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We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn-14(Mn0.11Co0.64Si0.25)(23) structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.

We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn-14(Mn0.11Co0.64Si0.25)(23) structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.

We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn-14(Mn0.11Co0.64Si0.25)(23) structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.

We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn-14(Mn0.11Co0.64Si0.25)(23) structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.

We report two new variants of the X-phase (orthorhombic, space group Pnnm) derived from the Mn-Co-Ge system. Two compositionally related crystals were investigated by means of single-crystal X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The Mn14.9Co15.5Ge6.6 and Mn14Co16.2Ge6.8 intermetallic compounds are part of the homogeneity region of the X-phase and adopt the Mn-14(Mn0.11Co0.64Si0.25)(23) structure type. The composition obtained from refinement of the XRD data is in agreement with the EDS results. In the present study, chemical disorder was only detected on the 8h positions. The ordering is compared with other members of the X-phase family and shows that the degree of disordering depends on the chemical composition. No completely ordered variants of the X-phase have yet been reported.

By means of ab initio calculations, we have estimated stability of 2D Me2X (Me = Mg, Ca, Sr, Ba and X = Si, Ge, Sn) in the T and Td phases, which are similar to the ones of 2D transition metal chalcogenides, in addition to their phonon spectra. The T phase is found to be more stable for 2D Ca2X, Sr2X and Ba2X, whereas the Td phase is predicted to be the ground state for 2D Mg2X. We have also discussed that imaginary frequencies in the calculated phonon spectra of 2D Me2X, which appeared in the vicinity of the Gamma point, were not necessarily associated with the dynamic instability.

By means of ab initio calculations, we have estimated stability of 2D Me2X (Me = Mg, Ca, Sr, Ba and X = Si, Ge, Sn) in the T and Td phases, which are similar to the ones of 2D transition metal chalcogenides, in addition to their phonon spectra. The T phase is found to be more stable for 2D Ca2X, Sr2X and Ba2X, whereas the Td phase is predicted to be the ground state for 2D Mg2X. We have also discussed that imaginary frequencies in the calculated phonon spectra of 2D Me2X, which appeared in the vicinity of the Gamma point, were not necessarily associated with the dynamic instability., QC 20190807

Nanomaterials derived from silicon and germanium have demonstrated several desirable properties for a variety of materials applications, such as optoelectronics, spintronics, catalysis, and thermoelectrics. Currently, the synthetic library for the production of technologically relevant Group IV nanomaterials comprised of silicon–germanium alloys, metal-silicides, and metal germanides are extremely limited, particularly with regard to solution-phase approaches. The work presented in this dissertation demonstrates the expansion of existing protocols to produce a variety of new Group IV-based nanomaterials using solution-phase syntheses. For the first time, silicon–germanium alloy nanocrystals are produced from a solution-phase approach. In addition, a new, generalizable scheme for the production of a variety of metal germanide nanocrystals is demonstrated through the use of metal(0) precursors. This methodology is then adapted to existing electroless etching methodologies used to produce silicon nanowire arrays, leading to the production of heterostructured silicon/metal silicide nanowires.

Nanomaterials derived from silicon and germanium have demonstrated several desirable properties for a variety of materials applications, such as optoelectronics, spintronics, catalysis, and thermoelectrics. Currently, the synthetic library for the production of technologically relevant Group IV nanomaterials comprised of silicon–germanium alloys, metal-silicides, and metal germanides are extremely limited, particularly with regard to solution-phase approaches. The work presented in this dissertation demonstrates the expansion of existing protocols to produce a variety of new Group IV-based nanomaterials using solution-phase syntheses. For the first time, silicon–germanium alloy nanocrystals are produced from a solution-phase approach. In addition, a new, generalizable scheme for the production of a variety of metal germanide nanocrystals is demonstrated through the use of metal(0) precursors. This methodology is then adapted to existing electroless etching methodologies used to produce silicon nanowire arrays, leading to the production of heterostructured silicon/metal silicide nanowires.

We performed single-crystal structure analysis of two ternary samarium platinum germanides SmPtGe2 and Sm2Pt3Ge5. SmPtGe2 crystallizes in the space group (S.G.) Immm (no. 71) with a=4.3679(9)angstrom, b=8.728(2) angstrom, c=16.378(4) angstrom, and V=624.4(2) angstrom(3). This compound is isotypic with YIrGe2 having a Ge10Pt4 subunit composed of edge-sharing five- and six-membered rings. SmPtGe2 shows a metallic conductivity from room temperature down to 2 K. The magnetic susceptibility measurement showed a 3+ oxidation state for the samarium. Sm2Pt3Ge5 crystallizes in the S.G. Ibam (no. 72) with a=10.174(1) angstrom, b=11.761(2) angstrom, c=6.2142(8) angstrom, and V=743.6(2) angstrom(3). It is isotypic with U2Co3Si5 with a structure closely related to ThCr2Si2.