Crystal Growth Research Articles (Page 1)

The L12-phase noncollinear antiferromagnet (AFM) Mn3Ir has emerged as a pioneering platform for realizing the zero-field giant anomalous Hall effect (AHE), thereby catalyzing the rapid advancement of antiferromagnetic spintronics. Despite its significant potential, the experimental investigation of the intrinsic magnetic and electronic properties of Mn3Ir has been greatly hindered, primarily due to the formidable challenges associated with the growth of bulk single crystals. Here, the successful growth of stoichiometric Mn3Ir bulk single crystals and characterization on the magnetization and AHE is reported. The (111)-oriented hexagonal Mn3Ir single crystals are successfully obtained using a high-throughput flux method. The smaller AHE is successfully detected. Intriguing results are attributed to the coexistence of A-domain and B-domain antiferromagnetic domains mutually cancelling the AHE response. This work reveals the key details of the intrinsic magnetic properties and AHE in bulk Mn3Ir. This provides a key material for the development of advanced antiferromagnetic spintronic devices.

Abstract Additives play a significant role not only in regulating crystal growth of formamidinium lead iodide (FAPbI3 ) by interacting with precursors but also in determining the phase stability by coordinating to the surface defect. While alkyl ammonium-based additives are widely utilized in a form of alkylammonium halide for the production of high-performing FAPbI3 , the simplest structure of hydroxylammonium (HA) is barely studied. In this study, hydroxylammonium formate (HAHCOO) is incorporated in a precursor solution of FAPbI 3 , coupled with methylammonium chloride. Fourier transform-infrared spectroscopy reveals that lone pairs in HA + and HCOO¯ function as Lewis base and interact with Pb 2+ as Lewis acid in the precursor solution, facilitating the crystal growth and resulting in an increased crystallinity with a large grain size, as evidenced by X-ray diffraction patterns and scanning electron spectroscopy. In the meantime, HA+ and HCOO-, being expelled to grain boundaries during the crystal growth, coordinate to the crystal surface, effectively retarding the α-to-δ phase transition of FAPbI3 .The inclusion of a new additive, HAHCOO, therefore, successfully leads to a slight PCE increase with an improved operational stability under maximum power point tracking.

Covalent organic frameworks (COFs) are crystalline porous polymers constructed from organic building blocks through dynamic covalent bonds. Their tunable structures, permanent porosity, and high chemical stability have enabled a wide range of applications across separation, electronics, and catalysis. While most COFs exist as polycrystalline powders, the development of single-crystal COFs (scCOFs) has unlocked new opportunities for precise structural characterization and property optimization. However, synthesizing scCOFs remains challenging due to the delicate balance between nucleation and crystal growth. This Highlight review surveys six key strategies for scCOF synthesis, including modulator-controlled growth, template- or additive-guided crystallization, interfacial synthesis, linker-directed design, rapid crystallization, and post-synthetic transformation. We further discuss emerging applications of scCOFs in separation, thermal conductivity, catalysts, electronics, and photonics, emphasizing how their long-range order and structural uniformity provide unique advantages. Overall, this review provides a concise, synthesis-focused overview that links structural control in scCOFs to application-relevant performance.

Summary Magma transport in dikes is usually modelled by means of lubrication theory, assuming that magma properties are uniform across the dike. We explore the influence of cross-dike temperature heterogeneity on the dynamics of dike propagation using a quasi-2D model, derived from a full 2D model with an assumption of small width to length ratio. The model couples elastic fracture mechanics with multiphase magma flow, solving the governing equations using a hybrid numerical approach that combines the Displacement Discontinuity Method for elasticity with finite volume discretization for fluid flow and heat transfer. The model includes heat exchange with wall rocks, shear heating and latent heat release. It accounts for non-equilibrium magma crystallization, implementing temperature-dependent crystallization kinetics using an Arrhenius formulation for the relaxation timescale. As a case study, we simulate the ascent of a volatile-rich dacite from a source at 30 km depth. The distribution of temperature, crystallinity, and, thus, viscosity across the dike leads to a plug-like velocity profile with magma stagnation near the walls, substantially different from the parabolic Poiseuille flow assumed in classical lubrication theory. With temperature-dependent crystallization rate, rapid cooling of magma near the dike walls can generate a glassy chilled margin. The adjacent magma has higher crystallinity due to intermediate cooling rates, while the hotter core remains depleted in crystals throughout dike propagation. The dike propagates further and is thinner than predicted by (1D) lubrication theory because the low-viscosity core continues to facilitate vertical transport while the wall zones become progressively more viscous due to cooling and crystallization. The latent heat of crystallization can have a substantial impact in slowing down cooling and prolonging propagation. Other important factors include the characteristic crystal growth time, initial magma temperature and water content. Our quasi-2D approach bridges the gap between oversimplified 1D models and computationally expensive 3D simulations, providing a practical framework for investigating magma transport in silicic dikes.

