STUDY ON ELASTIC, THERMODYNAMIC, AND OPTICAL PROPERTIES OF Y2TI2O7 PYROCHLORE DETERMINED BY A SEMI-EMPIRICAL METHOD AT 300 K
DIMPLE L. LILA
Department of Physics, Saurashtra University, Rajkot 360005, India.
SHREY K. MODI
Department of Environment Engineering, L. D. Engineering College, Ahmedabad 380015, India.
NIKETA P. JOSHI
Department of General, Government Polytechnic, Bhuj 370001, India.
POOJA Y. RAVAL
Department of Physics, C. U. Shah University, Wadhwan City, Surendranagar 363030, India.
NIMISH H. VASOYA
Department of Balbhavan, Children´s University, Sector-20, Gandhinagar 382021, India.
KUNAL B. MODI *
Department of Physics, Saurashtra University, Rajkot 360005, India.
HIREN H. JOSHI
Department of Physics, Saurashtra University, Rajkot 360005, India.
*Author to whom correspondence should be addressed.
Abstract
First-ever a straightforward semi-empirical method is employed to compute elastic parameters (elastic wave velocities, elastic moduli, Debye temperature), thermodynamic parameters (molar heat capacities at constant volume and pressure, Debye temperature, electronic contribution to molar heat capacity, lattice potential energy), and optical parameters (refractive index, optical energy bandgap, dielectric, electronic and ionic polarizabilities) for pyrochlore-type yttrium-titanate (Y2Ti2O7) at 300 K. The results of our calculations are compared with the existing experimentally and theoretically determined data. The quite satisfactory agreement between the two validates the approach adopted. The value of molar heat capacity at constant volume computed based on the Einstein theory for pyrochlore is accordant with theoretically predicted value from the law of Dulong and Petit while the Debye theory fails to estimate the consistent value at 300 K. It appeared that electronic molar heat capacity contributes ~ 0.5 % to the total molar heat capacity and the electronic and lattice molar heat capacities are comparable at 14.5 K. The applicability of the oxide additivity rule is examined and found successful in predicting the dielectric, electronic, ionic polarizabilities and lattice potential energy of the complex oxide composition. The semi-empirical method used in the present investigation is found quite simple as compared to previous cumbersome evaluation methods.
Keywords: Seed alfalfa, Pyrochlore, bee pollinators, elastic parameters, solitary wild bees, thermodynamic parameters, agro-ecosystems, optical parameters, southern Russia, oxide additivity rule, nomadic bee populations, neonicotinoids