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The quaternary selenide Ba4GeSb2Se11 was prepared by a high-temperature solid state reaction method. Ba4GeSb2Se11 crystallizes in an acentric orthorhombic space group Cmc21 with the lattice constants a = 9.370(11) A, b = 25.850(0) A, and c = 8.798(10) A. The compound is composed of a [SbSe3]3- trigonal pyramid, [GeSbSe5]3- dimers, V-shaped Se32-, and the adjacent Ba2+ ions. It has indirect band gap of 1.35 eV and exhibits a second harmonic generation intensity of about 0.2 times that of the benchmark compound AgGaS2 at the same particle size. Interestingly, theoretical analyses show that the central Se atom of Se32- has the largest contribution (8.1%) to d31 compared to that of other Se atoms, which may be due to its easy swing in the a-axis direction.

Two-photon entangled generation is used to produce an entangled photon source which is a key and core element concerning the technology applications of quantum computing, quantum communication, and quantum precision measurement. In this work, we have deduced the formulas of dynamic susceptibility and phase-matching angle of two-photon entangled generation in nonlinear optical crystals. The formulas are employed to compute the susceptibilities and phase-matching angles of these optical processes for uniaxial and biaxial crystals. The susceptibility magnitude and phase-matching condition of two-photon entangled generation affect the performance of the source. The calculated results by these formulas are employed to study properties and estimate the performance of an entangled photon source. In this way, we discuss the phase matching among waves and working wavelength in an entangled source that affects the efficiency of satellite communication with the ground during the day and night.

Birefringence of a crystal is an important optical property. For example, birefringence is crucial to realizing phase-matching condition for nonlinear optical crystals that are applied to laser technologies. However, it is difficult to analyze the origin of birefringence and then to tune it for practical applications. Here, we developed a method to apply the Bader charge analysis to the investigation of the birefringence of crystal on an atomic scale based on the density functional theory calculation. We calculated the birefringence of nonlinear optical crystals CsPbCO3F and KSrCO3F as a demonstration using this method. It is shown that [CO3]2– and F– make opposite contributions to the birefringence for both crystals. The birefringence contributions from cations are 22 and −29% for Pb and Cs, respectively, in the CsPbCO3F crystal, while the contributions from Sr and K is −11 and −4% to the birefringence of KSrCO3F, respectively. Using this Bader charge analysis method, we can obtain the individual ion’s c...

The quaternary selenide Ba

It is still a great challenge to prepare novel CuO-based crystal materials with low-dimensional magnetic structures. A new copper oxyborate, namely, PbCu6B6O16 was synthesized and structurally characterized for the first time. Its structure features a novel 3D framework which can be considered as building from the layers of [Cu6B6O16]2−∞ interconnected by corner or edge sharing of CuO4、BO3、B2O5、and B3O7 groups, where Pb2+ cations are located in the free space within the layer. It is unexpected that the compound contains fundamental building block (FBB) formed by three different borate anionic groups, including BO3 triangle, and condensed branched BO3 triangles (B2O5 and B3O7). In particular, according to our survey, the branched B3O7 group is unprecedented. Our work provides useful information on the design and search for novel low dimensional copper borates, and also helps to strengthen the understanding of the investigation of borate structures.

The mid/far-infrared (MFIR) nonlinear optical (NLO) materials are very important for the development of new laser sources through laser frequency conversion technologies. In this work, two new noncentrosymmetric chalcogenide compounds Ba10In6Zn7S10Se16 (S10Se16) and Ba10In6Zn7Se26 (Se26) were successfully synthesized for MFIR NLO materials. They are composed of T2 super tetrahedron and show excellent comprehensive NLO performance. Their NLO coefficients are approximately 0.7 and 0.8 times of AgGaS2 at 2.05 μm, and both have high laser induced damage threshold (LIDT) about 12.3 and 10.0 times of AgGaS2, respectively. Both compounds show consistent melting characteristics, which is beneficial for the growth of large-size crystals. The band gaps, NLO coefficients, and density of states (DOS) of the crystals are calculated by first principles simulations to study the origination of NLO response, which indicates that the NLO performance of Se26 is mainly derived from tetrahedrons and supertetrahedrons composed of In/Zn and Se.

Mid- and far-infrared nonlinear optical (MFIR NLO) materials are important in modern laser technologies. However, it is very challenging to develop materials that can achieve a subtle balance between the key requirements, such as large NLO response, high laser-induced damage threshold (LIDT), wide IR transparency, and phase-matching. In this work, a new wide IR transparency (0.38–15.3 μm) NLO crystal Ba10In6Zn7S26 (SS26) is synthesized. Further, its composite system Ba10In6Zn7S26-nZnS is synthesized by eutectic reaction. In particular, Ba10In6Zn7S26-14ZnS (SS40) shows excellent balanced NLO performance that includes a large band gap of 3.05 eV, high LIDT (13.3 × AgGaS2), large second harmonic generation (SHG) response (2.1 × AgGaS2 at 2050 nm, 5.2 × KDP at 1064 nm), and wide optical transmission window (0.37–15.4 μm). Importantly, the phase-matching condition is realized for SS40 by interfaces formed between the crystal face (112) of matrix SS26 and the crystal face (111) of reinforcement cubic ZnS by top...

