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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.

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...

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.

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.

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.

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 ...

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 ...

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.

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.

Three new ternary Ba-Sn-S system compounds, acentric Ba(7)Sn(5)S(15), centric BaSn(2)S(5), and centric Ba(6)Sn(7)S(20) have been designed and synthesized by a conventional high-temperature solid-state reaction method using the evacuated silica tubes. The crystal structure of Ba(7)Sn(5)S(15) shows the coexistence of a SnS(4) tetrahedral and a Sn(2)S(3) trigonal bipyramid. Importantly, the larger dipole moment of the [Sn(2)S(3)](2-) trigonal bipyramid group and the polarity enhancement of the bipyramidal arrangements result in a strong SHG effect at 2.05 μm, which is 10 times of the SHG intensity of the benchmark AgGaS(2) with the particle size of 30-46 μm and twice as much as that with the particle size of 150-212 μm. Evidently, the acentric Ba(7)Sn(5)S(15) is a novel IR NLO crystal material with a wide mid-IR window and a strong SHG effect, which is the first reported among the Ba-Sn-S ternary system. Moreover, Ba(7)Sn(5)S(15) can achieve type-I phase-matching that can be used for practical applications. In the centric BaSn(2)S(5,) all Sn atoms are coordinated by five S atoms to form novel SnS(5) trigonal bipyramid polyhedrons. In the other centric Ba(6)Sn(7)S(20), there is the coexistence of the two coordination patterns with a SnS(5) trigonal bipyramid and SnS(4) tetrahedral polyhedrons, featuring a special crystal structure in the Ba-Sn-S system.

The one-photon (OPA) and two-photon (TPA) absorption properties of three series of symmetrically substituted quadrupolar compounds with structure of donor-π bridge-donor (D–π–D) were investigated by time-dependent density functional theory (TDDFT) based on the Hartree–Fock (HF)-optimized geometrical structures. These compounds were constructed with either phenyl or fluorenyl groups connected by vinylene unit as the central π-conjugated bridges and either diphenylamine or difluorenylamine groups as terminal electron donors. The calculated OPA spectra are dominated by two strong transitions which are attributed to the charge transfers from the donor groups to central conjugated chains. The OPA and TPA transition strength all increase with the extension of conjugated chain length in each series and the corresponding wavelength shifts red in general. The transition strength in either OPA or TPA process also increases from series one to series two or three by replacing the phenyl groups with fluorenyl groups. The intramolecular charge transfers make significant contributions to the TPA activity. According to the three-state model, the enhanced TPA activity comes from the enhancement of transition moment between states–states as conjugated chain increases.

We present here the structures and magnetism of two quasi-1D linear chain compounds of BiM(2)BP(2)O(10) (M = Co, Ni), which were synthesized by traditional solid-state reactions for the first time. Two title compounds crystallize in the monoclinic system with space group P2(1)/c and feature novel 3D structures with a linear chain structure of {MO(6)}(n) further connected by [BP(2)O(10)](7-) anionic groups. The results of magnetic property measurements evidence the antiferromagnetic properties of both compounds in low magnetic field and a field-dependent metamagnetic transition from the antiferromagnetic to ferromagnetic ground state of the BiCo(2)BP(2)O(10) complex.

The second order polarizabilities (β) of the C(3)N(4) NT systems were investigated in this study. The β values of end groups substituted C(3)N(4) NTs were calculated to find their most favorable paradigm for nonlinear optical design. It was found that their electric dipole transitions are only allowed along the tube axis direction and the position of terminal groups has a great effect on NLO properties of substituted C(3)N(4) NTs. The obtained results provide us details to understand the relation between the structure and nonlinear optical properties. The results indicate that the second-order polarizabilities originate from charge transfer from a donor (-NH(2)) to an acceptor (-O(2)N) and the electron density redistribution in heptazine units. We employ a one-dimensional two-state model to analyze the nature of the second-order polarizabilities of studied materials. The frequency-dependent second-order polarizabilities were also calculated. The second-order polarizability of the O(2)N-C(3)N(4)-NH(2) NT is 2.51 × 10(-27) esu when the input photon energy is 2.232 eV, which is much larger (about two orders of magnitude) than static second-order polarizability (2.54 × 10(-29)).

