Molecular Crystal Structure Research Articles

Моделирование водородных связей в молекулярных кристаллах аланина

The study of hydrogen bonds (H-bonds) in biomolecules and living systems is currently one of the most urgent tasks. Changes in the structure of molecular crystals associated with h-bond instability may affect the state of drugs due to uncontrolled polymorphic transformations. Quantum chemical modeling is one of the methods for studying the nature and determining the strength of hydrogen bonds. The interaction energy in molecular alanine crystals and its decomposition were calculated using the Morokuma method (HF/6-31G (PC GAMESS)). The estimation of such energy components as electrostatic, repulsion exchange, polarization, charge transfer, and mixing is given. It is shown that for four model systems, the electrostatic component makes the main contribution to the interaction energy, and the trend of distribution of components  Е by values is the same for them. For the two model systems, there is a significant difference from the others both in the amount of interaction energy and in the distribution of individual energy components. The difference in the interaction energy and in the values of its components indicates a difference in the nature of hydrogen bonds in the studied associate. In four models, the H-bond system is the result of electrostatic interaction (Ees and Ect are respectively equal to -41.0 and -6.84 kcal/mol), and in two-the proportion of covalent interaction is significantly greater (Ees = -7.94 kcal/mol and Ect = -3.92 kcal/mol). The comparison of data allows us to conclude that there are three types of hydrogen bonds in the molecular crystal of alanine that differ from each other in energy characteristics.

Effect of different carboxymethyl cellulose structure parameters on tartrates stability of red wine: viscosity and degree of substitution

ABSTRACT The aim of this study was to investigate the effects of carboxymethyl celluloses (CMC) with different structures (viscosity and degree of substitution) on the stability of tartrates as well as the growth mechanism of potassium bitartrate (KHT) crystals. Six CMC samples with different viscosity and degree of substitution were investigated by GPC, XRD and SEM to establish their molecular weight, crystal structure, particle size and molecular morphology. As oenological additives, they were studied in model solution and in Cabernet Sauvignon wine. The tartaric stability and inhibitory efficiency were evaluated by conductivity via mini-contact test and compared with metatartaric acid and mannoproteins commercial additives. The results suggest that under the same degree of substitution (DS), with an increase of viscosity, CMC molecular chains agglomerate and fold, the solubility in the wine decreases, thus the effect of stabilising tartrate deteriorates. Whilst at the same viscosity, with an increase of DS, the charge density of CMC molecules increases and the binding ability of ions increases and thus the stabilising tartrate has an obvious effect. The negative charge on the −COO− groups extended from CMC polymer tends to repulse the HT− group in solution while attracting K+ ions to produce a concentration gradient at the crystal surface. In addition, CMC complexes with K+ ions in solution, reducing the number of K+ ions able to diffuse to the adsorption layer. Generally, CMC-6 with a higher the degree of substitution and lower viscosity had best application effect on tartrate stabilisation, and from the price and application performance, CMC was found to be superior to commercial additives like metatartaric acid and mannoproteins.

The Structural Details of Aspirin Molecules and Crystals.

We revisit, in the key of structural chemistry, one of the most known and important drugs: the aspirin. Although apparently simple, the factors determining the molecular structure and supramolecular association in crystals are not trivial. We addressed the problem from experimental and theoretical sides, considering issues from X-ray measurements and results of first-principle reconstruction of molecule and lattices by ab initio calculations. Some puzzling problems can give headaches to specialists and intrigue the general public. Thus, the reported polymorphism of aspirin is disputed, a so-called form II being alleged as a result of misinterpretation. At the same time, were presented evidences that the structure of common form I can be disrupted by domains where the regular packing is changed to the pattern of form II. The problems appear even at the level of independent molecule: the most stable conformation computed by various techniques of electronic structure differs from those encountered in crystals. Because the energy difference between the related conformational isomers (computed as most stable vs. the experimental structure) is small, about 1 kcal/mol, comprised in the error bars of used methods, the unresting question is whether the modelling is imprecise, or the supramolecular factors are mutating the conformational preferences. By a detective following of the issue, the intermolecular effects were made responsible for the conformation of the molecule in crystal. The presented problems were gathered from literature results, debates, glued with modelling and analysis redone by ourselves, in order to secure the unitary view of the considered prototypic topic.

