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Phase coherence and electron-electron interactions in epitaxial strained SrTiO3 films on Si(001)

Physical Review B 2025年第15期111卷 155307-155307页

作者： Ryan J. Cottier Barry D. Koehne John T. Miracle Daniel A. Currie Craig H. Swartz Nikoleta Theodoropoulou Department of Physics Texas State University San Marcos Texas 78666 USA Materials Science Engineering and Commercialization Program Texas State University San Marcos Texas 78666 USA

Oxide heterostructures based on SrTiO3 have emerged as a rich platform for exploring physical phenomena, most notably conductivity at interfaces between insulators. In this study, we investigate the electronic properties of an oxide-semiconductor heterostructure—SrTiO3 films grown epitaxially on Si(001). The lattice mismatch induces epitaxial strain, breaking the cubic symmetry of SrTiO3 and resulting in tetragonal distortion. Magnetotransport measurements reveal that the temperature and magnetic field dependence of the conductivity are dominated by two-dimensional quantum effects, weak localization, and electron-electron interactions. The low-temperature electronic properties indicate quantum confinement, strong electron correlations, exchange interactions, and Zeeman spin splitting. These findings underscore the potential of the SrTiO3/Si heterostructure for designing oxide-based quantum devices.

关键词： Lattice mismatch

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Bandgap of Epitaxial Single-Crystal BiFe1−xMnxO3 Films Grown Directly on SrTiO3/Si(001)

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materials 2025年第9期18卷 2022-2022页

作者： Cantrell, Samuel R. Miracle, John T. Cottier, Ryan J. Lindsey, Skyler Theodoropoulou, Nikoleta Materials Science Engineering and Commercialization Program Texas State University San MarcosTX78666 United States Department of Physics Texas State University San MarcosTX78666 United States

We report the growth and optical characterization of single-crystal BiFe1−xMnxO3 thin films directly on SrTiO3/Si(001) substrates using molecular beam epitaxy. X-ray diffraction confirmed epitaxial growth, film crystallinity, and sharp interface quality. Scanning electron microscopy and energy dispersive X-ray spectroscopy verified uniform film morphology and successful Mn incorporation. Spectroscopic ellipsometry revealed a systematic bandgap reduction with increasing Mn concentration, from 2.7 eV in BiFeO3 to 2.58 eV in BiFe0.74Mn0.26O3, consistent with previous reports on Mn-doped BiFeO3. These findings highlight the potential of BiFe1₋xMnxO3 films for bandgap engineering, advancing their integration into silicon-compatible multifunctional optoelectronic and photovoltaic applications. © 2025 by the authors.

关键词： Molecular beam epitaxy

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Revisiting ligand-exchange chromatography for valsartan chiral analysis using a conventional non-chiral column

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Journal of Pharmaceutical sciences 2025年第7期114卷 103797页

作者： Tho, Chanbopha Kerwin, Sean M. Jamnongtanachot, Promporn Vongsutilers, Vorasit Tuesuwan, Bodin Pharmaceutical Sciences and Technology Program Faculty of Pharmaceutical Sciences Chulalongkorn University Bangkok 10330 Thailand Department of Food and Pharmaceutical Chemistry Faculty of Pharmaceutical Sciences Chulalongkorn University Bangkok 10330 Thailand Materials Science Engineering and Commercialization Program Texas State University San Marcos 78666 TX United States Visatchana Consulting Co. Ltd. Bangkok 10230 Thailand

As the chiral drug market grows, developing efficient separation methods while ensuring quality has become a key focus for the pharmaceutical industries. Chiral column chromatography is effective but often impractical due to its expense. In our research, we established a cost-effective chiral analysis method for valsartan using ligand-exchange chromatography (LEC), an underutilized yet promising analytical technique with significant potential for further development in pharmaceutical research. This approach allows separation on a non-chiral column by forming complexes with metal ions in the mobile phase. Valsartan, a widely used antihypertensive drug, and its enantiomeric impurity were analyzed through LEC on a C₁₈ column. We optimized the conditions for chiral selectors, copper ions, and pH, achieving a resolution exceeding 2.7. The method, validated per ICH Q2(R1) guidelines for assay and impurity determination, exhibited outstanding linearity (r² > 0.999) and recovery (97.8 %–101.7 %), ensuring a complete separation of the target peak, even after forced degradation. LEC presents a cost-effective alternative for in-house chiral drug analysis, addressing the challenges posed by limited access to chiral columns in countries focused on local generic drug production, and offering a practical solution to the increasing global demand for efficient chiral separation. © 2025 American Pharmacists Association

