Pub Date : 2024-10-08DOI: 10.1016/j.physb.2024.416606
This study examines the effect of triphenylamine (TPA) interlayers on the electrical properties of Al/TPA/p-Si metal-interlayer/insulator material-semiconductor (MIS) capacitors. Using Gaussian software, TPA molecular structure was optimized, and HOMO-LUMO energy levels were simulated. Capacitance-conductance-voltage (C-G-V) measurements were performed at room temperature over −4 V to +4 V and 50 kHz–700 kHz. AFM and SEM analysis showed TPA films were smooth with a uniform thickness of about 178 nm. The C-V characteristics revealed a frequency-dependent decrease in capacitance, indicating a continuous distribution of interface states. Barrier height (ΦB) increased from 0.305 eV at 50 kHz to 0.655 eV at 700 kHz, while the active interface trap density (Dit) decreased from 6.73 × 1012 eV−1 cm−2 to 3.23 × 1011 eV−1 cm−2. Additionally, the accumulating region exhibited low series resistance values (between 6.88 and 8.44 Ω). These results suggest that TPA thin films are effective for MIS capacitors.
{"title":"Impact of voltage and frequency on electrical characteristics of MIS capacitors with triphenylamine layer","authors":"","doi":"10.1016/j.physb.2024.416606","DOIUrl":"10.1016/j.physb.2024.416606","url":null,"abstract":"<div><div>This study examines the effect of triphenylamine (TPA) interlayers on the electrical properties of Al/TPA/p-Si metal-interlayer/insulator material-semiconductor (MIS) capacitors. Using Gaussian software, TPA molecular structure was optimized, and HOMO-LUMO energy levels were simulated. Capacitance-conductance-voltage (<em>C</em>-<em>G</em>-<em>V</em>) measurements were performed at room temperature over −4 V to +4 V and 50 kHz–700 kHz. AFM and SEM analysis showed TPA films were smooth with a uniform thickness of about 178 nm. The <em>C</em>-<em>V</em> characteristics revealed a frequency-dependent decrease in capacitance, indicating a continuous distribution of interface states. Barrier height (Φ<sub>B</sub>) increased from 0.305 eV at 50 kHz to 0.655 eV at 700 kHz, while the active interface trap density (<em>D</em><sub><em>it</em></sub>) decreased from 6.73 × 10<sup>12</sup> eV<sup>−1</sup> cm<sup>−2</sup> to 3.23 × 10<sup>11</sup> eV<sup>−1</sup> cm<sup>−2</sup>. Additionally, the accumulating region exhibited low series resistance values (between 6.88 and 8.44 Ω). These results suggest that TPA thin films are effective for MIS capacitors.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.physb.2024.416597
Tuning the electronic properties of polyaniline remains one of the most important features for the development of advanced materials in electronics. In this contribution, we use density functional theory to investigate the electronic properties of polyaniline when coordinating transition metals (Mn, Fe, Co, Cu, Zn) are embedded in the polymer structure.
Importantly, the results reveal that in the presence of transition metal with high electronegativity, the coordinated polyaniline winds up with a decreased gap. Indeed, the band gap for H-PANI decreases from 0.911 eV to 0.513 eV for H-PANI-Mn (lower electronegativity) and to 0.201 eV for H-PANI-Zn (higher electronegativity). This reduction in the energy gap is attributed to enhanced electron delocalization due to increased overlap of electron wavefunctions in the hybrid structure. The results also reveal that the presence of transition metals lead to lower the chemical hardness from 3.252 eV in the case of H-PANI into 0.256 eV for H-PANI-Mn and 0.100 eV for H-PANI-Zn. Additionally, the results from molecular electrostatic potential highlight that PANI-Transition metal sustains more delocalization of charge density distribution compared to H-PANI, leading to molecule polarization which does play a crucial role in various chemical phenomena. These later reveal that the electron density polarization in polyaniline can interestingly be controlled through doping and coordinating the polymer structure with additional transition metals. Therefore, the obtained results might be used in the optimization of electrochemical charge storage in supercapacitors.
