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1. Synthesis of new M-layer solid-solution 312 MAX phases (Ta _1−x Ti _x ) ₃ AlC ₂ ( x = 0.4, 0.62, 0.75, 0.91 or 0.95), and their corresponding MXenes

   https://doi.org/10.1039/D0RA09761F  

   Rigby, Maxwell T.; Natu, Varun; Sokol, Maxim; Kelly, Daniel J.; Hopkinson, David G.; Zou, Yichao; Bird, James R.; Evitts, Lee J.; Smith, Matt; Race, Christopher P.; et al (January 2021, RSC Advances)

   null (Ed.)

   Quaternary MAX phases, (Ta 1−x Ti x ) 3 AlC 2 ( x = 0.4, 0.62, 0.75, 0.91 or 0.95), have been synthesised via pressureless sintering of TaC, TiC, Ti and Al powders. Via chemical etching of the Al layers, (Ta 0.38 Ti 0.62 ) 3 C 2 T z – a new MXene, has also been synthesised. All materials contain an M-layer solid solution of Ta and Ti, with a variable Ta concentration, paving the way for the synthesis of a range of alloyed (Ta,Ti) 3 C 2 T z MXenes with tuneable compositions for a wide range of potential applications. 

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2. Enhancement of voltage controlled magnetic anisotropy (VCMA) through electron depletion

   https://doi.org/10.1063/5.0086768  

   Peterson, Thomas J.; Hurben, Anthony; Jiang, Wei; Zhang, Delin; Zink, Brandon; Chen, Yu-Chia; Fan, Yihong; Low, Tony; Wang, Jian-Ping (April 2022, Journal of Applied Physics)

   Recent advancement in the switching of perpendicular magnetic tunnel junctions with an electric field has been a milestone for realizing ultra-low energy memory and computing devices. To integrate with current spin-transfer torque-magnetic tunnel junction and spin–orbit torque-magnetic tunnel junction devices, the typical linear fJ/V m range voltage controlled magnetic anisotropy (VCMA) needs to be significantly enhanced with approaches that include new materials or stack engineering. A possible bidirectional and 1.1 pJ/V m VCMA effect has been predicted by using heavily electron-depleted Fe/MgO interfaces. To improve upon existing VCMA technology, we have proposed inserting high work function materials underneath the magnetic layer. This will deplete electrons from the magnetic layer biasing the gating window into the electron-depleted regime, where the pJ/V m and bidirectional VCMA effect was predicted. We have demonstrated tunable control of the Ta/Pd(x)/Ta underlayer's work function. By varying the Pd thickness (x) from 0 to 10 nm, we have observed a tunable change in the Ta layer's work function from 4.32 to 4.90 eV. To investigate the extent of the electron depletion as a function of the Pd thickness in the underlayer, we have performed DFT calculations on supercells of Ta/Pd(x)/Ta/CoFe/MgO, which demonstrate that electron depletion will not be fully screened at the CoFe/MgO interface. Gated pillar devices with Hall cross geometries were fabricated and tested to extract the anisotropy change as a function of applied gate voltage for samples with various Pd thicknesses. The electron-depleted Pd samples show three to six times VCMA improvement compared to the electron accumulated Ta control sample. 

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3. Spectrophotometrically derived seawater CO ₂ ‐system assessments: Parameter calculations using pH do not require measurements at standard temperatures

   https://doi.org/10.1002/lno.12593  

   Schockman, Katelyn M; Byrne, Robert H; Carter, Brendan R; Feely, Richard A (July 2024, Limnology and Oceanography)

