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Single crystals of quaternary adamantine-type Cu☐GaGeS4 were grown using the chemical vapor transport technique, with iodine as the transport agent. Dark red transparent crystals were grown in a temperature gradient of ΔT = 900–750 °C. Chemical characterization by X-ray fluorescence showed the off-stoichiometric composition of Cu☐GaGeS4 crystals—in particular, a slight Ge deficiency was observed. By X-ray diffraction, Cu☐GaGeS4 was found to adopt the chalcopyrite-type structure with the space group I 4 ¯ 2 d . Cation distribution in this structure was analyzed by multiple energy anomalous synchrotron X-ray diffraction, and it was found that Cu and vacancies occupied the 4a site, whereas Ga and Ge occupied the 4b site. The band gap energies of several off-stoichiometric Cu☐GaGeS4 crystals were determined by UV-Vis spectroscopy and ranged from 2.1 to 2.4 eV. A non-linear correlation of the band gap energy with the Ge content of the compound was shown to follow the usual bowing behavior of semiconductor alloys, with a bowing parameter of b   = −1.45 (0.08). [ABSTRACT FROM AUTHOR]

• Phase-pure CuInSnS 4 was synthesized allowing for an investigation of the structure-property relationships. • Spinel CuInSnS 4 has an indirect bandgap with strong s -̶ p -̶ d orbital hybridization. • Low frequency optical modes and strong anharmonicity leads to very low thermal conductivity. • The bandgap and low thermal conductivity make it of interest for potential optoelectronic and thermoelectric applications. Quaternary chalcogenides of different structure types continue to be of interest due to the novel physical properties they exhibit and for applications ranging from optoelectronics to energy-related technologies. Herein we report on the electronic and thermal properties of spinel CuInSnS 4. UV–vis–NIR spectroscopy indicates strong absorption in the visible-light region with an indirect bandgap of 1.52 eV. First-principles computations corroborate our experimental data and reveal that the band-edge electronic properties are due to strong p − d and s − p hybridization and antibonding interactions. Analyses of temperature-dependent thermal properties together with first principles simulations reveal strong anharmonicity and low-lying optical branches that hybridize with the acoustic modes effectively suppressing thermal conductivity. This intrinsically very low thermal conductivity is much lower than that of related chalcogenides. Our findings are discussed in the light of ongoing interest in quaternary metal chalcogenide materials and may aid in the development of this and similar chalcogenides for applications of interest. [Display omitted] [ABSTRACT FROM AUTHOR]

Single crystals of quaternary adamantine-type Cu☐GaGeS4 were grown using the chemical vapor transport technique, with iodine as the transport agent. Dark red transparent crystals were grown in a temperature gradient of ΔT = 900–750 °C. Chemical characterization by X-ray fluorescence showed the off-stoichiometric composition of Cu☐GaGeS4 crystals—in particular, a slight Ge deficiency was observed. By X-ray diffraction, Cu☐GaGeS4 was found to adopt the chalcopyrite-type structure with the space group I4¯2d. Cation distribution in this structure was analyzed by multiple energy anomalous synchrotron X-ray diffraction, and it was found that Cu and vacancies occupied the 4a site, whereas Ga and Ge occupied the 4b site. The band gap energies of several off-stoichiometric Cu☐GaGeS4 crystals were determined by UV-Vis spectroscopy and ranged from 2.1 to 2.4 eV. A non-linear correlation of the band gap energy with the Ge content of the compound was shown to follow the usual bowing behavior of semiconductor alloys, with a bowing parameter of b = −1.45 (0.08).

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A sandwich-type sensitive voltammetric immunosensor for breast cancer biomarker human epidermal growth factor receptor 2 (HER2) detection was prepared. The electrochemical immunosensor was developed based on gold nanoparticles decorated copper-organic framework (AuNPs/Cu-MOF) and quaternary chalcogenide with platinum-doped graphitic carbon nitride (g-C3N4). Cu2ZnSnS4 nanoparticle (CZTS NP) quaternary chalcogenide with platinum (Pt)-doped g-C3N4 composite (Pt/g-C3N4) was tagged as CZTS NPs/Pt/g-C3N4. AuNPs/Cu-MOF composite was successfully synthesized by amidation reaction between AuNPs functionalized with amino group and Cu-MOFs containing carboxylic acid. After the conjugations of primer HER2 antibody and antigen HER2 protein to AuNPs/Cu-MOF as sensor platform, CZTS NPs/Pt/g-C3N4 composite was prepared by one-pot hydrothermal method. After immune reaction of 30 min, the prepared HER2 immunosensor was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The developed immunosensor showed high sensitivity with a detection limit of 3.00 fg mL−1. Additional properties of the voltammetric immunosensor are high selectivity, stability, reproducibility, and reusability. [ABSTRACT FROM AUTHOR]

