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LiZnSb is a Zintl phase that has been predicted to be a good material in thermoelectric applications for a long time. However, experimental work indicated that the synthesized LiZnSb materials were p type, and their maximum zT value is only 0.08 at 525 K. CaZn0.4Ag0.2Sb, which belongs to the LiGaGe structure type and is also closely associated with the LiZnSb structure, did show high zT plateaus in a wide range of temperature, with the mixed transition metal Zn/Ag sites regulated. By comparing their crystallographic and electronic band structures, it is evident that the interlayered distances in both compounds have a great effect on the regulation of the corresponding electrical transport properties. When alloying CaZn0.4Ag0.2Sb with LiZnSb, solid solutions form within a specific range, which led to a marked enhancement in the Seebeck coefficient through the orbital alignment and carrier concentration optimization. In addition, a low thermal conductivity was obtained owing to the reduced electronic component. With the above optimization, a maximum zT value of ∼1.3 can be realized for (CaZn0.4Ag0.2Sb)0.87(LiZnSb)0.13 at 873 K, more than twice that of the pristine CaZn0.4Ag0.2Sb and about 10-fold compared to that of LiZnSb. This work may shed new light on the optimization of thermoelectric properties based on Zintl phases, for which the crystal structures are usually very complicated and a direct correlation between the structures and properties is difficult to make.

Zintl phases with nominal 9–4–9 formulas are very interesting for their potential applications as thermoelectric materials. However, the formation of such phases usually requires divalent transitio...

Three new quaternary Zintl phases with the "9-4-9" formula, Ae9Mn4-xAlxSb9 (Ae = Ca, Yb, Eu), have been synthesized using Pb as the metal flux, and their crystal structures have been established by single-crystal X-ray diffraction. Both Ca9Mn2.91(4)Al1.09Sb9 and Yb9Mn3.59(6)Al0.41Sb9 are isostructural with Ca9Mn4Bi9, and they crystallize in the orthorhombic space group Pbam with unit cell dimensions of a = 12.4571(8), 12.2884(16) A, b = 22.1352(16), 22.024(3) A, and c = 4.6012(3), 4.6187(6) A, respectively. Their anionic structures can be viewed as infinite ribbons based on corner-shared tetrahedrons. Also, Eu9Mn2.87(4)Al1.13Sb9 has the space group Cmca and a = 9.4883(7) A, b = 23.6895(18) A, and c = 24.4845(19) A. The structural relationships between Ca9Mn2.91(4)Al1.09Sb9 and Eu9Mn2.87(4)Al1.13Sb9 are compared and discussed as well. The successful Al3+ substitution provides additional electrons to the compounds to achieve structural stability. Magnetic susceptibility and electrical resistivity measurements, performed on single crystals of Eu9Mn2.87(4)Al1.13Sb9, indicate complex magnetic properties and semiconductor behavior. The physical properties of Yb9Mn3.59(6)Al0.41Sb9 are similar to those observed for Yb9Mn4.18(2)Sb9.

A series of Mg/Mn mixed intermetallic compounds Mg

The exceptional structural tunability of organic metal halides endows them with fascinating electronic and photophysical properties, providing much scope for applications. In this work, single crystals of the organic metal halide (C4 H9 NH3 )2 MnI4 are found to show reversible thermo-induced luminescent chromism within a wide temperature range. The (C4 H9 NH3 )2 MnI4 single crystal exhibits two emission peaks at 550 and 672 nm, which are assigned to a d-d transition of Mn2+ -centered tetrahedra and self-trapped excitons, respectively. The temperature-dependent emission color change is attributed to the thermo-induced trapping and detrapping process of the self-trapped exciton. (C4 H9 NH3 )2 MnI4 exhibits a maximum photoluminescence quantum efficiency of up to 68 % at 70 °C. The disclosed interacted photoluminescence decay mechanisms may prove useful for the further design of organic metal halides for optical thermometry.

Mid-infrared (MIR) nonlinear optical (NLO) crystals are crucial in generating MIR lasers, which are important in civilian and military applications. Compared to the extensively investigated ternary...

