MACHINE LEARNING FOR THERMAL PROPERTIES OF INORGANIC CRYSTALS

Deuterated potassium dihydrogen phosphate (DKDP) crystals with different deuterium contents have a wide range of applications, such as frequency conversion in high power lasers, electro-optic modulation, and Q-switching crystals for Pockels cells. However, there is a lack of systematic research on the effect of deuterium content on the fundamental structure and properties of these DKDP crystals. To this end, in this study, a series of DKDP crystals with different deuterium contents have been grown using the "point-seed" rapid growth method, and the structure and properties of the crystals have been characterized. The results indicate that as the deuterium content increases, the cell parameter along the a(b)-axis direction gradually increases, and the transmittance gradually increases in the infrared range. A small amount of doping (low H or D ratio) reduces the structural integrity of the crystal, and the crystals at intermediate deuterium concentrations have better crystallinity. The thermal properties of the crystals do no change significantly with the variation in the deuterium content. Overall, these findings can serve as a useful reference for boosting the application of DKDP crystals with various deuterium contents.

Accurately and comprehensively representing crystal structures is critical for advancing machine learning in large-scale crystal materials simulations. However, effectively capturing and leveraging the intricate geometric and topological characteristics of crystal structures remains a significant challenge for most existing methods in crystal property prediction. Here, we propose MGT, a multi-view graph transformer that jointly models SE(3) invariant scalar representations and SO(3) equivariant directional representations, enabling the capture of both rotational-translational invariance and rotation-equivariant directional information in crystal structures. A mixture of experts inspired router serves as the key integration mechanism, adaptively weighting these complementary embeddings for each target task. Through multi-task self-supervised pretraining, MGT achieves up to 14% reduction in mean absolute error compared with previous state-of-the-art models on crystal property benchmarks. Comprehensive ablation and interpretability analyses confirm that both the self-supervised pretraining strategy and the mixture of experts inspired router contribute to the overall model performance. In transfer learning scenarios-including crystal catalyst adsorption energy and hybrid perovskite bandgap prediction-MGT achieves performance improvements of up to 58% over existing baselines, demonstrating strong domain-agnostic scalability. Overall, all the results suggest that MGT is an effective and generalizable framework for crystal material property prediction, with significant potential to accelerate the discovery of novel materials.

Phenylephrine oxazolidine is a new prodrug of phenylephrine developed for improving ocular absorption and reducing systemic side effects. In the present study, high- and low-melting phenylephrine oxazolidines (HMP and LMP) were characterized in terms of their stereochemistry and crystal properties. It was found that the molecular configuration of the prodrug in the crystals of either HMP or LMP is identical (5R/2R). The two crystals were shown to have the same IR spectra and X-ray diffraction patterns but different crystal habits, thermal properties, solubilities and intrinsic dissolution rates. Single crystal X-ray structure analysis indicates that crystals of both HMP and LMP are orthorhombic and belong to the P2(1)2(1)2(1) space group with four molecules in a unit cell (a = 20.697 A, b = 7.065 A, and c = 9.304 A). The molecules in the crystal are held together by an intermolecular hydrogen bonding interaction between N(3) and O(13). The different physical properties observed for LMP result from crystal imperfections caused by the presence of trace amounts (often at levels < 0.5%) of an unidentified, structurally related synthetic impurity which can be dispersed in the prodrug. It was observed that both HMP and LMP can sustain thermal and mechanical treatment in the solid state. However, LMP was partially converted to HMP when suspended in certain solvents.

Growth and optical properties of Pr-Mg co-doped LiNbO3 crystal using Bridgman method

Investigation on the impact of xylenol orange dye on the growth and properties of unidirectional grown KDP crystals for photonic applications