Explorations on a mixed metal phosphatoantimonate system led to the discovery of two new anhydrous phosphatoantimonates, namely, Cs4MSb6P4O28 (M=Mg, Zn), which represent the first examples of quinary AI – MII –SbV – PV– O systems. Single-crystal structure analysis reveals that the two title compounds crystallize in the tetragonal space group I41/a (No. 88). Their structures feature complicated 3D frameworks with interesting tunnel structures comprised of corner sharing MO4 tetrahedra, SbO6 octahedra and PO4 tetrahedra, with the Cs+ cations sitting in the tunnels to balance the valence. Optical reflectance spectrum measurements show that these two compounds are insulators with band gaps of about 4.5 eV.

Two new selenite chlorides: Ba2Zn(SeO3)2Cl2 and BaZn2(SeO3)2Cl2 in the Ba-Zn-Se-oxychloride system have been synthesized from hydrothermal reaction. Ba2Zn(SeO3)2Cl2 crystalizes in a one-dimensional structure with 1D ∞1[Zn(SeO3)2Cl2]4- anionic chain composed of ZnO4Cl2 octahedra and lone-paired Ψ-SeO3 pyramids through sharing corner-oxygen atoms. BaZn2(SeO3)2Cl2 crystalizes in a double-layered architecture with 2D ∞2[Zn2(SeO3)2Cl2]2- anionic layer built up of SeO3 pyramids and ZnO3Cl tetrahedra through corner-sharing manner. Thermal properties of the title compounds were analyzed by means of thermogravimetric (TG) and differential scanning calorimetric (DSC) measurements. UV–Vis–NIR diffuse reflectance examinations for powder examples indicate that two compounds feature similar optical absorption spectra, and their optical band gaps can be estimated to be ~ 5.5 eV with direct band gap. Furthermore, the first-principal calculations were performed to investigate the electronic band structures and density of states, and the results further interpreted the relationship between crystal structures and optical properties.

To investigate the clinical efficacy of total hip arthroplasty (THA) via the direct anterior approach (DAA) for the treatment of hip ankylosis in the lateral position.A retrospective analysis was performed on the clinical data of 24 patients (39 hips) who underwent THA via the DAA in the lateral position for the treatment of hip ankylosis between January 2016 and December 2018. We performed bilateral THA for fifteen patients and unilateral THA for nine patients. Operation time, intraoperative blood loss, length of incisions, straight leg-raising time, length of postoperative hospital stay, operation-related complication, prosthesis position, radiological outcomes, postoperative pain relief (evaluated by VAS) and functional rehabilitation [evaluated by Harris hip score and range of motion (ROM)] were analyzed to determine clinical efficacy. These clinical data were compared and statistically analyzed with the clinical data of another 23 patients (28 hips) who underwent THA via the posterolateral approach (PLA) for the treatment of hip ankylosis in the lateral position.Follow-up was performed at 12-15 months. The incision length in the DAA group and the PLA group was (11.12 ± 1.69 vs. 14.36 ± 3.42) cm, the intraoperative blood loss was (371.25 ± 120.55 vs. 396.80 ± 101.21) ml, the operation time was (122.47 ± 25.40 vs. 138.47 ± 24.45) min, the postoperative hospital stay was (9.59 ± 4.62 vs. 12.08 ± 3.58) days, and the straight leg elevation time was (9.20 ± 2.12 vs. 12.34 ± 3.25) days, respectively. The prosthesis of the two groups was in a good position: The average angle of cup anteversion in the DAA group and the PLA group was (10.76 ± 2.84 vs. 15.36 ± 3.42)°, and the average angle of cup abduction in the DAA group and the PLA group was (40.00 ± 3.45 vs. 41.21 ± 2.85)° (P 0.05). The VAS score, ROM and Harris score at different follow-up time points were significantly improved in the two groups compared with those before surgery. In the first 3 months after surgery, the VAS score, ROM and Harris score of the DAA group were significantly better than those of the PLA group (P 0.05), but with the extension of the follow-up time, there was no significant difference in the above indicators between the two groups (P 0.05). One case of greater trochanteric fracture occurred in the DAA group. Two cases of hip posterior dislocations occurred in the PLA group, and no dislocations occurred after manual closed reduction and hip fixation in bed for 1 month to the last follow-up. No complications such as infection, deep vein thrombosis, fat embolism, prosthesis loosening, limb length inequality or joint dislocation were reported.THA via the DAA for the treatment of hip ankylosis in the lateral position was safe and effective and had the advantage of reduced trauma, quicker recovery of hip function, lower incidence of postoperative dislocation and ability to expose the acetabulum fully and fit the prosthesis properly, providing satisfactory clinical efficacy.