With excellent electrical conductivity as well as low thermal conductivity, Zintl phases have been well investigated for possible thermoelectric applications, from which some materials configured with special structures and compositions were found especially interesting owing to their distinguished efficiency in energy conversion. Although the advantages of Zintl phases as thermoelectric materials are obvious due to their complex crystal structures, currently decent thermoelectric performance is primarily limited to some long-known systems. In this short review, recent progress on the Zintl-phase-based thermoelectric materials, including some newly developed series, were summarized and discussed. The ideas on the configuration and optimization of such materials were presented. With attempts to better understand the correlation between structures and properties, it is very hopeful that more Zintl thermoelectric systems can be discovered with high performance.

Intermetallic compounds with layered structures can be potential candidates for thermoelectric applications owing to the excellent electrical and thermal transport properties. Here a new polymorph of CaZnGe, was synthesized and characterized on structures and thermoelectric properties. Different from previously reported isomer, this newly discovered CaZnGe crystallizes in the hexagonal space group P-6m2 (NO. 187), which can be closely related to the LiZnGe structure type. First principle theoretical calculations were incorporated to investigate the electronic band structure, and the results indicated that this material might be poor metallic, consistent with the measured resistivity behaviour. The thermal conductivity of CaZnGe is rather low at room temperature, but starts to increase dramatically at high temperature region due to the bipolar effect.

LiZnSb is a Zintl phase that has been predicted to be a good material in thermoelectric applications for a long time. However, experimental work indicated that the synthesized LiZnSb materials were p type, and their maximum

Zintl phases with nominal 9-4-9 formulas are very interesting for their potential applications as thermoelectric materials. However, the formation of such phases usually requires divalent transition metals, for example, Zn, Mn, and Cd, which are covalently bonded to the pnictogen atoms. In this report, for the first time, two Mg-containing compounds with such structures as Sr

Germanium nanomaterials are important for their potential applications in many fields. However, current synthetic technologies usually involve either high-cost explosive reagents or complicated facilities, which make the mass production especially challenging. In this report, a method was developed to synthesize nano-Ge materials conveniently, realized by decomposing LiZnGe in air at room temperature. The process is nontoxic, inexpensive, and, most of all, very suitable for large-scale production in combination with ball milling. The as-prepared Ge nanomaterials are crystalline whose structures can be flexibly tuned through the ball milling syntheses. As the lithium-ion battery anode, such Ge nanomaterials exhibited long-term cycle ability with high specific capacity as well as excellent rate performance. These results not only provided a very efficient way to prepare nano-Ge in lab or even promising industry production but also suggested a universal method in synthesizing the tetrels elemental nanomaterials.

Three new quaternary Zintl phases with the "9-4-9" formula, Ae

An interesting phenomenon of two polymorphic heterojunctions is reported in this paper. The selective growth of the individual phases of high-quality α- and β-BaTeMo2O9 (BTM) crystals was successfully achieved using an optimized flux system and growth parameters. A biphasic BTM crystal based on a multiseeding technique used to control the nucleation and subsequent growth was realized in a one-flux system. The formation of a grain boundary, similar to a heterojunction, between the α- and β-BTM crystals emerged as an unavoidable consequence of this process, and the factors that led to the formation of the grain boundaries in the multiseeds were examined. Lattice mismatch and interfacial binding energy calculation verified that the BTM crystals were grown together rather than being physically adhered, and the chains at the grain boundary were linked by O5Mo–O–MoO5 dioctahedrons corner-sharing O atoms at the eutectic boundary. The screw dislocation growth mechanism was confirmed for β-BTM with the growth unit...

Two new quaternary compounds, Ba23Ga10Ge10Sb25 and Ba23In10Ge10Sb24.79, have been synthesized by using the high temperature solid-state reactions. These new phases exhibit huge unit cells (V = 17 514.6 and 18 455.8 A3 for Ga- and In-containing compounds, respectively),which comprise 544 atoms and feature “onion-like” M20Ge20Sb30 clusters connected through the Sb–Sb bonds. Among these clusters, substantial isolated units such as Ba, Sb, or Sb3 trimers are filled. With such a complex structure as well as the large unit cell and substantial heavy constituent atoms, ultralow lattice thermal conductivity (κl) was observed for Ba23Ga10Ge10Sb25, ranging from 0.2 to 0.38 W·m–1·K–1 from 323 to 823 K. As a result, a maximun ZT of 0.27 was achieved at 823 K.

