Crystal Growth Mechanism Research Articles

Revealing Atomistic Mechanisms of Gold-Catalyzed Germanium Growth Using Molecular Dynamics Simulations

The vapor-liquid-solid (VLS) method is considered a plausible technique for synthesizing germanium (Ge) nanostructures (e.g. nanowires), which have a broad range of applications due to their unique electronic properties and intrinsic compatibility with silicon. However, crystallization failures and material defects are still frequently observed in VLS processes, with insufficient understanding of their underlying mechanisms due to instrumental limitations for high-resolution in-situ characterizations. Employing an accurate interatomic potential well fitted to the gold-germanium (Au-Ge) phase diagram, we performed molecular dynamics simulations for a systematic investigation on the Au-catalyzed growth process of Ge crystals. From the simulations, relationships were established between the overall Ge growth rate and several main synthesis conditions, including substrate crystallographic orientation, temperature and Ge supersaturation in liquid. The dynamical behaviors of Ge atoms near the liquid-solid growing interface were captured, from which the atom surface stability and exchange rate were estimated for quantifying the atomistic details of the growth. These interface properties were further linked to the surface morphologies, to explain the observed orientation-dependent growing modes. This study sheds new lights into the understanding of the VLS growth mechanisms of Ge crystals, and provides scientific guidelines for designing innovative synthesis methods for similar nanomaterials.

In-situ observations of solidification process of Fe–Al–Ta eutectic alloy

The Fe–Al–Ta eutectic alloy can be formed by eutectic reaction in order to improve the performance of Fe–Al intermetallic compounds, and thus it is important to further clarify the crystal growth mechanism of the Fe–Al–Ta eutectic alloy during solidification. Thus, the melting and solidification temperatures of the Fe–Al–Ta eutectic alloy were determined by differential scanning calorimetry, and the melting and solidification processes of the Fe–Al–Ta eutectic alloy were observed in situ by high-temperature confocal scanning laser microscopy. In addition, the solidified structure of the Fe–Al–Ta eutectic alloy was observed and characterized by scanning electron microscopy and energy dispersive spectroscopy. No other types of phase transitions were found in the Fe–Al–Ta eutectic alloy when the temperature was below 1600 °C. The reinforced phase exhibited a certain orientation after solidification, and the microstructure at the center of the eutectic cell was much more regular than that at the grain boundary. The effect of the cooling rate on the microstructure morphology and the formation mechanism of the irregular divorced eutectic were analyzed.

A bottom-up sonication-assisted synthesis of Zn-BTC MOF nanosheets and the ppb-level acetone detection of their derived ZnO nanosheets

Two-dimensional metal-organic framework nanosheets, as a new member of the two-dimensional family, are attracting increasing research interest in various fields. Herein, a uniform two-dimensional Zn-BTC MOF nanosheet with a thickness of 14 ± 2 nm was synthesized through a simple, efficient, and scalable sonication-assisted bottom-up strategy. The ZnO nanoparticles were used as the Zn source, which can be corroded by H3BTC to form Zn-BTC MOFs under sonication conditions. The morphologies of Zn-BTC MOFs can be modulated from nanosheets to nanorods by changing the content of H3BTC. The crystal growth process is dominated by the thermodynamics of sonication and the stoichiometric ratio of the generated Zn2+ and H3BTC, and the crystal growth mechanism was elaborated by the oriented attachment. Consequently, a chemiresistive gas sensor based on Zn-BTC nanosheet derivatives was fabricated to detect ppb-level acetone. Notably, the experimental detection limit of concentration could reach as low as 100 ppb of acetone due to the functional surface, and the dynamic response linearity reached 99 %. Our work explored a new method of synthesizing two-dimensional Zn-BTC MOF, and the fabricated gas sensing device demonstrated promising potential in gas sensing fields.