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This study primarily focuses on utilizing hair strands to achieve the crystallization of lithium carbonate, aiming to investigate the factors influencing crystal formation and volume variation by altering external conditions. To research the reason of crystallization, we have identified the following influencing factors: the direction of crystal growth, the temperature, the evaporation rate, selection of containers. The study ultimately revealed that the container material, solution temperature, evaporation rate, and crystal growth surface all influence crystallization and crystal volume.

Bilayer rhombohedral-stacked transition-metal dichalcogenides (3R-TMDCs) combining high carrier mobility, good electrostatic control, and exotic switchable polarization are emerging as promising semiconducting channels for beyond-silicon electronics. However, despite great efforts, the growth of wafer-scale bilayer 3R-TMDCs single crystals remains difficult due to challenges in the synergistic control of phase structure and grain orientation. Here we design a hole-doping-assisted strategy to synthesize a series of two-inch bilayer 3R-TMDCs single crystals on c-plane sapphire. The introduction of hole dopants (e.g. Hf, V, Nb, Ta) not only increases the interlayer coupling to break the formation energy degeneracy of bilayer 3R-stacked and hexagonal-stacked TMDCs, but also promotes the parallel steps formation on sapphire surfaces to induce the unidirectionally aligned bilayer grain nucleation. The fabricated ferroelectric semiconductor field-effect transistors based on bilayer Hf-MoS2 demonstrate high endurance (more than 105 cycles) and long retention time (exceeding one year) due to the restriction of interlayer charge defect migration/aggregation caused by sliding ferroelectricity. This work proposes a promising strategy for synthesizing wafer-scale ferroelectric semiconductor single crystals, which could promote the further exploration of logic-in-memory chips.

Numerical Study of Temperature and Flow Field Characteristics of CdTe Crystal Growth in Low Gravity Field

Rubrene single crystals, renowned for their record-high hole mobility among organic semiconductors, are widely used in organic electronics where thermal management is essential. This study reports a comprehensive investigation of thermal transport in rubrene along its three primary crystallographic directions, integrating crystal growth, structural characterization, thermal measurements, and molecular dynamics (MD) simulations. Contrary to the well-established 2D nature of charge transport favored in the ab-plane, we observe that the room-temperature thermal conductivity along the interlayer c-axis (Λc = 0.29 W m-1 K-1) exceeds those along the a- and b-axes (Λa = 0.22 W m-1 K-1 and Λb = 0.24 W m-1 K-1), despite strong π-π stacking in the ab-plane. MD simulations reveal the origins of this counterintuitive observation, highlighting the pivotal role of phenyl side groups in facilitating phonon transport along the c-axis. Phonon dispersion and density of states analyses indicate enhanced low-frequency vibrational modes (0-3.7 THz) associated with the side groups. Participation ratio analyses confirm that vibrational modes in both the side groups and backbone have comparable degrees of spatial localization for carrying heat; however, higher phonon group velocities along the c-axis suggest more efficient thermal transport through the phenyl groups. Additionally, the 1/T temperature dependence of thermal conductivities along all three axes suggests crystalline behavior in rubrene as might be expected despite its complex molecular structure. These findings uncover a previously underappreciated role of side group dynamics in phonon transport in molecular crystals and provide new insights into developing thermal management strategies for organic electronic devices.