We systematically investigate saturated adsorption of H atoms on the SrTiO3 (001) surface to reveal the origin of H2 molecule formation using density functional theory methods. We find that H atoms prefer to adsorb on O sites at low coverage, while adsorbing on Ti sites at higher coverage. Interestingly, H on O sites and H on neighboring Ti sites (HTi) dimerize to form H2 molecules provided that enough electrons are doped in the conduction bands of SrTiO3. Bader charges and electronic structures show that negatively charged HTi plays a decisive role in the formation of H2. Both calculated hydrogen coverage and electron density at saturated adsorption are in good agreement with experimental values. Our results provide an illuminating instance of H2 formation on perfect oxide surface, which shall pave the way to further understanding the detailed mechanism of H2 evolution on more complex oxide surfaces.

We develop a new method to calculate nonlinear optical (NLO) susceptibility and give a definition of the extended figure of merit (EFOM) contributed from optical susceptibility, refractive index, and absorptions to evaluate the material intrinsic property. The calculated phonon frequency determines the infrared absorption coefficient and transparent cutoff edge. We calculate the conversion efficiencies of the terahertz source generating from chalcogenides PbM6Te10 (M = Ga, In), based on difference frequency generation of optical process in terms of the EFOM and experiment parameters. The calculated terahertz light conversion efficiencies of PbGa6Te10 and PbIn6Te10 are in the order of 10–3 to 10–2 at low side of THz wavelengths, and the conversion efficiency of PnIn6Te10 is larger than that of PbGa6Te10 at the same conditions. A small terahertz wavelength and absorption coefficient and a large nonlinear susceptibility, that is, a large EFOM will result in a large conversion efficiency. These studies give a...

In this work, we chose to explore the infrared (IR) nonlinear optical (NLO) materials centering on Cd and Ge elements, and finally synthesized a new IR NLO quaternary selenide BaCdGeSe4. Compound BaCdGeSe4 crystallizes in non-centrosymmetric (NCS) space group Fdd2 (No. 43), and it is built by parallel two-dimensional (2D) anionic [CdGeSe4]2- layers with the cation Ba2+ embedded between the layers. Under the 2050 ​nm laser excitation, compound BaCdGeSe4 appears type-I phase-matchable behavior and its second-harmonic generation intensities is about 0.5 times of AgGaS2.

Mid- and far-infrared nonlinear optical (MFIR NLO) materials are important in modern laser technologies. However, it is very challenging to develop materials that can achieve a subtle balance between the key requirements, such as large NLO response, high laser-induced damage threshold (LIDT), wide IR transparency, and phase-matching. In this work, a new wide IR transparency (0.38-15.3 μm) NLO crystal Ba

We present here the syntheses, crystal structures, and characterizations of three new mixed-metal phosphate of Ba2Bi2MII(PO4)4 (M= Mn, Ni, Cu), which synthesized by traditional solid-state reactions for the first time. Three title compounds crystallize in the orthorhombic system with space group Pnma, their structure can be described as adjacent zig-zag linear structure of [MP4O16]∞ along [100] further are connected by BiO6 distorted octahedra to form 3D framework, where the Ba2+ are located in tunnels running along the [001] direction. The Bi3+ cations, which are surrounded by six oxygen atoms, show strong stereoactivities of 6 s2 lone pair. The results of magnetic property measurements evidence on the antiferroagnetic properties of Ba2Bi2Mn(PO4)4 and ferromagnetic properties of Ba2Bi2MII(PO4)4 (M= Ni, Cu).

A new mixed-metal phosphate of BaBi2CoP2O10 was synthesized by high temperature solution growth (HTSG) method and structurally characterized by X-ray single crystal diffraction and powder diffraction for the first time. The title compound crystallizes in the monoclinic system with space group P2(1)/c and represents the first compound in the Ba–Bi–M–P–O (M = transition metal) quinary anhydrous system, which structure features a novel 2D open framework which can be considered as building from the layers of [Bi2CoP2O10]2−∞ parallel to the bc plane interconnected by corner or bridge sharing of BiO5, BiO7, CoO6, and PO4 groups, where Ba2+ cations are located in the space between two adjacent layers. It is worth to note that the Bi3+ cations containing two kinds of coordinations (5 and 7) show stereochemically activities of their 6s2 lone pairs. The results of magnetic property measurements evidence on the antiferromagnetic property of BaBi2CoP2O10.

