6 results on '"Rosello, Kate E."'
Search Results
2. Accurate X‐ray diffraction data required for proper evaluation of bond valence sums and global instability indexes: redetermination of the crystal structures of diamond‐like Cu2CdSiS4 and Cu2HgSnS4 as a case study
- Author
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Treece, Megan M., Kelly, Jordan C., Rosello, Kate E., Craig, Andrew J., and Aitken, Jennifer A.
- Subjects
VALENCE bonds ,CRYSTAL structure ,X-ray diffraction ,COPPER ,X-ray powder diffraction ,CADMIUM ,TRAFFIC circles ,DIAMOND-like carbon ,MERCURY - Abstract
Our calculations of the global instability index (G) values for some diamond‐like materials with the general formula I2–II–IV–VI4 have indicated that the structures may be unstable or incorrectly determined. To compute the G value of a given compound, the bond valence sums (BVSs) must first be calculated using a crystal structure. Two examples of compounds with high G values, based on data from the literature, are the wurtz–stannite‐type dicopper cadmium silicon tetrasulfide (Cu2CdSiS4) and the stannite‐type dicopper mercury tin tetrasulfide (Cu2HgSnS4), which were first reported in 1967 and 1965, respectively. In the present study, Cu2CdSiS4 and Cu2HgSnS4 were prepared by solid‐state synthesis at 1000 and 900 °C, respectively. The phase purity was assessed by powder X‐ray diffraction. Optical diffuse reflectance UV/Vis/NIR spectroscopy was used to estimate the optical bandgaps of 2.52 and 0.83 eV for Cu2CdSiS4 and Cu2HgSnS4, respectively. The structures were solved and refined using single‐crystal X‐ray diffraction data. The structure type of Cu2CdSiS4 was confirmed, where Cd2+, Si4+ and two of the three crystallographically unique S2− ions lie on a mirror plane. The structure type of Cu2HgSnS4 was also verified, where all ions lie on special positions. The S2− ion resides on a mirror plane, the Cu+ ion is situated on a fourfold rotary inversion axis and both the Hg2+ and the Sn4+ ions are located on the intersection of a fourfold rotary inversion axis, a mirror plane and a twofold rotation axis. Using the crystal structures solved and refined here, the G values were reassessed and found to be in the range that indicates reasonable strain for a stable crystal structure. This work, together with some examples gathered from the literature, shows that accurate data collected on modern instrumentation should be used to reliably calculate BVSs and G values. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Cu4MnGe2S7 and Cu2MnGeS4: two polar thiogermanates exhibiting second harmonic generation in the infrared and structures derived from hexagonal diamond.
- Author
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Glenn, Jennifer R., Cho, Jeong Bin, Wang, Yiqun, Craig, Andrew J., Zhang, Jian-Han, Cribbs, Marvene, Stoyko, Stanislav S., Rosello, Kate E., Barton, Christopher, Bonnoni, Allyson, Grima-Gallardo, Pedro, MacNeil, Joseph H., Rondinelli, James M., Jang, Joon I., and Aitken, Jennifer A.
- Subjects
SECOND harmonic generation ,DIFFERENTIAL thermal analysis ,OPTICAL susceptibility ,X-ray powder diffraction ,DIAMONDS ,SPACE groups - Abstract
The new, quaternary diamond-like semiconductor (DLS) Cu
4 MnGe2 S7 was prepared at high-temperature from a stoichiometric reaction of the elements under vacuum. Single crystal X-ray diffraction data were used to solve and refine the structure in the polar space group Cc. Cu4 MnGe2 S7 features [Ge2 S7 ]6− units and adopts the Cu5 Si2 S7 structure type that can be considered a derivative of the hexagonal diamond structure. The DLS Cu2 MnGeS4 with the wurtz-stannite structure was similarly prepared at a lower temperature. The achievement of relatively phase-pure samples, confirmed by X-ray powder diffraction data, was nontrival as differential thermal analysis shows an incongruent melting behaviour for both compounds at relatively high temperature. The dark red Cu2 MnGeS4 and Cu4 MnGe2 S7 compounds exhibit direct optical bandgaps of 2.21 and 1.98 eV, respectively. The infrared (IR) spectra indicate potentially wide windows of optical transparency up to 25 μm for both materials. Using the Kurtz–Perry powder method, the second-order nonlinear optical susceptibility, χ(2) , values for Cu2 MnGeS4 and Cu4 MnGe2 S7 were estimated to be 16.9 ± 2.0 pm V−1 and 2.33 ± 0.86 pm V−1 , respectively, by comparing with an optical-quality standard reference material, AgGaSe2 (AGSe). Cu2 MnGeS4 was found to be phase matchable at λ = 3100 nm, whereas Cu4 MnGe2 S7 was determined to be non-phase matchable at λ = 1600 nm. The weak SHG response of Cu4 MnGe2 S7 precluded phase-matching studies at longer wavelengths. The laser-induced damage threshold (LIDT) for Cu2 MnGeS4 was estimated to be ∼0.1 GW cm−2 at λ = 1064 nm (pulse width: τ = 30 ps), while the LIDT for Cu4 MnGe2 S7 could not be ascertained due to its weak response. The significant variance in NLO properties can be reasoned using the results from electronic structure calculations. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
4. Synthesis, structure, linear and nonlinear optical properties of noncentrosymmetric quaternary diamond-like semiconductors, Cu2ZnGeSe4 (CZGSe) and the novel Cu4ZnGe2Se7.