High-entropy alloys utilize high configurational entropy to stabilize solid solutions, suppress intermetallics, and broaden compositional possibilities. However, achieving homogeneity is challenging due to diffusion disparities, especially with refractory metals. Here, a unique kinetic pathway enabling the synthesis of a single-phase FeCoNiCuNb alloy with 8.39 at.% Nb, is reported. In situ transmission electron microscopy heating experiments demonstrate that Cu and Nb exhibit significantly lower propensity to participate in solid solution formation compared to Fe, Co, and Ni. However, suppressing FeCoNi nuclei growth allows Cu/Nb incorporation into an amorphous phase with Fe, Co, and Ni. The nano-sized FeCoNi nucleus undergoes dynamic transitions between crystalline and amorphous states, which increases the vacancy concentration and facilitates Cu and Nb diffusion, ultimately leading to the formation of FeCoNiCuNb nuclei. These phase transitions also enhance crystal growth during Ostwald ripening, ultimately yielding a stable single-phase polycrystalline FeCoNiCuNb alloy. This study highlights unconventional kinetic strategies that expand phase diagram boundaries by leveraging the high-entropy concept.

Abstract The present study introduces a method for recovering rare earth elements (REEs) by producing a master slag derived from apatite concentrate. The process begins with dephosphorization, which effectively removes over 90% of phosphorus at approximately 2000 ℃ with a holding time of 1 h, thereby significantly increasing the REE concentration within the concentrate. The resulting dephosphorized apatite is subsequently doped with neodymium oxide (Nd 2 O 3 ) and additional compounds, following the CaO–SiO 2 –Nd 2 O 3 phase diagram to target an optimal crystal phase composition. Initial evaluations using synthetic slag helped refine process parameters, including the multistage melting and crushing necessary to retrieve homogeneity. The master slag formation and crystal growth experiments were conducted at 1500–1600 ℃ with holding times ranging from 0 to 60 min, allowing assessment of REE incorporation and crystal growth behavior. Advanced characterization techniques were used to assess slag properties and crystal structure evolution, including DTA–TGA for thermal analysis, ICP-MS for chemical composition, and XRD and SEM–EDS for phase identification. The results confirm the formation of the desired (Ca, Nd) 2 SiO 4 phase within the slag, indicating that the process stabilizes REEs and enhances their concentration in a recoverable phase. This pyrometallurgical route also avoids the production of hazardous liquid waste and enables the simultaneous removal of phosphorus as a gaseous byproduct, offering additional value in sustainable processing. This approach demonstrates a viable pathway for efficient REE extraction from apatite concentrate and shows strong potential for industrial-scale applications in REE recovery and sustainability efforts within the REE supply chain. Graphical Abstract

Today, the engineering of load-bearing bone tissue after severe trauma still relies on metal-based (Ti, CoCrMo alloys or stainless steel) permanent implants. Such artificial scaffolds are typically applied in the body and come into direct contact with the recipient’s cells, whose adhesion affects the patient’s implant acceptance or rejection. The present study aims to create a nano-rough texture by means of ultra-short femtosecond laser (fs)-induced periodicity in the form of laser induced periodic surface structures (LIPSS) on the surface of a stainless steel implant model, which is additionally functionalized via magnetron-sputtering with a thin Cu layer, thus providing the as-created implants with a stable antimicrobial interface. Calcium phosphate (CaP) crystal growth was additionally applied due to the strong bioactive interface bond that CaPs provide to the bone connective tissue, as well as for the strong interface bond they create between the artificial implant and the surrounding bone tissue, thereby stabilizing the implanted structure within the body. The bioactive properties in the as-created antimicrobial hybrid topographical design, achieved through femtosecond laser-induced nanoscale surface structuring and micro-sized CaP crystal growth, have the potential for subsequent practical applications in bone tissue engineering.

