Non-linear optical chalcogenides with a wide band gap (Eg) and excellent NLO properties are key materials for highly desirable multiwaveband tunable optical parametric oscillators (OPOs). We exploit the "electronic structure engineer bucket effect" to develop a novel dual-waveband SrZnGeS4 with an ultrawide transparency window. It exhibits an asymmetric Fdd2 structure that consists of layers formed by corner-sharing [ZnGeS6] dimers. SrZnGeS4 is transparent from 0.30 to 23.6 μm, spanning the UV-, vis-, mid- and far-IR spectral regions and has the widest Eg (3.63 eV) in the AeMIIMIVQ4 family to date. It exhibits phase matching, high SHG intensities (e.g., 11.0 × KDP and 17.5 × AGS under λinc = 1450 and 950 nm, respectively), and a very high laser-induced damage threshold (35 × AGS). These results not only suggest bright prospects for high-power laser applications but may also enable applications of the multiwaveband OPO system from the UV-visible to far-IR regions.

SrZnGeS4: A Dual-Waveband Nonlinear Material With A Transparency Spanning UV-Vis and Far-IR Spectral Regions.

Energy storage enhancement of paraffin with a solar-absorptive rGO@Ni film in a controllable magnetic field

Gallium telluride (GaTe) is a van der Waals semiconductor, currently adopted for photonic and optoelectronic devices. However, the rapid degradation of GaTe in air, promoted by Te vacancies, is detrimental for device applications. Here, it is demonstrate that the surface oxidation of GaTe can be unexpectedly exploited for expanding the breadth of applications of GaTe. Specifically, the formation of a nanoscale sub‐stoichiometric wide‐band‐gap Ga2O3 skin, promoted by Te vacancies, over narrow‐band‐gap GaTex upon air exposure is beneficial for electrocatalysis, photocatalysis, and gas sensing . In particular, the Heyrovsky step (Hads + H+ + e− → H2) of hydrogen evolution reaction in an acidic medium is barrier‐free for the sub‐stoichiometric gallium‐oxide/gallium‐telluride heterostructure, which also enables a significant reduction of costs with respect to state‐of‐the‐art Pt/C electrodes. In the photocatalytic process, the photo‐generated electrons migrate from GaTe to Ga2Ox skin, which acts as the chemically active side of the interface. Moreover, the Ga2O3/GaTe heterostructure is a suitable platform for sensing of H2O, NH3, and NO2 at operational temperatures extended up to 600 °C (useful for gas detection in combustion processes), mainly due to the increased area of charge redistribution after adsorption achieved upon oxidation of GaTe.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/adfm.202205923

Improving the Efficiency of Gallium Telluride for Photocatalysis, Electrocatalysis, and Chemical Sensing through Defects Engineering and Interfacing with its Native Oxide

Preparation of silver nanoparticles decorated mesoporous silica nanorods with photothermal antibacterial property

Synthesis of copper nanoparticles with controllable crystallinity and their photothermal property

Transition metal dichalcogenides (TMDs) are of great promise for various nonlinear optical (NLO) applications due to their unique electronic and optoelectronic properties, such as tunable optical bandgap, strong spin–orbit coupling, and exciton effects. However, the desired NLO performances of regular 2H‐TMDs are usually restricted by their limited absorption at atomic thickness. With this regard, a structurally novel spiral MoTe2 (s‐MoTe2) nanopyramids is reported with unique and superior NLO response, enabled by their broken inversion symmetry, weak interlayer coupling, exciton resonance, and strong light–matter interaction from the edge‐rich 3R‐like quasi‐multilayer structure. The excellent NLO response over a wide spectral range from the near‐infrared to visible region is demonstrated, where second‐ and third‐order NLO responses have been simultaneously observed. Moreover, the second‐order nonlinear susceptibility of s‐MoTe2 is estimated to be around 1–2 order(s) of magnitude larger than those of most reported TMDs. The demonstration of a superior NLO response in such s‐MoTe2 not only paves a new way for designing the best NLO TMD structures, but also greatly prompts their practical applications in micro–nano NLO devices on chips in future.