Two new copper-rich antimonide polar intermetallics, Sr4Cu25.37(18)Sb12 and Eu4Cu26.06(13)Sb12, were synthesized through high-temperature flux reactions, and their structures were accurately determined through the single-crystal X-ray diffraction technique. Sr4Cu25.37(18)Sb12 and Eu4Cu26.06(13)Sb12 crystallize in their own structure type with an orthorhombic space group Cmcm (No. 63) (cell parameters: a = 4.3200(7)/4.2874(7) A, b = 14.528(2)/14.611(2) A, c = 12.2594(19)/12.1946(19) A, respectively). The anionic frameworks of these compounds can be described as composed of 16-vertex Cu10Sb6 polyhedra, which form edge-sharing cages filled with the cations. A simple electron counting implies that the on-stoichiometric composition as Sr4Cu28Sb12 or Eu4Cu28Sb12 should be electron-precise; however, metallic conducting properties were suggested by the measured electrical transport properties as well as by the extensive Cu vacancies in the structure. Magnetic susceptibility measurements on Eu4Cu26.06(13)Sb12 indi...

Thermoelectric materials with high average figure of merit (zT) over the applied temperature range are crucial for power generation applications. In this report, a new Zintl series, CaZn1−xAg1−ySb (0 < x < 1; 0 < y < 1), was discovered and carefully investigated for their thermoelectric potential. These phases feature unique anionic layers with extensive Zn/Ag defects. Such a characteristic ensures very low intrinsic thermal conductivity and meanwhile considerably high electrical conductivity for the corresponding materials. For an optimized composition CaZn0.4Ag0.18Sb, decent thermoelectric performance was proved with a broad high zT plateau (zT ∼ 1.0) observed from 800 to 1100 K. The discovery of this new Zintl series not only provides us a valuable resource for exploring high zT materials, but also sheds some new light on the design of such thermoelectrics on the basis of defect modulation.

As novel Zintl phases with the LiGaGe structure type, Ca1−xCexAg1−ySb has shown decent thermoelectric performance as well as complex structure transitions, which are closely related to the Ag defects in the anionic layers. In this report, La/Sr co-doped materials, Ca1−x−δSrδLaxAg1−ySb (0 ≤ δ ≤ 0.7), were prepared and studied regarding relevant thermoelectric properties. Interestingly, the incorporation of alkaline-earth metal Sr suggested a different structure transition mechanism from the LiGaGe type to the ZrBeSi-type, which seemed closely related to the Sr doping concentrations. Besides, significant enhancement of the thermoelectric performance resulted. For materials with a specific composition of Ca0.55Sr0.3La0.15Ag0.89Sb, a maximum zT of 0.7 has been achieved at 823 K, which also corresponded to a high average zT value of 0.66 between 774 and 1068 K.

Hg2Br2 crystals have drawn much attention in recent years due to their excellent acousto-optic properties in the field of spectral imaging and optical processing. The growth of high-quality Hg2Br2 crystals is critical for the characterization of crystal properties and the fabrication of acousto-optic devices. Herein, high-quality Hg2Br2 crystals with the size of 35 mm in diameter and 40 mm in length were successfully grown by physical vapor transport method. The properties of Hg2Br2 crystals before and after irradiation were systematically investigated. The as-grown Hg2Br2 crystals possess ultra-large birefringence of 0.97 and high optical transmittance of 70% in the wide wavelength range from 470 nm to 30 µm. However, the transparent Hg2Br2 crystals will darken gradually under the irradiation of light shorter than 450 nm, which origins from the photochemical decomposition of halides. Compared with the as-grown Hg2Br2 crystals, the darkened crystals have relatively narrow-band transmission and lower transmittance. Besides, the optical bandgap and the birefringence of darkened crystals also decrease. However, these properties could be restored after annealing at 160 °C for 72 h. Our study indicates that Hg2Br2 crystal is a potential medium for far-infrared acousto-optic devices, and the decrease in optical performance caused by photosensitivity could be restored by annealing.