Superstructures fabricated from carbohydrates and their derivatives hold an immense promise for the application in diverse fields. However, still many understudied problems challenge us, such as the roles of backbones and side chains during the formation of superstructures, precise control of their morphologies and the application of these unique structures. In this thesis, I first fabricated hydrophobic and superhydrophobic surfaces on wood by using cellulose stearoyl ester (CSE) and glycerol stearoyl ester (GSE). CSE was used for dip-coating (1st layer) the wood, leading to a hydrophobic surface and GSE was used for brush-coating (2nd layer) the wood, leading to a hierarchical superhydrophobic surface. Both hydrophobic and superhydrophobic woods exhibit better anti-fungal properties comparing with non-treated wood. Furthermore, superhydrophobic wood could thoroughly prevent fungal attachment to treated wood, while fungi could still be found inside hydrophobic wood after anti-fungal test. This study shows that both CSE and GSE can form hydrophobicity due to the full substitution of the hydroxyl groups by fatty side chains with 18 carbons. However, the backbone of cellulose and the monomer structure of glycerol result in the formation of membrane by CSE and hierarchical porous structure by GSE, respectively. The most commonly introduced microparticles from carbohydrates all hold conventional filled morphology. Nevertheless, microparticles with chiral and porous morphology are rarely mentioned from carbohydrates. Moreover, the formation of tunable chiral and porous flower-like microparticles using the same materials, especially monosaccharides without applying external stimuli, is still highly understudied. In this study, the formation of chiral, solid, and flower-like microparticles by only using monosaccharide stearoyl esters (MSSEs) were reported for the first time. Chiral, hierarchical superstructures can be obtained from D/L-glucose stearoyl esters (D/L-GlcSE). Chiral ‘left-handed’ (counterclockwise) spiralling morphology can be obtained by D-GlcSE, while ‘right-handed’ (clockwise) morphology can be induced by L-GlcSE. The formation of microparticles with chirality can only be achieved when the α/β ratio of anomer in D/L-GlcSE is 20/80, the concentration is 1 mg/mL from 60°C to 25°C with the aging time of 20 min. The α configuration leads to irregular aggregates, which show worse thermal and crystallization properties, while mature round smooth microparticles with better thermal and crystallization properties are beneficial from β configuration. Axially stretched α configuration improves the difficulties of stacking of MSSE molecules during self-assembly, while better stacking is beneficial from equatorially stretched β configuration. These results can be explained by the displacement during molecular stacking via self-assembly and chirality amplification in the hierarchical superstructures. In addition to the effects of configurations as D/L-configuration and α/β-anomers, the effect of the monosaccharides that contain more structural difference was further studied by using four different D-monosaccharide stearoyl esters (D-MSSEs), which are D-glucose stearoyl esters (D-GlcSE), D-xylose stearoyl esters (D-XylSE), D-galactose stearoyl esters (D-GalSE) and D-mannose stearoyl ester (D-ManSE). Based on the 1H NMR spectra, the α/β ratios at C1 for D-GlcSE, D-XylSE, D-GalSE and D-ManSE are 20/80, 15/85, 27/73 and 35/65, respectively. Besides, they also have diverse number of side chains and the bonds stretching axially/equatorially at C2, C4 and C6. By adjusting the number of side chains and the bonds stretching axially/equatorially, diverse microparticles with solid and porous flower-like morphologies can be adapted. More sidechains lead to lower precipitation temperature, worse thermal and crystallization properties. With the same side chains, axially instead of equatorially stretched bond configuration results in lower precipitation temperature, worse thermal and crystallization properties. This conclusion can be explained by the increased obstacles during the stacking of molecules from more side chains and more bonds stretched axially. Thus, both the number of side chains and the number of bonds stretching axially/equatorially play the pivotal rules when tuning the sugar-based superstructures from solid to chiral and porous morphology. This thesis is a cumulative work including 3 publications. One of them was already published and two are under submission. The background, the objective of the study, results and discussion of these three publications and the conclusion are presented in Sections 1-4.

Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) shows promise for use in bioplastic applications due to its greater flexibility over PLLA. However, further research is needed to improve PLLA-PEG-PLLA's properties with appropriate fillers. This study employed zinc phenylphosphate (PPZn) as a multi-functional filler for PLLA-PEG-PLLA. The effects of PPZn addition on PLLA-PEG-PLLA characteristics, such as crystallization and thermal and mechanical properties, were investigated. There was good phase compatibility between the PPZn and PLLA-PEG-PLLA. The addition of PPZn improved PLLA-PEG-PLLA's crystallization properties, as evidenced by the disappearance of the cold crystallization temperature, an increase in the crystallinity, an increase in the crystallization temperature, and a decrease in the crystallization half-time. The PLLA-PEG-PLLA's thermal stability and heat resistance were enhanced by the addition of PPZn. The PPZn addition also enhanced the mechanical properties of the PLLA-PEG-PLLA, as demonstrated by the rise in ultimate tensile stress and Young's modulus. We can conclude that the PPZn has potential for use as a multi-functional filler for the PLLA-PEG-PLLA composite due to its nucleating-enhancing, thermal-stabilizing, and reinforcing ability.

The microphysical properties of ice crystals are important because they significantly alter the radiative properties and spatiotemporal distributions of clouds, which in turn strongly affect Earth's climate. However, it is challenging to measure key properties of ice crystals, such as mass or morphological features. Here, we present a proof‐of‐concept framework for predicting three‐dimensional (3D) microphysical properties of ice crystals from in situ two‐dimensional (2D) imagery. First, we computationally generated synthetic ice crystals using 3D modeling software along with geometric parameters estimated from the 2021 Ice Cryo‐Encapsulation Balloon (ICEBall) field campaign. Then, we used synthetic crystals to train machine learning (ML) models to predict effective density , effective surface area , and number of bullets from synthetic rosette imagery. On unseen synthetic images, our ML models accurately predicted ice crystal properties. ResNet‐18 performed best, achieving values of 0.99 and 0.98 for and , respectively, and MAE of 0.10 for in single view tasks. Stereo view ResNet‐18 further reduced RMSE by 40% for and and reduced MAE by 0.08 for . This work provides a novel ML‐driven framework for estimating ice microphysical properties from in situ imagery, which will allow for downstream constraints on microphysical parameterizations, such as the mass‐size relationship.