Superior Nonlinear Optical Response in Non‐Centrosymmetric Stacking Edge‐Rich Spiral MoTe2 Nanopyramids

In this work, the effects of neutron irradiation and high temperature on the magnetic properties and structure of Sm2Co17 permanent magnets (PMs) were investigated. The phase composition in Sm2Co17 PMs does not change after neutron irradiation with fluence of 5 × 1014n/cm2. The magnetic domain structure and Mössbauer spectra of Sm2Co17 PMs were almost kept the same after neutron irradiation. The neutron irradiation almost does not influence the intrinsic coercivity and magnetic flux ϕ of Sm2Co17 PMs. When temperatures increase from room temperature to 300 °C, intrinsic coercivity Hcj, remanence Br and maximum energy product (BH)max have 52.8 %, 5.6 % and 15.4 % deterioration, respectively. Magnetic flux ϕ decreases by 4.1 %. When temperature increases to 550 °C, compared with room temperature, Hcj, Br and (BH)max decrease 88.8 %, 21.8 % and 54.3 %, respectively. ϕ has a 40 % deterioration. 

Effects of neutron irradiation and high temperature on structure and magnetic properties of Sm2Co17 permanent magnet

BiFeO3-BaTiO3 (BF-BT)-based lead-free piezoceramics are desired materials for high-temperature applications of piezoelectric sensors with a high Curie temperature and good piezoelectric properties. Recent studies have shown that oxygen vacancies have a significant effect on electrostrain and piezoelectric properties. Interestingly, two different phenomena exist, i.e., the increase in piezoelectric properties is often associated with a decrease in the concentration of oxygen vacancies, while the increase in electrostrain is often associated with an increase in the concentration of oxygen vacancies. Especially, for BF-based ceramics, the physical mechanisms related to property differences caused by oxygen vacancies are rarely reported, which needs further exploration. Here, two ceramics with differences in their oxygen vacancy concentrations are designed. Based on Rayleigh analysis, thermal/electric field-induced domain response (ferroelectric scaling), and macro-microstructural characterization, we can conclude that the transient piezoelectric response and the aging process are significantly affected by the oxygen vacancy concentration. In other words, the increasing concentration of oxygen vacancies in BF-BT ceramics enhances the reversible piezoelectric response contributed by lattice distortion and strengthens the response of domain switching and domain wall motion to electric and thermal fields but deteriorates their aging behavior, which leads to the degradation of piezoelectric performance. Besides, polarization saturation and defect pegging significantly improve the temperature stability of the strain.

Establishing a Relationship between the Piezoelectric Response and Oxygen Vacancies in Lead-Free Piezoelectrics.

Cerium-substituted yttrium iron garnet (Ce:YIG) thin films are promising magneto-optical (MO) materials for the application in optical isolators. Ce:YIG can be grown on the YIG seed layer, and the change of layer thickness ratio for Ce:YIG to YIG may result in different magnetic properties. In this work, Ce:YIG (Ce1Y2Fe5O12) to YIG (Y3Fe5O12) bilayer films, with different thickness ratios of 2:1, 4:1, 6:1, and 8:1, were grown by pulsed laser deposition (PLD); 2:1 and 4:1 films consist of pure YIG phase; 6:1 and 8:1 films consist of YIG phase, Y2Fe4O9 phase with hexagonal structure, and Y2O3 phase with cubic structure. Y2Fe4O9 and Y2O3 phases induce the decrease of saturation magnetization (<inline-formula> <tex-math notation="LaTeX">$M_{s}$ </tex-math></inline-formula>). The concentration of Fe2+ and Ce4+ ions increases with layer thickness ratio increasing, resulting in the decrease of saturation magnetization (<inline-formula> <tex-math notation="LaTeX">$M_{s}$ </tex-math></inline-formula>), coercivity (<inline-formula> <tex-math notation="LaTeX">$H_{c}$ </tex-math></inline-formula>), and magnetic anisotropy energy (<inline-formula> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula>). It is found that the best magnetic properties, including <inline-formula> <tex-math notation="LaTeX">$H_{c}$ </tex-math></inline-formula> (26.9 Oe), <inline-formula> <tex-math notation="LaTeX">$M_{s}$ </tex-math></inline-formula> (140.6 emu/cm3), and <inline-formula> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> (257.5 J/cm3), are obtained in the 2:1 film.

Xuanhong Zhao

Papers

Synthesis of copper nanoparticles with controllable crystallinity and their photothermal property

Superior Nonlinear Optical Response in Non‐Centrosymmetric Stacking Edge‐Rich Spiral MoTe2 Nanopyramids

Effects of neutron irradiation and high temperature on structure and magnetic properties of Sm2Co17 permanent magnet

Establishing a Relationship between the Piezoelectric Response and Oxygen Vacancies in Lead-Free Piezoelectrics.

Microstructures and Magnetic Properties of Single-Step Deposited Ce:YIG/YIG Bilayer Films With Different Layer Thickness Ratios