- Author
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Sinagra III, Charles W., Saouma, Felix O., Otieno, Calford O., Lapidus, Saul H., Zhang, Jian-Han, Craig, Andrew J., Grima-Gallardo, Pedro, Brant, Jacilynn A., Rosmus, Kimberly A., Rosello, Kate E., Jang, Joon I., and Aitken, Jennifer A.
- Subjects
- *
OPTICAL properties , *SEMICONDUCTORS , *SECOND harmonic generation , *X-ray powder diffraction , *OPTICAL devices , *COPPER surfaces - Abstract
• Cu 4 ZnGe 2 Se 7 is a new diamond-like semiconductor with the Cu 4 NiSi 2 S 7 structure type. • CZGSe and Cu 4 ZnGe 2 Se 7 possess optical bandgaps of 1.38 and 0.91 eV, respectively. • CZGSe and Cu 4 ZnGe 2 Se 7 are air stable and have wide windows of optical transparency. • CZGSe exhibits a strong second harmonic generation response at λ = 2900 nm. • CZGSe is an excellent candidate for low-powered infrared nonlinear optical devices. [Display omitted] In this study, two quaternary diamond-like semiconductors (DLSs) in the Cu-Zn-Ge-Se system, the known Cu 2 ZnGeSe 4 (also referred to as CZGSe) and the new Cu 4 ZnGe 2 Se 7 , are compared in terms of their crystal structures, electronic structures and physicochemical properties. Both compounds were prepared by high-temperature, solid-state synthesis at 800 °C. Single crystal X-ray diffraction was used to determine the structure of Cu 4 ZnGe 2 Se 7. The structures of both Cu 2 ZnGeSe 4 and Cu 4 ZnGe 2 Se 7 can be considered as derivatives of cubic diamond. Cu 4 ZnGe 2 Se 7 , with a reduced symmetry due to the cation ordering pattern, adopts the Cu 4 NiSi 2 S 7 structure type, with space group C 2. The corner-sharing tetrahedra in Cu 4 ZnGe 2 Se 7 are slightly distorted because the charge for some of the S2- anions is not compensated by the first-nearest-neighbor cations. Rietveld refinements using synchrotron X-ray powder diffraction data were used to assess the phase purity of the samples and confirm the bulk structural behavior. Diffuse reflectance UV/Vis/NIR spectroscopy shows that Cu 2 ZnGeSe 4 and Cu 4 ZnGe 2 Se 7 have direct optical bandgaps of 1.38 and 0.91 eV, respectively. Electronic structure calculations implementing density functional theory confirm the direct bandgap for Cu 4 ZnGe 2 Se 7 , with a calculated value of 0.62 eV. Both compounds are air stable, thermally stable up to relatively high temperatures, undergo phase transitions and have wide windows of optical clarity. The Kurtz-Perry powder technique was used to determine the second harmonic generation (SHG) responses using a commercial AgGaSe 2 standard. While Cu 4 ZnGe 2 Se 7 displays a weak SHG response, Cu 2 ZnGeSe 4 exhibits a response that is greater than several benchmark materials, with a large SHG coefficient, χ (2) , of 43 ± 6 pm/V at λ = 2900 nm. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
5. Accurate X-ray diffraction data required for proper evaluation of bond valence sums and global instability indexes: redetermination of the crystal structures of diamond-like Cu 2 CdSiS 4 and Cu 2 HgSnS 4 as a case study.