调节聚苯胺的电子特性仍然是开发先进电子材料的最重要特征之一。在这篇论文中，我们利用密度泛函理论研究了在聚合物结构中嵌入配位过渡金属（锰、铁、钴、铜、锌）时聚苯胺的电子特性。重要的是，研究结果表明，当存在电负性较高的过渡金属时，配位聚苯胺的带隙会减小。事实上，H-PANI-Mn（电负性较低）的带隙从 0.911 eV 减小到 0.513 eV，而 H-PANI-Zn（电负性较高）的带隙则减小到 0.201 eV。能隙的减小归因于混合结构中电子波函数重叠的增加导致电子析出的增强。结果还显示，过渡金属的存在导致化学硬度从 H-PANI 的 3.252 eV 降至 H-PANI-Mn 的 0.256 eV 和 H-PANI-Zn 的 0.100 eV。此外，分子静电势的研究结果表明，与 H-PANI 相比，PANI-过渡金属的电荷密度分布更分散，从而导致分子极化，而分子极化在各种化学现象中起着至关重要的作用。这些结果表明，聚苯胺中的电子密度极化可以通过在聚合物结构中掺杂和配位额外的过渡金属来控制。因此，所获得的结果可用于优化超级电容器中的电化学电荷存储。
{"title":"Computational study of transition metal coordinated polyaniline: A first principle investigation into tuning the electronic properties of the resulting hybrid material","authors":"","doi":"10.1016/j.physb.2024.416597","DOIUrl":"10.1016/j.physb.2024.416597","url":null,"abstract":"<div><div>Tuning the electronic properties of polyaniline remains one of the most important features for the development of advanced materials in electronics. In this contribution, we use density functional theory to investigate the electronic properties of polyaniline when coordinating transition metals (Mn, Fe, Co, Cu, Zn) are embedded in the polymer structure.</div><div>Importantly, the results reveal that in the presence of transition metal with high electronegativity, the coordinated polyaniline winds up with a decreased gap. Indeed, the band gap for H-PANI decreases from 0.911 eV to 0.513 eV for H-PANI-Mn (lower electronegativity) and to 0.201 eV for H-PANI-Zn (higher electronegativity). This reduction in the energy gap is attributed to enhanced electron delocalization due to increased overlap of electron wavefunctions in the hybrid structure. The results also reveal that the presence of transition metals lead to lower the chemical hardness from 3.252 eV in the case of H-PANI into 0.256 eV for H-PANI-Mn and 0.100 eV for H-PANI-Zn. Additionally, the results from molecular electrostatic potential highlight that PANI-Transition metal sustains more delocalization of charge density distribution compared to H-PANI, leading to molecule polarization which does play a crucial role in various chemical phenomena. These later reveal that the electron density polarization in polyaniline can interestingly be controlled through doping and coordinating the polymer structure with additional transition metals. Therefore, the obtained results might be used in the optimization of electrochemical charge storage in supercapacitors.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.physb.2024.416603
CaMn7O12 (CMO) is an outstanding multiferroic material known for its significant magnetically-induced electric polarization. Its strong magnetoelectric (ME) effect, i.e., electric polarization controlled via magnetic fields or vice versa, makes this material suitable for a variety of technological applications. In this study, we employed synchrotron X-ray powder diffraction to explore polycrystalline CMO's pressure-induced structural phase transitions (SPTs). Our results indicate that CMO undergoes two distinct pressure-induced SPTs: the first transition occurs at pressures above 7.0 GPa, changing from a rhombohedral to an orthorhombic structure, and the second occurs around 13.0 GPa, transforming into a monoclinic structure. These findings differ from the pressure-induced behavior of CMO single crystals and highlight CMO as one of the rare quadruple perovskites exhibiting multiple pressure-induced non-isostructural phase transitions. This study expands the understanding of phase stability behavior in multiferroic materials under high-pressure conditions.
