Mingjun Xia

Benefiting from quantum confinement and d–d transition of Mn centers, a hybrid halide (C ₃ H ₈ N ₆ ) ₂ MnCl ₆ features a broadband red emission with a PLQY of 78.8% under 415 nm photoexcitation.

A novel gallium-based nonlinear optical (NLO) crystal without the toxic Be element, K3Sr3Li2Ga4B6O20F, was successfully realized using a chemical substitution strategy from Sr2Be2B2O7 (SBBO), in which Sr2+ and Be2+ cations are cosubstituted by K+ and Sr2+ and Li+ and Ga3+, respectively. In the structure, BO3, GaO4, (Ga/Li)O4, GaO3F, and LiO3F units are connected by shared oxygen atoms to form two distinct types of single layers, [LiGa2B3O10F] and [(Ga/Li)3B3O11]. Two adjacent [LiGa2B3O10F] single layers are coupled through bridging oxygen atoms and fluorine atoms to generate the [Li2Ga4B6O20F] double layer, and two identical [(Ga/Li)3B3O11] single layers are interconnected by sharing apical oxygen atoms to produce the [(Ga/Li)6B6O21] double layer. These two distinct types of double layers are alternately stacked perpendicular to the ab plane, forming a 3D crystal network. The powder second-harmonic-generation efficiency of the title crystal at a fundamental wavelength of 1064 nm is 1/4 of that of KH2PO4. It exhibits a broad band gap of 5.9 eV and moderate birefringence (0.073 @ 532 nm). Simulation results reveal that the shortest phase-matching threshold is 232 nm, which can be utilized for Nd-based laser fourth-harmonic-generation output.

Tunable fluorescence emission endows luminescent materials with immense applications in optoelectronic devices and information security. Herein, broad-wavelength photoluminescence (PL) tuning from yellow to white to blue is realized in a zero-dimensional (0D) K4CdCl6 halide via a facile Rb/Sn codoping strategy. Interestingly, K4CdCl6 and isostructural Rb4CdCl6 halides exhibit yellow and blue PL emissions via the homovalent doping of Sn2+, respectively. The relative intensity ratio of yellow and blue emission bands can be effectively regulated in K4CdCl6:Sn2+ halides by Rb+ alloying; accordingly, the continuous luminescence color tuning covering yellow, white, and blue spectral regions was successfully achieved. Density functional theory calculations further verify that the doping of Sn2+ leads to the appearance of an impurity energy level within the band gap, accelerates electronic transitions, and ultimately enhances PL emission efficiency. On the basis of this rationally designed tunable luminescent system, the three-level color-coded intelligent password devices, combining multimode optical anticounterfeiting and digital information encryption, were developed. This work not only develops a reliable ion doping strategy for luminescence modulation in the metal halides but also expands their diversified application prospects in advanced optoelectronic fields.

In Li ₃ GaTe ₄ O ₁₁ , high framework density and small void space confine small Li ⁺ cations, enabling pronounced steric effects that regulate Te ⁴⁺ lone-pair orientations. Small cations act as “structural mediators” in high-dimensional tellurites.

In recent years, relaxor ferroelectric single crystals (1‐x)Pb(Mg _1/3 Nb _2/3 )O ₃ ‐xPbTiO ₃ (PMN‐xPT) have been widely investigated and attracted attention due to their excellent piezoelectric and electromechanical properties. Yet, their internal microdomain structure results in low transmittance, which limits their application in optical field. In this paper, 1% mol Sm‐doped 0.7Pb(Mg _1/3 Nb _2/3 )‐0.3PbTiO ₃ (Sm‐PMN‐30PT) crystals were successfully grown by a modified Bridgman technique. Sm ^{3 +} induces nanoscale structural disorder in the crystal, significantly enhancing contribution of polar nanoregions (PNRs) to macroscopic properties. Piezoelectric, ferroelectric, and electro‐optic performances were enhanced. Electromechanical coupling coefficients k ₃₃ and k _t reach 66% and 48%, respectively. Piezoelectric coefficient d ₃₃ value of Sm‐PMN‐30PT crystal is 5800–6100 pC/N with 55 Hz test frequency. After poled along [110] direction, transmittance along [001] direction reaches 56%. Effective electro‐optic coefficient γ _c is 240 pm/V at room temperature, and it can reach 1293 pm/V near the Curie temperature (109°C). These results show that Sm‐PMN‐30PT single crystals could be ideal materials for piezoelectric and electro‐optic devices.

Owing to the outstanding photoluminescent (PL) characteristics including the broadband emission and high PL quantum yield, metal halides with robust crystal structures have promising applications in information anticounterfeiting and encryption, optical temperature sensing, optoelectronic devices, etc. However, their intrinsic luminescent thermal quenching severely limits their practical applications at high temperatures. Herein, a novel three-dimensional all-inorganic metal halide CsCd₅Cl₁₁ with the distorted octahedra was successfully synthesized. Upon doping with Sb³⁺, the CsCd₅Cl₁₁:Sb³⁺ halides exhibit antithermal quenching orange PL over the temperature range of 260-440 K. Their integrated PL intensity at 440 K can reach approximately 610% and 320% of those at 260 and 300 K, respectively. Structure and thermoluminescence analysis indicates that the luminescent antithermal quenching originates from the intrinsic structural rigidity of the octahedra in the structure and the trapped excitons absorbing thermal energy to escape from the shallow traps, thereby compensating for the thermally induced nonradiative transition losses of excitons. Moreover, the CsCd₅Cl₁₁:Sb³⁺ underlying PL luminescence mechanism was systematically elucidated by first-principles calculations. Enlightened by the adaptable optical properties, the platform of the developed halides for high-temperature visualization and anticounterfeiting is demonstrated. This work not only presents a new halide material with antithermal quenching but also broadens versatile applications in optoelectronic fields.

Gas-pressure sintering yields submillimetre BaAl _x Si _{6− x} N _{8− x} O _{1+ x} crystals through ordered [AlO]/[SiN] substitution, enhancing birefringence by over twofold and producing SHG intensity >1.5× KDP with a 240 nm UV cutoff.