Two new bismuth(III) selenite/tellurite nitrates, [(Bi 3 O 2 )(SeO 3 ) 2 ](NO 3 ) and [Bi(TeO 3 )](NO 3 ), have been synthesized by conventional facile hydrothermal method at middle temperature 200 °C and characterized by single-crystal X-ray diffraction, powder diffraction, UV–vis–NIR optical absorption spectrum, infrared spectrum and thermal analylsis. Both [(Bi 3 O 2 )(SeO 3 ) 2 ](NO 3 ) and [Bi(TeO3)](NO3) crystallize in the monoclinic centronsymmetric space group P2 1 /c with a =9.9403(4) A, b =9.6857(4) A, c =10.6864(5) A, β= 93.1150(10)° for [(Bi 3 O 2 )(SeO 3 ) 2 ](NO 3 ) and a =8.1489(3) A, b =9.0663(4) A, c =7.4729(3) A, β= 114.899(2)° for Bi(TeO3)(NO3), respectively. The two compounds, whose structures are composed of three different asymmetric building units, exhibit two different types of structures. The structure of [(Bi 3 O 2 )(SeO 3 ) 2 ](NO 3 ) features a three-dimensional (3D) bismuth(III) selenite cationic tunnel structure [(Bi 3 O 2 )(SeO 3 ) 2 ] 3 ∞ with NO 3 − anion group filling in the 1D tunnel along b axis. The structure of [Bi(TeO 3 )](NO 3 ) features 2D bismuth(III) tellurite [Bi(TeO 3 ) 2 ] 2 ∞ layers separated by NO 3 − anion groups. The results of optical diffuse-reflectance spectrum measurements and electronic structure calculations based on density functional theory methods show that the two compounds are wide band-gap semiconductors.

It is a great challenge to explore deep-ultraviolet (deep-UV) nonlinear optical (NLO) materials that can achieve a subtle balance among large nonlinear coefficients, moderate birefringence, and deep-ultraviolet (UV) transparency. A new beryllium-free fluoride carbonate Ca2Na3(CO3)3F was successfully synthesized through molecular engineering design, and large single crystals were grown by spontaneous crystallization with molten fluxes. The substitution of NLO-active [BO3] groups for [CO3] groups resulted in an optimal balance among the SHG coefficient, birefringence, and UV transparency. Via comparison of these two iso-structural compounds, the second-harmonic generation coefficients and birefringence of Ca2Na3(CO3)3F have been greatly improved. Remarkably, Ca2Na3(CO3)3F exhibited a wide transparent region with a deep-UV absorption edge at 190 nm. These results demonstrated Ca2Na3(CO3)3F is a promising NLO material in the UV or deep-UV region.

Single-layered two-dimensional (2D) materials have become very attractive due to their novel electronic behavior after the discovery of graphene. Here, we report the electronic structure and thermoelectric properties of single-layered 2D selerium (selenene) and tellurium (tellurene) by using density functional theory calculation. Both selenene and tellurene show three-phonon limited thermal conductivity. The prominent anharmonic phonon scattering process for tellurene makes it show the lowest lattice thermal conductivity among 2D single elemental materials till now. Their special square unit cells give rise to a highly anisotropic electronic structure along the zigzag and the armchair direction. The large effective mass and Seebeck coefficient along the armchair direction suggest that the thermal performance is better than that of the zigzag direction. The effect of spin-orbit coupling increases the band gap and is found to be crucial for tellurene. These studies provide a way to tune the thermoelectric properties of selenene and tellurene in the future.

A new polar compound Pb 2 (SeO 3 )(NO 3 ) 2 was synthesized by the conventional facile hydrothermal method at middle temperature 200 °C and characterized by X-ray single crystal diffraction, powder diffraction, UV–vis−NIR optical absorption spectrum and infrared spectrum. It crystallizes in the orthorhombic system, space group Pmn 2 1 with a = 5.4669(3) A, b = 10.3277(6) A, c = 7.2610(4) A, V = 409.96(4) A 3 . The compound features a 2D [Pb 2 (SeO 3 )] 2 ∞ architectures composed of SeO 3 and PbO 2 /PbO 3 units. Two unequivalent N(1)O 3 and N(2)O 3 units is inserted between adjacent [Pb 2 (SeO 3 )] 2 ∞ layers to stabilize the whole crystal structure. Second-harmonic generation (SHG) efficiency has been evaluated for powder Pb 2 (SeO 3 )(NO 3 ) 2 samples, showing about 2 times that of KDP reference. Moreover, the compound can achieve I-type phase-matching according to measurements by the Kurtz–Perry method. Theoretical investigations based on the first-principle DFT method were also performed to gain further insights into the crystal structure and optical properties relationship. The calculated band gap value of 3.38 eV is consistent with the optical reflectance measurements value of 3.76 eV.

The compound of Ba 2 Sb 7 O 13 (OH) was synthesized by using hydrothermal method from starting reagents of Ba(OH) 2 ·8H 2 O, Sb 2 O 3 and KCl. The crystal structure of Ba 2 Sb 7 O 13 (OH) was determined and characterized by single crystal X-ray diffraction method. Ba 2 Sb 7 O 13 (OH) represents a novel two-dimensional layered structure which is composed of Sb V O 6 and Sb III O 4 polyhedra through sharing corner oxygen atoms. Two types of Sb cations with Sb 3+ in sphenoid SbO 4 polyhedra and Sb 5+ in octahedral SbO 6 fashion are mixed in the crystal structure. First-principles electronic structure calculations based on the density functional theory (DFT), as well as the optical diffuse reflectance spectroscopy measurements, indicate that the compound belongs to an indirect band semiconductor with optical band gap of 2.7 eV.

