Journal of Crystal Growth最新文献

This study focuses on the growth and characterization of crystalline LiNbO₃ (LN) piezoelectric fibers pulled by the Laser Heated Pedestal Growth (LHPG) technique. The electrical properties of the fibers were investigated using an impedance analyzer, which yielded values for resonance frequency, anti-resonance frequency, and phase angle. Subsequently, elastic constants and coupling factor were determined through calculations based on thickness resonance modes. The accuracy of the resonance method was validated through numerical simulations utilizing COMSOL software, demonstrating a close agreement between experimental and simulated results. Additionally, a temperature sensing was conducted, subjecting the fibers to a wide temperature range from 30 °C to 236 °C to assess their sensitivity to temperature variations. The coupling factors of K = 0.37 for LN-1 and K = 0.35 for LN-2 demonstrated efficient performance of the crystalline fibers. Furthermore, the numerical simulations exhibited strong correlation between simulated and experimental data. The sensitivity analysis revealed the potential of LN fibers for temperature sensor applications, exhibiting a sensitivity of −87 Hz.°C⁻¹. These findings underscore the promise of LN piezoelectric fibers in advanced sensing technologies.

In this work, we prepared both chemical and biogenic synthesis of MnSrO₂ (0, 5, 20 ml DLE) nanoparticles using datura metel leaf extraction by co-precipitation method and also prepared Sulfadiazine dye for catalytic activity. The applications and properties of green MnSrO₂ nanoparticles have compared and they were characterized via XRD, SEM, FT-IR, EDX, UV–visible, and PL techniques. These nanoparticles showed an 18–8 nm diameter range, which was arranged in a spherical form combined randomly. The evidence from FTIR spectra showed peaks around 492, 487, 483, 655, 606, and 603 cm⁻¹ for the creation of SrMnO₂ NPs. Antibacterial activity of MnSrO₂ (0, 5, 20 ml DLE) was measured by the well-diffusion method against pathogens, Staphylococcus aureus and Klebsiella pneumonia. The photocatalytic activity of the synthesized metal oxide nanoparticles was investigated by UV–visible spectroscopy for Sulfadiazine dye degradation with bare MnSrO₂ NPs, g-MnSrO₂ NPs [5 ml DLE], and g-MnSrO₂ NPs [20 ml DLE] in presence of visible light irradiation.

This study investigates the controversies about the gas-phase reaction path in the InN MOVPE process. Numerical modeling of the reaction-transport processes in three typical reactors was conducted for main reaction paths. By comparisons of the molar concentrations of the major In-containing species, it was determined that the different approaches of the gas mixing and heating led to three distinct reaction paths. When the non-premixed gas precursors are heated very fast upon entering the reactor, the adduct/amide formation path predominates and the pyrolysis path is negligible (Path 1). When the precursors are mixed at room temperature and heated gradually, the adduct TMIn:NH₃ dissociates back into TMIn, with the pyrolysis path dominating. However, the formation of amides DMInNH₂ intensifies the generation of nanoparticles (Path 2). When mixing occurs at warm temperature and heated fast, both the pyrolysis and adduct paths co-exist, but their effects are different (path 3). In the CCS reactor the dominant reaction path will be Path 1, while in the vertical reactor with a greater height, Path 2 is predominant. In the pre-mixed horizontal reactor, Path 3 is dominant, the pyrolysis path forms a competition with the adduct path near the substrate, and the adduct path dominating at the top of the reactor.

Tb_1-xHo_xVO₄ (THV) magneto-optical crystal with diameter of 27 mm and length of 40 mm was grown by the Czochralski (Cz) technique for the first time. The structural perfection of THV crystal was studied by the high-resolution X-ray diffraction rocking curve measurement, proving the high crystallinity quality of THV. THV shows high transmittance of greater than 75 % within the wavelength range of 665–1600 nm. The Verdet constants of THV at 532, 633 and 1064 nm are 370, 226 and 56 rad·m⁻¹T⁻¹, 40 %–95 % higher than these of commercial TGG crystal. Additionally, THV exhibits lower absorption coefficient (0.05 cm⁻¹), higher magneto-optical figure of merit (175 deg/dB) and extinction ratio (43 dB) at 1064 nm compared with TGG. Evaluation of thermal performance and laser-induced damage threshold of THV were also made to promote the potential application in high-power optical isolators.