{"title":"Pressure-induced multiple structural phase transitions on multiferroic CaMn7O12","authors":"","doi":"10.1016/j.physb.2024.416603","DOIUrl":"10.1016/j.physb.2024.416603","url":null,"abstract":"<div><div>CaMn<sub>7</sub>O<sub>12</sub> (CMO) is an outstanding multiferroic material known for its significant magnetically-induced electric polarization. Its strong magnetoelectric (ME) effect, i.e., electric polarization controlled via magnetic fields or vice versa, makes this material suitable for a variety of technological applications. In this study, we employed synchrotron X-ray powder diffraction to explore polycrystalline CMO's pressure-induced structural phase transitions (SPTs). Our results indicate that CMO undergoes two distinct pressure-induced SPTs: the first transition occurs at pressures above 7.0 GPa, changing from a rhombohedral to an orthorhombic structure, and the second occurs around 13.0 GPa, transforming into a monoclinic structure. These findings differ from the pressure-induced behavior of CMO single crystals and highlight CMO as one of the rare quadruple perovskites exhibiting multiple pressure-induced non-isostructural phase transitions. This study expands the understanding of phase stability behavior in multiferroic materials under high-pressure conditions.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.physb.2024.416596
Over the last two decades, the new branch of spintronics, i.e., semiconductor spintronics, has gained more attention because it integrates the properties of conventional semiconductors, such as optical bandgap and charge carriers, helpful for processing and computing pieces of information combined with magnets for data storage applications in a single device. Likewise, substituting transition metal (TM) ions to induce magnetism into semiconductors or oxides creates dilute magnetic semiconductors (DMSs) or oxides (DMOs) with high electronic, photonic, and magnetic functionality. This review article discusses the historical outline of magnetic semiconductors with their origin and mechanism. It also includes a concise overview of various DMO systems based on their conductivity (p-type and n-type) to elucidate the synthesis, origin, and control mechanisms and further evoke to prepare consumable spintronics devices. The occurrence of room temperature ferromagnetism (RTFM) with transparency and conductivity can be helpful in spintronics device fabrications, which is assumed to be governed by the formation of intrinsic defects, charge carriers, morphology, and the induced exchange interactions between ions. The DMOs-based spintronics devices, such as magneto-optical devices, transparent ferromagnets, and spin-based solar cells, exploit both semiconducting and magnetic properties, which have also been discussed in this review article with outlook and perspectives.
在过去二十年里，自旋电子学的新分支，即半导体自旋电子学，得到了越来越多的关注，因为它将传统半导体的特性，如光学带隙和电荷载流子，与用于数据存储的磁体结合在一个设备中，有助于信息的处理和计算。同样，用过渡金属（TM）离子取代半导体或氧化物以诱导磁性，可产生具有高电子、光子和磁性功能的稀磁半导体（DMS）或氧化物（DMO）。这篇综述文章讨论了磁性半导体的历史及其起源和机理。文章还简要概述了基于导电性（p 型和 n 型）的各种 DMO 系统，以阐明其合成、起源和控制机制，并进一步唤起人们制备可消耗的自旋电子器件。室温铁磁性（RTFM）与透明性和导电性的发生有助于自旋电子器件的制造，这被认为是由内在缺陷的形成、电荷载流子、形态以及离子间的诱导交换相互作用所决定的。基于 DMOs 的自旋电子器件，如磁光器件、透明铁磁体和自旋太阳能电池，同时利用了半导体和磁学特性，本文也对这些特性进行了展望和讨论。
{"title":"Harnessing the duality of magnetism and conductivity: A review of oxide based dilute magnetic semiconductors","authors":"","doi":"10.1016/j.physb.2024.416596","DOIUrl":"10.1016/j.physb.2024.416596","url":null,"abstract":"<div><div>Over the last two decades, the new branch of spintronics, i.e., semiconductor spintronics, has gained more attention because it integrates the properties of conventional semiconductors, such as optical bandgap and charge carriers, helpful for processing and computing pieces of information combined with magnets for data storage applications in a single device. Likewise, substituting transition metal (TM) ions to induce magneti<em>s</em>m into semiconductors or oxides creates dilute magnetic semiconductors (DMSs) or oxides (DMOs) with high electronic, photonic, and magnetic functionality. This review article discusses the historical outline of magnetic semiconductors with their origin and mechanism. It also includes a concise overview of various DMO systems based on their conductivity (<em>p</em>-type and <em>n</em>-type) to elucidate the synthesis, origin, and control mechanisms and further evoke to prepare consumable spintronics devices. The occurrence of room temperature ferromagnetism (RTFM) with transparency and conductivity can be helpful in spintronics device fabrications, which is assumed to be governed by the formation of intrinsic defects, charge carriers, morphology, and the induced exchange interactions between ions. The DMOs-based spintronics devices, such as magneto-optical devices, transparent ferromagnets, and spin-based solar cells, exploit both semiconducting and magnetic properties, which have also been discussed in this review article with outlook and perspectives.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.physb.2024.416595
This report presents the electronic, optical, vibrational, and thermodynamic properties of APdH3 (A = Ca, Sr, Ba) perovskites across the pressure range of 0 GPa–50 GPa employing ab initio calculations based on density functional theory. The computed electronic structures display the metallic behavior of these hydrides under both ambient and pressurized conditions. The electronic dispersions are strongly influenced by applied pressures. The pressure-induced optical properties demonstrate that the optoelectronic characteristics can be tuned by varying hydrostatic pressure. Phonon dispersion exhibits the dynamical stability of CaPdH3, and SrPdH3 hydrides at ambient condition, whereas BaPdH3 remains unstable under pressure below ∼10 GPa. Utilizing quasi-harmonic Debye approximation, pressure-induced thermodynamic properties are evaluated up to 1000 K. All thermodynamic parameters are significantly affected under pressure in a certain temperature. The Gibbs free energy analyses elucidate that CaPdH3 possesses the highest thermodynamic phase stability among these hydrides at temperatures up to 1000 K.