   Abstract The temperature range of Earth's open‐ocean waters is roughly 0–30°C, yet our understanding of the seawater carbon dioxide (CO₂) system is largely derived from analyses conducted within a narrow temperature range (e.g., laboratory temperature of 20°C or 25°C). Herein, we address two aspects of open‐ocean CO₂‐system measurements and modeling: (1) a highly precise spectrophotometric technique is used to determine bicarbonate dissociation constants (K₂) in seawater at temperatures as low as 3°C and (2) a cruise dataset uniquely including total scale pH measurements at two temperatures is used for CO₂‐system internal consistency comparisons at 12°C and 25°C. Our pK₂parameterization (where pK = −logK) is applicable for broad ranges of salinity (20 ≤ S_P ≤ 40) and temperature (3°C ≤ t ≤ 35°C). Our CO₂‐system internal consistency evaluation (comparison of measured and calculated CO₂‐system parameters) utilized data obtained during NOAA's 2021 West Coast Ocean Acidification Cruise: total alkalinity (TA), total dissolved inorganic carbon (DIC), pH measured at 25°C, and pH measured at 12°C (n = 265). Results demonstrate that, relative to calculations utilizing the TA, DIC pair, agreement between measured and calculated parameters is improved when either TA or DIC is paired with pH measurements at either temperature. Calculations of CO₂fugacity (fCO₂) and aragonite saturation state (Ω_ar) using pH measurements made at 25°C or 12°C (paired with either TA or DIC) are statistically indistinguishable. Results also suggest that the temperature dependence of current CO₂‐system dissociation constants need further refinement. 

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4. Intrinsic exchange bias from interfacial reconstruction in an epitaxial Ni _x Co _y Fe _{3− x −y} O ₄ (111)/ $\alpha$ -Al ₂ O ₃ (0001) thin film family

   https://doi.org/10.1088/1361-648X/ad789d  

   Yang, Detian; Liu, Yaohua; Xu, Xiaoshan (September 2024, Journal of Physics: Condensed Matter)

   Abstract Intrinsic exchange bias is known as the unidirectional exchange anisotropy that emerges in a nominally single-component ferro-(ferri-)magnetic system. In this work, with magnetic and structural characterizations, we demonstrate that intrinsic exchange bias is a general phenomenon in (Ni, Co, Fe)-based spinel oxide films deposited on $\alpha$ -Al₂O₃(0001) substrates, due to the emergence of a rock-salt interfacial layer consisting of antiferromagnetic CoO from interfacial reconstruction. We show that in Ni_xCo_yFe_3−x−yO₄(111)/ $\alpha$ -Al₂O₃(0001) films, intrinsic exchange bias and interfacial reconstruction have consistent dependences on Co concentrationy, while the Ni and Fe concentration appears to be less important. This work establishes a family of intrinsic exchange bias materials with great tunability by stoichiometry and highlights the strategy of interface engineering in controlling material functionalities. 

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5. The effect of surface termination on dielectric nonlinearity in potassium sodium niobate thin films

   https://doi.org/10.1111/jace.70084  

   Hříbalová, Soňa; Akkopru‐Akgun, Betul; Trolier‐McKinstry, Susan (November 2025, Journal of the American Ceramic Society)

   Abstract The impact of alkali‐rich and alkali‐depleted surface terminations on dielectric nonlinearity and ferroelectric properties was investigated in sputtered K_0.5Na_0.5NbO₃(KNN) films. For the alkali depleted surface termination, a ∼3 nm thick amorphous interfacial layer was found near the top electrode. The presence of a non‐ferroelectric interfacial layer reduces both the net remanent (P_r) and maximum polarization (P_max) while increasing the coercive field (E_c) in the KNN films.P_maxdecreased from 31.5 to 30.3 µC/cm², likely due to the reduced electric field in the bulk of the film. The influence of the interfacial layer on dielectric properties was evaluated using a capacitor in series model. After removing the effects of the interfacial layer, the Rayleigh coefficientsε_initand α increased by 11 and 47%, respectively. The interfacial layer has more impact on irreversible domain wall motion than on reversible contributions to the relative permittivity. It is believed that this occurs because a higher concentration of defects, such as or , associated with the alkali‐depleted interfacial layer generates internal fields that pin domain walls. Alkali depleted surface terminations also produce a higher pseudo‐activation energy for polarization reversal compared to films with alkali rich terminations, with deeper potential wells in the material's energy landscape. 

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