A new non-centrosymmetric polyborate, Li₅Rb₂B₇O₁₄, has been synthesized. The structure of the title compound was solved by single-crystal X-ray diffraction analysis. The infinite three-dimensional structure of Li₅Rb₂B₇O₁₄ is constructed from bridged LiO_n (n = 4, 5, 6) and RbO₁₀ polyhedra with two kinds of one-dimensional B–O chain fundamental building blocks through their vertex oxygen atoms. It melts congruently and exhibits a short-wavelength absorption onset at 190 nm. The feature of a short UV cut off edge is favourable in practical applications. The calculated band structure and the density of states of Li₅Rb₂B₇O₁₄ suggest that its indirect energy gap is 4.247 eV. The materials have also been characterized by infrared spectroscopy and thermal analysis.

Reconfigurable intelligent surface (RIS) is an emerging technique employing metasurface to reflect the signal from the source node to the destination node. Essentially, RIS can be considered as a passive relay between the source and destination node. By contrast, relay node in a traditional network has to be active, consuming energy when it is relaying the signal or information. It is worth investigating the differences between RIS and relay. In this paper, we compare the performances between RIS and active relay for a general multiple-input multiple-output (MIMO) system. To make the comparison fair and comprehensive, both the performances of RIS and active relay are optimized with best-effort, by formulating a non-convex optimization problem respectively. In case of RIS, transmit beamforming and reflecting coefficients are jointly optimized. In case of active relay including half-duplex relay and full-duplex relay, transmit beamforming for both source and relay are optimized. The original nonconvex optimization problems are transformed into to a weighted mean-square error (MSE) minimization problem and solved by the proposed alternating optimization algorithm, respectively. Numerical results are presented to demonstrate the validity of the proposed algorithm.

For ternary borates containing BO₃planar triangles only, α-/β-TM₃(BO₃)₂(TM = Zn, Cd), Cd₂B₂O₅, and M₃(BO₃)₂(M = Hg, Mg, Ca, Sr), a large optical permittivity Δεmakes a positive contribution to the birefringence Δn.

Pb_3.5GeS₄Br₃ is the first phase-matching thiogermanate halide infrared nonlinear optical material.

CdF(C ₆ H ₄ NO ₂ )(H ₂ O) emerges as a UV nonliner optical material that exhibits unprecedented second harmonicgeneration (3.2×KDP) and birefringence (0.26@546 nm), achieved through the presence of π-conjudated rings and a distinctive “Warren truss structure”.