本报告采用基于密度泛函理论的 ab initio 计算方法，介绍了 APdH3（A = Ca、Sr、Ba）包晶在 0 GPa-50 GPa 压力范围内的电子、光学、振动和热力学性质。计算得出的电子结构显示了这些氢化物在环境和加压条件下的金属特性。电子色散受到施加压力的强烈影响。压力诱导的光学特性表明，光电特性可以通过改变静水压力来调整。声子色散显示了 CaPdH3 和 SrPdH3 水化物在环境条件下的动态稳定性，而 BaPdH3 在低于 10 GPa 的压力下仍然不稳定。利用准谐波德拜近似，评估了高达 1000 K 的压力诱导热力学性质。吉布斯自由能分析表明，在高达 1000 K 的温度下，CaPdH3 在这些氢化物中具有最高的热力学相稳定性。
{"title":"Insights of pressure-mediated optoelectronic, vibrational and thermodynamic properties of APdH3 (A = Ca, Sr, Ba) perovskite hydrides from ab initio calculations","authors":"","doi":"10.1016/j.physb.2024.416595","DOIUrl":"10.1016/j.physb.2024.416595","url":null,"abstract":"<div><div>This report presents the electronic, optical, vibrational, and thermodynamic properties of <em>A</em>PdH<sub>3</sub> (<em>A</em> = Ca, Sr, Ba) perovskites across the pressure range of 0 GPa–50 GPa employing <em>ab initio</em> calculations based on density functional theory. The computed electronic structures display the metallic behavior of these hydrides under both ambient and pressurized conditions. The electronic dispersions are strongly influenced by applied pressures. The pressure-induced optical properties demonstrate that the optoelectronic characteristics can be tuned by varying hydrostatic pressure. Phonon dispersion exhibits the dynamical stability of CaPdH<sub>3</sub>, and SrPdH<sub>3</sub> hydrides at ambient condition, whereas BaPdH<sub>3</sub> remains unstable under pressure below ∼10 GPa. Utilizing quasi-harmonic Debye approximation, pressure-induced thermodynamic properties are evaluated up to 1000 K. All thermodynamic parameters are significantly affected under pressure in a certain temperature. The Gibbs free energy analyses elucidate that CaPdH<sub>3</sub> possesses the highest thermodynamic phase stability among these hydrides at temperatures up to 1000 K.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.physb.2024.416604
Ferroelectric tunnel junctions (FTJs) have attracted considerable attention for potential applications in the next-generation data storage technologies. In this work, we have grown high-quality LiNbO3 single crystal films on STO (111) substrates by rotational epitaxy. The certain ferroelectricity was achieved in nanoscale epitaxial LiNbO3 films. Then, the Au/LiNbO3/Nb: SrTiO3 FTJ was fabricated, and the nonvolatile resistive switching controlled by the nonvolatile polarization switching was observed. The Au/LiNbO3/Nb: SrTiO3 FTJs regulate the quantum tunneling effect through ferroelectric polarization reversal to obtain multi-level resistive states, thereby achieving data storage functionality. At room temperature, the ON/OFF current ratio can exceed 103. Furthermore, the FTJs also exhibit excellent retention for more than 103 s and good switching endurance for 2000 cycles. The results suggest the application potential of this LiNbO3-based FTJ for next generation nonvolatile ferroelectric memories.
