Scholarly Literature

Interplay of intermetallic precipitation and nano Y2O3 dispersion on microstructure evolution and strengthening in hydrogen sintered Mo-Ni-Si-Co alloys

Thu, 01 Jan 2026 00:00:00 GMT

Interplay of intermetallic precipitation and nano Y2O3 dispersion on microstructure evolution and strengthening in hydrogen sintered Mo-Ni-Si-Co alloys Swain, S.; Mishra, S.; Patra, A.; Husain, M. M; Debata, M. This work investigates liquid-phase-sintered Molybdenum (Mo) alloys, with and without Y2O3 dispersion, that integrate enhanced hardness and significant strength. Six alloys with compositions of Mo80Ni10Si10 (S1), Mo80Ni10Co10 (S2), Mo80Ni10Si5Co5 (S3), Mo79Ni10Si10(Y2O3)(1) (S4), Mo79Ni10Co10(Y2O3)(1) (S5), and Mo79Ni10Si5Co5(Y2O3)(1) (S6) (wt%) were consolidated by pressureless multistage H-2 sintering with maximum sintering temperature of 1500 degrees C for 90 min. Y2O3 persisted as a stable nanometric dispersion (<50 nm) refining grains in S6, with Mo3Si intermetallics (<90 nm) in S3. All alloys showed a Mo-rich bcc phase along with MoNi, Ni2Si, Mo3Si, and Mo3Co2. When paired with appropriate Si/Co partitioning, Y2O3 addition increased relative density to 96.15% in S6 compared to non-Y2O3 dispersed S1 (77.72%). The distortion parameter reduced from 2.41 (S1) to 0.09 (S6), Mo grain contiguity from 0.62 (S1) to 0.42 (S6), and dihedral angle from 71.28 degrees (S1) to 52.45 degrees (S6), illustrating superior densification and nominal geometric instability during sintering. HRTEM revealed a lattice misfit of -25.04% between the Mo matrix (110) and Y2O3 (213) in S6, indicating an incoherent interface. S2 exhibits outstanding hardness (11.78 +/- 0.58 GPa), maximum indentation fracture toughness (4.35 MPa root m), and S6 achieved the lowest pore vol% (6.68%), maximum compressive strength (1083.8 MPa), compressive strain (14.6%), and outstanding product of strength and elongation (PSE) (15.02 GPa %). These enhancements result from the synergistic interaction of regulated silicide precipitation, solid-solution hardening in the Ni-Co matrix, Y2O3 particle strengthening, Hall-Petch grain refinement. Intragranular dispersion strengthening of Y2O3 supersedes other strengthening contributions in S6, thereby achieving a significant strength/ductility trade-off.

Molecularly induced β-phase enhancement and piezoelectric response in all-organic PVDF-F16CuPc composite films

Thu, 01 Jan 2026 00:00:00 GMT

Molecularly induced β-phase enhancement and piezoelectric response in all-organic PVDF-F16CuPc composite films Maity, S.; Pradhan, R. K.; Rout, S.; Pradhan, P.; Abhisek, K.; Patra, B. K. Poly(vinylidene fluoride) (PVDF) is a fluoropolymer that is particularly promising for its electroactive, beta-phase-dependent functional performance. This study elucidates an all-organic composite approach to effectively alter the fraction of polar beta-phase formation in PVDF through the incorporation of an organic small molecule filler, fluorinated copper phthalocyanine (F16CuPc). Our studies using Fourier-transform infrared spectroscopy reveal an 88% enhancement of the polar beta-phase fraction, particularly at an optimal filler concentration of 2 wt% F16CuPc, relative to pristine PVDF. Studies using X-ray diffraction measurements corroborate this phase transformation by showing a preferential stabilization of the beta-phase and suppression of the nonpolar alpha-phase. Piezoresponse force microscopy further confirms the enhancement in nanoscale piezoelectric behavior, demonstrating a 20% increase in the piezoelectric coefficient (d33) upon optimal F16CuPc loading compared to pristine PVDF. This enhancement in beta-phase fraction upon optimal F16CuPc incorporation is mainly driven by highly electronegative fluorine-mediated C-F & centerdot;& centerdot;& centerdot;H-C interactions with the -CH2- dipole, along with electrostatic coupling between the Cu center and the -CF2- dipole. This cross-interaction between the fluorinated filler and fluoropolymer chains promotes conformational reorganization from the trans-gauche to the all-trans configuration, thereby stabilizing beta-phase formation. Our studies reveal that fluorinated metal phthalocyanines act as efficient electroactive beta-phase inducers in fluoropolymers without limiting mechanical compliance or electromechanical integration, thereby extending their applications in next-generation flexible energy harvesters, sensors, and wearable smart electromechanical devices.