Room-temperature-densified H3BO3 microwave dielectric ceramics with ultra-low permittivity and ultra-high Qf value

With the rapid development of mobile communication technology towards 5G and 6G, the microwave dielectric materials with ultra-low permittivity and ultra-high Qf value are urgently demanded. Here, the excellent microwave dielectric properties are reported in H3BO3 ceramics with the molecular crystal structure, whose permittivity (2.84) and density (1.46 g/cm3) are record-low among the low-loss ceramics. The ultra-high Qf value of 146,000 GHz (or the ultra-low dielectric loss of 1.03 × 10−4 at 15 GHz) is also distinguished. Besides, the H3BO3 ceramics can be densified at room temperature by a simple cold sintering process in a short time of 10 min, and this brings many advantages for the integration with microwave circuits. The large molecule volume originating from the molecular crystal structure and the low dielectric polarizabilities of H+ and B3+ are responsible for the ultra-low permittivity of H3BO3 ceramics, and more microwave dielectric materials with ultra-low permittivity and ultra-high Qf value are expected to be explored in the molecular crystals.

Molecular Determinants of Gap Junction Channels Conductance

Gap junction (GJ) channels are formed by two hemichannels, each contributed by the cells taking part in this direct cell-cell communication conduit. These hydrophilic protein channels mediate the transfer of small cytoplasmic molecules between adjacent cells, such as ions and metabolites including second messengers. GJ channels formed by protein monomers, called connexins, are found in most cell types in vertebrates. These ubiquitous yet specific proteins form poorly selective channels with unique properties, and differ in their ability to mediate the transfer of specific molecules. In order to provide insight into molecular determinants of GJ channels conductance, we used molecular crystal structures of Connexin 26 (Cx26, also known as GJB2), PDB ID: 2ZW3, and Connexin 50 (Cx50, also known as GJA8), PDB ID: 6MHY. Molecular dynamics simulations were conducted with an external applied electric field to test intercellular communication via these channels evaluating conductance and selectivity. We compared pore radius and electrostatic profiles of both channels. Also, we compared the values of the conductance estimated by the observed permeation events with those reported in the literature. Our preliminary results suggest that electrostatic profile is a key determinant of ion selectivity and conductance. GJ channels formed by Cx26 show fewer diffusion events than those formed by Cx50, which corresponds with conductance values reported in the literature. Finally, we identified energy barriers for passage of ions through each channel and elucidated the effect of pore structure on energy barriers. This work was supported by the following grants: CONICYT PFCHA/Doctorado 21161628 (to C. Pareja-Barrueto),FONDECYT Regular 1170733 and ICM-MINECON P09-022-F (to D. Gonzalez-Nilo and J. C. Sáez), Anillo ATC71 and FONDECYT Regular 1191329 (to J. C. Sáez).

