Chemistry of Materials最新文献

{"title":"Insights into the Selective Sulfurization of NiMn2O4 Ternary Metal Oxide and Enhanced OER Activity","authors":"Dorothy Sachdeva,&nbsp;Naveen Goyal,&nbsp;Meghabarna Gayen and Narayanan Ravishankar*,&nbsp;","doi":"10.1021/acs.chemmater.5c00461","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c00461","url":null,"abstract":"<p >The chemical transformation of ternary metal oxide nanocrystals offers a versatile strategy for tailoring their physiochemical properties. We investigated the controlled chemical transformation of ternary metal oxide NiMn₂O₄ to metal sulfides by employing different sulfur precursors to alter the composition and morphology of the resulting products. The distinct pH values of the precursor solutions, neutral for thiourea and alkaline for sodium sulfide, influence the selective precipitation of metal sulfides due to their pH-dependent solubility. Specifically, thiourea promotes the formation of intergrown NiS₂ cubes via the dissolution of NiMn₂O₄, followed by nucleation and growth, as evidenced by time-dependent studies. On the other hand, the use of sodium sulfide under alkaline conditions results in the formation of MnS that inherits the morphology from the parent ternary metal oxide. Employing an equimolar mixture of sulfurizing agents facilitates the synthesis of a NiS₂/MnS heterostructure. This transformation to sulfide enhanced the oxygen evolution reaction (OER) activity as compared with the activity using the ternary metal oxide. The overpotential decreased from 391 mV of NiMn₂O₄ to 352 and 340 mV for NiS₂ and MnS, respectively, at a current density of 10 mA cm^–2 in 1 M KOH solution. Notably, during a chronoamperometry test, the NiS₂/MnS heterostructure showed significant stability at 1.57 mV potential to achieve a current density of 10 mA cm^–2 for 25 h. This work establishes a synthetic route for the selective sulfurization of ternary metal oxide NiMn₂O₄ and the NiS₂/MnS heterostructure, which can be utilized for other materials.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5547–5557"},"PeriodicalIF":7.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advancing Sodium-Ion Battery Cathodes: A Low-Cost, Eco-Friendly Mechanofusion Route from TiO2 Coating to Ti4+ Doping","authors":"Vadim Shipitsyn,&nbsp;Guanyi Wang,&nbsp;Wenhua Zuo*,&nbsp;Ning Zhang,&nbsp;Yongkang Jin,&nbsp;Kangxuan Xia,&nbsp;Cheng Li,&nbsp;Rishivandhiga Jayakumar,&nbsp;Chanmonirath Michael Chak,&nbsp;Yan-Yan Hu,&nbsp;Riqiang Fu,&nbsp;Guiliang Xu,&nbsp;Xianghui Xiao,&nbsp;Jialin Mao,&nbsp;Wenbin Yin,&nbsp;Enyuan Hu,&nbsp;Eric McCalla and Lin Ma*,&nbsp;","doi":"10.1021/acs.chemmater.5c01485","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c01485","url":null,"abstract":"<p >Layered oxide battery cathodes often require extra stabilization strategies, such as surface coating or doping, to mitigate side reactions and enhance longevity. Conventional methods such as aqueous deposition and atomic layer deposition are costly and environmentally unfriendly and even damage the original structure, especially for air-sensitive sodium-ion battery (SIB) cathodes. Herein, we introduce an all-dry mechanofusion technique that modifies hydroxide precursors with TiO₂ coating before sintering with a sodium source. Using advanced characterizations including X-ray diffraction, neutron diffraction, and solid-state nuclear magnetic resonance for structural insights, X-ray absorption spectroscopy to study metal valence states, and transmission X-ray microscopy for nanoscale visualization of nickel oxidation states, we verified that postsintering transforms TiO₂ surface coating into Ti doping, leading to improved Ni-oxidation homogeneity, modified charge compensation, and enhanced thermal stability. Electrochemical tests reveal superior performance in capacity retention, rate capability, and air stability for these modified cathodes, with pouch cells maintaining over 85% capacity after 650 cycles. This method presents a sustainable, cost-effective route for advanced SIB cathode development.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"6059–6068"},"PeriodicalIF":7.