{"title":"LiNbO3-based ferroelectric tunnel junctions with changeable electroresistance for data storage","authors":"","doi":"10.1016/j.physb.2024.416604","DOIUrl":"10.1016/j.physb.2024.416604","url":null,"abstract":"<div><div>Ferroelectric tunnel junctions (FTJs) have attracted considerable attention for potential applications in the next-generation data storage technologies. In this work, we have grown high-quality LiNbO<sub>3</sub> single crystal films on STO (111) substrates by rotational epitaxy. The certain ferroelectricity was achieved in nanoscale epitaxial LiNbO<sub>3</sub> films. Then, the Au/LiNbO<sub>3</sub>/Nb: SrTiO<sub>3</sub> FTJ was fabricated, and the nonvolatile resistive switching controlled by the nonvolatile polarization switching was observed. The Au/LiNbO<sub>3</sub>/Nb: SrTiO<sub>3</sub> FTJs regulate the quantum tunneling effect through ferroelectric polarization reversal to obtain multi-level resistive states, thereby achieving data storage functionality. At room temperature, the ON/OFF current ratio can exceed 10<sup>3</sup>. Furthermore, the FTJs also exhibit excellent retention for more than 10<sup>3</sup> s and good switching endurance for 2000 cycles. The results suggest the application potential of this LiNbO<sub>3</sub>-based FTJ for next generation nonvolatile ferroelectric memories.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.physb.2024.416601
RE-based double perovskite (DP) oxides of the RE₂TMTM'O₆ family exhibit intriguing magnetodielectric (MD) properties and magnetocaloric effects (MCEs), making them promising candidates for applications in high-performance supercapacitors, memories, spintronic devices, and cryogenic magnetic refrigeration. This paper addresses the vibrational properties of RE2CoMnO6 (RE = Tb, Dy, Ho, Tm, and Yb) ceramics for the first time using infrared reflectance spectroscopy. The dielectric merit factors in the microwave (MW) range, including the quality factor (Qu) and the static dielectric constant (ɛ0), were estimated. It was observed that the intrinsic dielectric constants decrease from approximately 26.2 to 14.4 as the rare earth ionic radius decreases. The mean values of these compounds suggest their suitability for applications in MW circuitry devices.
{"title":"Polar phonons features and intrinsic dielectric properties of RE2CoMnO6 (RE = Tb, Dy, Ho, Tm and Yb) double perovskites","authors":"","doi":"10.1016/j.physb.2024.416601","DOIUrl":"10.1016/j.physb.2024.416601","url":null,"abstract":"<div><div>RE-based double perovskite (DP) oxides of the RE₂TMTM'O₆ family exhibit intriguing magnetodielectric (MD) properties and magnetocaloric effects (MCEs), making them promising candidates for applications in high-performance supercapacitors, memories, spintronic devices, and cryogenic magnetic refrigeration. This paper addresses the vibrational properties of RE<sub>2</sub>CoMnO<sub>6</sub> (RE = Tb, Dy, Ho, Tm, and Yb) ceramics for the first time using infrared reflectance spectroscopy. The dielectric merit factors in the microwave (MW) range, including the quality factor (<em>Q</em><sub><em>u</em></sub>) and the static dielectric constant (<em>ɛ</em><sub><em>0</em></sub>), were estimated. It was observed that the intrinsic dielectric constants decrease from approximately 26.2 to 14.4 as the rare earth ionic radius decreases. The mean values of these compounds suggest their suitability for applications in MW circuitry devices.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142425136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-04DOI: 10.1016/j.physb.2024.416587
In the present report, the combined effects of the co-doping of metal oxide (Bi2O3) and Lithium oxide (Li2O) into the glassy matrix with chemical composition xLi2O-(0.45-x)Bi2O3-(0.15ZnO-0.40P2O5) (x = 0.05, 0.15, 025, and 0.35 mol%) are investigated thoroughly. The FESEM and X-ray diffraction data affirm the crystalline nature of the studied glassy composites. The obtained band gap energy values are declined from (3.68–3.17) eV, while the Urbach energy values are declined from (0.38–0.27) eV. Moreover, the mechanism responsible for AC conductivity has been analyzed using Almond–West formalism and Jonscher's universal power law. The observed rise in both AC and DC conductivity in the glass samples is attributed to the mixed ionic electronic effect. In the ionic diffusion model, an increased defect site concentration improves Li+ ion migration through percolation channels. The reduction in both electrostatic binding energy and strain energy lowers the Anderson-Stuart activation energy, facilitating Li+ ion migration and enhancing conductivity. Additionally, in the small polaron hopping model, an increase in the density of defect states suggests more defect sites that facilitate electronic hopping, creating deep localized states and transitions between localized and extended states. Replacing a Bismuth atom with a Lithium atom increases the number of non-bridging oxygen, enhancing the conduction band tail, reducing the energy needed for hopping conductivity, and increasing conductivity.
