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1. Thermal and Electronic Properties of Ba ₂ MnSe ₃

   https://doi.org/10.1021/acs.inorgchem.2c04048  

   Ojo, Oluwagbemiga P.; Gunatilleke, Wilarachchige D.; Biacchi, Adam J.; Wang, Hsin; Nolas, George S. (February 2023, Inorganic Chemistry)
2. Surface and dynamical properties of GeI ₂

   https://doi.org/10.1088/2053-1583/ac4715  

   Dhingra, Archit; Lipatov, Alexey; Lu, Haidong; Chagoya, Katerina; Dalton, Joseph; Gruverman, Alexei; Sinitskii, Alexander; Blair, Richard G; Dowben, Peter A (January 2022, 2D Materials)

   Abstract GeI 2 is an interesting two-dimensional wide-band gap semiconductor because of diminished edge scattering due to an absence of dangling bonds. Angle-resolved x-ray photoemission spectroscopy indicates a germanium rich surface, and a surface to bulk core-level shift of 1.8 eV in binding energy, between the surface and bulk components of the Ge 2p 3/2 core-level, making clear that the surface is different from the bulk. Temperature dependent studies indicate an effective Debye temperature ( θ D ) of 186 ± 18 K for the germanium x-ray photoemission spectroscopy feature associated with the surface. These measurements also suggest an unusually high effective Debye temperature for iodine (587 ± 31 K), implying that iodine is present in the bulk of the material, and not the surface. From optical absorbance, GeI 2 is seen to have an indirect (direct) optical band gap of 2.60 (2.8) ± 0.02 (0.1) eV, consistent with the expectations. Temperature dependent magnetometry indicates that GeI 2 is moment paramagnetic at low temperatures (close to 4 K) and shows a diminishing saturation moment at high temperatures (close to 300 K and above). 

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3. Structural and thermal properties of Eu ₂ Ga ₁₁ Sn ₃₅

   https://doi.org/10.1063/5.0119852  

   Gunatilleke, Wilarachchige D.; Zhang, Mingjian; Wong-Ng, Winnie; Zavalij, Peter; Chen, Yu-Sheng; Nolas, George S. (March 2023, Journal of Applied Physics)

   Clathrates have been reported to form in a variety of different structure types; however, inorganic clathrate-I materials with a low-cation concentration have yet to be investigated. Furthermore, tin-based compositions have been much less investigated as compared to silicon or germanium analogs. We report the temperature-dependent structural and thermal properties of single-crystal Eu 2 Ga 11 Sn 35 revealing the effect of structure and composition on the thermal properties of this low-cation clathrate-I material. Specifically, low-temperature heat capacity, thermal conductivity, and synchrotron single-crystal x-ray diffraction reveal a departure from Debye-like behavior, a glass-like phonon mean-free path for this crystalline material, and a relatively large Grüneisen parameter due to the dominance of low-frequency Einstein modes. Our analyses indicate thermal properties that are a direct result of the structure and composition of this clathrate-I material. 

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4. Structural and energetic properties of RMX ₃ ‐NH ₃ complexes

   https://doi.org/10.1002/qua.26383  

   Phillips, James A.; Ley, Anna R.; Treacy, Patrick W.; Wahl, Benjamin M.; Zehner, Brittany C.; Donald, Kelling J.; Gillespie, Samuel (August 2020, International Journal of Quantum Chemistry)

   Abstract We have explored the structural and energetic properties of a series of RMX₃‐NH₃(M=Si, Ge; X=F, Cl; R=CH₃, C₆H₅) complexes using density functional theory and low‐temperature infrared spectroscopy. In the minimum‐energy structures, the NH₃binds axially to the metal, opposite a halogen, while the organic group resides in an equatorial site. Remarkably, the primary mode of interaction in several of these systems seems to be hydrogen bonding (C‐H‐‐N) rather than a tetrel (N→M) interaction. This is particularly clear for the RMCl₃‐NH₃complexes, and analyses of the charge distributions of the acid fragment corroborate this assessment. We also identified a set of metastable geometries in which the ammonia binds opposite the organic substituent in an axial orientation. Acid fragment charge analyses also provide a clear rationale as to why these configurations are less stable than the minimum‐energy structures. Matrix‐isolation infrared spectra provide clear evidence for the occurrence of the minimum‐energy form of CH₃SiCl₃–NH₃, but analogous results for CH₃GeCl₃–NH₃are less conclusive. Computational scans of the M‐N distance potentials for CH₃SiCl₃–NH₃and CH₃GeCl₃–NH₃, both in the gas phase and bulk dielectric media, reveal a great deal of anharmonicity and a propensity for condensed‐phase structural change. 

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5. Structural and magnetodielectric properties of BiFeO ₃ -GdMnO ₃ multiferroics

   https://doi.org/10.1088/2053-1591/abdd50  

   Masso, R.; Tripathy, S. N.; Aponte, F. A.; Pradhan, D. K.; Martinez, R.; Palai, R. (January 2021, Materials Research Express)

   Abstract We report on structural, microstructural, spectroscopic, dielectric, electrical, ferroelectric, ferromagnetic, and magnetodielectric coupling studies of BiFeO₃–GdMnO₃[(BFO)_1–x–(GMO)_x], wherexis the concentration of GdMnO₃(x= 0.0, 0.025, 0.05, 0.075, 0.1, 0.15, and 0.2), nanocrystalline ceramic solid solutions by auto-combustion method. The analysis of structural property by Rietveld refinement shows the existence of morphotropic phase boundary (MPB) atx= 0.10, which is in agreement with the Raman spectroscopy and high resolution transmission electron microscopy (HRTEM) studies. The average crystallite size obtained from the transmission electron microscopy (TEM) and x-ray line profile analysis was found to be 20–30 nm. The scanning electron micrographs show the uniform distribution of grains throughout the surface of the sample. The dielectric dispersion behavior fits very well with the Maxwell-Wagner model. The frequency dependent phase angle (θ) study shows the resistive nature of solid solutions at low frequency, whereas it shows capacitive behavior at higher frequencies. The temperature variation of dielectric permittivity shows dielectric anomaly at the magnetic phase transition temperature and shifting of the phase transition towards the lower temperature with increasing GMO concentration. The Nyquist plot showed the conduction mechanism is mostly dominated by grains and grain boundary resistances. The ac conductivity of all the samples follows the modified Jonscher model. The impedance and modulus spectroscopy show a non-Debye type relaxation mechanism which can be modeled using a constant phase element (CPE) in the equivalent circuit. The solid-solutions of BFO-GMO show enhanced ferromagnetic-like behavior at room temperature. The ferroelectric polarization measurement shows lossy ferroelectric behavior. The frequency dependent magnetocapacitance and magnetoimpedance clearly show the existence of intrinsic magnetodielectric coupling. The (BFO)_1–x–(GMO)_xsolid solutions withx= 0.025–0.075 show significantly higher magnetocapacitance and magnetoimpedance compared to the pure BFO. 

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