Two new ternary manganese bismuthides have been synthesized and their structures established based on single-crystal X-ray diffraction methods. Sr2MnBi2 crystallizes in the orthorhombic space group Pnma (a = 16.200(9) A, b = 14.767(8) A, c = 8.438(5) A, V = 2018(2) A3; Z = 12; Pearson index oP60) and is isostructural to the antimonide Sr2MnSb2. The crystal structure contains corrugated layers of corner- and edge-shared [MnBi4] tetrahedra and Sr atoms enclosed between these layers. Electronic structure calculations suggest that Sr2MnBi2 is a magnetic semiconductor possessing Mn2+ (high-spin d5) ions, and its structure can be rationalized within the Zintl concept as [Sr2+]2[Mn2+][Bi3-]2. The temperature dependence of the resistivity shows behavior consistent with a degenerate semiconductor/poor metal, and magnetic susceptibility measurements reveal a high degree of frustration resulting from the two-dimensional nature of the structure. The compositionally similar Ba2Mn1-xBi2 (x ≈ 0.15) crystallizes in a very different structure (space group Imma, a = 25.597(8) A, b = 25.667(4) A, c = 17.128(3) A, V = 11253(4) A3; Z = 64; Pearson index oI316) with its own structure type. The complex structure boasts Mn atoms in a variety of coordination environments and can be viewed as consisting of two interpenetrating 3D frameworks, linked by Bi-Bi bonds. Ba2Mn1-xBi2 can be regarded as a highly reduced compound with anticipated metallic behavior.

A series of new magnesium bismuth Zintl phases, A14MgBi11 (A = Ca, Sr, Eu), have been synthesized, and their thermoelectric properties were systematically evaluated. These novel phases belong to the well-known Yb14MnSb11 family, whose structure adopts the tetragonal space group I41/acd (No. 142) with cell parameters of a = 17.0470(17)/17.854(2)/17.6660(7) A and c = 22.665(5)/23.580(6)/23.2446(18) A for Ca14MgBi11, Sr14MgBi11, and Eu14MgBi11, respectively. Without intentional optimization, these materials exhibit high potential as new thermoelectric candidates. Especially for Sr14MgBi11, a high zT value of 0.72 has been approached at 1073 K. The discovery of these new Zintl series is very interesting, which implies the high possibility of extending the 14-1-11 thermoelectric system to the bismuth analogues in the development of highly efficient thermoelectric materials. Density functional theory (DFT) calculations were incorporated as well to help better understand the properties of these important compounds.

Zintl phases Ca1–xCexAg1–ySb (0 ≤ x ≤ 1; 0 ≤ y ≤ 1) have exhibited high-temperature thermoelectric potentials in previous studies. In this work, defect chemistry and thermoelectric properties related to the Ca1–xCexAg1–ySb series were carefully investigated. The results revealed that the Ce contents in Ca1–xCexAg1–ySb were very critical in governing the formation of various Ag-defect structures. With the Ce concentrations increased, several phase transition processes were observed, corresponding to closely related but obviously different [Ag1–ySb] anionic superlattices. Such a defect model makes these compounds very flexible in the optimization of thermoelectric properties. For a material with the nominal composition of Ca0.83Ce0.17Ag0.85Sb, a high figure of merit (ZT ∼ 0.6) can be maintained over a wide temperature range from 800 to 1025 K, which is a favorable characteristic for practical applications.

New Mg-containing antimonide Zintl phases, Sr14MgSb11 and Eu14MgSb11, were synthesized from high-temperature solid-state reactions in Ta tubes at 1323 K. Their structures can be viewed as derived from the Ca14AlSb11 structure type, which adopt the tetragonal space group I41/acd (No. 142, Z = 8) with the cell parameters of a = 17.5691(14)/17.3442(11) A and c = 23.399(4)/22.981(3) A for the Sr- and Eu-containing compounds, respectively. The corresponding thermoelectric properties were probed, which demonstrated high potential of these compounds as new thermoelectrics for their very low thermal conductivity and moderate Seebeck coefficient. Magnetism studies and theoretical calculations were conducted as well to better understand the structure-and-property correlation of these materials.

In this study, Cs2TeW3O12 (CTW) single crystals were grown successfully through a top-seeded solution growth (TSSG) method using TeO2 as a self-flux. We identified a complete set of growth process parameters suitable for facilitating the growth of a high-quality CTW crystal. The results indicate that, in the same thermal field and with an appropriate flux ratio, a smaller cooling rate of the melt facilitates the smooth growth of high-quality CTW single crystals. The melt-viscosity versus temperature curves for different flux ratios were measured, and their effects on the crystal quality were discussed. In addition, the morphology of the crystal can be controlled by adjusting the rotation speed and the orientation of the seed. To investigate piezoelectric performance, complete sets of dielectric, elastic, and piezoelectric coefficients of CTW crystals were measured using both resonance and impedance analysis. The piezoelectric coefficients d33 and d15 reached 19.1 pC N−1 and 25.9 pC N−1, respectively. The electromechanical coupling coefficient, k33, was 37.7%, slightly higher than that of Cs2TeMo3O12 (CTM). Furthermore, the extent of dipole moment and polyhedron distortion of the CTW crystal were analysed in detail, and the relationship between the crystal structure and the piezoelectric properties was also discussed.