In this paper, we describe the preparations of inorganic noncentrosymmetric (NCS) chalcogenides and their infrared nonlinear optical properties. We present a reasonable synthesis of inorganic NCS compounds by considering the genetic development processes of a living organism. The basic unit having an NCS structure is selected as a chromophore of NCS materials. The NCS compounds are obtained from the NCS chromophore development of normal growth. Chromophore development is an alienation process of growth if the NCS compound is not formed by an NCS chromophore. The normal development of the NCS chromophores (SnS4) and (Sn2S3) affords the NCS crystal of Ba7Sn5S15; and the normal development of the NCS chromophores of (BiS5) and (InS4) affords a compound of Ba2BiInS5 maintaining an NCS structure. In both of them, the Ba2+ ions are a charge-compensating agent. The NCS crystals SnGa4Q7 (Q = S, Se) were obtained from NCS chromophores of (GaQ4) and (SnQ4). However, the centrosymmetric (CS) compound of Ba6Sn7S20 was obtained because the development of NCS chromophores of the (SnS4) and (SnS5) is alienated from the normal process of growth. We give more examples of the NCS chromophore development of normal and alienable processes in this paper. For NCS compounds, we have examined their nonlinear optical (NLO) properties of micro-crystals (powders) and the electronic origin of the NLO response. The intensity of second harmonic generation (SHG), laser-induced damage threshold (LIDT), and infrared transparency were measured, and the conversion efficiency, figure of merit (FOM), and energy band structure were calculated for these NCS compound materials. It is found that the NCS materials of SnGa4Q7 (Q = S, Se) possess large conversion efficiencies, high damage threshold and wide transparencies in the mid-infrared region. Moreover, the study of the micro-mechanism elucidates that the stereochemically active lone-pair electrons of Sn2+ can significantly improve the polarity of the [SnQ4] chromophore. Their large NLO responses originate from the covalent interactions of Sn–Q and the cooperative effects of polarities between the chromophores [SnQ4] and [GaQ4]. It is also found that the Ba7Sn5S15 material has type-I phase- matchability, and that the SHG conversion efficiency and FOM are about twice that of AgGaS2 at the saturated particle size (particle size of 150–212 μm). The Ba8Sn4S15 is not a phase-matching material. The SHG intensity and conversion efficiency of Ba8Sn4S15 are separately about 250 times those of α-SiO2, and the SHG intensity and conversion efficiency are separately about 10 times those of AgGaS2 at the particle size of 25–45 μm.

The novel oxychloride BaBi(SeO3)2Cl with polar crystal structure was first synthesized by using hydrothermal method at a mild temperature of 200 °C. It crystallizes in the orthorhombic Cmc21 (36) space group with cell parameters of a = 5.2804(2) A, b = 20.0535(9) A, c = 6.9070(3) A, V = 731.39(5) A3, and Z = 4. The compound features a two-dimensional [Bi(SeO3)2Cl]2− anionic layer structure stacking along the crystallographic b-axis direction. Within the [Bi(SeO3)2Cl]2− layer, BiO4 quadrangular pyramids bridge two types of Se(1)O3 and Se(2)O3 triangular pyramid through corner-sharing manner into a [Bi(SeO3)2]− chain. The [Bi(SeO3)2]− chains are aligned along c-axis direction with chloride ions adjacent to bismuth cations, and the 2D [Bi(SeO3)2Cl]2− forms. As a consequence, local dipole moments of the building block layers are arranged in a constructive fashion, which is favourable to enhance the second-order nonlinear properties of materials. Powder Kurtz–Perry method was utilized to evaluate the second-harmonic generation (SHG) efficiency, indicating a strong SHG effect (about 16 times that of KH2PO4 (KDP) reference). More excitingly, BaBi(SeO3)2Cl can achieve type I phase-matching, which make the compound feasible for practical applications. In addition, first-principles density functional theory (DFT) calculations were also performed to illustrate the relationships between crystal structure and optical properties.

A new vanadate of BaMn9(II)(VO4)6(OH)2 was synthesized by a conventional hydrothermal method. BaMn9(II)(VO4)6(OH)2 crystallizes in the cubic space group Pa3[combining macron], which exhibits an edge-sharing MnO6 octahedral network structure with cavities occupied by Ba(VO4)6(16-) groups. The lattice built by Mn(2+) ions shows the reverse triangular dipyramid Mn7 in the system, which can be considered as a broken spin lattice of B-sites in spinels. The title compound shows a ferrimagnetic behavior with TC = 18 K.