Genarris 2.0: A random structure generator for molecular crystals

Genarris is an open source Python package for generating random molecular crystal structures with physical constraints for seeding crystal structure prediction algorithms and training machine learning models. Here we present a new version of the code, containing several major improvements. A MPI-based parallelization scheme has been implemented, which facilitates the seamless sequential execution of user-defined workflows. A new method for estimating the unit cell volume based on the single molecule structure has been developed using a machine-learned model trained on experimental structures. A new algorithm has been implemented for generating crystal structures with molecules occupying special Wyckoff positions. A new hierarchical structure check procedure has been developed to detect unphysical close contacts efficiently and accurately. New intermolecular distance settings have been implemented for strong hydrogen bonds. To demonstrate these new features, we study two specific cases: benzene and glycine. Genarris finds the experimental structures of the two polymorphs of benzene and the three polymorphs of glycine. Program summaryProgram Title: Genarris 2.0Program Files doi:http://dx.doi.org/10.17632/grx6mz4pjn.1Licensing provisions: BSD-3 ClauseProgramming language: Python, CExternal routines/libraries: Spglib, ASE, pymatgen, SciPy, mpi4py, scikit-learn, PyTorch, FHI-aims.Nature of problem: Molecular crystal structure prediction.Solution method: Genarris 2.0 generates molecular crystal structures over the 230 space groups, on general and special Wyckoff positions, using physical constraints. Down-sampling of the generated structures may be performed subsequently, based on molecular crystal packing descriptors and an unsupervised machine learning algorithm. Lastly, ab initio structure relaxation may be performed for the final pool. Depending on the user-defined workflow implemented, Genarris may be used to generate diverse molecular crystal datasets to seed evolutionary algorithms or to train machine learning algorithms or as a standalone crystal structure prediction method.Restrictions: For crystal structure generation, the molecule of interest must be semi-rigid with no bond rotational degrees of freedom.Unusual features: Genarris 2.0 is a highly distributed program, making use of MPI for Python parallelization. The user has the ability to design and implement workflows by executing a user-defined list of procedures. Genarris 2.0 offers new features including a machine learning model for estimating the molecular volume in the solid state from the single molecule structure, structure generation in special Wyckoff positions of space groups, hierarchical structure checks including rigorous treatment of non-orthogonal structures, and clustering and down-selection workflows combining first principles simulations with machine learning.

Synthesis of novel carboranyl amidines

The nucleophilic addition reactions of primary and secondary amines to the ethylnitrilium derivative of nido-carborane 10-EtC≡N-7,8-C2B9H11 were studied and a series of new nido-carboranyl amidines 10-EtC(N(R)R’) = HN-7,8-C2B9H11 was prepared. It was found that the nucleophilic addition of primary amines to 10-EtC≡N-7,8-C2B9H11 leads to mixtures of E- and Z-isomers, whereas the addition of secondary amines results in the formation of solely E-isomers. The crystal molecular structures of E-10-EtC(NEt2) = HN-7,8-C2B9H11 and E-10-EtC(NС4H8O) = HN-7,8-C2B9H11 were determined by single crystal X-ray diffraction study.

Morphology Dependent Conductivity and Photoconductivity of Ionic Porphyrin Crystalline Assemblies

The influence of morphology on the photoconductive properties of binary ionic porphyrin assemblies is examined. Micro-to millimeter sized crystalline rods and complex hyperbranched structures, or sheaves, were grown in a controlled manner by combining stoichiometric amounts of meso-tetra(4-aminophenyl)porphyrin, H2[H2TAPP]2+, and meso-tetra(4-sulfonatophenyl)porphyrin, [H4TSPP]2−, metal-free ionic tectons. The H2TAPP:H4TSPP structures were characterized by X-ray diffraction, microscopic methods, optical spectroscopy, conductivity and photoconductivity measurements. The two different H2TAPP:H4TSPP morphologies (rods and sheaves) exhibit similar molecular organization and crystal structure but possess different optoelectronic properties. The rods and sheaves exhibit weak dark conductivity and become more conducting upon illumination into the tetrapyroles Soret and Q bands. The primary charge carriers in these solids upon photoexcitation are electrons and the charge recombination mechanism follows monomolecular kinetics. The sheaves also display some persistent photoconductivity, as well as a long “grow in” period of the photoconductivity upon initial illumination. Both of these actions may be attributed to the presence of defects in the sheaves that form during their growth. The measured photoresponse of the H2TAPP:H4TSPP sheaves is higher than that of the rods. This work provides evidence that optoelectronic properties of organic semiconductors can be effectively tuned by controlling their molecular organization and growth morphology.

A guide to crystal-related and nano- or microparticle-related tissue responses.

