Search

From recent research findings, toxic compounds have sparked a lot of interest in theoretical and experimental research as a result of their great potential for harvesting and generating energy from multiple sources at a higher power conversion rate. Despite their great energy production, their hazardous nature limits their practical usage. To overcome this issue, toxic materials can be replaced with more environmentally friendly alternatives, such as germanate glass, even if their power conversion rate is limited. In this article, the adjustment of properties that thereby improves the efficiency of the proposed material, i.e. germanate glass-Li$_2$2GeO$_3$3 is performed by inducing compressive isotropic pressures using DFT simulation. Herein, interesting results of electronic and structural phase transitions from indirect $\rightarrow$→ direct at ${\rm P} = 11$P=11 GPa and from orthorhombic $\rightarrow$→ tetragonal structures at ${\rm P}=50$P=50 GPa, respectively, are reported. For stability, we present the dynamical, thermal and mechanical stabilities by computing the phonon dispersion curves, MD simulation calculated at room temperature and the elastic constants. An anomalous behaviour of the investigated compound at ${\rm P}\sim 10$P∼10–11 GPa has been identified and thoroughly discussed. The piezoelectric response improves with pressure, with the maximum piezoelectric constant, ${\rm e}_{33}=1.42$e33=1.42 Cm$^{-2}$−2 at ${\rm P}=15$P=15 GPa. The orthorhombic-Li$_2$2GeO$_3$3 being with higher electromechanical conversion rate than its tetragonal phase by more than 10-fold reveals a superior piezoelectric performance of the orthorhombic phase. To the best of our knowledge, the present literature represents the first theoretical analysis of TE properties for this type of material. The calculated TE efficiency using GGA+SOC formalism at ${T}=1200$T=1200 K is ${\rm ZT}\sim 0.63$ZT∼0.63 and 0.72 for pristine orthorhombic (${\rm P}=0$P=0 GPa) and tetragonal (${\rm P}=50$P=50 GPa) structures, respectively. The maximum TE efficiency achieved at ${\rm P}=15$P=15 GPa yields ${\rm ZT}=0.97$ZT=0.97 and 1.56 using the GGA and GGA + SOC formalisms. [ABSTRACT FROM AUTHOR]

With the help of density functional theory calculations, we explored the recently synthesized double perovskite material Ca 2 CrOsO 6 and found it to be a ferrimagnetic insulator with a band gap of ∼0.6 eV. Its effective magnetic moment is found to be ∼0.23 μ B per unit cell. The proposed behavior arises from the cooperative effect of spin-orbit coupling and Coulomb correlation of Cr-3d and Os-5d electrons along with the crystal field. Within the ferrimagnetic configuration, doping with 50% Ni in the Cr-sites resulted in a half-metallic state with a total moment of nearly zero, a characteristic of spintronic materials. Meanwhile, the optical study reveals that both ε 1 xx and ε 1 zz decrease first and then increase rapidly with increasing photon energy up to 1.055 eV. We also found optical anisotropy up to ∼14 eV, where the material becomes almost optically isotropic. This material has a plateau like region in the σ xx and σ zz parts of the optical conductivity due to a strong 3d-5d interband transition between Cr and Os. In addition, we performed thermoelectric calculations whose results predict that the material might not be good as a thermoelectric device due to its small power factor., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)