The bridge photoisomerization of the chromophores of fluorescent proteins has been suggested as the possible mechanism of radiationless decay in fluorescent proteins. It indicates that this internal structure changing of chromophores great influence the optical properties of fluorescent proteins. The two-photon absorption (TPA) properties of fluorescent proteins might also be influenced by the bridge photoisomerization of the chromophores. In this work, we simulate the dynamic conformations through rotating the bridge bond of chromophore of green fluorescent protein, and employ the time dependent density functional theory combining with the sum-over-states method to study their TPA characters. With our study, we find that the TPA characters of chromophore will be improved through controlling rotation of the bridge bond of chromophore. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

LSSmKate1 and LSSmKate2 are monomeric red fluorescent proteins (RFPs) with large Stokes shifts (LSS). The hydrogen-bonding (H-bonding) network within LSSmKate1 or LSSmKate2, which is composed of a chromophore and some surrounding amino acid residues, supports their special spectral properties. In this work, we propose H-bonding complex models to simulate the H-bonding network of LSSmKate1 and LSSmKate2 and employ the time-dependent density functional theory combining with the sum-overstates method to calculate their one- and two-photon absorption characters. We discuss the influence of the hydrogen bond on the one- and two-photon absorption properties of these H-bonding complexes through intermolecular hyperconjugation of the hydrogen-bond form.

We report the frequency-dependent third-order polarizabilities ( γ ) of a series of hydrogen-capped silicon clusters obtained using time-dependent density functional theory. We find that the magnitude of γ increases with a decrease in silicon cluster size, while the sign of γ at low input photon energy changes from positive to negative when the ratio of hydrogen saturation increases. At higher input photon energy, the sign of γ is determined mainly by cluster size. Our results rationalize several recent experiments on the optical properties of silicon nanostructures and are helpful for designing opto-electronic devices based on them.

Geometrical structures of three investigated molecules Sc3N@C80, Sc3N@C80-Fc, and C60-Fc were optimized by density functional theory (DFT) at the B3LYP/6-31G* level. Then the time-dependent DFT was employed to investigate the excited states of these molecules. After exohedral functionalization by ferrocene (Fc-) group as the electron donor or replacing C60 with Sc3N@C80 as the electron acceptor, the wavelengths of the first one-photon absorption peak and the strongest two-photon absorption (2PA) and three-photon absorption (3PA) peaks shift red. The corresponding cross sections of Sc3N@C80-Fc in the 2PA and 3PA processes increase as compared with those of Sc3N@C80, which originate from the contributions of charge transfers from Fc- group to C80 cage and simultaneously the transfers from the C80 cage to the encapsulated Sc3N cluster. When compared with C60-Fc, the 2PA and 3PA cross sections of Sc3N@C80-Fc decrease, which may result from the more negative charge surface of C80 cage in Sc3N@C80-Fc molecule which blocks the charge transfers from Fc- moiety to the C80 cage in the excitation processes by compared with C60-Fc. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012

Using the first-principle DFT method, the band structure and density of state are investigated. Then using the anharmonic oscillator model, the linear and nonlinear optical properties of frequency dependence are calculated for CBOB (Cd4BiO(BO3)3) crystal material. It is shown that the calculated SHG coefficient is well matched with our experimental value at a wavelength of 1064 nm, and a large nonlinear optical response originates from the charge transfers within the irregular BiO6, CdOngroups and BO3group for Cd4BiO(BO3)3.