人体生物矿化与病态结晶研究进展

<p indent="0mm">In the chemical industry, crystallization is an indispensable unit operation in the separation of the solid-liquid phase and a ubiquitous method to manufacture high-value crystal products. In nature, crystallization resulting in mineralization is a more general phenomenon in organisms. Modern crystallization technology is gradually expanding into the field of biomolecular engineering. However, biomineralization, in which organisms form tissues with biological functions by controlling the precipitation and crystallization of inorganic nanocrystals in organic matrices, is a dynamic, complex process that accompanies the organism throughout its life. But, when abnormal fluctuations occur in the body’s internal chemical environment, pathological mineralization occurs, resulting in the precipitation of inorganic or organic salt crystals which are aberrant crystallizations, a process known as pathological crystallization, causing disease and endangering human health, such as kidney stones, gall stones, malaria, and gout. Compared to the conventional crystallization from solution in chemical engineering which contains crystal nucleation, growth, and aggregation, biomineralization involves many microscopic and macroscopic processes such as ion/molecular assembly into nuclei, crystal-liquid interface mass transfer, and particle aggregation, which strongly couples with the physiological environment. The limitation of conventional crystallization hinders the advancement in understanding the mechanism of the ion/molecular crystallization process and the regulation of complex environments <italic>in vivo</italic>, resulting in the blindness of the screening and development of drugs for the treatment and prevention of such diseases. The study of biomineralization is a frontier research field and their discoveries in pathological crystallization are supposed to promote the development of clinical medicine. Based on the latest research in crystal engineering and crystallography, we take the common pathological mineralization-induced diseases (malaria, kidney stones, atherosclerosis, gall stones, gout) as examples, and select recent representative and significant findings from the perspective of understanding the mechanism of the crystallization process. The mechanisms of inorganic and organic crystal crystallization processes related to these diseases are reviewed, focusing on the molecular mechanisms of crystal nucleation, growth, agglomeration, and adhesion at diverse scales during different stages of the disease. The mechanisms of the crystallization inhibitors (molecules that inhibit the nucleation, growth, aggregation, or agglomeration process of pathological crystal) are also reviewed. The aim of the research on the crystallization and inhibition mechanisms is to build up guidelines for the screening and designing of effective inhibitors. Based on these findings, researchers have successfully designed many potent molecules that hold promise as a novel therapeutic modality. At the end of the review, the key research challenges and future directions in pathological mineralization are given. To meet the practical needs of clinical drug development, pathological mineralization researchers still face many challenges in understanding the mechanism of the crystallization process, screening drugs, establishing platforms and models, and building guidelines for medical advancement. Due to the complex environments <italic>in vivo</italic>, it is difficult to understand the mechanism of crystallization under the interaction between multiple ions/molecules and drugs, where molecular recognition plays important role in specific binding to crystal surface sites. The research on crystallization mechanism aims to screen potential pathological crystal inhibitors. Because considerable studies are based on <italic>in vitro</italic> experiments, more attention should be paid to the building platforms and models that can mimic human environments and use molecular design tools to selectively inhibit the crystallization process, which is believed to be the most potent strategy to find the specific drug for the biomineralization-induced disease. Finally, it is necessary to establish scientific and efficient guidelines for medicine development and provide effective therapeutic and preventive measures for biomineralization-induced diseases.

In situ synthesis of hierarchically-assembled three-dimensional ZnS nanostructures and 3D printed visualization

Nanomaterials have gained enormous interest in improving the performance of energy harvest systems, biomedical devices, and high-strength composites. Many studies were performed fabricating more elaborate and heterogeneous nanostructures then the structures were characterized using TEM tomographic images, upgrading the fabrication technique. Despite the effort, intricate fabrication process, agglomeration characteristic, and non-uniform output were still limited to presenting the 3D panoramic views straightforwardly. Here we suggested in situ synthesis method to prepare complex and hierarchically-assembled nanostructures that consisted of ZnS nanowire core and nanoparticles under Ag2S catalyst. We demonstrated that the vaporized Zn and S were solidified in different shapes of nanostructures with the temperatures solely. To our knowledge, this is the first demonstration of synthesizing heterogeneous nanostructures, consisting of a nanowire from the vapor–liquid–solid and then nanoparticles from the vapor–solid grown mechanism by in situ temperature control. The obtained hierarchically-assembled ZnS nanostructures were characterized by various TEM technologies, verifying the crystal growth mechanism. Lastly, electron tomography and 3D printing enabled the nanoscale structures to visualize with centimeter scales. The 3D printing from randomly fabricated nanomaterials is rarely performed to date. The collaborating work could offer a better opportunity to fabricate advanced and sophisticated nanostructures.

Synthesis and Crystal Growth Mechanism of PST-2: An Aluminosilicate SBS/SBT Zeolite Intergrowth.