International audience; Developing cost-effective and high-performance oxygen reduction reaction (ORR) catalysts is a fundamental issue in fuel cells and metal-air batteries. To this aim, carbon materials catalysts (CMCs) are extensively investigated, because of their performance comparable to noble-metal-based catalysts in alkaline solution. Yet, acidic solutions are desirable for an efficient proton exchange across Nafion membranes to yield high power density for commercial applications. However, the ORR performance of CMCs in acidic solutions is rather low, because of undesirable two-electron processes and OH radical formation. By using first-principles simulations, we elucidate the mechanisms and identify the active sites of 2e– ORR processes for indirect 4e– ORR. We provide evidence for the fact that nitrogen-doped Stone–Wales defects in graphene favor an indirect four-electron ORR upon H2O2 formation and reduction. The low ORR potential for metal-free CMCs is ascribed to H2O2 formation via hydrogen abstraction and the critical point for OH radical generation on transition-metal-based CMCs is 0.82 V. Moreover, we provide an insight into the indirect 4e– ORR, which serves as a guide for suppressing undesired 2e– ORR, avoiding OH production, and promoting direct four electron ORR on CMCs. These results disclose a new strategy for developing high-efficiency ORR on CMCs in acidic solutions.

Two nonlinear optical crystal carbonates (Na4La2(CO3)5 and CsNa5Ca5(CO3)8 were successfully synthesized by hydrothermal method, and both of them crystallized in the same noncentrosymmetric hexagonal space group P63mc (No. 186). The structure of Na4La2(CO3)5 consists of a three-dimensional network made up of [CO3] triangles as well as irregular [Na0.67La0.33O10] and [NaO8] polyhedra. The structure of CsNa5Ca5(CO3)8 can be described as the standing-on-edge [CO3] groups connect the adjacent infinite [CaCO3]∞ layers in the ab plane to construct a framework with four types of channels running parallel to [010]. The Na, Cs, and [Na0.67Ca0.33] atoms reside in these channels. The measurement of second harmonic generation (SHG) by the method adapted from Kurtz and Perry indicated that Na4La2(CO3)5 and CsNa5Ca5(CO3)8 were phase-matchable in the visible region and exhibited SHG responses of approximately 3 and 1 × KH2PO4 (KDP). Meanwhile, they exhibited wide transparent region with short UV cutoff edge at about 235 ...

First-principles calculations are performed to investigate linear electro-optical tensors and piezoelectric constants for zinc-blende compounds ZnX (X = O, S, Se, Te). The obtained results are compared with experimental and other theoretical results available. The findings are the followings: (1) there is no soft mode in these compounds because the electronic contributions and ionic contributions to the dielectric constants are of the same order of magnitude; (2) ZnO is the best candidate as an electro-optical material because of its largest electronic contribution to electro-optical effect among zinc-blende ZnX (X = O, S, Se, Te) compounds; (3) the abilities to resist volume compression, elastic deformation and linear compression reduce, and the second-order piezoelectric coefficients B 114 p become small from X = O to X = Te for ZnX (X = O, S, Se, Te) in turn.

A new rubidium europium polyphosphate, RbEu(PO3)4, was synthesized by the high-temperature solution reaction and studied by single-crystal X-ray diffraction (XRD) technique. RbEu(PO3)4 belongs to the monoclinic space group P21/n (Z = 4) and characterizes a three-dimensional framework made up from double PO4 spiral chains, RbO11, and EuO8 polyhedra. The absorption spectrum indicates that the compound has no absorption above 320 nm with insulator characteristic. In addition, the infrared spectroscopy was carried out.

Two new ternary noncentrosymmetric (NCS) isostructural compounds, SnGa4S7 (1) and SnGa4Se7 (2), have been synthesized by a high-temperature solid-state reaction method. Both compounds crystallize in the monoclinic polar space group Pc (7), and their three-dimensional (3D) frameworks are assembled from [SnQ4] tetragonal pyramids and tetranuclear [Ga4Q11] units. The two crystals show large second harmonic generation (SHG) conversion efficiencies, high laser-induced damage thresholds (LIDTs), and wide transparent regions in the mid-infrared (MIR) zone. Compound 2 exhibits the largest SHG conversion efficiency among type-I phase-matchable chalcogenides of about 3.8 × AgGaS2 at 2.05 μm radiation and a high LIDT of 4.6 × AgGaS2. Theoretical studies elucidate that the stereochemically active lone-pair (SCALP) electrons of Sn2+ can significantly improve the polarity of the [SnQ4] unit. Large nonlinear optical (NLO) responses for 1 and 2 originate from the covalent interactions of Sn–Q and the cooperative effects ...