本报告深入研究了在化学成分为 xLi2O-(0.45-x)Bi2O3-(0.15ZnO-0.40P2O5)（x = 0.05、0.15、025 和 0.35 mol%）的玻璃基体中共同掺杂金属氧化物 (Bi2O3) 和锂氧化物 (Li2O) 的综合效应。FESEM 和 X 射线衍射数据证实了所研究的玻璃状复合材料的结晶性质。获得的带隙能值从 (3.68-3.17) eV 下降到 (3.68-3.17)eV，而乌巴赫能值从 (0.38-0.27) eV 下降到 (0.38-0.27)eV。此外，还利用阿尔蒙德-韦斯特形式主义和容舍尔普遍幂律分析了交流导电性的机理。在玻璃样品中观察到的交流和直流电导率的上升归因于混合离子电子效应。在离子扩散模型中，缺陷点浓度的增加会促进 Li+ 离子通过渗流通道迁移。静电结合能和应变能的降低降低了安德森-斯图尔特活化能，从而促进了 Li+ 离子迁移并提高了导电性。此外，在小极子跳跃模型中，缺陷态密度的增加表明有更多的缺陷点可促进电子跳跃，从而产生深局部态以及局部态和扩展态之间的跃迁。用锂原子取代铋原子，增加了非桥接氧的数量，从而增强了导带尾部，降低了跳电所需的能量，提高了导电性。
{"title":"Electrical conduction and optical characteristics of Li2O and Bi2O3 Co-doped zinc-phosphate glassy nanocomposites: A critical observation of mixed ionic electronic effect","authors":"","doi":"10.1016/j.physb.2024.416587","DOIUrl":"10.1016/j.physb.2024.416587","url":null,"abstract":"<div><div>In the present report, the combined effects of the co-doping of metal oxide (Bi<sub>2</sub>O<sub>3</sub>) and Lithium oxide (Li<sub>2</sub>O) into the glassy matrix with chemical composition xLi<sub>2</sub>O-(0.45-x)Bi<sub>2</sub>O<sub>3</sub>-(0.15ZnO-0.40P<sub>2</sub>O<sub>5</sub>) (x = 0.05, 0.15, 025, and 0.35 mol%) are investigated thoroughly. The FESEM and X-ray diffraction data affirm the crystalline nature of the studied glassy composites. The obtained band gap energy values are declined from (3.68–3.17) eV, while the Urbach energy values are declined from (0.38–0.27) eV. Moreover, the mechanism responsible for AC conductivity has been analyzed using Almond–West formalism and Jonscher's universal power law. The observed rise in both AC and DC conductivity in the glass samples is attributed to the mixed ionic electronic effect. In the ionic diffusion model, an increased defect site concentration improves Li<sup>+</sup> ion migration through percolation channels. The reduction in both electrostatic binding energy and strain energy lowers the Anderson-Stuart activation energy, facilitating Li<sup>+</sup> ion migration and enhancing conductivity. Additionally, in the small polaron hopping model, an increase in the density of defect states suggests more defect sites that facilitate electronic hopping, creating deep localized states and transitions between localized and extended states. Replacing a Bismuth atom with a Lithium atom increases the number of non-bridging oxygen, enhancing the conduction band tail, reducing the energy needed for hopping conductivity, and increasing conductivity.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.physb.2024.416594
The electrical resistivity of Co-Cu alloys with Cu content of 10, 20, 30, 40, 50, 60, 70, 80, and 90 at.% was measured in the temperature range from 1400 to 2100K. The experiments were performed during of heating and subsequent cooling of the samples. For alloys with Cu content of 30, 40, 60, 70, 80, and 90 at.%, a bend in the cooling curve specific to the liquid-liquid phase separation (LLPS) process was observed. LLPS is shown when the melt is undercooled to the binodal temperature T∗. The phase transition model of LLPS was proposed for to theoretically determine the temperatures T∗. The LLPS model demonstrates the possibility of percolation phenomena occurring in Cu-Co heterogeneous melts rich in cobalt. The LLPS model shows good agreement with experimental data and the abnormal resistivity behavior of Co–Cu alloys.