关键词： Analytical Chemistry Chromatography HPLC Liquid Chromatography (LC) United States Pharmacopeia (USP)

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Gost effectiveness of crack treatment methods:A field study

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Journal of Traffic and Transportation engineering(English Edition) 2019年第6期6卷 598-607页

作者： Mithil Mazumder Hyun Hwan Kim Soon-Jae Lee Moon-Sup Lee Materials Science Engineeringand Commercialization ProgramTexas State UniversitySan MarcosTX 78666USA Department of Engineering Technology Texas State UniversitySan MarcosTX 78666USA Korea Institute of Civil Engineering and Building Technology Gyeonggi-do 10223South Korea

In the United States,more than 94%highways are paved with asphalt materials and placing crack sealant materials has been a common pavement maintenance for *** sealing treatment includes the use of a router to create a reservoir on the intended cracks whereas crack filling is given without doing any modification to the crack *** the initial cost of crack sealing is higher,it is expected to have a longer service period compared to crack *** is little research on comparison of short and long term cost effectiveness between these two treatments using the real field cost data *** this study four test sites in Texas were treated with crack filling and sealing using the same sealant material and finishing *** effectiveness of both treatments was measured in terms of initial,annual average and life cycle cost based on the cost inputs during *** general,the results of this study indicated that(1)on an average approximately 45%initial cost increase was estimated with the two routing configurations of crack sealing;(2)material and labor cost is found to have the most significant effect on the higher initial cost of crack sealing compared to other associated costs;(3)annual average and life cycle costs have shown that crack sealing is more cost effective pavement maintenance compared to crack filling over a long period of time;(4)agency cost is observed to be reduced by approximately 24%with crack sealing treatment based on the35 year analysis period.

关键词： Crack sealing Crack filling Initial cost Annual average cost Life cycle cost

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Structural insights of mechanically induced aluminum-doped hydroxyapatite nanoparticles by Rietveld refinement

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Chinese Journal of Chemical engineering 2017年第2期25卷 238-247页

作者： Abbas Fahami Bahman Nasiri-Tabrizi Gary W. Beall Wan Jefrey Basirun Materials Science Engineering and Commercialization Program Texas State University San Marcos 78666 TX USA Advanced Materials Research Center Materials Engineering Department Najafabad Branch Islamic Azad University Najafabad lsfahan lran Department of Chemistry and Biochemistry Texas State University San Marcos 78666 TX USA Physics Department Faculty of Science King Abdulaziz University Jeddah 21589 Saudi Arabia Department of Chemistry Faculty of Science University of Malaya150603 Kuala Lumpur Malaysia

Aluminum doped hydroxyapatite （HA：AI3 ＋） nanopowders were successfully prepared via a simple and efficient one-pot mechanochemical route. The effects of dopant loading on phase compositions and structural features were assessed by Rietveld analysis. The XRD-Rietveld refinement revealed the stabilization of HA in hexagonal structure for all the samples. The sharpness and intensity of the apatite-derived XRD peaks decreased as the dopant content increased to 10% due to the increase in lattice imperfections and mechanically induced amorphization. The incorpo- ration of A13 ＋ into the HA lattice decreased the unit cell parameters. From the FfiR measurements, the representing bands of apatite were identified in all cases. The mechanosynthesized nanopowders consisted of nanospheroids with an average size of 44 - 20 nm and therefore are promising for bone tissue regeneration.

关键词： SynthesisIon exchangeMechanochemicalRietveld refinement

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DEVELOPMENT OF A LOW THERMAL EXPANSION SLA RESIN FOR NICKEL PLATING APPLICATIONS

DEVELOPMENT OF A LOW THERMAL EXPANSION SLA RESIN FOR NICKEL ...