Large sized α-Li 3 Fe 2 (PO 4 ) 3 single crystals with high quality are successfully grown by a flux method. Magnetic behaviors of the grown crystals are investigated by means of magnetic susceptibility, magnetization, and heat capacity measurements along different directions. The results confirm that α-Li 3 Fe 2 (PO 4 ) 3 exhibits weak ferrimagnetic behaviors at low temperature, which are in good agreement with those reported previously. However magnetic anisotropy is confirmed for the first time, suggesting that the c -axis is the likely magnetic easy axis and the a -axis is the magnetic hard one. Two anomalies are clearly observed in magnetic susceptibility along the a -axis and heat capacity data at zero field, suggesting the appearance of two successive magnetic transitions at ~26 and ~22 K in the system.

The search for spin frustrated magnets has attracted great scientific interest. Here we report on the synthesis of a novel two dimensional spin-frustrated compound KNa3Mn7(PO4)6 with a diamond-like chain structure. Our results confirm spin freezing at Tc = 3.9(1) K with the Weiss constant θ = −64.1(2) K, showing a remarkable spin frustration effect in the system. The origin of spin frustration is also suggested.

A new noncentrosymmetric (NCS) ternary sulfide, Ba8Sn4S15, was synthesized by a conventional solid-state reaction. The compound crystallizes in the orthorhombic space group Pca21 (29), with unit cell parameters a = 28.727(5) A, b = 8.5220(14) A, c = 25.438(4) A, Z = 8, and V = 6227.5(18) A3. The major structure of Ba8Sn4S15 formed by isolated SnS4 tetrahedra and SnS3 pyramids features the zero-dimensional (0D) characteristic and shows the coexistence of divalent Sn(II) and tetravalent Sn(IV). The optical band gap of Ba8Sn4S15 is 2.31 eV with a wide transparent region of 0.73–25 μm. Importantly, the large dipole moment and the polarity enhancement of the SnS3 pyramid unit make Ba8Sn4S15 exhibit strong second harmonic generation (SHG) nonlinear optical response, which is about 10 times larger than that of the benchmark AgGaS2 in the particle size of 25–45 μm at the laser radiation wavelength of 2.05 μm with a non phase-matchable behavior. The density functional theory (DFT) studies confirm the experimental ...

The combination of Pb(2+) cations with lone-pair electrons and F(-) anions with the largest electronegativity into the carbonate generates a new nonlinear optical material, CsPbCO3F, with the largest powder second-harmonic generation (SHG) response among carbonates of about 13.4 times that of KDP (KH2PO4), and transparency over the near-UV to middle-IR region. The optical characterization of the compound indicates that it is phase matchable. Its crystal structure exhibits the stacking of [CsF]∞ and [Pb(CO3)]∞ layers, and the coplanar alignment of [CO3] triangles which are oriented in the same direction. Yet the Pb(2+) cation has an inert or nonstereoactive lone-pair, as indicated by its more spherical shape. Theoretical calculations confirm that the extremely large SHG efficiency indeed originates from enhancement via p-π interaction between Pb(2+) and [CO3](2-) within the [Pb(CO3)] layers.

A new ternary sulfide Ba 3 Sb 2 S 7 was synthesized from high temperature solid-state reactions in a flame-sealed silica ampoule. It crystallizes in the C 2/ c space group of the monoclinic system with a = 18.380(2) A, b = 12.266(2) A, c = 13.164(2) A, β = 110.054(6)°, V = 2788.0(7) A 3 , and Z = 8. The compound features an interesting zero-dimensional structure built of two types of isolated SbS 3 and SbS 2 (S 2 ) units surrounded with the charge balanced Ba 2+ cations. The UV–Vis–NIR optical diffuse reflectance measurements along with the electronic band structure calculations indicate that Ba 3 Sb 2 S 7 belongs to an indirect semiconductor with the band gap of 2.4 eV. Electronic density of states (DOS) analyses were also performed to interpret the intrinsic behavior of charge transfers in the SbS 3 and SbS 2 (S 2 ) units, respectively.

Two ternary-layered chalcogenides, MnBi4S7 (1) and FeBi4S7 (2), have been synthesized by using a conventional solid-state reaction method with sealed evacuated quartz tubes. The two isostructural compounds crystallize in the monoclinic space group C2/m (12), with unit cell parameters (1/2) a = 12.916(12)/12.823(19) A, b = 3.970(3)/3.987(6) A, c = 11.0397(15)/11.878(18) A, β = 104.755(14) /104.38(2), and Z = 2 at room temperature. The remarkable structural features of these are the one-dimensional Heisenberg antiferromagnetic (1D HAF) chain, 1∞[XS6], and the two-dimensional [Bi2S3] and [MBi2S4] layers built up from the 1D 1∞[XS6] chain, 1∞[BiS6], and 1∞[BiS5] double chains. Magnetic property measurements indicate strong predominance of antiferromagnetic (AFM) interactions, with Neel temperatures (TN) of 31 K for 1 and 67 K for 2, respectively. The density functional theory (DFT) study indicates that both compounds are indirect-band semiconductors with band gaps of 0.79 eV for 1 and 1.24 eV for 2, respectively.