The synthesis of PST-2, an aluminosilicate zeolite intergrowth of cage-based, large-pore SBS and SBT topologies, and its intergrowth characteristics are presented. With the Si/Al ratio and crystallization inorganic structure-directing agent in zeolite synthesis mixtures fixed to 8.0 and Cs+ ions, respectively, pure PST-2 is obtained at 120 °C using tetraalkylammonium ions with C/N+ ratios of 5-9 as a charge density mismatch (CDM) organic structure-directing agent (OSDA). More interestingly, the intergrowth ratio between SBS and SBT in PST-2 was found to vary notably not only with the type of CDM OSDA employed but also with the crystallization time, unlike the case of other well-known zeolite intergrowths such as β and MFI/MEL. When tetraethylammonium ions are used as a CDM OSDA at 100 °C in the presence of Cs+, the SBS portion in PST-2 decreases from over 60% to less than 45% with increasing crystallization time from 2.5 to 14 days, suggesting that SBS formation is kinetically more favorable than SBT formation. A thorough characterization of changes in the crystallite dimension of PST-2 with crystallization time, together with those in the chemical composition, allowed us to propose a plausible crystal growth mechanism of this large-pore zeolite intergrowth.

Organic Crystal Growth: Hierarchical Self-Assembly Involving Nonclassical and Classical Steps

Organic crystal nucleation and growth are complex processes that often do not fit into the framework of the existing crystallization theories. We investigated a crystal growth mechanism of an organic dye, perylene diimide, using high-resolution cryogenic transmission electron microscopy and optical spectroscopy. The elucidated mechanism involves classical (monomer attachments) and nonclassical pathways, exhibiting a self-assembly sequence where all steps are interconnected. It starts from the assembly of molecular π-stacks that are initially disordered. They gradually optimize their structure, rigidify, and interact to form crystalline domains. The latter further evolve via the addition of individual molecules, and crystal fusion (via oriented attachment). All the observed supramolecular transformations are connected and follow a clear hierarchy starting from the molecular-scale interactions. The elucidation of the complex pathway of organic crystallization as a series of coordinated supramolecular transformations at multiple scales conceptually advances the understanding of order evolution in organic matter.

A facile approach to improve the methane catalytic performance of LaCoO3 perovskite

Some series of LaCoO3 perovskite metal oxide catalysts were modified with different molar amounts of transition metal Co and Fe, namely LaCoO3-xCo and LaCoO3-yFe. They were applied to methane catalytic combustion, and the effects of Co and Fe doping on the defect structure mechanism of LaCoO3 crystal growth and on the performance of methane catalytic combustion were investigated, respectively. The results showed that hydrothermal addition of Co and Fe could both significantly improved the performance of LaCoO3 catalyst for methane catalytic combustion, with the best catalytic methane activity at x=2 and y=7, the T50 was 425 ℃ and 397 ℃, the T90 was 480 ℃ and 457 ℃, respectively. The performance of the hydrothermally modified catalysts were investigated by characterization techniques such as BET, XRD, SEM and XPS, and it turned out that the excellent activity was mainly due to the significantly enhanced oxygen migration rate and the altered LaCoO3 crystal growth mechanism constructing surface defects during the hydrothermal process. In conclusion, this study provides an efficient and simple method for the synthesis of methane combustion catalysts.

Precipitation phase diffusion kinetics of AZ61 alloy under electrical pulse treatment

In this work, electrical pulse treatment and isothermal heat treatment are employed to tailor the microstructure of the hot-rolled AZ61 alloy. The influence of pulsed current on the crystal growth mechanism and precipitation phase diffusion was investigated. According to the findings, electrical pulses enhance the recrystallization and dissolution of Mg17Al12 precipitate in hot-rolled AZ61 alloy. The recrystallization fraction of EPTed samples is higher than that of the isothermal HTed counterparts. The amount of Mg17Al12 phase is considerably reduced with the increased EPT duration. In contrast, the Mg17Al12 phase fraction in isothermal HTed samples is just slightly changed. The Nernst–Einstein formula indicates that the electrical pulse effectively improves the total diffusion flux in the diffusion system via the coupling of athermal effect and thermal effect.

