A simple adduct from tin tetraiodide SnI4 and octasulfur S8, SnI4⋅(S8)2 (1), is obtained employing a facile reaction. The combination of Sn4+ ions with d10 electron configuration, acentric SnI4 ...tetrahedra, and lone‐pair effects of S8, makes 1 a phase‐matchable infrared NLO crystal with a moderate second‐harmonic generation (SHG) response and a very high laser‐induced damage threshold (LIDT), which is well confirmed by the DFT calculations.
The adduct SnI4⋅(S8)2, obtained by a solid‐state reaction, shows a moderate nonlinear optical (NLO) intensity and a large laser induced damage threshold (LIDT). Its phase‐matchable character and wide IR transparency make it a very promising IR NLO crystal, comparable to the benchmark system AgGaS2 (AGS).
A big challenge for nonlinear optical (NLO) materials is the application in high power lasers, which needs the simultaneous occurrence of large second harmonic generation (SHG) and high laser induced ...damage threshold (LIDT). Herein we report the preparation of a new Ga2Se3 phase, which shows the SHG intensities of around 2.3 times and the LIDT of around 16.7 times those of AgGaS2 (AGS), respectively. In addition, its IR transparent window ca. 0.59–25 μm is also significantly wider than that of AGS (ca. 0.48–≈11.4 μm). The occurrence of the strong SHG responses and good phase‐matching indicate that the structure of the new Ga2Se3 phase can only be non‐centrosymmetric and have a lower symmetry than the cubic γ‐phase. The observed excellent SHG and phase‐matching properties are consistent with our diffraction experiments and can be well explained by using the orthorhombic models obtained through our high throughput simulations.
A simple but perfect case: A new phase of gallium selenides (δ‐Ga2Se3) has been obtained via solid‐state reactions. δ‐Ga2Se3 is phase‐matchable with large second harmonic generation (SHG) responses, high laser‐induced damage thresholds (LIDTs), and wide transparent range of 0.59–25 μm. These properties are all required for the application of NLO materials with high‐power lasers.
Using a panel sample from the Panel Study Income Dynamics (1999–2015), I find that homeowners' contemporaneous spending and nonhome wealth increased with home equity withdrawals, but their longer ...term spending and wealth declined if their home equity was extracted during the housing boom period. Following Hurst and Stafford's (2004) definition of liquidity constraint, I find that the constrained homeowners' contemporaneous spending increased less, while their financial wealth increased more than those of the unconstrained. Unconstrained homeowners invested more than constrained homeowners in nonhome real estate and businesses. In the long run, the consumption spending of both groups persistently declined, while their wealth recovered from initial declines.
The electrocaloric effect (ECE) in dielectric materials has great potential in realizing solid‐state cooling devices with compact size and high efficiency, which are highly desirable for a broad ...range of applications. This paper presents the general considerations for dielectric materials to achieve large ECE and reviews the experimental efforts investigating ECE in various polar dielectrics. For practical cooling devices, an ECE material must possess a large isothermal entropy change besides a large adiabatic temperature change. We show that polar dielectrics operated at temperatures near order–disorder transition have potential to achieve large ECE due to the possibility of large change in polarization induced by electric field and large entropy change associated with the polarization change. We further show that indeed the ferroelectric poly(vinylidene fluoride–trifluoroethylene)‐based polymers display a large ECE, i.e., an isothermal entropy change of more than 55 J (kgK)−1 and an adiabatic temperature change of more than 12 °C, at temperatures above the order–disorder transition.
Applying an electrical field to a dielectric may induce a large entropy and temperature change which is attractive for solid‐state cooling. We present the general considerations and review the experimental efforts to achieve large electrocaloric effect (ECE) in dielectrics. We show that by operating above the order‐disorder transitions, a large ECE can be achieved in a ferroelectric polymer.
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•Recent achievements on three main types of middle and far-infrared NLO materials are reviewed.•Materials with double types of anion are promising.•Alkali-metal and Ba chalcogenides ...are studied extensively.•Functional moiety theory is employed to help exploration of NLO materials.
The exploration and development of second-order nonlinear optical (NLO) materials in the middle- and far infrared (MFIR) region are important and high profile topics in the fields of NLO, solid-state chemistry and laser. Common MFIR NLO materials are chalcogenides, halides, and iodates, which have a wide MFIR transparent range and large NLO coefficients. This review summarizes recent achievements on MFIR NLO materials, and specifically focuses on their crystal structures and NLO properties. Compared to known materials, the common choice for cations are alkali-metal Li, Na, K, Rb and Cs, the coin-metal Ag, and the alkali-earth metal Ba. Exploring mixed-anions materials could be one of the most promising solutions to obtaining NLO materials with both large second-harmonic generation (SHG) intensities and high laser induced damage thresholds (LIDTs). This review also summarizes functional moiety theory to elucidate the design of promising NLO materials.