{"title":"Abnormal resistivity behavior of Co–Cu alloys and responsible metastable liquid phase separation","authors":"","doi":"10.1016/j.physb.2024.416594","DOIUrl":"10.1016/j.physb.2024.416594","url":null,"abstract":"<div><div>The electrical resistivity of Co-Cu alloys with Cu content of 10, 20, 30, 40, 50, 60, 70, 80, and 90 at.% was measured in the temperature range from 1400 to 2100K. The experiments were performed during of heating and subsequent cooling of the samples. For alloys with Cu content of 30, 40, 60, 70, 80, and 90 at.%, a bend in the cooling curve specific to the liquid-liquid phase separation (LLPS) process was observed. LLPS is shown when the melt is undercooled to the binodal temperature <em>T∗</em>. The phase transition model of LLPS was proposed for to theoretically determine the temperatures <em>T∗</em>. The LLPS model demonstrates the possibility of percolation phenomena occurring in Cu-Co heterogeneous melts rich in cobalt. The LLPS model shows good agreement with experimental data and the abnormal resistivity behavior of Co–Cu alloys.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.physb.2024.416593
The article presents a comprehensive study of the synthesis, phase formation, electronic structure, and optical properties of cobalt-doped aluminum oxynitride Al5O6N (AlON) in the concentration range of 0.01–5 at%. The solubility limit of cobalt in AlON is found to be 0.1–0.2 at% compared to Al. No corundum is detected even at the lowest cobalt content (0.01 at%), but a low amount of AlN and Co or Co4N is observed. Cobalt ions are incorporated into AlON with the typical oxidation state of Co2+ and form Co–O and Co–N bonds in a ratio of 92/8. The bandgap (Eg) and lattice parameters of AlON:Co are found to be in the range of 5.72–5.84 eV and 7.9411–7.9539 Å, respectively, and are influenced by the oxygen content. Pulsed cathodoluminescence spectra show five emission bands, with some attributed to (VAl–ON)-type defects. The luminescence intensity of AlON:Co decreases with higher contents of cobalt ions.
{"title":"Synthesis, phase composition, electronic and spectroscopic properties of cobalt-doped aluminum oxynitride","authors":"","doi":"10.1016/j.physb.2024.416593","DOIUrl":"10.1016/j.physb.2024.416593","url":null,"abstract":"<div><div>The article presents a comprehensive study of the synthesis, phase formation, electronic structure, and optical properties of cobalt-doped aluminum oxynitride Al<sub>5</sub>O<sub>6</sub>N (AlON) in the concentration range of 0.01–5 at%. The solubility limit of cobalt in AlON is found to be 0.1–0.2 at% compared to Al. No corundum is detected even at the lowest cobalt content (0.01 at%), but a low amount of AlN and Co or Co<sub>4</sub>N is observed. Cobalt ions are incorporated into AlON with the typical oxidation state of Co<sup>2+</sup> and form Co–O and Co–N bonds in a ratio of 92/8. The bandgap (E<sub>g</sub>) and lattice parameters of AlON:Co are found to be in the range of 5.72–5.84 eV and 7.9411–7.9539 Å, respectively, and are influenced by the oxygen content. Pulsed cathodoluminescence spectra show five emission bands, with some attributed to (V<sub>Al</sub>–O<sub>N</sub>)-type defects. The luminescence intensity of AlON:Co decreases with higher contents of cobalt ions.</div></div>","PeriodicalId":20116,"journal":{"name":"Physica B-condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.8,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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