Study of the growth mechanism of ε-Fe2O3 crystals in Chinese sauce glaze replications

The ferric oxide ε-Fe2O3 has recently been at the center of interest of scientists to understand its physical properties and find efficient methods of synthesis. In parallel to those studies, ε-Fe2O3 was discovered in several ancient brown and black glazed ware produced in different Chinese kilns and time periods. The ubiquity of such phase in ancient glaze in spite of its low stability could be a very interesting indicator to understand both the traditional manufacturing of ancient Chinese glaze and the growth of ε-Fe2O3 in a glassy matrix. This study is based on a set of glazed samples taken out from the kiln at different stages of the firing. Analyses show that ε-Fe2O3 crystals begin to grow at high-temperature at the beginning of the cooling stage. The growth continues through iron ion pumping from the glaze. The iron depletion of the glaze causes the dissolution of iron rich particles, which were formed during the heating and ion diffusion from deeper in the glaze. Al-substitution in ε-Fe2O3 was observed, with a higher Al concentration in more developed crystals. Ti- and Mg-substitutions were also highlighted. A set of equation is proposed to model the formation process.

Effects of accelerating and retarding agents on nucleation and crystal growth of calcium aluminate cement

Although calcium aluminate cement (CAC) has been widely used, one of the critical unclear issues in the field of cement chemistry focuses on certain mechanisms that manipulate the rate of cement hydration. A better understanding of hydration provides critical information such that issues, such as setting time, strength gain, and durability, can be better addressed. This study aimed to initially provide theoretical predictions using experimental information on the dissolution, nucleation, and precipitation mechanisms of ions, induction time (tind), interfacial free energy (γ), and the crystal growth mechanism of CAC containing accelerating and retarding agents in microstructural systems. We also aimed to investigate the early-age performance of CAC, including the setting time of pastes and strength development of mortars. Results found that adding accelerating and retarding agents affected the dissolution, nucleation, and precipitation mechanisms of the CAC hydration. This finally affected the phase formation of the final products.

Study of Nanocrystallization Kinetics in Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 Finemet Type Alloy by Differential Thermal Analysis and Using Different Models

The study of the crystallization processes in the FINEMET type nanocrystalline amorphous alloy is interesting not only from the fundamental aspect of establishing reaction mechanism of crystal nucleation and growth, but also from a technological point of view. The process and nature of crystallization phase constitution of nanocrystalline amorphous alloy of composition Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 prepared by rapid quenching method is investigated in the present study. The amorphous nature of the alloy has been verified by x-ray diffraction (XRD). The differential thermal analysis (DTA) experiments were performed at different continuous heating rates of 10, 20, 30, 40 and 50 0 C/min. Two different crystalline phases are observed. The crystallization temperatures, the volume fraction of crystallizations and enthalpies of two different crystalline phases of the alloy have been determined from DTA traces. The dependence of on-set crystallization temperature (T x ) on the heating rate of different phases have been used for the determination of different crystallization parameters such as, the activation energy of crystallization, the order parameter or Avrami exponent (n). The results of crystallization were discussed on the basis of different models such as Kissinger’s approach and modification for non-isothermal crystallization of Matusita in addition to Kolmogorov, Johnson, Mehl, Avrami and Ozawa.

Ln2Te6O15 (Ln = La, Gd, and Eu) "Anti-Glass" Phase-Assisted Lanthanum-Tellurite Transparent Glass-Ceramics: Eu3+ Emission and Local Site Symmetry Analysis.

The presence of lanthanide-tellurite "anti-glass" nanocrystalline phases not only affects the transparency in glass-ceramics (GCs) but also influences the emission of a dopant ion. Therefore, a methodical understanding of the crystal growth mechanism and local site symmetry of doped luminescent ions when embedded into the precipitated "anti-glass" phase is crucial, which unfolds the practical applications of GCs. Here, we examined the Ln2Te6O15 "anti-glass" nanocrystalline phase growth mechanism and local site symmetry of Eu3+ ions in transparent GCs produced from 80TeO2-10TiO2-(5 - x)La2O3-5Gd2O3-xEu2O3 glasses, where x = 0, 1, 2. A crystallization kinetics study identifies a unique crystal growth mechanism via a constrained nucleation rate. The extent of "anti-glass" phase precipitation and its growth in GCs with respect to heat-treatment duration is demonstrated using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis. Qualitative analysis of XRD confirms the precipitation of both La2Te6O15 and Gd2Te6O15 nanocrystalline phases. Rietveld refinement of powder X-ray diffraction patterns reveals that Eu3+ ions occupy "Gd" sites in Gd2Te6O15 over "La" sites in La2Te6O15. Raman spectroscopy reveals the conversion of TeO3 units to TeO4 units with Eu2O3 addition. This confirms the polymerizing role of Eu2O3 and consequently high crystallization tenacity with increasing Eu2O3 concentration. The measured Eu3+ ion photoluminescence spectra revealed its local site symmetry. Moreover, the present GCs showed adequate thermal cycling stability (∼50% at 423 K) with the highest activation energy of around 0.3 eV and further suggested that the present transparent GCs would be a potential candidate for the fabrication of red-light-emitting diodes (LEDs) or red component phosphor in W-LEDs.

