Mixed Crystals Research Articles

КОЛИЧЕСТВЕННО-КАЧЕСТВЕННАЯ ХАРАКТЕРИСТИКА КРИСТАЛЛИЧЕСКОГО СТРОЕНИЯ РОТОВОЙ ЖИДКОСТИ ЧЕЛОВЕКА С ИСПОЛЬЗОВАНИЕМ ТЕОРИИ ФРАКТАЛОВ. ЧАСТЬ I

The subject of the study is a dried drop of human oral fluid (facies). The goal is to propose a method for quantitative characteristic for the crystalline structure of oral fluid using fractal theory. The task is to create a computer program to calculate the fractal dimension, the area of crystals; length and width of the axes of mixed human saliva crystals. Methodology. To create a computer program for quantitative description of the crystalline structure of the oral fluid facies. The program was created within the framework of cooperation between Omsk State Medical University and Omsk State Technical University. The program, called FracSquare, was developed using the Python programming language version 3.1 and the built-in libraries math, cv2 and plt, which implement algorithms for finding the Minkowski fractal dimension, searching and counting pixels located inside the desired object, as well as an algorithm for finding the hypotenuse. After installing on the computer and launching the program, you need to load a photo of the saliva facies and calculate the fractal dimension and crystal area by pressing the appropriate buttons; the result will appear on the screen in the form of numerical values. Results. The computer program FracSquare allows you to mathematically calculate the fractal dimension, the area of crystals, and also measure the length and width of the branches of human saliva crystals. These digital values provide a quantitative characterization of the crystalline pattern of the saliva facies. Conclusion. The operator receives accurate digital values using a developed computer program, on its basis he can objectively evaluate the microcrystalline pattern of the facies of human saliva in order to identify pathological processes occurring in the body. The indicator of these processes is oral fluid.

Study on the treatment of pyrolysis products from the nitric acid pressure leach liquor of laterite

As the demand for nickel increases sharply, it is of great significance to extract valuable metals such as nickel and cobalt from lateritic nickel ore with huge reserves. Based on the nitric acid pressure leaching process (NAPL) of laterite nickel ore, a clean process of laterite nickel ore treatment is proposed. The process includes concentration and crystallization of pressure leaching solution of nitric acid, pyrolysis of mixed nitrate crystal, alkaline leaching of mixed oxides and acid leaching of alkaline leaching residue. Based on previous work, the high-pressure alkaline leaching process of pyrolysis products (mixed oxides) and atmospheric pressure sulfuric acid leaching process of alkaline leaching residue were studied in this paper. First, the Eh-pH diagrams of metal-water system of common elements in laterite nickel ore was summarized according to the reaction equations of different substances in aqueous solution, and the subsequent wet leaching process was guided. The following alkaline leaching experiments showed that under the conditions of 300 g/L NaOH concentration, 3.5 mL/g liquid–solid ratio, 160 °C leaching temperature and 1 h leaching temperature, 85.0 % of aluminum in mixed oxides can be leached and scandium can be enriched by 13 times. Finally, under the conditions of initial sulfuric acid concentration of 4 M, temperature of 100 °C, leaching time of 30 min and liquid–solid ratio of 4 mL/g, the leaching rates of Al, Ni, Mg, Co, Mn, Fe and Sc in alkaline leaching residue were 92.0 %, 97.5 %, 98.4 %, 92.3 %, 62.7 % and 68, respectively. A new procedure for treating lateritic nickel ore is proposed, allowing for thorough recovery and usage of important components. The technique is green and environmentally benign, resulting in closed-loop production of laterite-nickel ore treatment with numerous application possibilities.

The Rise in Tubular pH during Hypercalciuria Exacerbates Calcium Stone Formation.