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/pdf/10.1021/acs.chemmater.5c01485","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strain Engineering Boosts Piezo-/Ferroelectricity in AlScN Alloy: Insights from First-Principles Calculations","authors":"Zenghui Liu*,&nbsp;Zhenjun Shao,&nbsp;Yunjian Cao,&nbsp;Hao Li,&nbsp;Lin Yang,&nbsp;Hangyu Zhou,&nbsp;Jun Xu,&nbsp;Jingrui Li*,&nbsp;Gang Niu*,&nbsp;Wei Ren and Zuo-Guang Ye,&nbsp;","doi":"10.1021/acs.chemmater.5c01383","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c01383","url":null,"abstract":"<p >AlScN is a highly promising novel ferroelectric material featuring excellent high-temperature stability and CMOS compatibility, making it a potential candidate for 5G RF front-end filters, next-generation power devices, memories, and emerging in-memory computing devices. However, the rather mediocre piezoelectric coefficient and relatively large coercive field remain critical bottlenecks for its widespread adoption in applications. To provide theoretical guidance and effective strategies for optimizing the AlScN performance, we propose a synergistic regulation strategy based on alloying and strain engineering and conduct first-principles calculations using density functional theory to investigate the effects of Sc concentration and epitaxial tensile strain on the properties of AlScN. The proposed strategy is found to effectively enhance the piezoelectric strain coefficient (<i>d</i>₃₃ &gt; 300 pC·N^–1) and electromechanical coupling coefficient (<i>k</i>₃₃² ∼ 55%) of AlScN, and reduce its coercive field (<i>E</i>_C), while maintaining a large polarization (<i>P</i>_sp &gt; 68 μC·cm^–2). The substantial increase in <i>d</i>₃₃ and <i>k</i>₃₃² is highly beneficial for optimizing the performance of bulk acoustic wave resonators for signal processing in RF applications. Meanwhile, the reduction in <i>E</i>_C provides new opportunities for low-power ferroelectric memory devices, such as ferroelectric random-access memory and in-memory computing synaptic devices. The weakened bond strength and enhanced Born effective charge are found to be crucial in these performance optimizations. Furthermore, we examine the high-temperature stability of strain-engineered AlN-based piezo-/ferroelectric materials through ab initio molecular dynamics simulations. This work not only provides an effective strategy and valuable insights for physical property optimization in AlScN from the theoretical point of view but also clarifies the mechanisms of enhanced piezo-/ferroelectricity in wurtzite alloy systems by application of epitaxial strain and chemical modification.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"6026–6036"},"PeriodicalIF":7.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Turning Foes to Friends: Endogenous Magnesium Ion Translocation-Mediated Pyroptosis for Amplifying Immunotherapy","authors":"Weiguang Chen,&nbsp;Jiawei Zhu,&nbsp;Fang Pu*,&nbsp;Minhao Jiang,&nbsp;Anjun Song,&nbsp;Wenting Zhang,&nbsp;Bin Luo,&nbsp;Changhao Li,&nbsp;Jinsong Ren* and Xiaogang Qu*,&nbsp;","doi":"10.1021/acs.chemmater.5c00759","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c00759","url":null,"abstract":"<p >Pyroptosis, a type of programmed cell death characterized by GSDMD cleavage and the release of pro-inflammatory content, has emerged as a promising avenue for cancer therapy due to its ability to elicit effective immune responses. However, magnesium ions (Mg²⁺) in tumor cells inhibit pyroptosis by diminishing mitochondrial reactive oxygen species (mtROS) and preventing the oligomerization and membrane localization of cleaved GSDMD. On the contrary, the bioavailability of Mg²⁺ outside the tumor is crucial for T lymphocyte development and functional activation. Herein, an endogenous Mg²⁺ translocation-based strategy is proposed to effectively induce the pyroptosis of cancer cells and activate immune cells for amplifying immunotherapy through the utilization of a covalent organic framework (COF)-based nanoconverter. The nanoconverter facilitates the release of Mg²⁺ from the endoplasmic reticulum and subsequently renders the efflux of the released Mg²⁺ from cancer cells. As endogenous Mg²⁺ is transferred out of the cancer cells, mtROS are generated abundantly, synchronized with the effective induction of pyroptosis. Besides, Mg²⁺ translocated into microenvironments promotes the activity of T lymphocytes. The “turning foes to friends” therapeutic strategy enhances the efficacy of antitumor immunotherapy through the effective translocation of endogenous Mg²⁺, resulting in tumor growth inhibition rates of 85.2% and 94.7% for primary and distant tumors, respectively, and survival extension rate of 85.7%. This work provides a paradigm for antitumor immunotherapy through endogenous metal ion translocation, offering an innovative insight into effective cancer therapy.