Search

The quaternary diamond-like semiconductor, Cu2ZnSiS4, was synthesized by high-temperature solid-state synthesis at 1000 °C. High-resolution synchrotron X-ray powder diffraction of this product revealed the presence of two polymorphs. This data confirms that the known α-Cu2ZnSiS4 exists with the wurtz-stannite structure in the noncentrosymmetric space group Pmn21. The new polymorph, β-Cu2ZnSiS4, crystallizes in the noncentrosymmetric space group Pn with a = 6.134092(6) Å, b = 6.392752(5) Å, c = 7.421228(8) Å, β = 90.056(1)°, Z = 2, χ2 = 5.554, Rp = 0.0857 and wRp = 0.1173. Electronic structure calculations performed for both polymorphs indicate direct bandgaps of 1.3 and 1.7 eV at the Γ-point, respectively. [ABSTRACT FROM AUTHOR]

The quaternary diamond-like semiconductor, Cu2ZnSiS4, was synthesized by high-temperature solid-state synthesis at 1000 °C. High-resolution synchrotron X-ray powder diffraction of this product revealed the presence of two polymorphs. This data confirms that the known α-Cu2ZnSiS4 exists with the wurtz-stannite structure in the noncentrosymmetric space group Pmn21. The new polymorph, β-Cu2ZnSiS4, crystallizes in the noncentrosymmetric space group Pn with a = 6.134092(6) Å, b = 6.392752(5) Å, c = 7.421228(8) Å, β = 90.056(1)°, Z = 2, χ2 = 5.554, Rp = 0.0857 and wRp = 0.1173. Electronic structure calculations performed for both polymorphs indicate direct bandgaps of 1.3 and 1.7 eV at the Γ-point, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Single crystals of the new diamond-like semiconductor Ag2ZnSiS4 have been synthesized using high-temperature, solid state synthesis at 800°C. The compound crystallizes in the monoclinic, noncentrosymmetric space group Pn with a =6.4052(1)Å, b =6.5484(1)Å, c =7.9340(1)Å, β =90.455(1)° and R1 (for all data)=2.42%. The electronic band structure and density of states were calculated using density functional theory (DFT) and the full potential linearized augmented plane wave (LAPW) method within the Wien2k program suite. The calculated band structure suggests that Ag2ZnSiS4 is a direct band gap semiconductor with a calculated band gap of 1.88eV at the Γ-point. The calculated density of states of Ag2ZnSiS4 is compared with that of AgGaS2. The band gap of Ag2ZnSiS4 was also determined experimentally as 3.28eV via optical diffuse reflectance spectroscopy. [Copyright &y& Elsevier]

Cu2ZnSiS4 is synthesized by solid state reaction of the elements (graphite crucible, 1000 °C, 96 h). [ABSTRACT FROM AUTHOR]

Abstract: The Mn-substituted CuInS2 compounds (CuIn1 – x Mn x S2 with x = 0–0.20 and Cu1 – y Mn y InS2 with y = 0.05–0.10) were synthesized using high-temperature solid–state reactions. Single-phase materials with the chalcopyrite structure persist with up to 10% of the Cu/In sites being replaced with Mn. The introduction of manganese results in a linear expansion of the lattice parameters as a function of Mn concentration, following Vegard''s law. Rietveld refinements on a combination of X-ray and neutron powder diffraction data reveal a site preference of Mn for the In site under In-poor conditions and the existence of cation anti-site occupation, CuIn and InCu. The Mn substitution increases the anion displacement, accentuating the cation-anion bond length mismatch. The greater variance in the bond alternation and the addition of Mn d–S p hybridization near the Fermi level result in a decrease in the bandgap by ∼0.1 eV. The CuInS2:Mn compounds display paramagnetic behavior with short-range antiferromagnetic interactions. X-ray photoelectron spectroscopy suggests the presence of Cu+, Mn2+, and In3+ in the samples. [Copyright &y& Elsevier]

Highlights: [•] The title compounds were prepared by a high-temperature, direct-combination route. [•] The room temperature structure of Li4SnS4 is reported in space group Pnma. [•] The Li(2)S4 tetrahedra invert upon going from the RT to low temperature structure. [•] Electronic structure calculations indicate the Li–S bonding to be primarily ionic. [•] Li4GeS4 and Li4SnS4 have shown to be stable up to ∼850 and 950°C respectively. [ABSTRACT FROM AUTHOR]