In calcium nephrolithiasis (CaNL), most calcium kidney stones are identified as calcium oxalate (CaOx) with variable amounts of calcium phosphate (CaP), where CaP is found as the core component. The nucleation of CaP could be the first step of CaP+CaOx (mixed) stone formation. High urinary supersaturation of CaP due to hypercalciuria and an elevated urine pH have been described as the two main factors in the nucleation of CaP crystals. Our previous in vivo findings (in mice) show that transient receptor potential canonical type 3 (TRPC3)-mediated Ca2+ entry triggers a transepithelial Ca2+ flux to regulate proximal tubular (PT) luminal [Ca2+], and TRPC3-knockout (KO; -/-) mice exhibited moderate hypercalciuria and microcrystal formation at the loop of Henle (LOH). Therefore, we utilized TRPC3 KO mice and exposed them to both hypercalciuric [2% calcium gluconate (CaG) treatment] and alkalineuric conditions [0.08% acetazolamide (ACZ) treatment] to generate a CaNL phenotype. Our results revealed a significant CaP and mixed crystal formation in those treated KO mice (KOT) compared to their WT counterparts (WTT). Importantly, prolonged exposure to CaG and ACZ resulted in a further increase in crystal size for both treated groups (WTT and KOT), but the KOT mice crystal sizes were markedly larger. Moreover, kidney tissue sections of the KOT mice displayed a greater CaP and mixed microcrystal formation than the kidney sections of the WTT group, specifically in the outer and inner medullary and calyceal region; thus, a higher degree of calcifications and mixed calcium lithiasis in the kidneys of the KOT group was displayed. In our effort to find the Ca2+ signaling pathophysiology of PT cells, we found that PT cells from both treated groups (WTT and KOT) elicited a larger Ca2+ entry compared to the WT counterparts because of significant inhibition by the store-operated Ca2+ entry (SOCE) inhibitor, Pyr6. In the presence of both SOCE (Pyr6) and ROCE (receptor-operated Ca2+ entry) inhibitors (Pyr10), Ca2+ entry by WTT cells was moderately inhibited, suggesting that the Ca2+ and pH levels exerted sensitivity changes in response to ROCE and SOCE. An assessment of the gene expression profiles in the PT cells of WTT and KOT mice revealed a safeguarding effect of TRPC3 against detrimental processes (calcification, fibrosis, inflammation, and apoptosis) in the presence of higher pH and hypercalciuric conditions in mice. Together, these findings show that compromise in both the ROCE and SOCE mechanisms in the absence of TRPC3 under hypercalciuric plus higher tubular pH conditions results in higher CaP and mixed crystal formation and that TRPC3 is protective against those adverse effects.

Preparation and microstructure of Cu-Al2O3 composites by a novel supercritical water liquid phase in-situ reaction method

The high solubility, reactivity and solubility of supercritical water provide a new way for the preparation of advanced metal matrix composites. In this paper, Cu-Al2O3 composites are prepared by supercritical water liquid phase in situ reaction (SW-LIR). In this method, the Cu-Al atomized alloy powder are used as raw material, deionized water as reaction medium, H2O2 as liquid phase oxygen source, and the Cu-Al2O3 composite powder are prepared at 380 ℃ and 22.1 MPa for 10 min. The Cu-Al2O3 composite block is prepared by spark plasma sintering (SPS). The results show that Al2O3 has an average size of 41.8 nm and mainly exists in the form of mixed crystals. The interface with the matrix is coherent or semi-coherent. With the increase of Al2O3 content, the mechanical properties of the composites are obviously improved. When the Al2O3 content is 1.12 wt%, the microhardness is as high as 164.52 HV and the tensile strength is 441 MPA, while still maintaining a high electrical conductivity (75 %IACS). At the same time, it shows quite excellent high temperature performance. It can still retain the characteristics of high strength at 1000℃, which solves the shortcomings of high thermal conductivity but low strength of pure copper. Compared with the traditional method, SW-LIR method has the characteristics of low reaction temperature, fast reaction speed and green environmental protection.

Ordered phases in ternary wurtzite group-III nitrides: A first-principles study

A first-principles-based lattice model is applied to investigate the ordered phases of mixed group-III nitride ternary alloys. The model surveys the atomistic configurations with the lowest formation enthalpy for a wide range of compositions. We found novel ordered phases in wurtzite structures having specific compositions of three- and four-sevenths molar fractions of group-III cations. The configurations of group–III atoms on cation sites in those phases consist of a characteristic fragment of the ordered phases of one-third and one-half ordered phases that were previously reported. The simulation results indicate that group-III cations in ternary nitrides follow spatial positioning “atomistic distancing rules” that can be described by the pairwise interaction energy of group-III cations to realize the stabilities of the ordered structures. To minimize the formation enthalpy of a mixed crystal, the minor B, Al, Ga, and In atoms on cation sites remain neither too close to nor too distant from each other, allowing those ordered phases to be realized.