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SAMPE 2022 Conference and Exhibition

作者： Hammond, Connor Tate, Jitendra Texas State University Ingram School of Engineering 601 University Drive San MarcosTX78666 United States Materials Science Engineering and Commercialization Program

ISBN: (纸本)9781934551417

Applications in the aerospace and defense industries are demanding stronger and lighter parts for use in aircraft and spacecraft. Additive manufacturing (AM) has allowed engineers to create complex parts that would be difficult or even impossible to create through standard manufacturing methods. Stereolithography (SLA) additive manufacturing offers an easy and affordable way to create extremely complex and detailed geometries by selectively curing thin layers of a photopolymer resin. To increase part performance, a nickel coating can then be applied to increase strength, chemical resistance, and heat deflection. This works well in lab environments, but in harsh conditions such as those presented in aerospace applications, large thermal gradients cause the nickel and resin to expand at different rates. This causes high internal stresses and can even result in part failure. The development of a strong, reliable resin that could match the coefficient of thermal expansion of nickel could fill a gap in additive manufacturing between fully plastic or metal parts, allowing for production of high-performance parts. In this paper we will cover the development of an SLA resin with good mechanical properties and a thermal expansion rate similar nickel for aerospace applications. Copyright 2022. Used by the Society of the Advancement of Material and Process engineering with permission.

关键词： 3D printers

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Improvement approach for gas barrier behavior of polymer/clay nanocomposite films

Improvement approach for gas barrier behavior of polymer/cla...

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MRS Advances

作者： Dabbaghianamiri, Maedeh Das, Sayantan Beall, Gary W. Materials Science Engineering and Commercialization Program Texas State University TX78666 United States Department of Chemistry and Biochemistry Texas State University TX78666 United States

Polymer nanocomposites (PNC) include a copolymer or polymer which has nanoparticles dispersed in the polymer matrix at the nano-level. One of the most common types of polymer nanocomposites contain smectic clays as the nanoparticles. These clay minerals increase the mechanical properties of standard polymers and improve barrier properties. For optimum barrier properties, Layer-by-Layer assembly (LbL) is one of the most effective methods for depositing thin films. LbL methods however, are quite tedious and produce large quantities of waste. A newly discovered phenomenon of self-assembled polymer nanocomposites utilizes entropic forces to drive the assembly to spontaneously form a larger nanostructured film. This approach allows polymers and nanoparticles with high particle loadings to be mixed, and create the super gas barrier films. We have developed a coating technique which can be employed to make self-assembled gas barrier films via inkjet printing. This technique is industrially scalable and efficient. This is because it does not need any rinsing step and drying steps as required in LbL. The influence of different polymers Polyvinylpyrrolidone (PVP) and Poly (acrylic acid) PAA with Montmorillonite (MMT) nanoclay solutions on Polyethylene terephthalate (PET) substrate is examined to study their effectiveness as a gas barrier film. The results showing the excellent oxygen barrier behavior of a combination of PVP and MMT Nano clay nanocomposite with high transparency. These high barrier gas nanocomposite films are good candidates for a variety of food packaging applications. © Copyright materials Research Society 2017.

关键词： Self assembly

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Mechanical and electrical properties of 3d printed pa6 nanocomposites

Mechanical and electrical properties of 3d printed pa6 nanoc...

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International SAMPE Conference and Exhibition 2020

作者： Tate, Jitendra S. Arigbabowo, Oluwasola K. Lepere, Micheal Okeke, Henry Garcia, Jesse Nahar, Aziza Materials Science Engineering and Commercialization Program Texas State University United States Ingram School of Engineering Texas State University United States Texas State University San MarcosTX78666 United States