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5672–5683"},"PeriodicalIF":7.0,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regulating the Local Order of Cations Significantly Enhances the Thermoelectric Performance of Pb-Doped AgSbSe2","authors":"Yaqiong Zhong,&nbsp;Xili Wen,&nbsp;Tingting Luo,&nbsp;Hao Luo,&nbsp;Keke Liu,&nbsp;Junjie Li,&nbsp;Pierre Ferdinand Poudeu Poudeu,&nbsp;Jinsong Wu,&nbsp;Qingjie Zhang,&nbsp;Xianli Su* and Xinfeng Tang*,&nbsp;","doi":"10.1021/acs.chemmater.5c01034","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c01034","url":null,"abstract":"<p >The high configurational disorder of Ag and Sb on the cation sites in the AgSbSe₂ crystal structure leads to ultralow thermal conductivity. However, such random cation disorder also disrupts delocalized charge carriers, leading to intrinsically low carrier mobility and poor electrical transport properties. All these pose a great challenge for improving the thermoelectric performance of AgSbSe₂ compounds. Here, we demonstrate that the partial substitution of trivalent Sb³⁺ ions with divalent Pb²⁺ ions on the disordered cation sites enhances the cation ordering within AgSbSe₂, forming a partially ordered structure. This cation ordering decreases the activation energy associated with electronic hopping conduction, consequently lowering the potential barrier for localized electrons and restricting them to a lower temperature. This effect significantly mitigates electron localization, thereby substantially enhancing the carrier mobility from 0.01 cm² V^–1 s^–1 for pristine AgSbSe₂ to 5.2 cm² V^–1 s^–1 for AgSb_0.94Pb_0.06Se₂ at 30 K. In conjunction with the improved carrier concentration upon doping with Pb, the power factor increases from 0.11 mW m^–1 K^–2 for pristine AgSbSe₂ to 0.6 mW m^–1 K^–2 for AgSb_0.96Pb_0.04Se₂ at 300 K. Coupled with the ultralow thermal conductivity of AgSbSe₂, the figure of merit (<i>zT</i>) improved from 0.35 for AgSbSe₂ to 1.26 at 690 K for AgSb_0.96Pb_0.04Se₂, indicating an enhancement of approximately 3.5 times. This study presents a novel approach to augmenting the thermoelectric efficiency of materials through the manipulation of cation ordering.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5825–5835"},"PeriodicalIF":7.0,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrochemical Oxidation in Garnet-Type Solid Electrolyte by Formation of Point Defects","authors":"Subhash Chandra,&nbsp;Shikha Saini,&nbsp;Cole D. Fincher,&nbsp;Joshua T. Wright,&nbsp;Iradwikanari Waluyo,&nbsp;Adrian Hunt,&nbsp;Carlo U. Segre,&nbsp;Yet-Ming Chiang and Bilge Yildiz*,&nbsp;","doi":"10.1021/acs.chemmater.5c01174","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c01174","url":null,"abstract":"<p >All-solid-state batteries hold greater promise for improving safety and energy density over conventional battery technology employing organic liquid electrolytes. One of the required features of a Li⁺ conducting solid electrolyte is electrochemical stability, attained thermodynamically or kinetically, within the targeted operating voltage and temperature ranges. Therefore, understanding of the oxidative or reductive degradation mechanism is important to allow the design of stable solid electrolyte materials. This work contributes to building an understanding of the oxidative degradation mechanism in lithium solid electrolytes at cell operating conditions. Here, we have focused on resolving the oxidative decomposition mechanism of Al-doped lithium garnet Li_6.28Al_0.24La₃Zr₂O₁₂ (LLZO) as a state-of-the-art inorganic ceramic electrolyte. By combining experimental and computational analyses, we show that oxidation of LLZO occurs by simultaneous loss of oxygen and lithium from the structure, resulting in substoichiometric LLZO, at a moderate temperature (80 °C) and a high electrode potential (4.3 V vs Li/Li⁺). Based on X-ray absorption and diffraction analyses, we find that the zirconium coordination shells in LLZO contract while the crystal structure experiences positive chemical strain upon electrochemical oxidation. The results from ex situ structural characterization of both the local structure and crystal symmetry are supported by a substoichiometric LLZO with lithium and oxygen vacancies, modeled by density functional theory (DFT) calculations. These chemical and structural changes in LLZO suppress effective lithium-ion conductivity by an order of magnitude. Formation of lithium and oxygen vacancies in LLZO upon electrochemical oxidation is different from prior thermodynamic predictions of phase decomposition of LLZO. The difference here is that the experiments were conducted at near-room temperature, which can hinder the kinetics of phase separation, and thus, the resultant LLZO solid electrolyte is still single-phase but substoichiometric in Li and O. These findings contribute an important degradation mechanism of the electrolyte, relevant for practical operational conditions of solid-state batteries.