This paper aims to investigate the water absorption of wood flour/polypropylene composites and its effects on dimensional stability and crystallization properties. Wood-plastic composites (WPCs) makes using polydopamine modified wood flour (WF-D), virgin polypropylene, maleic anhydride-grafted polypropylene (MA) and antioxidant, by using hot-pressing moulding. Water absorption (WA), thickness swelling (TS) and failure of flexural properties of the composites have studied for a range of immersion times. It is found that the WA and TS have increased with WF content and immersion time. The water absorption and thickness swelling of WPCs are 0.85% and 0.99%, respectively, after 8 days immersion. With the prolonging of immersion time, the impact strength, flexural strength and flexural modulus of WPCs increase first and then decrease. The impact strength decreases from 3.32 kJ/m2 to 2.94 kJ/m2, the retention rate is 88.55%; the flexural strength and flexural modulus by 68.58 Mpa and 3.92 Gpa, respectively. WPCs crystallization and thermal properties decrease slightly. Microstructures of the composites are examined to understand the mechanisms for the wood-plastic interaction which affects the water absorption and thickness swelling. Our work demonstrates that using polydopamine treatment wood flour for preparing WPCs can be an efficient way to improve the water resistance of WPCs.

The high-temperature piezoelectric crystal Ga3PO7is a versatile functional material widely used in many electromechanical devices. As the Curie temperature of this crystal is as high as 1346 ℃, it can break through the current temperature limitations(1200 ℃) and then be used in extremely high-temperature condition. However, it is very difficult to explore its properties in such a high-temperature environment. Moreover, the relevant theoretical research has not been reported to date. Aiming at this problem, the density function theory combined with quasi harmonic approximation theory is used to investigate the structural, thermal and surface acoustic wave (SAW) properties of Ga3PO7. Firstly, the Gibbs energies of Ga3PO7 crystal with different stains are calculated, and the equilibrium structures of Ga3PO7 crystal at different temperatures (from 0 ℃ to 1200 ℃) are found according to minimal energy principle. Secondly, based on the result above, we optimize Ga3PO7 crystal at different temperatures, and then, the thermal and elastic properties of Ga3PO7 crystal within 0-1200 ℃ are calculated using CASTEP package based on the density functional theory in the generalized gradient approximation. The results show that its lattice constants increase almost linearly as temperature increases while its density decreases. Owing to anisotropy, its lattice constant along the c axis increases much more greatly than along the a axis. The coefficients of thermal expansion along the a and c axis are evaluated to be 1.6710-6 K-1 and 3.5810-6 K-1, respectively, and the volumetric heat capacity is evaluated to be 2.067 J/gK. These values all agree well with the experimental values. Finally, the elastic constants, bulk modulus and SAW properties of Ga3PO7 crystal at different temperatures (from 0 ℃ to 1200 ℃) are calculated. The results show that the bulk modulus can reach 175 GPa, and it changes very little as temperature increases. The fluctuation of elastic constants has slight influences on SAW velocity and the electric-mechanical coupling factor. When the propagation angle is 151, it possesses the stablest SAW properties and the largest electric-mechanical coupling factor which can reach 0.7%. The comprehensive analyses of the thermal, mechanical and SAW properties show that Y-cut Ga3PO7 possesses a greater potential application in high temperature environment.

In this work, the important thermal and kinetic characteristics of crystals are calculated. It was shown that in a state of thermodynamic equilibrium, the thermal properties of crystals are additive, and their value for an entire crystal is calculated by summing the values of thermal properties of the crystal lattice and the properties of the gas of free charge carriers in a crystal. These properties are fully characterized by the appropriate Gibbs potentials. In this work it was also shown that when the electric field E and temperature gradient ΔrT are created in a crystal, and this crystal is placed in the magnetic field with the magnetic inductance vector B, then there the electric charge and heat transport processes begin to exist in the crystal. These processes are described by the generalized electric and heat conduction equations. The tensors and the scalar coefficients in these equations – these are the kinetic properties of the crystals. They describe the nature of their actual properties and they have widespread and pragmatic applications in modern solid-state electronics