Abstract Floating Zone (FZ) silicon crystal growth is essential for high‐power electronics and advanced detection systems. The increasing pressure to scale up the process is challenging due to competing objectives. This study presents a surrogate‐based optimization framework to address Multi‐Objective Optimization (MOO) in FZ growth, considering eight relevant objectives related to productivity, geometrical and growth parameters, and crystal quality. A Deep Ensemble (DE) of Neural Networks serves as a surrogate model, trained on numerical data from a Finite Element Model (FEM). Optimization is carried out using NSGA‐II and NSGA‐III, two variants of Genetic Algorithms that explore trade‐offs between competing objectives and identify high‐performing candidate solutions. Results show that NSGA‐II outperforms NSGA‐III. The optimal solutions correctly capture known trends, such as correlations between crystal size, pulling rate, and thermal stress. A subset of the more intricate solutions is validated through new simulations, showing excellent prediction performance. However, candidate solutions must still be verified by the FEM prior to experimental validation. This framework establishes a foundation for systematic, data‐driven process optimization in FZ growth and can be extended to accelerate improvements in other crystal growth methods.

Abstract Crystal nucleation and growth reshape the mechanical, transport and reactive properties in subsurface porous media. We visualize CO 2 hydrate formation and growth in a microfluidic unsaturated porous medium and uncover novel multiscale dynamics: (a) hydrate crystals preferentially grow in narrower paths and seal low‐permeability regions, despite lower surface energy in wider pathways; (b) explosive crystallization emerges at water‐gas interface when growing crystals touch water pockets, that enables efficient hydrate propagation across disconnected water clusters. These observations are theoretically rationalized. We therefore provide an interpretation of field observations of early stage hydrate enrichment in low permeability zones, and discover a new nucleation propagation mechanism. The mechanism may also emerge in other reactive crystallization in unsaturated media.

In the present work, an attempt is made to carry out a comprehensive theoretical analysis and interpretation of a large body of industrial and laboratory experimental data accumulated in the field of the synthesis of polycrystalline diamond of the carbonado type. The study covers the physicochemical mechanisms of phase transitions in carbon systems, barodiffusion processes, and the role of catalytic components, as well as the kinetic aspects of crystal structure growth. The analysis is based both on experimental data obtained from industrial high-pressure high-temperature (HPHT) installations and on results of targeted laboratory series in which key parameters — pressure, temperature, composition, and dwell time — were varied. Particular attention is paid to correlating industrial and laboratory results with theoretical models of phase equilibrium and growth dynamics, which not only makes it possible to explain the observed phenomena but also to propose approaches for the targeted optimization of the process.

Recent developments in nanomaterial self-assembly demonstrate the capability to create tailored nanostructures by engineering both the binding coordination and specificity of interactions between material subunits. DNA origami frames allow for the design and fabrication of a broad variety of ordered 3D nanoscale architectures through self-assembly, facilitated by frame-to-frame bonds with designable strength and specificity. While the bond design is critical to lattice formation, the assembly process itself is often dependent on a thermal pathway. Highly ordered nanoscale frameworks, assembled from DNA frames, are predominantly crystallized through thermal annealing pathways that typically follow a "slow" cooling approach, with experiments on the time scale of days yielding DNA origami crystals in the range of 1-10 μm. This extended assembly time scale hinders the study of crystal formation pathways, necessitating a deeper understanding of factors governing successful annealing. Lack of insight into time scale also presents a practical limitation for material fabrication. Here, we investigate key factors affecting lattice assembly pathways and demonstrate that precise engineering of assembly conditions greatly reduces assembly times by up to nearly 2 orders of magnitude. We evaluate the nucleation and growth of crystals via optical and electron microscopy, and small-angle X-ray scattering techniques, mapping the time-temperature-transformation of superlattices from the melt through single-crystal optical tracking. The results show that origami frame assembly can be described by classical nucleation and growth theory, which can, in turn, be used to prescribe the growth of the crystals. Lastly, these findings are applied to demonstrate thermal pathway-dependent assembly, forming distinct assemblies based on different thermal annealing profiles.