Zintl phases with the nominal compositions Ca1−δREδAg1−δSb (RE = La, Ce, Pr, Nd, Sm; δ ≈ 0.15) are interesting due to their unique crystal structures and potential as high temperature thermoelectrics. Their structures generally feature the LiGaGe type structure with substantial vacancies on the Ag sites. The formation of such defects can be explained by the electronic effects, with which 18 electrons are required to stabilize the CaAgSb Zintl system. Since the substitution of Ca2+ with RE3+ will lead to electron excess, the formation of Ag defects will be an intrinsic character of such compounds to maintain their electron precise nature. In this work, the material Ca0.85Ce0.15Ag0.85Sb was selected for a detailed study on defect chemistry. In order to better understand the mechanism related to the defect formation and control in this system, we conducted a series of experiments aimed at controlling the point defects in Ca0.85Ce0.15Ag0.85Sb. This strategy was realized by intentionally doping Nb, which resulted in the discovery of a series of low defect density materials Ca0.725+xNb0.1−xCe0.15AgSb (0 ≤ x ≤ 0.05). In this work, an interesting defect controlling strategy on Zintl phases was demonstrated, which suggested the high flexibility of Ca1−δREδAg1−δSb in the optimization of thermoelectric properties.

Thermoelectric properties of ZrCuSiAs-typed Ce 1−x Sr x ZnSbO (x = 0, 0.04, 0.08, 0.10) ceramic samples were investigated in the temperature range from 330 K to 727 K. Thermal conductivity is extremely low in the pristine CeZnSbO, and increases after Sr doping. In addition, with the rare-earth cations doped by alkaline-earth metals, the power factor and figure of merit ZT are significantly enhanced. In our research, a ZT value of 0.12 was achieved at 727 K for the sample with a composition of Ce 0.92 Sr 0.08 ZnSbO. Although the figure of merits of CeZnSbO materials are not very impressive compared to other regular TE materials, it still provide a new type of interesting TE compounds formed between intermetallics and oxides.

Tris(8-hydroxyquinoline)aluminum(III) (Alq3) is characterized by crystallization in polymorphism both under vapor deposition and solvent evaporation. In this article, crystal growth of Alq3 in several organic solvents is studied. High quality bulk single crystals or crystalline microstructures are obtained, which depends on the varied conditions of crystallization. Two new crystalline solvates of Alq3(HCON(CH3)2) and Alq3((CH2OH)2) growing in N,N-dimethylformamide (DMF) and ethylene glycol (EG) have been obtained. X-ray diffraction analysis shows that their structures belong to new polymorphism bearing identical crystal symmetry, which is different to any solvated crystal phases reported before. The photoluminescent (PL) properties of the crystalline Alq3(HCON(CH3)2) and Alq3((CH2OH)2) are measured. Both crystals exhibit high quantum yield and long PL lifetime. In addition, the optical waveguide properties of Alq3(HCON(CH3)2) microstructures are investigated. It shows that solvated single-crystals or microstructures can be used as excellent light-emitting and propagation materials in miniaturized optoelectronic devices.

The complex Zintl phase Ca9Zn4.5Sb9 is a promising thermoelectric material due to its low thermal conductivity. Initial studies revealed that undoped Ca9Zn4.5Sb9 has a maximum zT value of 0.37 at 823 K. Hall effect measurements on Ca9Zn4.5–xAl2x/3Sb9 (x = 0, 0.5, 1), which nominally feature identical carrier concentration, suggested that control of the interstitial chemistry is critical in affecting the mobility of this system. Removal of the interstitial atoms results in rapid decrease in the carrier mobility, which has negative effects on the overall thermoelectric performance. Further material optimization was successfully carried out via Cu-doping in Ca9Zn4.5Sb9, with the aid of theoretical predictions. This resulted in high concentration of interstitial atoms as in Ca9Zn4.5–xCuxSb9 (x = 0.05, 0.1, 0.15, 0.2). For the optimized composition Ca9Zn4.35Cu0.15Sb9, a maximum of the figure of merit (zT = 0.72) was obtained at 873 K, which is increased by more than twice compared to the undoped material Ca9Zn...