Crystals and nano- and microparticles form inside the human body from intrinsic proteins, minerals, or metabolites or enter the body as particulate matter from occupational and environmental sources. Associated tissue injuries and diseases mostly develop from cellular responses to such crystal deposits and include inflammation, cell necrosis, granuloma formation, tissue fibrosis, and stone-related obstruction of excretory organs. But how do crystals and nano- and microparticles trigger these biological processes? Which pathomechanisms are identical across different particle types, sizes, and shapes? In addition, which mechanisms are specific to the atomic or molecular structure of crystals or to specific sizes or shapes? Do specific cellular or molecular mechanisms qualify as target for therapeutic interventions? Here, we provide a guide to approach this diverse and multidisciplinary research domain. We give an overview about the clinical spectrum of crystallopathies, about shared and specific pathomechanisms as a conceptual overview before digging deeper into the specialty field of interest.

Paper] Systematic Investigation of Molecular Structure of Nematic-phase Liquid Crystals for Reduction of Dielectric Loss in Microwave Control Applications

Paper] Systematic Investigation of Molecular Structure of Nematic-phase Liquid Crystals for Reduction of Dielectric Loss in Microwave Control Applications

Effects of the molecular structure on the second-order nonlinear optical properties of stilbazolium derivative single crystals: a review

In this review, we present the relationship between the molecular structure and NLO effects in stilbazolium family single crystals.

Correlation Between Thermal Parameters and Morphology of Cross-Linked Polyethylene

This paper reveals a correlation between morphology and thermal parameters on cross-linked polyethylene (XLPE) cable with different insulating states. Several cables were selected to detect the physicochemical and thermal parameters of the XLPE. The results show that the cable ampacity is determined by the thermal parameters, which are deeply subjected to the morphology of the XLPE. The molecular chain and crystal structure of the XLPE have a close connection with the thermal resistivity. The physicochemical parameters of carbonyl index ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> ) and unsaturated band index ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">UBI</i> ) from Fourier transform infrared spectrum (FTIR) and melting range ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{m}$ </tex-math></inline-formula> ) from differential scanning calorimetry (DSC) can be the indicator to evaluate the diversity of the thermal resistivity. The change of thermal capacity is governed by the crystal distribution of the XLPE. The physicochemical parameters of crystallinity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\chi$ </tex-math></inline-formula> ) and lamellar thickness ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> ) from DSC can be the indicator to evaluate the change of the thermal capacity. In addition, FWHM of the crystallization peak <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta W$ </tex-math></inline-formula> , crystalline rate index ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{0}$ </tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{\mathrm {P}}$ </tex-math></inline-formula> ) and cross-linking degree ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$G$ </tex-math></inline-formula> ) can also be the indicator of the thermal parameters. Finally, this paper proposes a more accurate on-line monitoring method for electric power industry by detecting thermal parameters to diagnose the operating cables in the practical application.

Overcoming the difficulties of predicting conformational polymorph energetics in molecular crystals via correlated wavefunction methods.

Molecular crystal structure prediction is increasingly being applied to study the solid form landscapes of larger, more flexible pharmaceutical molecules. Despite many successes in crystal structure prediction, van der Waals-inclusive density functional theory (DFT) methods exhibit serious failures predicting the polymorph stabilities for a number of systems exhibiting conformational polymorphism, where changes in intramolecular conformation lead to different intermolecular crystal packings. Here, the stabilities of the conformational polymorphs of o-acetamidobenzamide, ROY, and oxalyl dihydrazide are examined in detail. DFT functionals that have previously been very successful in crystal structure prediction perform poorly in all three systems, due primarily to the poor intramolecular conformational energies, but also due to the intermolecular description in oxalyl dihydrazide. In all three cases, a fragment-based dispersion-corrected second-order Møller-Plesset perturbation theory (MP2D) treatment of the crystals overcomes these difficulties and predicts conformational polymorph stabilities in good agreement with experiment. These results highlight the need for methods which go beyond current-generation DFT functionals to make crystal polymorph stability predictions truly reliable.

Alloxan under pressure-squeezing an extremely dense molecular crystal structure.

