar to that of the emission at 411 nm is faster than the detection limit of the instrument, i.e. less than 1 ns, and the average decay time of the emission near 680 nm is about 183 ns. The results can provide a useful guide to optimize the scintillation properties of γ-CuI single crystal.

•Ordered Lu3Al5O12:Ce3+ nanowire arrays were synthesized for the first time.•The nanowires with a uniform diameter are dense and homogenous.•AAO template has a confinement effect on the coalescence of nanocrystallites.•The PL and radioluminescence of nanowires embedded in AAO template were studied.Uniform Lu3Al5O12:Ce3+ nanowire arrays were successfully synthesized in Anodic Aluminum Oxide (AAO) templates by a sol–gel method. The as-prepared nanowires with ordered, homogenous and dense structure had a uniform diameter, corresponding to the pore diameter of the AAO template. The polycrystalline garnet structure of the as-prepared nanowires was found by X-ray diffraction and selected area electronic diffraction. AAO template has a confinement effect on the coalescence of Lu3Al5O12:Ce3+ nanocrystallites. Both photoluminescence and radioluminescence spectra of Lu3Al5O12:Ce3+/AAO composite consist of double peaks, which correspond to the electron transition of Ce3+ from the lowest crystal-field splitting component of 5d level to the 4f spin–orbit splitting 2F5/2 and 2F7/2 states.

•CuI nanowires were successfully fabricated via AAO template.•Pre-processed AAO template does help in forming dense nanowires of CuI at lower pressure.•Iodine-doped CuI nanowires show a strong near-band emission.CuI nanowires with uniform diameter were successfully fabricated by vacuum melting and gas pressure injection via AAO template. The nanowires exhibit the characteristics of continuous and compact at the gas pressure of 5 MPa, and the gas pressure can be reduced to 1 MPa with a CuI pre-processed AAO template, The results of XRD and EDS indicate that the nanowires belong to the zinc-blende structure and the amount of copper is more than that of iodide in the sample. The CuI nanowires present a weak near-band emission with a fast decay time and a strong defect emission with a slow decay time, and the intensity of fast emission component can be improved by iodine doping.

Er3+ doped K0.5Na0.5NbO3 (KNN) lead-free piezoelectric ceramics were synthesized by the solid-state reaction method. The upconversion emission properties of Er3+ doped KNN ceramics were investigated as a function of Er3+ concentration and incident pumping power intensity. Bright green (~555 nm) and red (670 nm) upconversion emission bands were obtained under 980 nm excitation at room temperature, which are attributed to (2H11/2, 4S3/2)→4I15/2 and 4F9/2→4I15/2 transitions, respectively. The upconversion emission intensity can be adjusted by changing Er3+ concentration, and the mechanism of upconversion processes involve not only a two-photon absorption but also a three-photon absorption. In addition to the admirable intrinsic piezoelectric properties of KNN, this kind of material may have potential application as a multifunctional device by integrating its upconversion and piezoelectric property.

•The luminescence properties of CuI crystals are influenced by the quality of the as-grown crystals.•The emission peaks of free-exciton and bound-exciton are observed in the CuI single crystals.•The ultrafast component luminescence is warranted to the donor-acceptor pair recombination.•The exciton absorption and electron excitation multiplication processes were observed in CuI.The photoluminescence spectra of CuI crystals using synchrotron radiation as an excitation light source were obtained at 60 K. The emission peaks at 405, 415, 420 and 443 nm were observed. The possible origins of these peaks were discussed by the temperature dependence of luminescence spectra for CuI material. Meanwhile, the photoluminescence spectra of CuI powder with different excitation intensity were measured and the ultrafast luminescence component of CuI crystals was warranted to be attributed to the recombination of donor acceptor pair. Furthermore, the excitation process was studied by measuring the photoluminescence excitation spectra of CuI crystals and powder.

Based on the negative temperature dependence of CuI solubility in acetonitrile solvent, a novel evaporation technique combined with increasing temperature programming was used to grow CuI crystals. It was found that the nucleation and growth of the CuI crystals can be adjusted by changing the temperature in the evaporation technique and a large transparent CuI single crystal of nearly 1 cm was first grown under a suitable temperature gradient. The growth process of the large CuI crystal in solution was then studied by measuring the evolution of the solute concentration with a spectrophotometer. The suitable temperature and solute concentration for the growth of large CuI crystals were in the range of 50–51.9 °C and 0.050–0.058 mol L−1, respectively. The variation of the CuI crystal growth mechanism at different stages was also discussed. These results could provide a useful clue to further optimize the experimental scheme to grow larger CuI crystals.

Lu2SiO5:Ce (LSO:Ce) is a well-known scintillator with high light yield, fast decay time and high density. In experiments, Li, Na and Ca are reported to influence its light yield and thermoluminescence intensity related to the oxygen vacancies in the host. The stability of Li, Na and Ca ions in LSO has been investigated using the density functional theory. Li and Na ions have lower formation energies at substitutional sites than interstitial sites. The formation energy of the defect complex of Na and the oxygen vacancy is lower than the isolated oxygen vacancy. Ca ions are found to be stable at interstitial sites and the complex of Ca and the oxygen vacancy is not as stable as the isolated oxygen vacancy. Some shallow thermodynamic transition levels are introduced by substituents. The dopants are responsible for some unoccupied states above the top of the valence band and occupied states below the bottom of the conduction band.Highlights► Na can introduce oxygen vacancies in LSO. ► Ca can suppress oxygen vacancies in LSO. ► Dopants induce unoccupied and occupied states near VBM and CBM.

•The substitutional Zn is predicted to be preferred in CuI lattice.•The substitutional Zn introduces some additional states in the band gap of CuI.•Zn is expected to enhance the concentration of copper vacancies in CuI.The structural and electronic properties of CuI doped with Zn, Ga and Al are investigated using density functional theory. The calculated results find that the solubility of the cation dopants considered is primarily determined by the difference in the electronic configurations between host and dopants. The order of the formation energy of the dopants is predicted to be E(ZnCu)>E(AlCu)>E(GaCu) in CuI. Furthermore, dopants at the octahedral interstitial sites have lower formation energies as compared to dopants located at the tetrahedral interstitial sites in the lattice. The defect complex consisting of ZnCu and the copper vacancy (ZnCu+VCu) is predicted to be preferred in the lattice, suggesting that incorporation of Zn is expected to enhance the concentration of copper vacancies in CuI.

Cerium-doped lutetium pyrosilicate (LPS:Ce) has attracted much attention for its extensive applications. However, oxygen vacancies will lower its luminescent efficiency. The charge transfer transition between cerium ions and neighboring oxygen vacancies has a long decay time. First-principles calculations on oxygen vacancies, cerium substitution and their complexes in LPS have been performed to research their influence on luminescence. The bridging-oxygen vacancy has the lowest formation energy among oxygen vacancies. We discuss the process of luminescence quenching due to oxygen vacancies. The cerium substitution is less favorable in the oxygen-rich condition. The defect complex of the cerium substitution and bridging-oxygen vacancy has the lowest formation energy among defect complexes. The charge transfer transition between cerium ions and neighboring oxygen vacancies is not related to it but to other two defect complexes. All defect complexes have high formation energies in oxygen-rich condition. We discuss the density of states of perfect and defective crystals.Highlights► Bridging-oxygen vacancy is dominant among all the oxygen vacancies. ► Ce substitution decreases with the increase of the oxygen abundance. ► Bridging-oxygen vacancy and Ce substitution complex is the dominant defect complex. ► The charge transfer transition can be suppressed under oxygen-rich condition.