The hybrid perovskites with special optoelectronic properties have attracted more attention to the scientific and industrial applications. However, because of the toxicity and instability of lead complexes, there is interest in finding a nontoxic substitute for the lead in the halides perovskites and solving the ambiguous crystal structures and phase transition of NH(CH3)3SnX3 (X = Cl, Br). Here, we report the bulk crystal growths and different crystal morphologies of orthorhombic hybrid perovskites NH(CH3)3SnX3 (X = Cl, Br) in an ambient atmosphere by bottom-seeded solution growth (BSSG) method. More importantly, detailed structural determination and refinements, phase transition, band gap, band structure calculations, nonlinear optical (NLO) properties, XPS, thermal properties, and stability of NH(CH3)3SnX3 (X = Cl, Br) single crystals are demonstrated. NH(CH3)3SnCl3 single crystal undergoes reversible structural transformation from orthorhombic space group Cmc21 (no. 36) to monoclinic space group Cc (n...

Two new ternary copper-containing arsenides, Sr2Cu3As3 and Eu2Cu3As3, were synthesized through Pb-flux reactions. In combination with theoretical calculations, the crystal structures of these compounds were determined through single-crystal X-ray diffraction. Both compounds crystallize in the orthorhombic space group Cmcm (no.63) with the cell parameters a = 4.2465(6)/4.1866(5) A, b = 17.604(3)/17.486(2) A, and c = 4.2552(6)/4.2096(5) A for the Sr- and Eu-containing compounds, respectively. Temperature-dependent magnetic susceptibility measurements suggest that both ferromagnetic and antiferromagnetic coupling exists in the structure of Eu2Cu3As3 for the Eu 4f states. According to DFT calculations, these compounds are metallic, and the Cu 3d orbitals make significant contributions to the states around the Fermi level.

Hybrid perovskites have generated a great deal of interest because of their potential in photovoltaic applications. However, the toxicity of lead means that there is interest in finding a nontoxic substitute. Bulk single crystals of both cubic CH3NH3 SnI3 and CH(NH2)2 SnI3 were obtained by using the top-seeded solution growth method under an ambient atmosphere. Structural refinement, band gap, thermal properties, and XPS measurements of CH3NH3 SnI3 and CH(NH2)2 SnI3 single crystals are also reported in detail. These results should pave the way for further applications of CH3NH3 SnI3 and CH(NH2)2 SnI3.

A series of new magnesium copper pnictide intermetallics, A2Mg3Cu9Pn7 (A = Sr, Eu; Pn = P, As) and Eu5Mg2.39Cu16.61As12, were synthesized through high temperature flux reactions. By the single-crystal X-ray diffraction technique, their structures were accurately determined. Sr2Mg3Cu9P7, Eu2Mg3Cu9P7, Sr2Mg3Cu9As7 and Eu2Mg3Cu9As7 crystallize in the Zr2Fe12P7 structure type (S.G. P, no. 174) with cell parameters: a = 9.7736(19)/9.7417(7)/10.0550(10) A/10.0410(8) A, c = 3.9280(16)/3.9008(5)/4.0544(9)/4.0364(6) A, respectively, while Eu5Mg2.39Cu16.61As12 adopts the Zr5Co19P12 structure type (S.G. P2m, no. 189) with cell parameters of a = 13.2521(6) A and c = 4.0910(3) A. These compounds can be viewed as an extensive branch of the ternary RE−M−Pn system (RE = rare-earth elements; M = transition metals; Pn = pnictogen) with the metal-to-nonmetal ratio being close or equal to 2 : 1. Interestingly, with the divalent alkaline-earth cations being introduced, these metal-rich phases exhibit electron deficiency according to the DFT calculations. Eu2Mg3Cu9As7 is metallic based on the resistivity measurement, consistent with theoretical prediction, and the magnetic susceptibility data of Eu2Mg3Cu9As7 confirmed the divalent oxidation state and weak ferromagnetic coupling for the europium cations.