The crystal structure of the small organic molecule, alloxan, has been explored using high-pressure neutron diffraction; its already efficiently-packed structure provides a 'chemical head-start' on the pressure experiment. At the highest pressure measured, alloxan reaches a density of 2.36 g cm-3-unprecedented for a C, H(D), N, O-containing organic material of appreciable molecular weight. Its crystal structure is stable until ca. 6.5 GPa above which the sample starts to undergo amorphisation.

Synthesis, crystal structure, optical, thermal, mechanical, dielectric and DFT studies of 3, 5-dimethylprazole:1,3,5-benzene tricarboxylic acid molecular adduct crystal

An organic molecular adduct, 3, 5-Dimethylpyrazole:1,3,5-benzene tricarboxylic acid was synthesized and single crystals grown in methanol-acetone (1:1) solvent mixture by slow solvent evaporation solution growth technique at room temperature. The formation of the molecular adduct and crystal structure have been confirmed by single crystal X-ray diffraction studies and NMR spectroscopic techniques. Further, the title crystal belongs to monoclinic crystal system with space group, P21/c and the supramolecular architecture of adduct involves extensive intermolecular O-H…N, N-H…O, O-H…O and C-H…O hydrogen bonding interactions. UV–Vis-NIR spectrum was recorded to find out the lower cut-off wavelength, percentage transmission and optical band gap energy. The fluorescence properties of the title crystal were identified by Photoluminescence spectral studies. Fourier transform infrared (FT-IR) spectral analysis was carried out to confirm the presence of various functional groups in the grown crystal. The quantum chemical analyses were performed by density functional theory (DFT) using B3LYP/6-311G (d,p) basis set. The thermal and mechanical properties of the grown crystal have been investigated by TG/DTA analyses and Vickers micro hardness measurement, respectively. The dielectric behaviours of title single crystal have also been investigated as a function of frequency at different temperatures.

Qualitative as well as quantitative analysis of interactions present in chlorine and bromine substituted aromatic organic crystals: A DFT linked Crystal Explorer study

The effect of noncovalent interactions in shaping a crystal structure is explored qualitatively as well as quantitatively in a DFT linked Crystal Explorer (CE) study of nine different Chlorine and Bromine substituted benzene derivatives. The qualitative approach to analyze interactions is based on Hirshfeld surface that locates electronic charge distribution on the surface, quantitative estimation is obtained by linking DFT computations withCE.In the halogen substituted benzene derivatives considered here, in addition to conventional hydrogen and halogen bonding other interactions such as those between Chlorine–Hydrogen, Bromine–Hydrogen, Bromine-Oxygen have been deciphered. The molecular crystal structure of a variety of halogen substituted aromatic molecules has been rationalized and attributed to specific interactions.

10-NCCH2CH2OCH2CH2C[tbnd]N-7,8-C2B9H11: Synthesis and reactions with various nucleophiles

The 10-(3-cyanoethoxypropionitrilium) derivative of nido-carborane 10-NCCH2CH2OCH2CH2CN-7,8-C2B9H11 (1) was prepared by the reaction of the parent nido-carborane [7,8-C2B9H12]− with bis(2-cyanoethyl) ether in the presence of HgCl2. Hydrolysis of 1 produces the corresponding iminol 10-NCCH2CH2OCH2CH2C(OH)HN-7,8-C2B9H11 (2). Treatment of iminol 2 with triethylamine results in the side chain shortening with formation of the acrylamide derivative 10-CH2CH-C(O)HN-7,8-C2B9H11 (3). Reactions of 1 with alcohols produce two main products – imidates derived from 3-hydroxypropionic acid 10-HOCH2CH2C(OR)HN-7,8-C2B9H11 (R = Me (4), Et (6), iPr (8), Bu (10)) and imidates derived from acrylic acid 10-CH2CH-C(OR)HN-7,8-C2B9H11 (R = Me (5), Et (7), iPr (9), Bu (11)). Reactions of 1 with thiols lead to thioimidates with preserved side chain 10-NCCH2CH2OCH2CH2C(SR)HN-7,8-C2B9H11 (R = Et (12), Bu (13)) as mixtures of E and Z isomers which were separated by column chromatography on silica. The reaction of 1 with diethylamine results in the 3-hydroxypropionic acid derived amidine 10-HOCH2CH2C(NEt2)HN-7,8-C2B9H11 (14). The crystal molecular structure of imidate 10-CH2CH-C(OEt)HN-7,8-C2B9H11 (7) was determined by single crystal X-ray diffraction.

