Rare-earth (RE)-based frustrated magnets are fertile playgrounds for discovering exotic quantum phenomena and exploring adiabatic demagnetization refrigeration applications. Here, we report the synthesis, structure, and magnetic properties of a family of rare-earth cyanurates RE5(C3N3O3)(OH)(12) (RE = Gd-Lu) with an acentric space group P62m. Magnetic susceptibility chi(T) and isothermal magnetization M(H) measurements manifest that RE5(C3N3O3)(OH)(12) (RE = Gd, Dy-Yb) compounds exhibit no magnetic ordering down to 2 K, while Tb-5(C3N3O3)(OH)(12) shows long-range magnetic ordering around 3.6 K. Among them, magnetically frustrated spin-(7)/(2) Gd-5(C3N3O3)(OH)(12) shows long-range magnetic ordering around 1.25 K and a large magnetocaloric effect with a maximum magnetic entropy change Delta S-m of up to 58.1 J kg(-1) K-1 at Delta H = 7 T at liquid-helium temperature regimes.

Utilizing the asymmetry of the micro-nano structure to excite Fano resonance in dielectric metasurfaces presents low loss and high field enhancement factors, and has a broad range of applications in optical sensing. Nevertheless, the asymmetry of the structure often leads to polarization-sensitive characteristics, significantly reducing the quality factor and sensitivity of the metasurface, thereby hindering its further application. In this study, the metasurface composed of dielectric materials is designed to be completely insensitive to x and y polarization. The metasurface is composed of semicircular disks, which are asymmetrically and periodically placed on a quartz substrate. By controlling the radius of the two semicircular disks, the symmetry is broken, and the bound states in the continuum (BIC) transition to quasi-bound states in the continuum (q-BIC), resulting in an ultra-narrow Fano resonance peak. Simulation results show that the magnetic dipole (MD) dominates the resonance. The designed metasurface structure was fabricated and then integrated into a microfluidic system for spectral refractive index sensing experiments. In the near-infrared band, our tests demonstrate refractive index sensing performance of 405 nm/RIU and a Q factor of up to 319, with significant symmetry of the polarization angle, which agrees well with theoretical simulations. Furthermore, the spectral response of the designed structure can be flexibly controlled by adjusting the polarization angle of the incident light. We believe that this study provides a novel integrated platform for applications such as biosensing and environmental detection, and also has certain reference value for the design of polarization optical switches and metasurface absorbers for encrypted communication.

The metasurface refractive index sensor has a high degree of tunability and flexibility, providing excellent performance for high precision refractive index sensing applications. The metasurface absorber with metallic structure has been hindered in further sensor applications due to the inherent Ohmic loss of the metallic material. In this study, a dual nanorod metasurface structure based on semiconductor Si was designed, introducing a symmetry-breaking structure to excite dual ultra-narrow q-BIC resonance peaks with Fano line shapes. Both peaks are located in the near-infrared region, and multipole analysis shows that this strong field enhancement effect is induced by a magnetic dipole. Experimental results demonstrate the potential of this sensor to provide dual-channel detection while achieving high sensitivity and high Q-factor. We believe that this device exhibits outstanding performance and high practicality, providing a reference for the development and application of biological and environmental sensors.

Three polymorphisms and two-step phase transitions of LiCdBO3 were investigated by the combination of powder X-ray diffraction, thermal analysis experimental techniques and the first principles calculations for the first time. The SHG switching was also achieved with a NLO switching contrast of about 625, indicating the potential applications in the sensors and optoelectronics.Image 1

Herein we report the facile syntheses of tetrazoles enabled by FSO2N3 under mild conditions. FSO2N3 has been shown as the most powerful diazotizing reagent, which converts thousands of primary amines to azides fast and orthogonally. As the follow-up studies of the diazo transfer reaction using FSO2N3, we discover that amidines and guanidines are rapidly transformed into tetrazole derivatives when reacting with FSO2N3 under an aqueous environment, which is unprecedented for tetrazole synthesis.

Nonlinear optical (NLO) crystal, simultaneously exhibits second-harmonic generation response and linear electric-optical (EO) susceptibility, is of great significance for optoelectronics due to its frequency extension technique and optical modulation effect. In this paper, the growth system of K3B6O10Br (KBB) crystal in the green-flux K2MoO4–KBF4 was systematically investigated to get rid of the non-intrinsic absorption in the ultraviolet wavelength range, which is beneficial for high-power applications. Bulk KBB NLO crystals were successfully grown by the top-seeded solution growth method from different fluxes for comparison. Moreover, the electro-optical (EO) property of KBB crystal was explored, and the effective EO coefficient γ22 along transverse modulation was determined to be 1.10 p.m./V.