Defects, Diffusion, and Dopants in Li2Ti6O13: Atomistic Simulation Study

In this study, force field-based simulations are employed to examine the defects in Li-ion diffusion pathways together with activation energies and a solution of dopants in Li2Ti6O13. The lowest defect energy process is found to be the Li Frenkel (0.66 eV/defect), inferring that this defect process is most likely to occur. This study further identifies that cation exchange (Li–Ti) disorder is the second lowest defect energy process. Long-range diffusion of Li-ion is observed in the bc-plane with activation energy of 0.25 eV, inferring that Li ions move fast in this material. The most promising trivalent dopant at the Ti site is Co3+, which would create more Li interstitials in the lattice required for high capacity. The favorable isovalent dopant is the Ge4+ at the Ti site, which may alter the mechanical property of this material. The electronic structures of the favorable dopants are analyzed using density functional theory (DFT) calculations.

Defect, Diffusion and Dopant Properties of NaNiO2: Atomistic Simulation Study

Sodium nickelate, NaNiO2, is a candidate cathode material for sodium ion batteries due to its high volumetric and gravimetric energy density. The use of atomistic simulation techniques allows the examination of the defect energetics, Na-ion diffusion and dopant properties within the crystal. Here, we show that the lowest energy intrinsic defect process is the Na-Ni anti-site. The Na Frenkel, which introduces Na vacancies in the lattice, is found to be the second most favourable defect process and this process is higher in energy only by 0.16 eV than the anti-site defect. Favourable Na-ion diffusion barrier of 0.67 eV in the ab plane indicates that the Na-ion diffusion in this material is relatively fast. Favourable divalent dopant on the Ni site is Co2+ that increases additional Na, leading to high capacity. The formation of Na vacancies can be facilitated by doping Ti4+ on the Ni site. The promising isovalent dopant on the Ni site is Ga3+.

Effect of Lanthanum and Strontium Doped on PZT Properties Prepared via High Planetary Mill for Piezofan Application

Lead Zirconate Titanate (PZT) ceramics are of great technological interest because of their excellent piezoelectric and ferroelectric properties. In this research, an effort will be made to enhance the PZT properties by doping with other elements. The objective of this research is to enhance the dielectric, hence increase the efficiency and performance of piezofan. Properties that piezoelectric fan should have are high mechanical piezoelectric coupling factor, high dielectric constant, easily polarized and high piezoelectric charge constant. Soft and isovalent dopant was a very suitable candidate to fulfill this requirement. The samples will be prepared via high planetary mill and use optimum compaction pressure due to these processes can skip calcinations process, which can reduce a lot of cost. This process also can avoid PbO loss during firing process. The proposed elements are isovalent dopant which is Sr2+ and donor dopant which is La3+ to subtitude Pb2+ at the A-site of PZT. Dopant is beneficial to the enhancement of physical properties of PZT – based ceramics. It also effectively improved the dielectric properties of PZT ceramics due to the effect of average grain size.