Decoding crystal growth kinetics and structural evolution in supercooled ZnSe by molecular dynamics simulation

Crystallization is a vital process in nature and technology; however, the detailed microscopic mechanisms of crystal nucleation and growth in most materials and the associated theoretical models are still elusive. In this work, we applied molecular dynamics (MD) simulations of spontaneous and seeded growth to infer the crystallization kinetics in supercooled zinc selenide (ZnSe) liquid - used as a model material for which an excellent interatomic potential already exists. ZnSe is a type II-VI semiconductor with a wide bandgap. We determined the growth velocity, υ(T), in a range of temperatures and the structural evolution of both inserted and spontaneously formed nuclei. By determining υ(T) at shallow supercooling using the seeding method and extrapolating towards deep supercooling, where spontaneous nucleation and growth could also be detected by MD, we showed that the most probable growth mechanism in ZnSe and the related theoretical model is the Normal Growth (N-model). We also followed the growth kinetics dependency on the crystallographic orientation. The structure of the final crystal in both approaches, seeded and spontaneous growth, at different supercoolings, is a mixture of the two most stable phases of this material: zinc blende and wurtzite, with predominance of the latter. These results shed light on unknown aspects of crystal growth in this important supercooled liquid and indicate the best theoretical model (N-model), which could be further tested for other materials using the proposed approach - MD simulations of seeded combined with spontaneous crystallization.

In situ observation of riming in mixed-phase clouds using the PHIPS probe

Abstract. Mixed-phase clouds consist of both supercooled liquid water droplets and solid ice crystals. Despite having a significant impact on earth's climate, mixed-phase clouds are poorly understood and not well represented in climate prediction models. One piece of the puzzle is understanding and parameterizing riming of mixed-phase cloud ice crystals, which is one of the main growth mechanisms of ice crystals via the accretion of small, supercooled droplets. Especially the extent of riming on ice crystals smaller than 500 µm is often overlooked in studies – mainly because observations are scarce. Here, we investigated riming in mixed-phase clouds during three airborne campaigns in the Arctic, the Southern Ocean and US east coast. Riming was observed from stereo-microscopic cloud particle images recorded with the Particle Habit Imaging and Polar Scattering (PHIPS) probe. We show that riming is most prevalent at temperatures around −7 ∘C, where, on average, 43 % of the investigated particles in a size range of 100≤D≤700 µm showed evidence of riming. We discuss the occurrence and properties of rimed ice particles and show the correlation of the occurrence and the amount of riming with ambient microphysical parameters. We show that riming fraction increases with ice particle size (&lt;20 % for D≤200 µm, 35 %–40 % for D≥400 µm) and liquid water content (25 % for LWC ≤0.05 g m−3, up to 60 % for LWC = 0.5 g m−3). We investigate the aging of rimed particles and the difference between “normal” and “epitaxial” riming based on a case study.

The influence of crystal growth mechanism based on various sulfur sources on the morphology, component and electrochemical performance of cobalt sulfide as anode material for sodium-ion batteries