Structure, Optical, and Thermal Properties of 9, 10-Diphenylanthracene Crystals

9,10-diphenylanthracene (DPA) single crystal is a promising scintillator material for fast-neutron detection. Two centimetre-sized polymorph crystals of DPA were grown by melting and solution methods (DPA-Melt and DPA-Solution, respectively), and characterised by single-crystal X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, fluorescence spectroscopy, UV-Vis absorbance spectroscopy, and thermogravimetric/differential scanning calorimetry. The DPA-Melt crystal possessed a P21/n structure, with excitation bands at approximately 331, 348, 367, and 387 nm, and the strongest emission wavelength at approximately 454 nm. On the other hand, the DPA-Solution crystal possessed a C2/c structure, with excitation bands at approximately 335, 353, 372, and 396 nm, and the strongest emission wavelength at approximately 468 nm. The two kinds of DPA crystals have the same molecular formula but different crystal structures, crystal lattice constants, and cell parameters. The theoretical density of the DPA-Solution crystal was 1.239 g/cm3, while that of the DPA-Melt crystal was 1.211 g/cm3. The two types of crystals exhibited the same melting point, but the thermal stability of the DPA-Solution crystal is better than that of the DPA-Melt crystal.

Predictions on High-Power Trivalent Metal Pentazolate Salts.

High-energy-density materials (HEDMs) have been intensively studied for their significance in fundamental sciences and practical applications. Here, using the molecular crystal structure search method based on first-principles calculations, we have predicted a series of metastable energetic trivalent metal pentazolate salts MN15 (M= Al, Ga, Sc, and Y). These compounds have high energy densities, with the highest nitrogen content among the studied nitrides so far. Pentazolate N5- molecules stack up face-to-face and form wave-like patterns in the C2221 and Cc symmetries. The strong covalent bonding and very weak noncovalent interactions with nonbonded overlaps coexist in these ionic-like structures. We find MN15 molecular structures are mechanically stable up to high temperature (∼1000 K) and ambient pressure. More importantly, these trivalent metal pentazolate salts have high detonation pressure (∼80 GPa) and velocity (∼12 km/s). Their detonation pressures exceeding that of TNT and HMX make them good candidates for high-brisance green energetic materials.

Influence of Steric Hindrance on Ferro‐ and Piezoelectric Performance of Poly(vinylidene fluoride)‐Based Ferroelectric Polymers

AbstractPoly(vinylidene fluoride) (PVDF) and copolymers possess excellent ferro‐ and piezoelectric properties, and highly expected to be utilized as sensors in the areas covering the smart wearer, hydrophone, speaker, and medical ultrasonic devices. Besides PVDF in β crystalline phase, the copolymers with trifluoroethylene (TrFE) and tetrafluoroethylene (TFE) are widely investigated both in academia and industry. To illustrate how the steric hindrance between VDF and TrFE/TFE affects the condensed‐state structure and electric properties of the polymers, the electric properties and their dependences on molecular configuration and crystal structures of PVDF, P(VDF‐TrFE), and P(VDF‐TFE) are comparatively investigated. The introduction of same molar contents (20 mol%) of TrFE and TFE monomers into PVDF chain leads to the similar conformation transformation from α (γ ) phase to β phase and similar crystallinity in resultant P(VDF‐TFE) and P(VDF‐TrFE) thanks to the depressed energy of trans conformation and the increased energy barrier between anti‐gauche and trans conformation. That leads to the more preferred β‐phase and ferroelectric domains generated in P(VDF‐TrFE) and P(VDF‐TFE). Both the size of ferroelectric phase, the polarity of the polymer chain, the organization and orientation of the grains along the field are responsible for the excellent piezoelectric field resulted by the varied composition as well.