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1. Understanding the β–K ₂ CO ₃ -Type Na(Na _0.5 Sc _0.5 )BO ₃ :Ce ₃ + Phosphor

   https://doi.org/10.1149/2162-8777/ac2780  

   Zhong, Jiyou; Zhuo, Ya; Zhang, Hongshi; Zhao, Weiren; Wen, Jun; Brgoch, Jakoah (September 2021, ECS Journal of Solid State Science and Technology)
2. Refine Intervention: Characterizing Disordered Yb _0.5 Co ₃ Ge ₃

   https://doi.org/10.1021/acs.cgd.0c00865  

   Weiland, Ashley; Eddy, Lucas J.; McCandless, Gregory T.; Hodovanets, Halyna; Paglione, Johnpierre; Chan, Julia Y (October 2020, Crystal Growth & Design)

   null (Ed.)
3. Strengthened relaxor behavior in (1− x )Pb(Fe _0.5 Nb _0.5 )O ₃ – x BiFeO ₃

   https://doi.org/10.1039/C9TC05883D  

   Prah, Uroš; Dragomir, Mirela; Rojac, Tadej; Benčan, Andreja; Broughton, Rachel; Chung, Ching-Chang; Jones, Jacob L.; Sherbondy, Rachel; Brennecka, Geoff; Uršič, Hana (March 2020, Journal of Materials Chemistry C)

   null (Ed.)

   A systematic study of (1− x )Pb(Fe 0.5 Nb 0.5 )O 3 – x BiFeO 3 ( x = 0–0.5) was performed by combining dielectric and electromechanical measurements with structural and microstructural characterization in order to investigate the strengthening of the relaxor properties when adding BiFeO 3 into Pb(Fe 0.5 Nb 0.5 )O 3 and forming a solid solution. Pb(Fe 0.5 Nb 0.5 )O 3 crystalizes in monoclinic symmetry exhibiting ferroelectric-like polarization versus electric field ( P–E ) hysteresis loop and sub-micron-sized ferroelectric domains. Adding BiFeO 3 to Pb(Fe 0.5 Nb 0.5 )O 3 favors a pseudocubic phase and a gradual strengthening of the relaxor behavior of the prepared ceramics. This is indicated by a broadening of the peak in temperature-dependent permittivity, narrowing of P–E hysteresis loops and decreasing size of ferroelectric domains resulting in polar nanodomains for x = 0.20 composition. The relaxor behavior was additionally confirmed by Vogel–Fulcher analysis. For the x ≥ 0.30 compositions, broad high-temperature anomalies are observed in dielectric permittivity versus temperature measurements in addition to the frequency-dispersive peak located close to room temperature. These samples also exhibit pinched P–E hysteresis loops. The observed pinching is most probably related to the reorganization of polar nanoregions under the electric field as shown by synchrotron X-ray diffraction measurements as well as by piezo-response force microscopy analysis, while in part affected by the presence of charged point defects and anti-ferroelectric order, as indicated from rapid cooling experiments and high-resolution transmission electron microscopy, respectively. 

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4. High performance, electroforming-free, thin film memristors using ionic Na _0.5 Bi _0.5 TiO ₃

   https://doi.org/10.1039/D1TC00202C  

   Yun, Chao; Webb, Matthew; Li, Weiwei; Wu, Rui; Xiao, Ming; Hellenbrand, Markus; Kursumovic, Ahmed; Dou, Hongyi; Gao, Xingyao; Dhole, Samyak; et al (April 2021, Journal of Materials Chemistry C)

   null (Ed.)

   Here, in ionically conducting Na 0.5 Bi 0.5 TiO 3 (NBT), we explore the link between growth parameters, stoichiometry and resistive switching behavior and show NBT to be a highly tunable system. We show that the combination of oxygen ionic vacancies and low-level electronic conduction is important for controlling Schottky barrier interfacial switching. We achieve a large ON/OFF ratio for high resistance/low resistance ( R HRS / R LRS ), enabled by an almost constant R HRS of ∼10 9 Ω, and composition-tunable R LRS value modulated by growth temperature. R HRS / R LRS ratios of up to 10 4 and pronounced resistive switching at low voltages (SET voltage of <1.2 V without high-voltage electroforming), strong endurance (no change in resistance states after several 10 3 cycles), uniformity, stable switching and fast switching speed are achieved. Of particular interest is that the best performance is achieved at the lowest growth temperature studied (600 °C), which is opposite to the case of most other perovskite oxides for memristors, where higher growth temperatures are required for optimum performance. This is understood based on the oxygen vacancy control of interfacial switching in NBT, whereas a range of other mechanisms (including filamentary switching) occur in other perovskites. The study of NBT has enabled us to determine key parameters for achieving high performance memristors. 

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5. Special quasirandom structures description of the local structure of disordered Bi _0.5 K _0.5 TiO ₃

   https://doi.org/10.1063/5.0123468  

   Jiang, Bo; Lin, De-Ye; Wang, Xin; Selbach, Sverre M.; Page, Katharine (December 2022, Journal of Applied Physics)

   Polar nanoregions (PNRs) are believed to play a decisive role in the local and macroscopic polarization in relaxor ferroelectrics. The limited microscopic understanding of the structure and dynamics of PNRs hampers the rational design of new lead-free materials. Here, the local structure of A-site disordered Bi 0.5 K 0.5 TiO 3 (BKT) is investigated using synchrotron x-ray and neutron pair distribution function (PDF) analysis and density functional theory (DFT) optimized special quasirandom structures (SQSs). DFT-relaxed SQS with a 4 × 4 × 4 supercell size can reproduce the experimental PDFs of disordered BKT, as well as the partial PDFs and total polarization, with comparable results to those reported from a combined analysis of x-ray and neutron PDF data with large-box reverse Monte Carlo methods. We find that small Bi 3+ -rich polar clusters are likely to be the microscopic origin of relaxor behavior in disordered BKT, and that the existence of large polar nanoregions (PNRs) is not necessary to explain the relaxor properties. Our results also highlight the great potential of the SQS approach to gain a nanoscale-to-microscopic understanding of other relaxor solid solutions. 

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