Cobalt sulfides (CoS x ) have been paid lots of attention as promising anode candidates for sodium-ion batteries owing to their merits of high theoretical capacity, good electrochemical reversibility and superior thermal stability. However, the preparation of cobalt sulfide with the excellent rate capability and long-term cyclic stability is still a great challenge. Herein, we have prepared cobalt sulfides by one-step solvothermal method using four sulfur sources including sodium thiosulfate, thioacetamide, thiourea and L -Cysteine, respectively. And the mechanism of the bond energies and groups of sulfur source molecules influence the crystal growth process are studied. Moreover, the four cobalt sulfides with different components, morphologies and structures are tested and analyzed as the anode materials for sodium-ion batteries (SIBs). The CoS x using sodium thiosulfate as the sulfur source achieves an excellent cycling performance, which still has a capacity of 690.0 mAh g −1 after 1000 cycles at 2 A g −1 with the retention of 98.1% and an outstanding rate capability of 626.6 mAh g −1 at 5 A g −1 . This superiority may be attributed to its pure component cobalt disulfide (CoS 2 ) with abundant active sites and the unique morphology leading to the high material utilization. Our studies give a clear evidence that sulfur sources play an important role in the crystal growth and constructing high-performance sulfide-based anode materials. • Cobalt sulfides were prepared by solvothermal method with different sulfur sources. • The bond energies and amino group of sulfur sources play an important role in the cobalt sulfide crystal growth mechanism. • The phase components and micromorphologies of cobalt sulfides are influenced by the species of sulfur source. • A high-performance cobalt sulfide is obtained with 626.6 mAh g −1 at 5 A g −1 and 690.0 mAh g −1 after 1000 cycles at 2 A g −1 .

Evolution of MOF single crystals

The mechanism of MOF crystal growth is fundamentally important to their design. In this issue of <i>Chem</i>, Deng and co-workers use an optical method to visualize and track the crystal interface during MOF growth. They derive a reaction kinetic equation for individual crystals of MOFs, thereby offering guidance to MOF synthesis.

Extended sectional quadrature method of moments for crystal growth and nucleation with application to seeded cooling crystallization

• Extended sectional quadrature method of moments for crystal growth and nucleation. • Modified expression of particle number density is established for all sections in the size range. • Interval merging strategy for dealing with the particle flux flow between sections. • A multi-objective optimization algorithm is given to improve model parameter estimation. • Experiments on seeded cooling crystallization of β form L-glutamic acid are given for illustration. In this paper, an extended sectional quadrature method of moments (ESQMOM) is proposed to describe the kinetics of crystal growth and nucleation process, since the existing SQMOM could only be used for crystal aggregation and breakage process. A modified expression of particle number density is established with respect to the boundary nodes of all sections divided in the particle size range, and meanwhile, an interval merging strategy is developed to tackle the problem arising from particle flux flow between sections due to the crystal growth mechanism, such that moments could be predicted more precisely compared to the existing methods. Correspondingly, improved prediction of crystal size distribution (CSD) could be obtained. Based on these estimated moments, a multi-objective optimization algorithm is given to further improve estimation on the kinetic parameters of β form L-glutamic acid (β-LGA) cooling crystallization process. Simulation results on benchmark examples and experiments on seeded cooling crystallization of β-LGA are given to illustrate the effectiveness and merits of the proposed method.

Ice Crystal Growth Mechanism and Structure-activity Relationships of Graphene Oxide/Poly(vinyl alcohol) Aerogels

Ice Crystal Growth Mechanism and Structure-activity Relationships of Graphene Oxide/Poly(vinyl alcohol) Aerogels

A Kinetic Isotope Effect in the Formation of Lanthanide Phosphate Nanocrystals.

Mechanisms of nucleation and growth of crystals are still attracting a great deal of interest, in particular with recent advances in experimental techniques aimed at studying such phenomena. Studies of kinetic isotope effects in various reactions have been useful for elucidating reaction mechanisms, and it is believed that the same may apply for crystal formation kinetics. In this work, we present a kinetic study of the formation of europium-doped terbium phosphate nanocrystals under acidic conditions, including a strong H/D isotope effect. The nanocrystal growth process could be quantitatively followed through monitoring of the europium luminescence intensity. Hence, such lanthanide-based nanocrystals may serve as unique model systems for studying crystal nucleation and growth mechanisms. By combining the luminescence and NMR kinetics data, we conclude that the observed delayed nucleation occurs due to initial formation of pre-nucleation clusters or polymers of the lanthanide and phosphate ions, which undergo a phase transformation to crystal nuclei and further grow by cluster attachment. A scaling behavior observed on comparison of the H2O and D2O-based pre-nucleation and nanocrystal growth kinetics led us to conclude that both pre-nucleation and nanocrystal growth processes are of similar chemical nature.