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While X-ray powder diffraction (XRPD) is a fundamental analytical technique used by solid-state laboratories across a breadth of disciplines, it is still underrepresented in most undergraduate curricula. In this work, we incorporate XRPD analysis into an inquiry-based project that requires students to identify the crystalline component(s) of familiar household products. Centering the project on materials which students encounter in their everyday lives helps to demystify the technique, making it accessible to everyone with a basic understanding of crystallinity and unit cells. In an XRPD study, each crystalline component generates a unique set of peaks in the diffractogram. Comparing the collected diffractogram to a library of diffractograms for known crystalline materials allows students to identify the crystalline components in their unknown. Students must determine for themselves the chemical compositions of the possible unknowns, and link their findings back to the analysis of the collected data. Initially challenging, this is the part of the work they respond to most strongly. This lab includes a data collection component, but its inquiry-based objectives can still be achieved by providing the students with simulated diffractograms when the appropriate instrumentation is unavailable.

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]

Cu2CdSnS4 and ɑ/β-Cu2ZnSiS4 meet several criteria for promising nonlinear optical materials for use in the infrared (IR) region. Both are air-stable, crystallize in noncentrosymmetric space groups, and possess high thermal stabilities. Cu2CdSnS4 and ɑ/β-Cu2ZnSiS4 display wide ranges of optical transparency, 1.4-25 and 0.7-25 µm, respectively, and have relatively large second-order nonlinearity as well as phase matchability for wide regions in the IR. The laser-damage threshold (LDT) for Cu2CdSnS4 is 0.2 GW/cm², whereas ɑ/β-Cu2ZnSiS4 has a LDT of 2.0 GW/cm² for picosecond near-IR excitation. Both compounds also exhibit efficient third-order nonlinearity. Electronic structure calculations provide insight into the variation in properties. [ABSTRACT FROM AUTHOR]

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

Abstract: Three series of quaternary rare-earth transition-metal pnictides REMM′Pn 2 (M=Cu, Ag; M′=Zn; Pn=P, As) have been prepared by reaction of the elements at 800°C, with crystal growth promoted through the addition of iodine. The extent of RE substitution is broad in these series: RECuZnAs2 (RE=Y, La Nd, Sm, Gd–Lu), REAgZnP2 (RE=La–Nd, Sm, Gd–Dy), and REAgZnAs2 (RE=La Nd, Sm, Gd Dy). Powder and single-crystal X-ray diffraction analysis revealed that they adopt the trigonal CaAl2Si2-type structure (space group P m1, Z=1), in which Cu or Ag atoms are disordered with Zn atoms over the unique tetrahedrally coordinated transition-metal site. Magnetic measurements indicated Curie–Weiss behavior for several members of the RECuZnAs2 and REAgZnP2 series. Core-line X-ray photoelectron spectra (XPS) collected on some RECuZnAs2 members corroborate the charge assignment deduced by the Zintl concept for these compounds, (RE 3+)(M 1+)(Zn2+)(Pn 3−)2. Optical diffuse reflectance spectra and valence band XPS spectra established that these compounds are small band-gap semiconductors (up to ~0.8eV in REAgZnP2) or semimetals (RECuZnAs2). Band structure calculations also support this electronic structure and indicate that the band gap can be narrowed through appropriate chemical substitution (RE=smaller atoms, M=Cu, and Pn=As). [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]

Three series of quaternary pnictides, LnCuZnAs2 (Ln: Y, La-Nd, Sm, Gd-Lu), LnAgZnP2 (Ln: La-Nd, Sm, Gd-Dy), and LnAgZnAs2 (Ln: La-Nd, Sm, Gd-Dy) are prepared by solid reaction of the elements (evacuated silica tubes, 1. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, (C(6)H(20)N(4))(2)[Sn(2)S(6)], comprises half of a [Sn(2)S(6)](4-) anion and a diprotonated tris-(2-amino-eth-yl)amine cation. The anion lies on an inversion center, while the atoms of the cation occupy general positions. An intra-molecular N-H⋯N hydrogen bond is observed in the cation. In the crystal, strong N-H⋯S hydrogen bonding between the terminal sulfur atoms of the anion and the protonated amine N atoms of the cations result in a three-dimensional network.