Structural, Electronic and Elastic Properties of TMAl (TM=Co, Ni and Ru) Intermetallics: An ab-initio Study

The structural, electronic, elastic, mechanical and thermal properties of transition metal aluminides (CoAl, NiAl and RuAl) have been investigated systematically using first principle density functional theory (DFT). Ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B?) are calculated which show well agreement with the experimental and other theoretical results. The electronic properties have been analyzed quantitatively. The values of elastic constants are also reported. The ductility of these compounds has been analyzed using the Pugh’s rule, Cauchy’s pressure (C12-C44) and electronic structure.  Our calculated results indicate that NiAl is ductile while CoAl and RuAl are brittle. The elastic properties such as Young's modulus (E), Poisson's ratio (?) and anisotropic ratio (A) are also reported. We have also correlated the ductility and bonding behaviour of these compounds. Keywords: Density functional theory; intermetallic compounds; electronic properties; ductility; thermal properties

Structural, Electronic, Thermal and Elastic Properties of Ductile PdSc and PtSc Intermetallic Compounds

The ab-initio calculations were performed to investigate structural, electronic, thermal and elastic properties of the binary ductile intermetallic compounds PdSc and PtSc with B2 (CsCl-type) structure using full potential linear augmented plane wave method (FP-LAPW) on the basis of density functional theory (DFT).The generalized gradient approximation (PBE-GGA and WC-GGA) is applied for PdSc and PtSc. The calculated equilibrium properties such as lattice constant (a0), bulk modulus (B) and its first derivative (B') are in better agreement with experimental and theoretical results. The elastic constants (C11, C12 and C44) of these compounds are reported first time. The value of B/GH ratio for both the compounds are larger than 1.75, indicating the ductile manner of these materials. From density of states and Band structure, it is observed that these intermetallic compounds are metallic in nature. We report first time mechanical and thermal properties which are predicted from the calculated values of elastic constants. Keywords: Intermetallic compounds, Ab-initio calculations, Thermal properties, Mechanical properties, Density of states, Ductilit

Ab-initio Study of Structural, Electronic and Elastic Properties of ErCu

First principles density functional calculations were performed to study the structural, electronic, elastic and mechanical properties of erbium copper intermetallic compound (ErCu). The calculations are carried out within the generalized gradient approximation (GGA) for the exchange and correlation potential. The total energy as a function of volume is obtained by performing spin-polarized calculation. Magnetically the ErCu compound is stable in ferromagnetic (FM) state and its crystal structure is CsCl-type. Ground state properties such as lattice constant (a0), bulk modulus (B), its pressure derivative (B?) and magnetic moment (?B) are calculated. The density of states at the Fermi level, N(EF) and specific heat coefficient are also estimated in majority and minority spin channels. The electronic properties such as band structure and density of states (DOS) reveal that no band gap lead to metallic character of ErCu. The elastic constants (C11, C12 and C44) and mechanical properties such as Poisson’s ratio (? ), Young’s modulus (E), shear modulus (GH), anisotropic factor (A) are also calculated .  Ductility for these compounds is further analyzed by calculating  the ratio of (B/GH )  and Cauchy pressure (C12 - C44). Keywords: Density functional theory, Band structure, Density of states, Lattice constant, Bulk Modulus, Specific heat

First Principles Study of Electronic, Elastic and Thermal Properties of B2-type RECd (RE =La, Ce and Pr) Compounds

The electronic, elastic and thermal properties of RECd (RE =La, Ce and Pr) intermetallic compounds crystallizing in B2-type structure have been studied using first principles density functional theory within generalized gradient approximation (GGA), and the local spin density approximation (LSDA) for the exchange correlation potential. From energy band structure and density of states we found that these intermetallics are metallic in nature. The thermal and mechanical properties are predicted from the calculated values of elastic constants. The ductility of these compounds is determined by calculating the bulk to shear ratio B/GH. Our calculated results indicate that PrCd is most ductile amongst all the RECd compounds. To the best of our knowledge this is the first theoretical prediction of the elastic properties of these compounds. Keywords: Intermetallics, Density Functional Theory, Elastic Constant, Ductility