Organic electronics, featuring π-conjugated small molecules and polymers, have gained significant attention for their potential in flexible, lightweight devices. However, characterization of the ordered, π-stacking domains within these materials using microscopy or X-ray diffraction (XRD) is challenging with complex systems or when crystallography is impractical. This study applied 1D 13C multiple cross-polarization magic angle spinning (multiCP/MAS) and 2D 1H-13C heteronuclear correlation (HetCor) solid-state nuclear magnetic resonance (ssNMR) to systematically characterize π-stacking motifs in a series of N,N'-dialkyl naphthalene diimides (NDIs). These techniques were shown to distinguish between the electronic environments attributed to different π-stacking motifs adopted in these NDIs, such that distinct packing types could be identified by their ssNMR "fingerprints" without requiring growth of XRD-quality crystals. Density functional theory (DFT) supported the experimental data by linking observed motifs with calculated chemical shifts and electronic effects due to stack-bonding interactions. These results lay the foundation for systematic ssNMR characterization of π-stacking domains in diverse organic materials, particularly in complex or blended systems where crystallography is challenging.

The material properties of the high-quality MAPbI3 (FAPbI3) based thin films were optimized using a linear organic (carbon ring) based antisolvent in order to understand the photovoltaic performance of resultant solar cells. We found that the miscible and immiscible antisolvents influenced the nucleation kinetics and crystal growth of the perovskite thin films, thereby determining the photovoltaic responses. The photovoltaic responses of the MAPbI3 and FAPbI3 based solar cells are better when the miscible chlorobenzene and immiscible diethyl ether (DE) are used as the antisolvent, respectively. It is noted that a high power conversion efficiency of 20.8% can be achieved in the FA based mixed perovskite solar cells fabricated with the immiscible DE. The findings from this study should assist in establishing reproducible fabrication processes for various perovskite-related solar cells.

Aluminum nitride (AlN) thin films with (0002) orientation have exceptional piezoelectric and optoelectronic properties for various applications. It remains challenging to grow highly oriented AlN films at low temperature (e.g., below 200 °C) using conventional magnetron sputtering. This study introduces a broad beam ion source-enhanced pulsed DC magnetron sputtering, which enables the growth of (0002) preferentially oriented polycrystalline AlN films at room temperature. The effects of the ion energy and ion flux on surface roughness, crystal orientation, and piezoelectric properties are systematically studied. The film crystallinity is significantly improved under an optimum ion energy; X-ray diffraction shows that the full width at half-maximum (FWHM) of the (0002) peak decreases from 0.7298 to 0.3751°. The average surface roughness is reduced from 2.65 to 0.95 nm. The effective piezoelectric d33eff value increases from 1.69 to 6.06 pm/V. These findings demonstrate that the ion beam facilitates crystal growth under nonthermal equilibrium conditions, offering significant advantages over conventional thin film growth.

Solution-processed organic-inorganic hybrid perovskite films suffer from halide vacancies, uncoordinated lead cations (Pb2+), and excessive iodide at surfaces and grain boundaries, inducing non-radiative recombination, hysteresis, and energy loss. In this study, cyclized polyacrylonitrile (CPAN) was introduced as a multifunctional semiconductor additive into the perovskite, effectively regulating the crystallization and passivating defects of perovskite films. The cyano group (C≡N) and carbonyl groups (C═O) in CPAN effectively suppressed the premature nucleation of lead iodide (PbI2) clusters via their interaction, minimizing the formation of δ-phase perovskite facilitating the formation of larger, more homogeneous grains and thus favoring oriented crystal growth. In the meanwhile, the Pb defects and shallow-level iodine vacancy defects in the film were passivated via strong-coordinating C≡N and moderately coordinating C═O. Furthermore, the CPAN semiconductor with high electron mobility enables well-aligned perovskite energy band structures, facilitating charge extraction. Additionally, the inherent hydrophobic nature of the cyano group (C≡N) created a water-resistant barrier at grain boundaries, significantly inhibiting the penetration of moisture into the perovskite film. Consequently, the power conversion efficiency of the perovskite solar cells (PSCs) increased from 20.56 to 22.38%, while the open-circuit voltage rose from 1.08 to 1.11 V. Notably, after 900 h of storage under ambient conditions without illumination, the initial efficiency of PSCs was retained at 84%, demonstrating a marked enhancement in operational stability. This work presents a novel strategy for controlling the crystal orientation and fabricating high-performance PSCs.