150 mm Indium Phosphide wafers are now commercially available with crystal quality comparable to wafer of smaller radius. This may pave the way for scaling up the production of a multitude of photonic devices for Datacoms operating in the 1.30-$1.55\mu m$ infrared range with a gain in wafer surface of factor 4 and a reduction of roughly 50% in die cost. To achieve this goal, it is of utmost importance to prove that both AlGaInAs and InGaAsP quaternary compound semiconductors can be grown by metal–organic chemical vapor deposition (MOCVD) on wafers of larger sizes with both thickness and composition uniformities comparable to those achievable on 75 mm. In this article, we report pioneering production technology developments based on the Planetary Reactor® design. Both reactor and related inlet geometry have been deeply revisited with the introduction of a novel 4-fold injector, which in combination with Cl${}_2$ In-situ chamber clean, prove to enable such transition in wafer size. Sub-nanometric photoluminescence in-wafer uniformities are demonstrated and historic challenges, such as drift in material composition of highly sensitive InGaAsP alloys during a production campaign, are addressed thanks to this unique combination. Uniformity, tunability and reproducibility results are thus presented for two prototypical case scenarios: a highly strained AlGaInAs multiple quantum well (MQW) and a bulk InGaAsP layer with wavelength emission of 1550 nm and 1100 nm respectively to corroborate reactor flexibility in meeting industry requirements for next device generation.

We investigate the local structural distortion induced by

This work highlights the capabilities and limits of X-ray computed tomography in crystallization monitoring through a use case involving paracetamol as the solute, recrystallized from ethanol, methanol, or a mixture of both. The cooling crystallization operation was set up in two different containers, prepared with cotton yarns stretched vertically, acting as linear nucleation sites that immobilize the grown crystals in the recording area. The largest container (10 mL test tubes) allowed the acquisition of a larger number of crystals (up to 300 particles) for a more appropriate bulk analysis. The smallest container (5 mL pipette tips) allowed for a finer resolution of the recorded solid phase at the expense of a reduced recording volume. Crystallization was monitored in terms of the number of individual crystals, their size, and the overall volume, thus leading to the nucleation and growth rates, and solid-phase production rate. The main benefit of X-ray computed tomography is in the 3D analysis of the reconstructed solid phase. The crystal habit of paracetamol form I was predicted using force-field modeling. The predicted habit was in great accordance with the reconstructed solids, confirming the polymorphic form. Furthermore, face-specific growth rates of reconstructed crystals were measured, paving the way for a novel approach to the investigation of crystal-solvent interactions.

AlGaN alloys with very high AlN mole fraction (∼90 %) were grown by plasma-assisted molecular beam epitaxy (PA-MBE) and their alloy properties were investigated by high-resolution X-ray diffraction (HR-XRD) measurements. Growth was carried out employing a series of group III/V ratios and for samples grown under a high group-III regime, phase-segregation in the alloy was evident from a characteristic splitting of the AlGaN (0002) peak in the HR-XRD pattern. With decreasing excess group-III conditions the separation of peak positions continuously reduced, till a single peak was observed. However, for samples where such splitting was absent, spontaneous superlattice peaks were seen at lower incident angles of the XRD patterns indicating the presence of long-range atomic ordering (LRAO). Thus, for AlGaN alloys with extremely high Al content, effects of phase-segregation, or of LRAO were observed, depending on the kinetics of growth. These results on phase-segregation effects are expected to promote the development of high-efficiency deep ultraviolet emitters for skin-safe germicidal action by mitigating the detrimental effect of dislocations and related non-radiative recombination centers through carrier localization processes at potential minima.

We propose a mathematical model of the thin molten silicon film to describe the quasi-steady shape of the inhomogeneous structures on the open melting front of polycrystalline feed rod during the floating zone process for single crystal silicon growth. As a result, precise shapes of the phase boundaries in a three-phase environment on a local scale were determined with the use of moving meshes. The presence of the local structures influences the heat transfer on the open melting front. Consequently, the global phase boundary model can be adjusted, resulting in improved agreement with the experimentally measured interface shape.

The rare-earth palladium silicides host an array of complex magnetic phases. In this paper, we report the growth of large single crystals of the $R_2$PdSi₃ family, (where $R=$ Ce, Nd, Gd, Tb, Ho and Er) by the floating zone technique using a high-power xenon arc-lamp furnace. The crystal boules obtained have been examined for their quality using x-ray diffraction techniques, elemental analysis, and their magnetic properties have been investigated through temperature dependent magnetisation measurements.