First Principles Study of Structural, Electronic, Elastic and Mechanical Properties of GdSn3 and YbSn3 Intermetallic Compounds

First principles study of structural, electronic, elastic and mechanical properties of ferromagnetic GdSn3 and non-magnetic YbSn3 rare-earth intermetallics, which crystallize in AuCu3-type structure, is performed using density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. The ground state calculations are carried out within PBE-GGA, PBE-sol GGA and LSDA approximations   for the exchange correlation potential. The calculated ground state properties such as lattice constants and bulk moduli agree well with the experiment as well as other theoretical results. We report elastic constants for these compounds for the first time. Both these compounds are found to be ductile in nature. The computed electronic band structures show metallic character. We also report mechanical properties of these compounds for the first time.    Keywords: Rare-earth; Density functional theory; Elastic constants

First Principles Study on Structural, Electronic, Elastic and Thermal Properties of Equiatomic MTi (M = Fe, Co, Ni)

We have investigated the structural, electronic, elastic and thermal properties of MTi (M = Fe, Co and Ni) using ab-initio full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) and local spin density approximation (LSDA). We have calculated the ground state and electronic properties such as lattice constant (a0), bulk modulus (B), pressure derivative of bulk modulus (B') and density of states at Fermi level N(EF) which are in good agreement with experimental and available other theoretical results. The elastic constants (C11, C12 and C44) and mechanical properties such as Poisson’s ratio (? ), Young’s modulus (E), shear modulus (GH), anisotropic factor (A) are also calculated which are agree well with the experimental and other theoretical results. Ductility for these compounds have been analyzed by Pugh’s rule (B/GH ratio) and Cauchy pressure (C12 - C44). Our calculated results reveals that NiTi is most ductile amongst the MTi (M = Fe, Co and Ni) compounds.Keywords: Ab-initio, electronic properties, elastic properties, thermal properties

A pilot study to analyze the quality of sleep by pittsburgh sleep quality index in patients with polycystic ovary syndrome

Background: Various studies have shown that polycystic ovary syndrome (PCOS) patients have sleeping problems and disturbances associated with depression, anxiety, stress, drowsy driving, and other clinical symptoms. This study was taken to investigate the sleep status in POCS women according to the Rotterdam criteria. Aim: This was a pilot study to analyze the quality of sleep by Pittsburgh Sleep Quality Index (PSQI) in patients with poly ovary cystic disease in Bhopal. Materials and Methods: Sixty-two PCOS patients (mean age-24.54 ± 2.63 years) and 31 healthy controls (mean age: 23.20 ± 3.9 years) were recruited from AIIMS, Bhopal, who were evaluated for specific sleep quality by means of PSQI questionnaires. A PSQI global score of ≥5 confirmed the presence of poor quality of sleep. Results: The POCS patients have a global score of 7.97 ± 3.61 than the non-POCS control group 5.42 ± 2.73, thereby indicating that POCS patients have poor sleep quality. Among the seven components, “sleep latency” has a maximum mean score of 1.85 ± 0.99 (control = 1.23 ± 0.85) and a minimum mean score of 0.32 ± 0.82 (control = 0.21 ± 0.75) was attributed to the “use of sleeping Medicine” component. The PSQI mean scores of POCS patients were 1.44 ± 1.44, 1.39 ± 0.61, and 0.89 ± 1.10 for “Subjective sleep quality,” “sleep disturbance,” and “sleep duration,” respectively, and the results were statistically significantly (P < 0.05) when compared to other components and control. Conclusion: This study on the basis of substantiation data found evidence that PCOS women have a relatively poor quality of sleep when compared with the normal control group