Local ligand distortion broadens the near-infrared emission of Kramers neodymium ions by partially replacing La with Gd in NaLa(WO4)2 crystals

A series of x at% Gd3+: NaLa0.975-xNd0.025Gdx(WO4)2 mixed crystals were grown by means of the Czochralski method. The mixed crystals are formed by replacing La3+ ions in a part of NaLa(WO4)2 host with Gd3+ ions, and the first principle proves that doping Gd3+ improves the disorder and activity of NaLa(WO4)2 crystals. For NaLa0.915Nd0.025Gd0.06(WO4)2 mixed crystals, the physical and thermal properties were characterized by using structural refinement, infrared spectrum and thermal expansion coefficient. The results show that the grown crystal belongs to the space group Ι41/a with high phase purity, and has excellent thermal stability and anisotropy. Compared with NaLa0.975Nd0.025(WO4)2 single crystal, with the introduction of Gd3+, the local distortion electric field is generated, the original degenerate state of Nd3+ is changed, and the intensity of Nd3+ emission peak at 1062 nm and 1332 nm is increased by 2.34 and 1.89 times, respectively. The spectral bands of absorption and emission spectra are broadened by about 4 nm. The broadening of spectral band is discussed in detail by using the theory of uniform and non-uniform broadening. For uniform band broadening, the density functional theory is used to calculate the phonon state density and vibration mode of the mixed crystal, and the Raman spectrum proves that the spectral band broadening is caused by the introduction of Gd3+, which generates a new vibrational level and increases the electron-phonon coupling, thus widening the band. For the non-uniform broadening of the spectral band, combined with the variation of the dipole moment caused by the electric field distortion, the spectral band is proved. Finally, the J-O theoretical parameters, absorption and emission cross-sections of mixed crystals are calculated. The experimental results show that NaLa0.915Nd0.025Gd0.06(WO4)2 mixed crystals are excellent laser crystal materials, which can improve the utilization of laser pump light and improve the efficiency of laser.

Quantitative analysis of element substitution in mixed-vanadate LuxGd1-xVO4 single crystals at the atomic scale

In mixed crystals, two or more elements exhibit comparable properties and can be substituted freely. As a special type of “substitutional doping,” the properties of materials can be adjusted by altering the doping ratio of elements. Mixed-vanadate crystal LuxGd1-xVO4 is a promising laser host material with excellent chemical stability, mechanical property and thermal conductivity. The substitutional doping ratio of the two rare-earth elements determines the value of x. The thermal, optical, and laser properties of the material vary with x. However, the two types of atoms showing little difference in the same location in mixed crystals form substitutional solid solutions with alike atomic radii as well as electronic structures. Therefore, distinguishing comparable elements in mixed crystals at the atomic scale and quantitatively analyzing the doping ratio in mixed crystals are challenging. In this study, combining high-angle annular dark field (HAADF) and electron energy-loss spectroscopy (EELS), we accurately characterize the atomic structure of mixed-vanadate single crystal LuxGd1-xVO4 along the [111] orientation as well as the distribution of two rare-earth elements at the atomic scale. The ratio of Lu and Gd and the doping rules in the crystals are quantitatively analyzed. In addition, combined with the energy dispersive X-ray spectroscopy (EDS) results of the [100] crystal orientation, a uniform random distribution of Lu and Gd in the LuxGd1-xVO4 crystal is confirmed. This study provides a new means of understanding mixed-crystal structures and solves the problem of quantitative analysis of elemental doping in materials at the atomic scale, thus laying the foundation for exploring the relationships among composition, structure, and function in materials.

Approach to the "Missing" Diarylsilylene: Formation, Characterization, and Intramolecular C-H Bond Activation of Blue Diarylsilylenes with Bulky Rind Groups.

The treatment of the bulky Rind-based dibromosilanes, (Rind)2SiBr2 (2) [Rind = 1,1,7,7-tetra-R1-3,3,5,5-tetra-R2-s-hydrindacen-4-yl: EMind (a: R1 = Et, R2 = Me) and Eind (b: R1 = R2 = Et)], with two equivalents of tBuLi in Et2O at low temperatures resulted in the formation of blue solutions derived from the diarylsilylenes, (Rind)2Si: (3). Upon warming the solutions above -20 °C, the blue color gradually faded, accompanying the decomposition of 3 and yielding cyclic hydrosilanes (4) via intramolecular C-H bond insertion at the Si(II) center. The molecular structures of the bulky Eind-based 3b and 4b were confirmed by X-ray crystallography. Thus, at -20 °C, blue crystals were formed (Crystal-A), which were identified as mixed crystals of 3b and 4b. Additionally, colorless crystals of 4b as a singular component were isolated (Crystal-B), whose structure was also determined by an X-ray diffraction analysis. Although the isolation of 3 was difficult due to their thermally labile nature, their structural characteristics and electronic properties were discussed based on the experimental findings complemented by computational results. We also examined the hydrolysis of 3b to afford the silanol, (Eind)2SiH(OH) (5b).

