Interface and Defect Engineering Enable Fast and High-efficiency Li Extraction of Metatitanic Acid Adsorbent

Graphitic carbon nitride (g-C3N4) with a porous nano-structure, nitrogen vacancies, and oxygen-doping was prepared by the calcination method. Then, it was combined with ZnIn2S4 nanosheets containing zinc vacancies to construct a three-dimensional (3D) flower-like Z-scheme heterojunction (pCN-N/ZIS-Z), which was used for photocatalytic hydrogen evolution and the degradation of mixed pollutants. The constructed Z-scheme heterojunction improved the efficiency of photogenerated charges separation and migration, and the large surface area and porous characteristics provided more active sites. Doping and defect engineering can change the bandgap structure to improve the utilization of visible light, and can also capture photogenerated electrons to inhibit recombination, so as to promote the use of photogenerated electron-hole pairs in the photocatalytic redox process. Heterojunction and defect engineering synergized to form a continuous and efficient conductive operation framework, which achieves the hydrogen production of pCN-N/ZIS-Z (9189.8 µmol·h−1·g−1) at 58.9 times that of g-C3N4 (155.9 µmol·h−1·g−1), and the degradation rates of methyl orange and metronidazole in the mixed solution were 98.7% and 92.5%, respectively. Our research provides potential ideas for constructing a green and environmentally friendly Z-scheme heterojunction catalyst based on defect engineering to address the energy crisis and environmental restoration.

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Defect‐Engineering‐Enabled High‐Efficiency All‐Inorganic Perovskite Solar Cells

Advanced Materials ◽

10.1002/adma.201903448 ◽

2019 ◽

Vol 31 (51) ◽

pp. 1903448 ◽

Cited By ~ 26

Author(s):

Jia Liang ◽

Xiao Han ◽

Ji‐Hui Yang ◽

Boyu Zhang ◽

Qiyi Fang ◽

...

Keyword(s):

Solar Cells ◽

High Efficiency ◽

Perovskite Solar Cells ◽

Defect Engineering ◽

Inorganic Perovskite

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Magnetic Resonance Study of Non-Equivalent Centers Created by 4f-Ions in Congruent and Stoichiometric Lithium Niobate

MRS Proceedings ◽

10.1557/proc-1111-d01-03 ◽

2008 ◽

Vol 1111 ◽

Cited By ~ 1

Author(s):

Galina Malovichko ◽

Valentin Grachev ◽

Jonathan Jorgensen ◽

Martin Meyer ◽

Mark Munro ◽

...

Keyword(s):

Lithium Niobate ◽

Frequency Conversion ◽

High Efficiency ◽

Telecommunication Network ◽

Charge Compensation ◽

Defect Engineering ◽

Impurity Site ◽

All Optical ◽

Charge Excess ◽

Low Symmetry

AbstractLithium Niobate doped with 4f-ions is of great interest for both fundamental science and advanced applications including high efficiency lasers with frequency conversion, elements for an all-optical telecommunication network and quantum cryptography. Our study has shown that 4f-ions create an unexpected variety of completely different non-equivalent centers in both stoichiometric and lithium deficient congruent crystals. Dominant Nd1 and Yb1 centers have C3 point symmetry (axial center), whereas all Er and most other Nd and Yb centers have the lowest C1 symmetry. Distant defects create small distortions of the crystal field at the impurity site, which cause line broadening, but do not change the C3 symmetry of observed EPR spectra. Defects in the near neighborhood can lower center symmetry from C3 to C1. We concluded that Nd1 has distant charge compensation, whereas the charge excess in low-symmetry Nd(Li) centers is compensated by near lithium or niobium vacancies. Since no axial centers were found for Er, models with cation vacancies can not describe our experimental data. The dominant axial Yb1 center has no defects in its surrounding. One axial and one low-symmetry Yb centers are self compensating Yb(Li)-Yb(Nb) pairs. Six other centers are different complexes of Yb3+ and intrinsic defects. Obtained data can be used for defect engineering for tailoring properties of photonic materials.

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Microcalorimeters for X-Ray Spectroscopy

International Astronomical Union Colloquium ◽

10.1017/s0252921100107365 ◽

1988 ◽

Vol 102 ◽

pp. 41

Author(s):

E. Silver ◽

C. Hailey ◽

S. Labov ◽

N. Madden ◽

D. Landis ◽

...

Keyword(s):

High Resolution ◽

High Efficiency ◽

Thermal Response ◽

Low Noise ◽

High Resolution Spectroscopy ◽

Superconducting Transition ◽

Sapphire Substrates ◽

Laboratory Plasmas ◽

Adiabatic Demagnetization ◽

Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

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Imaging and diffraction modes in Scanning Transmission Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144814 ◽

1986 ◽

Vol 44 ◽

pp. 684-687

Author(s):

J. M. Cowley ◽

R. Glaisher ◽

J. A. Lin ◽

H.-J. Ou

Keyword(s):

Scanning Transmission Electron Microscopy ◽

High Efficiency ◽

Fiber Optic ◽

Image Intensifier ◽

Detector System ◽

Detector Plane ◽

Secondary Electrons ◽

Transmission Electron ◽

Scanning Transmission ◽

Special Detector

Some of the most important applications of STEM depend on the variety of imaging and diffraction made possible by the versatility of the detector system and the serial nature, of the image acquisition. A special detector system, previously described, has been added to our STEM instrument to allow us to take full advantage of this versatility. In this, the diffraction pattern in the detector plane may be formed on either of two phosphor screens, one with P47 (very fast) phosphor and the other with P20 (high efficiency) phosphor. The light from the phosphor is conveyed through a fiber-optic rod to an image intensifier and TV system and may be photographed, recorded on videotape, or stored digitally on a frame store. The P47 screen has a hole through it to allow electrons to enter a Gatan EELS spectrometer. Recently a modified SEM detector has been added so that high resolution (10Å) imaging with secondary electrons may be used in conjunction with other modes.

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Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118692 ◽

1985 ◽

Vol 43 ◽

pp. 364-365

Author(s):

K.M. Hones ◽

P. Sheldon ◽

B.G. Yacobi ◽

A. Mason

Keyword(s):

High Efficiency ◽

Lattice Mismatch ◽

Low Cost ◽

Growth Conditions ◽

Nonradiative Recombination ◽

Device Structure ◽

Si Substrates ◽

Transmission Electron ◽

Dislocation Densities ◽

Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

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