The calculated results based on the density functional theory are employed to simulate the nonlinear optical properties of a new compound of Ba7Sn5S15(BSS). The frequency (ω=eV/ħ) dependent SHG tensor components of the BSS are calculated from 0.0 to 2.0 eV energy range. The calculated components d31(20.3 pm/V) and d33(18.8 pm/V) are close to the experimental value of of 19.5 pm/V at a wavelength of 2.10 μm. The SHG conversion efficiency and the figure of merit of BSS material are about two fold as compared with those of AgGaS2material. The charge transfers within the (Sn2S3) and (SnS4) polyhedrons lead to the most contribution to SHG response, and the polarity superposition of the [Sn2S3]2-groups will strengthen the crystal polarity and result in a large SHG response in a BSS material.

Two nonlinear optical fluoride carbonate crystals (Na8Lu2(CO3)6F2 and Na3Lu(CO3)2F2) have been synthesized under subcritical hydrothermal condition. Both crystals crystallize in the noncentrosymmetric space group Cc (No. 9). The structure of Na8Lu2(CO3)6F2 with high density of [CO3] groups is described as 1D [Na5Lu(CO3)2F2] chains connected by [CO3] triangles, forming an intricate three-dimensional framework. Lu3+ and Na+ cations are alternatively ordered and disordered in the cavities of the 3D network. The structure of Na3Lu(CO3)2F2 is built up from the [NaLu(CO3)2F2] layers which are separated by other Na+ cations. The [CO3] anionic groups arrange approximately coparallel to the plane. The second harmonic generation (SHG) measurement indicates that Na8Lu2(CO3)6F2 and Na3Lu(CO3)2F2 have large SHG responses that are approximately 4.29 and 4.21 times KH2PO4 (KDP), respectively. The responses are also phase-matchable in the visible region. In addition, it exhibits wide transparent regions ranging from UV t...

A new strontium antimonate{sup III}, Sr{sub 5}Sb{sub 22}O{sub 38}, has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. It crystallizes in the P2{sub 1}/n space group of the monoclinic system with a=11.739(9) A, b=12.014(10) A, c=16.412(13) A, β=91.460(8)°, V=2314.0(3) A{sup 3}. The crystal structure is built of seven trigonal–pyramidal SbO{sub 3} and four sphenoid SbO{sub 4} polyhedra which are connected through sharing corner-oxygen atoms to form the complex three-dimensional {sub ∞}{sup 3}[Sb{sub 22}O{sub 38}]{sup 10−} anionic network with two different intersectant tunnels along the [111-bar ] and [11-bar 1-bar ] directions accommodating the electric charge balanced Sr{sup 2+} cations. First-principles electronic structure calculations based on the density functional theory (DFT) and the UV–vis diffuse reflectance spectroscopy measurements both indicate that the compound belongs to a direct band insulator with an optical gap value of 3.3 eV. - Graphical abstract: The 2D Sb–O slabs are stacked through sharing oxygen atoms to form the 3D network structure of the new strontium antimonate{sup III} Sr{sub 5}Sb{sub 22}O{sub 38}. - Highlights: • A new strontium antimonate{sup III}, Sr{sub 5}Sb{sub 22}O{sub 38}, has been hydrothermally synthesized. • The single crystal structure was determined by X-ray diffraction. • The powder XRD and UV–vismore » absorption spectroscopy were studied. • Theoretical studies interpret the relationships between optical absorption and crystal structure.« less

We used ab initio evolutionary algorithm to predict the stable and energetically competitive metastable structures of the nonlinear optical materials BiInS3 crystal. The powerful evolutionary algorithm allows us to find the global minimum of the energy landscape with dramatic reduced candidate numbers. Combining geometry optimization with density functional method and the phonon dispersion calculation it is possible for us to determine the stable structure of BiInS3 within only several tens of thousand candidates. The proposed most stable structure adopts the P21 space group, and its second-harmonic generation coefficient is as large as 59 pm/v. The former synthesized BiInS3 is probable corresponding to the metastable Pnma structure. The existence of iso-energy structures at the metastable energy range suggests that more delicate synthetic method is required to obtain high quality BiInS3 crystal.

We investigate the effect of side chain on the first-order hyperpolarizability in α-helical polyalanine peptide with the 10th alanine mutation (Acetyl(ala) 9 X(ala) 7 NH 2 ). Structures of various substituted peptides are optimized by ONIOM (DFT: AM1) scheme, and then linear and nonlinear optical properties are calculated by SOS//CIS/6-31G ∗ method. The polarizability and first-order hyperpolarizability increase obviously only when ‘X’ represents phenylalanine, tyrosine and tryptophan. We also discuss the origin of nonlinear optical response and determine what caused the increase of first-order hyperpolarizability. Our results strongly suggest that side chains containing benzene, phenol and indole have important contributions to first-order hyperpolarizability.