Zhong-Zhen Luo

Syntheses, Characterization, and Optical Properties of Ternary Ba–Sn–S System Compounds: Acentric Ba7Sn5S15, Centric BaSn2S5, and Centric Ba6Sn7S20

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.

Syntheses and magnetic properties study of isostructural BiM2BP2O10 (M = Co, Ni) containing a quasi-1D linear chain structure.

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.

Designing the syntheses and photophysical simulations of noncentrosymmetric compounds

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.

Design of SHG materials with mid-infrared transparency based on genetic engineering for Ba2BiInA5 (A = Se, Te)

We have employed genetic engineering through a four-step roadmap to design second-harmonic generation materials with infrared transparency. Firstly, we constructed virtual crystals of Ba2BiInA5 (A = Se, Te) using the “genome” BiA5 pyramid and InA4 tetrahedron. We then carried out reliable predictions of the crystal structures and revealed the asymmetric central group of these crystal compounds. Thirdly we carried out ab initio computations of the band structures and simulations of the optical properties. We surveyed the nonlinear optical figure of merit for the optical transparent range and the SHG parameters for these crystals. Finally, we provide evidence for the predictions by experimental synthesis, crystal structural determinations and optical measurements for the Ba2BiInSe5 compound.

Syntheses, crystal structures and characterizations of two new quaternary thioborates: PbMBS4 (M = Sb, Bi)

Two new quaternary thioborates, PbSbBS(4) and PbBiBS(4), have been synthesized from solid-state reaction methods at temperatures from 1073 to 1123 K in evacuated sealed quartz tubes. The crystal structures have been determined by means of single crystal X-ray diffraction and they both crystallize in the P2(1)/m space group of the monoclinic system with a = 5.9532(18) Å, b = 6.2031(13) Å, c = 9.250(3) Å, β = 108.200(16)°, Z = 2 for PbSbBS(4) and a = 5.971(10) Å, b = 6.273(9) Å, c = 9.132(15) Å, β = 107.75(2)°, Z = 2 for PbBiBS(4), respectively. The two compounds are isostructural and both constructed with the infinite one-dimensional [MBS(4)](2-) (M = Sb or Bi) chains as building blocks, which are composed of [BS(3)](3-) trigonal plane units with [MS(3)](3-) (M = Sb or Bi) trigonal pyramids connected alternatively through corner-sharing along the crystallographic b axis. Two adjacent [MBS(4)](2-) chains are further bridged by the intermediate Pb(2+) cations, forming a novel S-shaped Pb-[MBS(4)] dimeric chain structure. In addition, first-principles electronic structure calculations based on the density functional theory (DFT) were performed on compound PbSbBS(4), indicating that the compound belongs to direct semiconductor with a band gap of 1.803 eV, which is in good agreement with the experimental value estimated from the UV-Vis diffuse reflectance spectroscopy.

Syntheses and Properties of Some Bi-Containing Compounds with Noncentrosymmetric Structure

A genetic engineering method is employed to design the second harmonic generation (SHG) materials with infrared transparency. The compounds of Ba2BiInA5 (A = S, Se, Te) are constructed in views of “genome” BiA5 pyramid and InA4 tetrahedron. Then, the crystal structures of these compounds are predicted or reproduced to show their non-centrosymmetry based on global optimization evolutionary methodology. Thirdly, the ab initio computations of band structures and simulations of optical properties are carried, and the nonlinear optical figure of merit in views of optical transparent range and the SHG parameters are surveyed for these crystals. Finally, we provide the substance evidences by the experimental synthesis, crystal structural determinations, and optical measurements for Ba2BiInA5 (A = S, Se) compounds.

Syntheses, crystal and electronic structures, and characterizations of the mixed anions compounds Ba4In2Te2Q5 (Q = S, Se)

Two new quaternary chalcogenides, Ba4In2Te2Q5 (Q = S, Se), have been synthesized by using a conventional high-temperature solid-state reaction method. These two isostructural compounds crystallize in the space group P4/mbm (127), with a = b = 8.3669(9) A, c = 11.0397(15) A, and Z = 2 for Ba4In2Te2S5 (1) and a = b = 8.6021(4) A, c = 11.3047(9) A, and Z = 2 for Ba4In2Te2Se5 (2) at room temperature. The special structural feature of the compounds is the unique dimeric [In2Te2Q4]6− units by the ordered arrangement leading to the covalent layer. First-principles electronic structure calculation by density functional theory (DFT) shows that the two compounds are both indirect-band semiconductors with band gaps of 2.07 eV for 1 and 1.75 eV for 2, respectively.