Rapid Lithium Insertion and Location of Mobile Lithium in the Defect Perovskite Li0.18Sr0.66Ti0.5Nb0.5O3

Symmetry-mode analysis for intuitive observation of structure-property relationships in the lead-free antiferroelectric (1-x)AgNbO3-xLiTaO3

Functional materials are of critical importance to electronic and smart devices. A deep understanding of the structure-property relationship is essential for designing new materials. In this work, instead of utilizing conventional atomic coordinates, a symmetry-mode approach is successfully used to conduct structure refinement of the neutron powder diffraction data of (1-x)AgNbO₃-xLiTaO₃ (0 ≤ x ≤ 0.09) ceramics. This provides rich structural information that not only clarifies the controversial symmetry assigned to pure AgNbO₃ but also explains well the detailed structural evolution of (1-x)AgNbO₃-xLiTaO₃ (0 ≤ x ≤ 0.09) ceramics, and builds a comprehensive and straightforward relationship between structural distortion and electrical properties. It is concluded that there are four relatively large-amplitude major modes that dominate the distorted Pmc2₁ structure of pure AgNbO₃, namely a Λ3 antiferroelectric mode, a T4+ a ^- a ^- c ⁰ octahedral tilting mode, an H2 a ⁰ a ⁰ c ⁺/a ⁰ a ⁰ c ^- octahedral tilting mode and a Γ4- ferroelectric mode. The H2 and Λ3 modes become progressively inactive with increasing x and their destabilization is the driving force behind the composition-driven phase transition between the Pmc2₁ and R3c phases. This structural variation is consistent with the trend observed in the measured temperature-dependent dielectric properties and polarization-electric field (P-E) hysteresis loops. The mode crystallography applied in this study provides a strategy for optimizing related properties by tuning the amplitudes of the corresponding modes in these novel AgNbO₃-based (anti)ferroelectric materials.

SmFeO3 and Bi-doped SmFeO3 perovskites as an alternative class of electrodes in lithium-ion batteries

The search for new electrodes in alkali-ion batteries requires the investigation of a variety of classes of materials, each showing subtly different crystal structure motifs or frameworks.

In situ neutron powder diffraction using custom-made lithium-ion batteries

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles. However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications. This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries. We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the 'roll-over' cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.