Single-molecule magnets (SMMs) containing only one metal center may represent the lower size limit for molecule-based magnetic information storage materials. Their current drawback is that all SMMs ...require liquid-helium cooling to show magnetic memory effects. We now report a chemical strategy to access the dysprosium metallocene cation (Cp
)Dy(Cp*)
(Cp
, penta-iso-propylcyclopentadienyl; Cp
pentamethylcyclopentadienyl), which displays magnetic hysteresis above liquid-nitrogen temperatures. An effective energy barrier to reversal of the magnetization of
= 1541 wave number is also measured. The magnetic blocking temperature of
= 80 kelvin for this cation overcomes an essential barrier toward the development of nanomagnet devices that function at practical temperatures.
Oxygen‐containing heterocycles are an important class of compounds with diverse biological activities. In recent years, direct α‐C–H functionalization of inexpensive and abundant readily available ...ethers and alcohols by oxidative radical cross‐coupling with different nucleophilic partners (C–H, N–H, O–H and S–S), leading to the construction of C–C and C–X (X=C, N, O, S) bonds, has emerged as one of the vital strategies among oxidative cross‐coupling reactions. Owing to the features of being atom‐economic, environmentally benign, having a simple operation and biologically properties, a series of ether α‐C(sp3)–H bond activation reactions have been developed by metal or metal‐free systems via the radical oxidative coupling pathway, since the radical oxidative coupling reactions have wide range of applications. This review aims to highlight the recent advances in direct α‐C(sp3)–H bond functionalization of ethers and alcohols via radical oxidative process.
Infrared nonlinear optical (IR NLO) materials are significant in laser technology for civil and military uses. Here, we report the synthesis, structural chemistry and NLO properties of a halogen‐rich ...chalcohalide Sn7Br10S2. Its noncentrosymmetric (NCS, P63) structure can be considered as partially aliovalent anion substitution of SnBr2 (P63/m) induced centrosymmetric (CS) to NCS structural transformation. The 3D ∞Sn(1)6Sn(2)6Br6X66− (X=Br/S) channel framework consists of Sn(1)BrX2 and Sn(2)X3 trigonal pyramids. It exhibits excellent NLO performance, including a strong phase‐matchable NLO response of 1.5 × AgGaS2and high laser‐induced damage threshold of 6.3 × AgGaS2.Investigation of the structure–NLO performance relationship confirms that the effective arrangement of Sn(1)BrX2 and Sn(2)X3 units predominantly contributes to the large SHG response. These results indicate Sn7Br10S2 is a potential IR NLO candidate and provides a new feasible system for promising NLO materials.
The first ternary halogen‐rich nonlinear optical chalcohalide Sn7Br10S2 exhibits a strong phase‐matchable second‐harmonic generation response (1.5 × AGS@2.1 μm) and high laser‐induced damage threshold (6.3 × AGS). This work provides a competitive candidate with good performance, facile synthesis and simple chemical composition for infrared nonlinear optical (IR NLO) applications, and also introduces a facile strategy to obtain high‐performance NLO materials via a symmetry break.
Host–guest complexation between calix5arene and aggregation‐induced emission luminogen (AIEgen) can significantly turn off both the energy dissipation pathways of intersystem crossing and thermal ...deactivation, enabling the absorbed excitation energy to mostly focus on fluorescence emission. The co‐assembly of calix5arene amphiphiles and AIEgens affords highly emissive supramolecular AIE nanodots thanks to their interaction severely restricting the intramolecular motion of AIEgens, which also show negligible generation of cytotoxic reactive oxygen species. In vivo studies with a peritoneal carcinomatosis‐bearing mouse model indicate that such supramolecular AIE dots have rather low in vivo side toxicity and can serve as a superior fluorescent bioprobe for ultrasensitive fluorescence image‐guided cancer surgery.
Calix5arene‐based supramolecular AIE nanodots were synthesized with high quantum yields in water by virtue of the host–guest complexation. The absorbed excitation energy was mostly focused on fluorescence emission, leading to an ultrahigh signal‐to‐background ratio in fluorescence‐image‐guided cancer surgery.
Metal chalcogenophosphates are receiving increasing interest, specifically as promising infrared nonlinear optical (NLO) candidates. Here, a rare‐earth chalcogenophosphate Eu2P2S6 crystallizing in ...the monoclinic noncentrosymmetric space group Pn was synthesized using a high‐temperature solid‐state method. Its structure features isolated P2S64− dimer, and two types of EuS8 bicapped triangular prisms. Eu2P2S6 exhibits a phase‐matchable second‐harmonic generation (SHG) response ≈0.9×AgGaS2@2.1 μm, and high laser‐induced damage threshold of 3.4×AgGaS2, representing the first rare‐earth NLO chalcogenophosphate. The theoretical calculation result suggests that the SHG response is ascribed to the synergetic contribution of P2S64− dimers and EuS8 bicapped triangular prisms. This work provides not only a promising high‐performance infrared NLO material, but also opens the avenue for exploring rare‐earth chalcogenophosphates as potential IR NLO materials.
Eu2P2S6 exhibits excellent NLO properties, including a phase‐matchable second‐harmonic generation (SHG) response ≈0.9×AgGaS2@2.1 μm, and a high laser‐induced damage threshold of 3.4×AgGaS2. Eu2P2S6 is the first NLO‐active rare‐earth‐based chalcogenophosphate.
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