DFT studies on the thermodynamic properties of Na₂Ti₃O₇ under high temperature and high pressure

Abstract

The equilibrium structure of the compound Na2Ti3O7 has been obtained via the minimization of the total energy within Local Density Approximation (LDA) based on Density Functional Theory (DFT), the calculated equilibrium volume are in agreement with available experimental value. In the meantime, the thermodynamic properties under high temperature and high pressure are investigated applying nonempirical Debye model combining with the first principle theory in the quasi‐harmonic approximation. The evaluated equilibrium volume using this model agrees with the value obtained from ab intio and from experiment. The results demonstrate that this method can provide reliable predictions for the temperature and pressure dependence of these quantities such as the equation of state (EOS), the entropy, the isothermal bulk modulus, the heat capacity, and the thermal expansion in detail. In addition, the calculated thermodynamic properties are all in agreement with available experimental data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Nanomechanical and nanotribological properties of bioactive titanium surfaces prepared by alkali treatment

“…Besides, the stoichiometry of films produced by AT or AHT is not well known, as discussed previously. Since the Poisson's ratio varies little in the same group of material (Meyers and Chawla, 1999), the ν = 0.33 value was assumed for sodium titanate, based on the average values for barium, bismuth, lithium, sodium and zirconium titanates from the literature (Chan et al, 2008;Dent et al, 2007;Forrester and Kisi, 2004;Jian et al, 2006;Lin et al, 2004;Tani, 1998;Tsuchiya et al, 2006;Xiang et al, 2004;Zhang and Wu, 2008). Fig.…”

Structural and Electronic Properties of Na2Ti3O7 and H2Ti3O7

“…It is therefore of great interest to understand the electronic and chemical properties of both compounds, H 2 Ti 3 O 7 and Na 2 Ti 3 O 7 similar in their composition and structure. In the literature, more attention was devoted to the sodium titanate, its structure, and thermodynamic stability at high pressure were determined by first‐principles simulations . Na 2 Ti 3 O 7 and H 2 Ti 3 O 7 are two related structures.…”

First-principle calculations for electronic structure and bonding properties in layered Na2Ti3O7

“…Due to the high-performance ionexchange property of Na 2 Ti 3 O 7 , it may be used for removal and recovery of heavy metal ions from industrial wastewaters [18], lithium-ion batteries and hydrogen storage materials [5,16]. In contrast to extensive studies on the synthesis and modification of titanate nanostructures, very few theoretical studies were carried out [20,23,24]. Recently, Xu et al [23] , however, the study on the electronic structure and structure stability has not been disclosed.…”