Two new quaternary sulfides, Ba(2)SbFeS(5) and Ba(2)BiFeS(5), were synthesized by using a conventional high-temperature solid-state reaction method in closed silica tubes at 1123 K. The two compounds both crystallize in the orthorhombic space group Pnma with a = 12.128(6) Å, b = 8.852(4) Å, c = 8.917(4) Å, and Z = 4 for Ba(2)SbFeS(5) and a = 12.121(5) Å, b = 8.913(4) Å, c = 8.837(4) Å, and Z = 4 for Ba(2)BiFeS(5). The crystal structure unit can be viewed as an infinite one-dimensional edge-shared MS(5) (M = Sb, Bi) tetragonal-pyramid chain with FeS(4) tetrahedra alternately arranged on two sides of the MS(5) polyhedral chain via edge-sharing (so the chain can also be written as (1)(∞)[MFeS(5)](4-)). Interestingly, the compounds have the structural type of a Ba(3)FeS(5) high-pressure phase considering one Ba(2+) is replaced by one Sb(3+)/Bi(3+), with Fe(4+) reduced to Fe(3+) for in order to maintain the electroneutrality of the system. As a result, the isolated iron ions in Ba(3)FeS(5) are bridged by intermediate MS polyhedra in Ba(2)MFeS(5) (M = Sb, Bi) compounds and form the (1)(∞)[MFeS(5)](4-) chain structure. This atom substitution of Ba(2+) by one Sb(3+)/Bi(3+) leads to a magnetic transition from paramagnetic Ba(3)FeS(5) to antiferromagnetic Ba(2)MFeS(5), resulting from an electron-exchange interaction of the iron ions between inter- or intrachains. Magnetic property measurements indicate that the two compounds are both antiferromagnetic materials with Néel temperatures of 13 and 35 K for Ba(2)SbFeS(5) and Ba(2)BiFeS(5), respectively. First-principles electronic structure calculations based on density functional theory show that the two compounds are both indirect-band semiconductors with band gaps of 0.93 and 1.22 eV for Ba(2)SbFeS(5) and Ba(2)BiFeS(5), respectively.

Incorporating silver in ZnO has attracted a lot of interest in recent years to fabricate p-type ZnO, as the naturally occurring ZnO is n-type material due to its native defects such as zinc interstitials and oxygen vacancies. In this work, the structural, electronic, and optical properties of pure and Ag-doped (8, 0) ZnO SWNTs were investigated by using density functional theory (DFT). The optimized structures present buckling side wall surfaces. The configurations with Ag atoms replacing Zn atoms are p-type semiconduction materials while the configuration with Ag atom added out of the surface of ZnO SWNTs is n-type semiconduction material. The optical properties based on dielectric function and absorption coefficient were discussed. It was found that the Ag-doped (8, 0) ZnO SWNTs have absorption in the visible-light region, and the absorption intensity is enhanced with the increase of Ag concentration. Our results indicate that the Ag-doped ZnO nanotubes could have a better performance as a photocatalyst...

Two new barium indium phosphates BaIn2P4O14 and Ba3In2P4O16 were synthesized by high temperature solution growth method and structurally characterized by single crystal X-ray diffraction analysis. They represent first compounds in the Ba–In–P–O systems. BaIn2P4O14 and Ba3In2P4O16 display different types of 3D architectures. The projections of both structures concern about the existence of the intersecting tunnels. In compound BaIn2P4O14, the tunnels are built up of the corner-sharing InO6 octahedra and P2O7 groups, whereas in compound Ba3In2P4O16, they are formed by corner sharing of PO4 tetrahedra and InO6 octahedra. The electronic band structure calculations of two compounds have been performed with the density functional theory method. The study of calculations and optical diffuse reflectance experimental results show both compounds are insulators with direct band-gap.

The geometrical and electronic structures of a series of dyads NMPC60–AN n (n = 1–5) were investigated at B3LYP/6-31G* level. Then, the excited states were calculated at TDB3LYP/3-21G* level to investigate the photophysical properties. The third-order polarizabilities of degenerate four-wave mixing (DFWM), electric-field-induced second-harmonic generation (EFISHG), and third-harmonic generation (THG) were calculated in combination with the sum-over-states (SOS) method. The obtained absorption spectra show a remarkable red shift. The average value of third-order polarizabilities 〈γ〉 away from the resonant region increases with n for NMPC60–AN n. The charge transfers from the oligoanilines to C60 cage make the main contribution to the large third-order polarizabilities of this series of compounds. It is found that 〈γ〉 can be expressed as a function of the chain length of linked oligoaniline and 11.74 × 10-34 esu is the upper limit after n = 7 for NMPC60–AN n in the static state.

