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Herein, Cr3+ and Er3+ codoped zinc gallogermanate (ZGGO) nanoparticles with average size of ~60 nm was synthesized via a hydrothermal path. It was found that near infrared (NIR)‐III (~1540 nm) afterglow was realized in ZGGO:Cr3+,Er3+ nanoparticles based on the successive energy transfer (ET) from Cr3+ to Er3+ after the stoppage of low‐dose (60 mSv) X‐ray irradiation. Meanwhile, the upconverted afterglow at 696 nm was produced via the ET from Er3+ to Cr3+ under different NIR light (808, 980, and 1532 nm) irradiations. Our results demonstrated that an X‐ray pre‐irradiation and a subsequent 980‐nm light re‐excitation might be a good strategy for realizing potential bioimaging. In particular, local‐tissue NIR‐I afterglow imaging using Cr3+ and Er3+ codoped ZGGO nanoparticles can be easily acquired by one‐step 980‐nm laser radiation. Furthermore, NIR‐I/III afterglow mechanisms of ZGGO:Cr3+,Er3+ nanoparticles after stopping X‐ray or different NIR lights (808, 980, and 1532 nm) irradiations were given. [ABSTRACT FROM AUTHOR]

Addressable flat-panel x-ray source has important applications in next-generation low-dose x-ray imaging technology. In this study, a fully vacuum-sealed addressable flat-panel x-ray source has been fabricated using a ZnO nanowire cold cathode. The x-ray source was formed by assembling gated ZnO nanowire field emitters and a molybdenum thin film transmission anode target. Pulsed and addressable x-ray emission was achieved by applying voltages to the extraction gate. Radiation dose rates of 235 nGy/s were achieved when the device was operated at 21 kV anode voltage and 140 V gate voltage. Projection x-ray images of objects were obtained by the flat-panel x-ray source. Our results demonstrated the feasibility of a fully addressable cold cathode flat-panel x-ray source. [ABSTRACT FROM AUTHOR]

A fully vacuum-sealed flat-panel X-ray source was fabricated composed of molybdenum metal anode and ZnO nanowire field emitters array cathode. The cathode current and X-ray radiation dose rate of the device were measured when the anode is applied with direct current (DC) and pulsed voltage, respectively. It is found that the peak emission current and corresponding dose rate under pulsed voltage driving are much higher than those under DC voltage driving. The phenomena may be explained by a plasma induced field emission enhancement related to the electron bombardment induced gas desorption. Clear projection X-ray imaging of moving objects was obtained using pulsed voltage driving. The result shows that owing to the enhanced emission current driven by the pulsed voltage, the flat-panel X-ray source can achieve fast and clear imaging of high-speed moving objects. Our results are of significance for the application of large area flat-panel X-ray source in dynamic imaging. • Fully vacuum-sealed diode-structure flat-panel X-ray source was fabricated using ZnO nanowire field emitters arrays. • Peak emission current and dose rate under pulsed voltage driving are observed to be higher than that under DC voltage. • The enhanced emission current was explained by plasma induced emission enhancement. • Clear imaging of high-speed moving objects was achieved using the pulsed voltage driving flat-panel X-ray source. [ABSTRACT FROM AUTHOR]

Large-area zinc oxide (ZnO) nanowire arrays have important applications in flat-panel X-ray sources and detectors. Doping is an effective way to enhance the emission current by changing the nanowire conductivity and the lattice structure. In this paper, large-area indium-doped ZnO nanowire arrays were prepared on indium-tin-oxide-coated glass substrates by the thermal oxidation method. Doping with indium concentrations up to 1 at% was achieved by directly oxidizing the In-Zn alloy thin film. The growth process was subsequently explained using a self-catalytic vapor-liquid-solid growth mechanism. The field emission measurements show that a high emission current of ~20 mA could be obtained from large-area In-doped sample with a 4.8 × 4.8 cm2 area. This high emission current was attributed to the high crystallinity and conductivity change induced by the indium dopants. Furthermore, the application of these In-doped ZnO nanowire arrays in a flat-panel X-ray source was realized and distinct X-ray imaging was demonstrated. [ABSTRACT FROM AUTHOR]