Polyamide 6 (PA 6) nanocomposites are viable engineered nanocomposite materials with potential application in electrostatic discharge dissipation applications. Creating an electrically conductive path to dissipate electrostatic charges in such materials can be a viable solution to Electrostatic Discharge (ESD) concerns. The addition of nanofillers can also enhance mechanical properties of the parent polyamide 6, a structural thermoplastic ideal for 3D printing via fused deposition modelling (FDM). While improving the ESD capability, it is imperative to sustain the structural integrity of the nanocomposites. Hence, this study evaluated the mechanical, thermal and electrical properties of 3D printed PA6 Nanocomposites for electrostatic discharge applications. 3 and 5 wt.% of Carbon Nanofiber (CNF) was compounded with PA6 using co-rotating twin screw extruder) to produce 1.75mm diameter monofilaments for fused deposition modelling (FDM). The test samples were printed using commercial-off-the-shelf (COTS) 3D printer, Lulzbot TAZ 6 FDM printer. Mechanical, electrical and thermal characterization were carried out according to their respective ASTM standard. The tensile and flexural properties were enhanced by 3wt% addition of CNF, but no significant improvement was observed at 5wt%. The CNF nanocomposites exhibited good thermal stability and crystallization phenomenon at both loading levels. The volume resistivity of the PA6 matrix was reduced to order of 10 11 and 1012 by 3wt% and 5wt% CNF addition respectively, which seems promising for manufacturing static discharge products. © 2020 Soc. for the Advancement of Material and Process engineering. All rights reserved.

关键词： Carbon nanofibers

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Mid-IR Gain of Tensile Germanium Waveguide Lasers with SiNx Stress Liners

Mid-IR Gain of Tensile Germanium Waveguide Lasers with SiNx ...

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2021 IEEE Photonics Society Summer Topicals Meeting Series, SUM 2021

作者： Reza, Md Shamim Gulyas, Istvan Wistey, Mark A. Materials Science Engineering and Commercialization Program Texas State University San MarcosTX78666 United States Department of Physics Texas State University San MarcosTX78666 United States

ISBN: (纸本)9781665416009

We used ab-initio and finite element strain modeling to explain high threshold current densities in reported tensile Ge lasers. Anisotropic strains improve carrier confinement but reduces optical confinement, and intervalence band absorption still dominates. Strain anisotropy increases Jth compared with simple slab models. © 2021 IEEE.

关键词： Germanium

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DEVELOPMENT OF A LOW THERMAL EXPANSION NANOCOMPOSITE RESIN FOR MSLA 3D PRINTER

DEVELOPMENT OF A LOW THERMAL EXPANSION NANOCOMPOSITE RESIN F...

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SAMPE 2024 Conference and Exhibition

作者： Sufian, Muhammad A. Sheley, Rahul R. Shadman, Wasi Tanim, Ibrahim K. Cooper, Benicia Tate, Jitendra Materials Science Engineering and Commercialization Program Texas State University 601 University Drive San MarcosTX78666 United States Ingram School of Engineering Texas State University San MarcosTX78666 United States

ISBN: (纸本)9781934551455

Masked Stereolithography (MSLA) is a 3D printing technique that uses an LCD screen and a UV LED light source operated digitally to selectively cure photosensitive resin, forming a three-dimensional object through successive layers cured upon one another. Using MSLA offers superior dimensional precision, efficient surface finish, and printing resolution limits of 30 µm to 140µm, allowing to obtain complex 3D geometries. Using this technique gives advantage of astonishing results in the resolution of 3d printer surface but many times lacks in obtaining desired material properties compared to other available techniques. To overcome this lacuna one of the methods is to create a thin layer coating of nickel plating over the resin which enhances the mechanical strengths, heat diffraction, and resistance to chemicals. In this scenario, the CTE of resin does not align with that of nickel metal. This results in internal stresses when exposed to the harsh environment of space causing the part failure. In this work, an attempt has been made by using epoxy as a base resin and introducing nanomaterial Multi-Walled Carbon Nanotubes (MWCNTs) to reduce the CTE. Out of all different loading levels of MWCNT 0.5 wt% loading showed maximum reduction in terms of CTE which is more than 25% compared to neat resin. Tensile strength and tensile modulus increased by more than 47% and 61%. While flexural modulus increased by 66% and percentage elongation showed a reduction by 38% compared to neat resin. © 2024 Soc. for the Advancement of Material and Process engineering. All rights reserved.

关键词： Nickel plating

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