The synthesis and crystal structure of Li3AlB2O6 with different cell parameters are reported and these cells are transformed each other from the confirmation of crystallographic structural analyses. The absorption spectrum, luminescence and lifetimes of the Li3AlB2O6 and LiSrBO3 solid compounds are measured and the comparisons are made between them. It is shown that the absorption edges are at about 400 run (or band gap 3.1 eV) and there is one of absorption peaks at about 350 run for the Li3AlB2O6 and LiSrBO3. The emission band (530 nm) makes a red shift and fluorescence decay time (24.39 ns) of the Li3AIB2O6 becomes smaller compound with the emission band (480 nm) and lifetime (93.16 ns) of the LiSrBO3 at the visible region. The transition energies and oscillator strengths of the clusters (Li3AlB2O6)2 and (LiSrBO3)2 lying at low excited states are calculated by the time-dependent Har-tree-Fock method. The obtained results arc used to model the photophysical properties and discuss the origin of spectral bands of the Li3AlB2O6 and LiSrBO3.

The cluster (SrB2O4)2 existing in crystalline states is employed to model the electronic structure and linear optical properties of solid state compound SrB2O4. This compound is synthesized by high temperature solution reaction, and it crystallizes in the orthorhombic space group Pbcn with cell dimensions a = 1.1995(3), b = 0.4337(1), c = 0.6575(1) nm, V = 0.34202 nm3, and Z = 4, μ = 15.14 cm−1, Dcaled = 3.36 g/cm3. The dynamic refractive indices are obtained in terms of INDO/SCI following combination with the Sum-Over-States method. A width of the calculated gap is 4.424 eV between the valence band and conduction band, and the calculated average refractive index is 1.980 at a wavelength of 1.065 μm. The charge transfers from O2- anion orbitals to Sr2+cation orbitals make the significant contributions to linear polarizability in terms of analyses of atomic state density contributing to the valence and conduction bands.

Two new quaternary thioborate compounds with strongly one-dimensional growth, BaSb(BS(3))S and BaBi(BS(3))S, have been synthesized using the conventional solid state reaction method in closed tubes at 1100 K. The single crystal X-ray diffraction analysis has shown that compound BaSb(BS(3))S crystallizes in space group Pnma of the orthorhombic system with unit cell parameters of a = 9.6898(15) A, b = 6.2293(13) A, c = 11.670(2) A, V = 704.4(2) A(3), and Z = 4, while compound BaBi(BS(3))S crystallizes in space group C2/m with unit cell parameters of a = 14.9890(17) A, b = 6.2457(6) A, c = 7.5591(9) A, beta = 101.604(5) degrees , V = 693.19(13) A(3), and Z = 4. The two compounds both crystallize in the structure of infinite one-dimensional chains with [BS(3)](3-) trigonal plane coordination alternately bridged by [MS(3)](3-) (M = Sb, Bi) trigonal pyramids through sharing two sulfur atoms along the crystallographic b axis. First-principles electronic structure calculations performed with the density functional theory (DFT) method show that the calculated band gaps of BaSb(BS(3))S and BaBi(BS(3))S are 2.29 and 2.16 eV, respectively, which are in good agreement with the experimental values estimated from UV-vis absorption spectra using the Kubelka-Munk equation, and the observed absorption peak is assigned as charge transfers from S-3p states to Sb-5p (Bi6p) states.

Two members of MIII2BP3O12 borophosphates, namely Fe2BP3O12 and In2BP3O12, were synthesized by the solid-state method and characterized by the X-ray single crystal diffraction, the powder diffraction and the electron microscopy. They both crystallize in the hexagonal system, space group P6(3)/m (no. 176) and feature 3D architectures, build up of the M2O9 units and B(PO4)3 groups via sharing the corners; however, they are not isomorphic for the different crystallographically distinct atomic positions. Optical property measurements of both compounds and magnetic susceptibility measurements of Fe2BP3O12 also have been performed. Moreover, in order to gain further insights into the relationship between physical properties and band structure of the MIII2BP3O12 borophosphates, theoretical calculations based on density functional theory (DFT) were performed using the total-energy code CASTEP.