Sterically Crowded Hexaterpyridyl-BODIPY: A Multiresponsive Far-Red Emissive AIE-Active Probe for Zn(II) Recognition and Biological Applications

Thu, 01 Jan 2026 00:00:00 GMT

Sterically Crowded Hexaterpyridyl-BODIPY: A Multiresponsive Far-Red Emissive AIE-Active Probe for Zn(II) Recognition and Biological Applications Behera, K. C.; Das, Suprava Sterically crowded aggregation-induced emission (AIE)-active fluorophores provide a powerful approach to constructing multifunctional platforms for sensing and bioimaging. Herein, we describe the rational design and synthesis of a highly crowded hexaterpyridyl-functionalized BODIPY, obtained through hexabromination of the BODIPY core followed by Suzuki-Miyaura coupling with terpyridyl boronic acid derivatives. Spectroscopic characterization confirms the structure, while the installation of six terpyridine units at the alpha/beta positions generates substantial steric crowding, leading to pronounced AIE behavior, far-red emission, cooperative metal-ion coordination, and efficient cellular imaging. Systematic aggregation studies in THF/water mixtures reveal significant fluorescence enhancement correlated with the formation of well-defined spherical nanoaggregates, as confirmed by TEM and SEM analyses. The hexaterpyridyl-BODIPY further exhibits selective Zn(II) recognition with distinct fluorescence responses. Comparative studies with alpha,alpha- and beta,beta-diterpyridyl analogs emphasize the critical role of multiligand steric crowding in tuning aggregation, photophysical properties, and biological performance. Notably, the hexaterpyridyl derivative shows efficient cellular uptake, bright intracellular fluorescence, excellent biocompatibility in normal and cancer cell lines, and enhanced phototoxicity compared to its counterparts. DFT calculations elucidate the structure-property relationships, establishing a versatile molecular design strategy that integrates AIE, metal-ion sensing, and bioimaging within a single BODIPY scaffold.

Effect of Co/Y co-doping concentrations on the tailoring structure and optical properties of ZnO nanostructures

Thu, 01 Jan 2026 00:00:00 GMT

Effect of Co/Y co-doping concentrations on the tailoring structure and optical properties of ZnO nanostructures Sawyasasin, D.; Gajendiran, J.; Kasilingam, T.; Gnanam, S.; Thennarasu, G.; Ramasamy, B.; Jeyanthi, C. E. Undoped and 0.01, 0.03 and 0.05 mol% concentrations of Co/Y co-doped ZnO nanostructures were attempted by solid-state method. In this study, to investigate experimentally how Co/Y co-doping concentrations impact the crystalline structure, surface particle dimension, and optical characteristics of ZnO nanostructures. Hexagonal structure was found in the XRD pattern of undoped ZnO. However, distortion in the hexagonal structure were noticed in the ZnO by introducing co-dopant concentrations (Co/Y) from 0.01 to 0.05 mol% in the XRD pattern. Non-uniform size with agglomerated spherical, coalescence with spherical, porous structure with smaller size spherical, and highly porous with well dispersed spherical particles were noticed for the undoped, 0.01, 0.03 and 0.05 mol% of Co/Y co-doped ZnO in the SEM studies. FT-IR spectra indicate that the Zn-O vibrational shift towards to the lower wavenumber with an increasing Co/Y dopant concentrations in the ZnO. Raman spectra were studied to understand the structural confirmation of the synthesized compounds. The molecular elements, chemical composition, elemental oxidation states and its corresponding binding energy of the synthesized undoped ZnO and Co/Y-doped ZnO were recorded from the EDX/mapping and XPS studies. Optical absorption spectra were evaluated for the synthesized compounds and their optical band gap (Eg = 1.76 to 1.46 eV) results narrowing in the ZnO by increasing co-dopant concentrations from 0.01 to 0.05 mol% when compared to the undoped ZnO (Eg = 3.16 eV). The PL emission bands (UV and visible portion) and colour coordinates (x, y) position values were slightly tuned under the impact of co-dopant concentrations in the synthesized ZnO nanostructures.