The credit for the commencement of inter ionic potential function goes to Born and Lande, one of whose milestone has been their expression into inverse function. Similarly, Born and Mayer also proposed the exponential function of the potential for the repulsive component. However none of them could get the desired success. Subsequently, many more prominent scientists devoted their effort towards these thermal properties of the crystals, among which the endeavour of Jha and Thakur cannot be overlooked, who proposed a new interionic function to observe the properties of ionic crystal under high pressure. During its formulation they included both an inverse power function due to Born and Lande and an exponential function due to to Born and Mayer. Appreciably, Jha and Khan used it for studying the hyped thermal properties of NAI and CsI crystal under high pressure up to 100 Kilo bar. DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7180 BIBECHANA 9 (2013) 88-91

<p indent=0mm>Inorganic crystals surround us and play important roles in our daily life. They form integral parts of our body (e.g., bones), make up all the ground we stand on (ours and any other rocky planet consist of crystals), as well as show significant necessity for industrial processes and technologies (from table salt over concrete to biomedical nanoparticles). Accordingly, the formation mechanisms and properties of crystals have been extensively studied over the past decades. While there are longstanding theories on both the birth of crystals (nucleation) and their subsequent evolution (growth, recrystallization, and/or transformation), a vast amount of evidence suggests that the classical view on crystallization is over-simplified. In addition to the monomer-by-monomer (i.e., atoms, ions, or molecules) addition described in the classical theories, the particle attachment has been recognized as one of the most important pathways to inorganic crystallization. These particles range from the ion pairs to well-crystallized nanoparticles, such as amorphous precursors, magic-size clusters, nanocrystals, etc. The complexity of both the free-energy landscapes and reaction kinetics leads to diverse crystallization pathways. While experimental observations clearly demonstrate the non-classical crystallization pathways, many fundamental aspects remain unknown—Particularly the interaction of solution structure, interfacial forces, and particle motion. Thus, a predictive description linking molecular details to ensemble behavior is lacking. As such description develops, long-term interpretations of inorganic crystal formation should be revisited, which is important to broaden the scope of research across various disciplines such as geological events, biomineralization mechanisms, environmental remediation, and the development of environmentally functional materials. Based on several exemplary spotlights, the current state of the art in non-classical nucleation has been firstly illustrated in our review. Specifically, two non-classical nucleation pathways (i.e., the prenucleation clusters (PNCs) and aggregation pathway) in the current crystal research field are summarized. According to the PNCs pathway, PNCs were considered as the stable solute species with chainlike structural that are precursors to nucleation. Once system reaches the equilibrium ion activity product, the change in the chemistry of linkages within PNCs causes PNCs aggregation, as a consequence of nucleus formation. Another non-classical view (aggregation pathway) pointed that the fine crystalline nuclei first form in solution and then aggregate into a larger and more stable nucleus. Besides, the non-classical oriented attachment (OA) and random attachment (RA) growth pathways are also elucidated. OA and RA growth are similar in involving the self-assembly of primary nanocrystals. However, their main difference is the orientation of the crystal lattice at the grain boundary. For RA growth pathway, there is no particular preference for the attachment whereas for the OA growth, there is a common crystallographic alignment of the attachment to occur, which is allowing for continuous crystallographic planes. Finally, the implications and perspective of non-classical crystallization research are proposed. The aim of this review is to guide the readers through the complex world of crystallizing systems, highlighting a new perspective on non-classical crystallization of inorganic materials, which drives a true renaissance in the field and provides completely new perspectives on the underlying crystallization mechanisms. Additionally, through a mechanism-based understanding, we believed that non-classical crystallization processes can be used to produce innovative structures that retain the dimensional properties of their nanoscale building blocks and create materials with enhanced or novel physical and chemical properties.

For the purpose of the development of ultrahigh molecular weight polyethylene (UHMWPE) fibers with improved tensile properties, the stearic acid (SA) was added to the gel spinning of UHMWPE and acted as a lubricant film. SA addition was intended to be 0.2, 0.4, 0.6, 0.8, and 1.0 wt% of UHMWPE for forming the SA modified UHMWPE fibers. The tensile properties, thermal properties, crystallization properties, and orientation properties of the prepared UHMWPE fibers were systematically investigated. Results show that there is a more significant tensile property for UHMWPE fibers as SA addition is 0.6 wt%. Their tensile strength and tensile modulus reach 32.86 and 1580.89 cN/dtex, which are raised to an extent of 12.0% and 7.7%, respectively, compared with UHMWPE fibers alone. Moreover, the thermal properties, crystallization properties, and orientation properties of the prepared UHMWPE fibers are enhanced observably when the SA addition is 0.6 wt%.

Crystal growth, defects, mechanical, thermal and optical properties of Tb3Sc2Al3O12 magneto-optical crystal