The quaternary chalcogenide Cu2ZnSnS4 has emerged as a potential thermoelectric (TE) material due to its low thermal conductivity (κ), high Seebeck coefficient (S) and composition including earth-abundant, low-cost and non-toxic elements. In this work, Cu2ZnSnS4 was synthesised from a mixture of Cu, Zn, Sn and S powders using a mechanical alloying method. As a result, Cu2ZnSnS4 powders were formed after 16 h of milling, without additional heat treatment. After milling, the powders were heat-treated at 723 K for 24 h and then sintered by spark plasma sintering under an applied pressure of 60 MPa at 873 K for 10 min. The heat-treated Cu2ZnSnS4 sample showed a wide-band-gap of 1.49 eV. The sintered Cu2ZnSnS4 sample exhibited S and κ values of 170 μV K−1 and 1.06 W m−1 K−1, respectively with an electrical conductivity σ of 1240 S m−1 and a dimensionless figure of merit (ZT) of 0.022 at 663 K. [ABSTRACT FROM AUTHOR]

Quaternary chalcogenide Cu2CdSnSe4 distributed with ex-situ homogeneous nanoinclusions has been synthesized by ball milling, followed by spark plasma sintering. The Cu2CdSnSe4 nanocrystallites with sizes ranging from 20 to 30 nm were prepared via colloidal synthesis, while the Cu2CdSnSe4 matrix was made by the traditional solid state reaction method. It is found that nanocrystallite inclusions strongly enhance electrical conductivity while preserving the Seebeck coefficient. In addition, these inclusions significantly reduce the lattice thermal conductivity through scattering phonons with all-scale length due to the polymorphous structure feature of Cu2CdSnSe4 composites. These concomitant effects result in an enhanced thermoelectric performance with the dimensionless figure of merit ZT reaching a peak value of 0.5 at 760 K, which is a 65% improvement compared to that of the pure Cu2CdSnSe4 matrix. These observations demonstrate an exciting scientific opportunity to raise the figure of merit via ex-situ homogeneous nanoinclusions, not only for quaternary chalcogenides but also for other promising thermoelectric materials.

Self-assembly uniform flower-liked Cu2FeSnS4 (CFTS) microspheres have been successfully synthesized by a facial and promisingly mixed solvent method for the first time. In this study, we adopted ethylene glycol (EG) and deionized water (DIW) as the mixed solvent and controlled the specific volume ratio of these two solvent. Besides, the addition of polyvinyl pyrrolidone (PVP) for the formation of flower-like CFTS microspheres also play a crucial role. The as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and transmission election microscopy (TEM). [ABSTRACT FROM AUTHOR]

The madocite Pb 17 (Sb 0.75 As 0.25 ) 16 S 41 was synthesized by reaction of binary compounds and densified using hot pressing. The optical band-gap, thermal stability, and temperature-dependent heat capacity and thermal conductivity are reported for the first time. The thermal properties are evaluated using the Debye model. The findings in this work lay the foundation for a more detailed understanding of the physical properties of this material, and is part of the continuing effort in investigating materials with new compositions that possess low thermal conductivity for potential low-cost thermal barrier coating and energy-related applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel quaternary chalcogenide KBiCu2S3 has been synthesized via a facile hydrothermal approach. [•] The critical influencing factors for the crystal growth were discussed in detail. [•] The magnetic and electrical properties of KBiCu2S3 were also studied. [•] The band gap of the compound is 1.29 eV. [•] Its photoelectric response was also characterized, which demonstrated the potential for applications in photovoltaic devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] The results show that LDA+U improve the description of the electronic structure. [•] The CuFe2GaSe4 is HM ferromagnetic when the coulomb repulsion U is used. [•] The HM gap reaches 0.62eV at the equilibrium volume. [•] The total magnetic moment is 8μB coming predominantly from the Fe atoms. [ABSTRACT FROM AUTHOR]

Abstract: Quaternary chalcogenide Cu2FeSnS4 (CFTS) particles, a potential candidate for application as absorber layer in thin film solar cells, were successfully synthesized by using a convenient solvothermal method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that the CFTS particles possessed pure tetragonal structure with high crystallinity. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) results showed that the average size of the CFTS particles was about 200nm and the composition of products was close to the stoichiometry of CFTS. UV–vis absorption spectrum showed that the CFTS particles had a broad absorption band in the whole visible range with a band gap of 1.28eV, which are promising for photovoltaic applications. [Copyright &y& Elsevier]