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5913–5922"},"PeriodicalIF":7.0,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Density Self-Assembled Monolayers of N-Heterocyclic Carbenes on Au(111)─Observation of Normal and Mesoionic Bonding Modes","authors":"Michael Furlan,&nbsp;Patrick Melix,&nbsp;Mark D. Aloisio,&nbsp;Robert Jahn,&nbsp;Alastair B. McLean*,&nbsp;Ralf Tonner-Zech* and Cathleen M. Crudden*,&nbsp;","doi":"10.1021/acs.chemmater.5c00886","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c00886","url":null,"abstract":"<p >N-heterocyclic carbenes (NHCs) continue to attract interest as ligands for self–assembled monolayers on metals due to their propensity to form strong bonds to a variety of metals. However, understanding of the effect of NHC structural elements on adsorption geometry, NHC mobility, and on-surface intermolecular interactions remains limited. Herein, we report the self-assembly of 1,3-diisopropyl imidazolylidene I-NHC^<i>i</i>Pr on the Au(111) surface. This relatively simple NHC has never previously been examined on Au surfaces experimentally. We combine scanning tunnelling microscopy (STM) and density functional theory (DFT) calculations to provide detailed insight into this NHC-based SAM, which is the densest packed NHC-based SAM reported to date, utilizing approximately 14.5% of the available binding sites of the Au(111) surface. STM interrogations of the surface show the occasional formation of brighter adsorbates that we suggest can be attributed to metalation at the backbone C-4, rather than the expected C-2 site. This type of ″abnormal″ or mesoionic bonding mode is commonly observed in related organometallic compounds, suggesting that such complexes can provide a useful analogy for surface reactivity. The high density of the I-NHC^<i>i</i>Pr SAM and the generally high thermal and chemical robustness of NHC-based SAMs make this molecule ideally suited for a range of applications, providing an exciting platform for more complex surface functionalization.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5753–5763"},"PeriodicalIF":7.0,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Narrow-Band Electrochromism of Ferrocene-Substituted Rhodamine B","authors":"Varunprasaath Ramasamy Selvaraju,&nbsp;Roberto Venta,&nbsp;Ishanka Rajapaksha,&nbsp;Junxiang Zhang,&nbsp;Stephen Barlow,&nbsp;Seyhan Salman,&nbsp;Colleen N. Scott* and Seth R. Marder*,&nbsp;","doi":"10.1021/acs.chemmater.5c00514","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c00514","url":null,"abstract":"<p >Here, we report on a rhodamine dye containing a redox-active ferrocene group, in which we investigate the coupling of the light-absorbing properties of the rhodamine dye to the electroactive properties of the ferrocene unit. The closed and reduced form of the ferrocene-substituted rhodamine dye, 3′,6′-bis(diethylamino)-2-ferrocenyl-4<i>a</i>′,9<i>a</i>′-dihydrospiro[isoindoline-1,9′-xanthen]-3-one, was obtained following the reaction of aminoferrocene with the corresponding open rhodamine acyl chloride. The effect of the oxidation state of the ferrocene on the equilibrium between the closed and open forms of the dye was examined using chemical and spectroelectrochemical studies. One-electron oxidation of ferrocene unit to the ferrocenium species (at +0.45 V vs FeCp*₂^+/0; Cp* = –C₅Me₅) resulted in a small extent of opening of the rhodamine spirolactam moiety, leading to a moderate increase in the absorbance at 560 nm. However, a more oxidizing potential (ca. +1.0 V vs FeCp*₂^+/0) resulted in a dramatic increase in the absorbance at 560 nm, which we attribute to the formation of a ring-opened rhodamine cation linked to a FeCp(η⁶-6-azafulvene) cation. The dye could be repeatedly switched between its colorless neutral closed form, and this vividly colored doubly oxidized species.