Single crystal LiVMoO6, with dimensions up to 20 mm × 15 mm × 12 mm, has been grown successfully for the first time from a high-temperature solution with MoO3 as a flux. LiVMoO6 crystalizes in the monoclinic system with space group C2/m (no. 12) and unit cell parameters of a = 9.3531(9) A, b = 3.6477(4) A, c = 6.647(4) A, β = 111.643° and Z = 2. The crystal structure consists of MO6 (M = Mo and V) and LiO6 octahedrons mutually combined via corner sharing to form a 3D network. The as-grown LiVMoO6 crystal has well-developed faces with major forms {1−11}, {−1−11}, {001}, {100}, {11−1}, and {−11−1}. The crystal exhibits good transmittance from 490 to 4950 nm. High-resolution X-ray diffraction (HRXRD) shows that the full-width at half-maximum (fwhm) of the rocking curve is 47.22′′, indicating high crystal quality. The refractive index coordinate is established using a polarizing microscope. Spontaneous Raman spectra along the Z-axis with different configurations exhibit strong Raman shifts at 963.7 cm−1 and 830.5 cm−1, which are comparable to those of crystalline YVO4. The results indicate that LiVMoO6 should be an excellent Raman crystal.

A new ytterbium copper antimonide, YbCu0.52(2)Sb, was synthesized from the Pb-flux reactions, and its crystal structure was determined by the single-crystal X-ray diffraction method. The compound crystallizes in the trigonal space group R 3 ¯ m (No. 166), a = 4.4494(4) A, c = 33.767(7) A, which adopts the same structure as Ca0.61(1)Ce0.39(1)Ag0.60(1)Sb. The crystal structure of this compound can be rationalized as a combination of the YbCuSb and YbSb structures. Also, the formula can be written as a sum of these two components, [(Yb2+)(Cu+)(Sb3−)]0.52[(Yb3+)(Sb3−)]0.48. The magnetic susceptibility measurements indicated coexistence of Yb2+ and Yb3+ in the structure, which was further supported by the X-ray photoelectron spectroscopy. The temperature dependent resistivity measurements indicated the metallic nature of the material. Since the Yb-Cu-Sb system contains very limited member compounds, the discovery of this ternary YbCu0.52(2)Sb phase is important, which represents a completely new fashion in stabilizing the crystal structure.

A new generation of orthogonally polarized dual-wavelength lasers was demonstrated using a dye mode-locked neodymium-doped yttrium aluminum garnet laser for the first time. With a hexagonal C s 2 T e M o 3 O 12 as the Raman medium, efficient dual-wavelength stimulated Raman scattering was obtained at 1175 and 1154 nm with similar output power, corresponding to the stretching vibration of Mo-O and the asymmetric stretching vibrations of Mo-O and Te-O groups, respectively. The power ratio of two Raman components can be flexibly adjusted by tuning the polarization of the incident laser, which can be tuned from 0% to 100%. Laser sources with such a small wavelength separation could prove interesting for the difference-frequency generation of terahertz waves in the 4.6 THz range. Our study provides a simple and flexible method to achieve a promising dual-wavelength laser source in orthogonal polarization by Raman-based nonlinear frequency conversions.

The copper-containing antimony compounds with the general formulae ACuSb (A = Ca, Sr, Eu) were reported to adopt the ZrBeSi structure type, which feature a planar CuSb layer composed of honeycomb-like Cu3Sb3 rings. The Zn-containing analogues can crystallize in such a structure type too, but with ∼50% occupancy at the transition metal site and a disordered A2ZnSb2 structure. Interestingly, phase transition was proven from the ZrBeSi type to the LiGaGe type when Cu and Zn were both incorporated in the anionic structure, which led to the discovery of a series of new Cu/Zn-mixed Zintl phases, CaZn0.36(1)Cu0.28(1)Sb, EuZn0.25(3)Cu0.50(3)Sb and SrZn0.17(3)Cu0.65(3)Sb. The crystal structures of these novel phases were accurately determined through the single-crystal X-ray diffraction method, which indicated the P63mc (no. 186) space group with cell parameters: a = 4.5234(3)/4.5705(6)/4.5863(9) A and c = 7.9562(10)/8.431(2)/8.698(3) A for the Ca-, Sr- and Eu-containing compounds, respectively. Thermoelectric properties were systematically investigated by materials AZn0.25Cu0.5Sb (A = Ca, Sr, Eu) with nominally the same compositions. Electronic band structure calculations were performed by various models constructed based on the Sr compounds, which suggested significant convergence of the valence bands with structure transition from the ZrBeSi type to the LiGaGe type.