- Author
-
Treece MM, Kelly JC, Rosello KE, Craig AJ, and Aitken JA
- Abstract
Our calculations of the global instability index (G) values for some diamond-like materials with the general formula I
2 -II-IV-VI4 have indicated that the structures may be unstable or incorrectly determined. To compute the G value of a given compound, the bond valence sums (BVSs) must first be calculated using a crystal structure. Two examples of compounds with high G values, based on data from the literature, are the wurtz-stannite-type dicopper cadmium silicon tetrasulfide (Cu2 CdSiS4 ) and the stannite-type dicopper mercury tin tetrasulfide (Cu2 HgSnS4 ), which were first reported in 1967 and 1965, respectively. In the present study, Cu2 CdSiS4 and Cu2 HgSnS4 were prepared by solid-state synthesis at 1000 and 900 °C, respectively. The phase purity was assessed by powder X-ray diffraction. Optical diffuse reflectance UV/Vis/NIR spectroscopy was used to estimate the optical bandgaps of 2.52 and 0.83 eV for Cu2 CdSiS4 and Cu2 HgSnS4 , respectively. The structures were solved and refined using single-crystal X-ray diffraction data. The structure type of Cu2 CdSiS4 was confirmed, where Cd2+ , Si4+ and two of the three crystallographically unique S2- ions lie on a mirror plane. The structure type of Cu2 HgSnS4 was also verified, where all ions lie on special positions. The S2- ion resides on a mirror plane, the Cu+ ion is situated on a fourfold rotary inversion axis and both the Hg2+ and the Sn4+ ions are located on the intersection of a fourfold rotary inversion axis, a mirror plane and a twofold rotation axis. Using the crystal structures solved and refined here, the G values were reassessed and found to be in the range that indicates reasonable strain for a stable crystal structure. This work, together with some examples gathered from the literature, shows that accurate data collected on modern instrumentation should be used to reliably calculate BVSs and G values.- Published
- 2023
- Full Text
- View/download PDF
6. Cu 4 MnGe 2 S 7 and Cu 2 MnGeS 4 : two polar thiogermanates exhibiting second harmonic generation in the infrared and structures derived from hexagonal diamond.
- Author
-
Glenn JR, Cho JB, Wang Y, Craig AJ, Zhang JH, Cribbs M, Stoyko SS, Rosello KE, Barton C, Bonnoni A, Grima-Gallardo P, MacNeil JH, Rondinelli JM, Jang JI, and Aitken JA
- Abstract
The new, quaternary diamond-like semiconductor (DLS) Cu
4 MnGe2 S7 was prepared at high-temperature from a stoichiometric reaction of the elements under vacuum. Single crystal X-ray diffraction data were used to solve and refine the structure in the polar space group Cc. Cu4 MnGe2 S7 features [Ge2 S7 ]6- units and adopts the Cu5 Si2 S7 structure type that can be considered a derivative of the hexagonal diamond structure. The DLS Cu2 MnGeS4 with the wurtz-stannite structure was similarly prepared at a lower temperature. The achievement of relatively phase-pure samples, confirmed by X-ray powder diffraction data, was nontrival as differential thermal analysis shows an incongruent melting behaviour for both compounds at relatively high temperature. The dark red Cu2 MnGeS4 and Cu4 MnGe2 S7 compounds exhibit direct optical bandgaps of 2.21 and 1.98 eV, respectively. The infrared (IR) spectra indicate potentially wide windows of optical transparency up to 25 μm for both materials. Using the Kurtz-Perry powder method, the second-order nonlinear optical susceptibility, χ(2) , values for Cu2 MnGeS4 and Cu4 MnGe2 S7 were estimated to be 16.9 ± 2.0 pm V-1 and 2.33 ± 0.86 pm V-1 , respectively, by comparing with an optical-quality standard reference material, AgGaSe2 (AGSe). Cu2 MnGeS4 was found to be phase matchable at λ = 3100 nm, whereas Cu4 MnGe2 S7 was determined to be non-phase matchable at λ = 1600 nm. The weak SHG response of Cu4 MnGe2 S7 precluded phase-matching studies at longer wavelengths. The laser-induced damage threshold (LIDT) for Cu2 MnGeS4 was estimated to be ∼0.1 GW cm-2 at λ = 1064 nm (pulse width: τ = 30 ps), while the LIDT for Cu4 MnGe2 S7 could not be ascertained due to its weak response. The significant variance in NLO properties can be reasoned using the results from electronic structure calculations.- Published
- 2021
- Full Text
- View/download PDF
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