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5558–5568"},"PeriodicalIF":7.0,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design Strategies and Perspectives on the Toughening of Hydrogels via Fully Physical Cross-Linking","authors":"Sirawit Pruksawan*,&nbsp;Yi Ting Chong,&nbsp;Yuki Sum Yong Lee,&nbsp;Daryl Kai Foong Lam and FuKe Wang*,&nbsp;","doi":"10.1021/acs.chemmater.5c01421","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c01421","url":null,"abstract":"<p >Conventional hydrogels are inherently brittle and mechanically weak, limiting their application in load-bearing or dynamic environments. Although extensive development has been made in hydrogel toughening, the most dominant techniques rely upon chemical cross-linking, which restrains their adaptability and functionality because of the permanence of covalent bonds. While dynamic covalent bonds have been introduced to enhance reversibility in covalently cross-linked systems, they often require harsher conditions, display delayed responsiveness, and involve more complex chemistry. Given these challenges, physical cross-linking methods─such as metal–ligand coordination cross-links, crystalline region formation, electrostatic interactions, hydrophobic association, polymer chain entanglement, host–guest interaction, and hydrogen bonding─have been considered promising strategies to enhance both toughness and dynamic features. These characteristics provide high versatility and practicality, enabling advanced applications in areas such as soft robotics and tissue engineering. This review presents a comprehensive analysis of strategies and perspectives for toughening hydrogels via fully physical cross-linking and highlights emerging applications that exploit the unique advantages of reversible physical networks.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5436–5453"},"PeriodicalIF":7.0,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanism of Thermal Atomic Layer Etching of Hafnium Zirconium Oxide, HfO2 and ZrO2 Using Sequential HF and Acetylacetone Exposures","authors":"Troy A. Colleran,&nbsp;Aziz I. Abdulagatov,&nbsp;Jonathan L. Partridge,&nbsp;Andrew S. Cavanagh and Steven M. George*,&nbsp;","doi":"10.1021/acs.chemmater.5c01228","DOIUrl":"https://doi.org/10.1021/acs.chemmater.5c01228","url":null,"abstract":"<p >The mechanism of hafnium zirconium oxide (HZO), HfO₂ and ZrO₂ thermal atomic layer etching (ALE) was explored using sequential hydrogen fluoride (HF) and acetylacetone (Hacac) exposures. HF modifies the metal oxide surface by forming a metal fluoride layer. Hacac then removes the metal fluoride layer by forming volatile metal acac products. Initial in situ spectroscopic ellipsometry investigations revealed that amorphous and crystalline HZO, HfO₂ and ZrO₂ films were etched by sequential HF and Hacac exposures. Amorphous HZO was etched at a rate of 0.80 Å/cycle at 230 °C. Crystalline HZO was etched at rates of 0.50 and 0.74 Å/cycle at 250 and 270 °C, respectively. Amorphous HfO₂ and ZrO₂ were etched at rates of 0.20 and 0.36 Å/cycle at 250 °C, respectively. The crystalline HfO₂ and ZrO₂ films were etched at 250 °C at rates of 0.02 and 0.18 Å/cycle, respectively. To understand the etching mechanism, the volatile etch products during HfO₂ and ZrO₂ thermal ALE at 250 °C were identified with high sensitivity quadrupole mass spectrometry (QMS) techniques using HfO₂ and ZrO₂ powder samples. The QMS studies determined that HF exposures yielded H₂O during fluorination of the metal oxide at 250 °C. After fluorination of HfO₂ and ZrO₂, QMS analysis identified Hf(acac)₂F₂ and Zr(acac)₂F₂ etch products, respectively. These mixed ligand fluoro(acetylacetonate) compounds of Hf and Zr have not been reported earlier in the literature. The volatile fluoro(acetylacetonate) compounds appeared immediately with the onset of Hacac exposures. The main Hf(acac)F₂⁺ and Zr(acac)F₂⁺ ion intensities from Hf(acac)₂F₂ and Zr(acac)₂F₂, respectively, also decreased with time during the Hacac exposures. This decrease was consistent with a self-limiting surface reaction. In addition, Hacac exposures on the fluorinated metal oxide surfaces were observed to produce volatile HF at the onset of Hacac exposures at 250 °C. Some of the HF reaction product from the Hacac reaction can potentially return to refluorinate the metal oxide surface and minimize the amount of HF required for additional etching. Experiments with multiple Hacac exposures after the HF fluorination reaction revealed that the Hf(acac)F₂⁺ and Zr(acac)F₂⁺ ion intensities decreased progressively with each Hacac exposure after the initial HF exposure. These results confirm that the Hacac reaction is self-limiting even though some HF etch product can remain and refluorinate the HfO₂ and ZrO₂ surfaces.</p>","PeriodicalId":33,"journal":{"name":"Chemistry of Materials","volume":"37 15","pages":"5935–5945"},"PeriodicalIF":7.0,"publicationDate":"2025-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}