Reaction amplification with a gain: Triplet exciton–mediated quantum chain using mixed crystals with a tailor-made triplet sensitizer

Photochemical valence bond isomerization of a crystalline Dewar benzene (DB) diacid monoanion salt with an acetophenone-linked piperazinium cation that serves as an intramolecular triplet energy sensitizer (DB-AcPh-Pz) exhibits a quantum chain reaction with as many as 450 product molecules per photon absorbed (Φ ≈ 450). By contrast, isomorphous crystals of the DB diacid monosalt of an ethylbenzene-linked piperazinium (DB-EtPh-Pz) lacking a triplet sensitizer showed a less impressive quantum yield of ca. Φ ≈ 22. To establish the critical importance of a triplet excited state carrier in the adiabatic photochemical reaction we prepared mixed crystals with DB-AcPh-Pz as a dilute triplet sensitizer guest in crystals of DB-EtPh-Pz. As expected from their high structural similarities, solid solutions were easily formed with the triplet sensitizer salt in the range of 0.1 to 10%. Experiments carried out under conditions where light is absorbed by the triplet sensitizer-linked DB-AcPh-Pz can be used to initiate a triplet state adiabatic reaction from 3DB-AcPh-Pz to 3HB*-AcPh-Pz, which can serve as a chain carrier and transfer energy to an unreacted DB-EtPh-Pz where exciton delocalization in the crystalline solid solution can help carry out an efficient energy transfer and enable a quantum chain employing the photoproduct as a triplet chain carrier. Excitation of mixed crystals with as little as 0.1% triplet sensitizer resulted in an extraordinarily high quantum yield Φ ≈ 517.

Optimizing Thermoelectric Performance of Hybrid Crystals Bi2O2Se1-xTex in the Bi2O2X System.

In addressing the global need for sustainable energy conversion, this study presents a breakthrough in thermoelectric materials research by optimizing the Bi2O2Se1-xTex system in the Bi2O2Se/Bi2O2Te pseudobinary series. Leveraging the principles of innovative transport mechanisms and defect engineering, we introduce tellurium (Te) doping into Bi2O2Se to enhance its thermoelectric properties synergistically. With the help of various advanced characterization tools such as XRD, SEM, TEM, XPS, FTIR, TGA, LFA, and DSC, combined with relevant resistance and density measurement techniques, we conducted an in-depth exploration of the complex interactions between various factors within thermoelectric materials. We recognize that the balance and synergy of these factors in the thermoelectric conversion process are crucial to achieving efficient energy conversion. Through systematic research, we are committed to revealing the mechanisms of these interactions and providing a solid scientific foundation for the optimal design and performance enhancement of thermoelectric materials. Finally, the advantage coefficient (ZT) of the thermoelectric material has been significantly improved. The crystallographic analysis confirms the formation of a continuous series of mixed crystals with varying Te concentrations, adhering to Vegard's law and exhibiting significant improvements in electrical and thermal conductivities. The Bi2O2Se1-xTex crystals, particularly the Bi2O2Se0.6Te0.4 composition, demonstrate a peak ZT of 0.86 at 373 K. This achievement aligns with recent advancements in defect-enabled mechanisms and band convergence and sets a new standard for high-performance thermoelectrics. The study's findings contribute significantly to the ongoing quest for efficient thermal-to-electrical energy conversion, offering a promising avenue for future sustainable energy technologies.

Preliminary study of the superlubricity behavior of ZrO2/PI lubricating with liquid crystal

This article has investigated the friction behavior of a tribological system composed of a liquid crystal and polyimide. In this tribological system, ZrO2 and PMDA-ODA polyimide film used as a friction pair, and the liquid crystals used as lubricants including the single liquid crystal 5CB and the mixed liquid crystals LCs1 (5CB-5CEPO2), LCs2 (5CB-3CEPC3), LCs3 (5CB-2CEPPN), and conducted friction coefficient comparison experiments with n-hexadecane. It was found that the average friction coefficient of the LCs3 (90% 5CB + 10% 2CEPPN) is the smallest at the load of 5 N and the velocity of 200 rpm, which is 0.00113. Load and velocity selection experiments were investigated of LCs3, as well as polyimide film’s surface analysis including scanning electron microscope, white-light interference, polarization microscope, and surface-enhanced Raman scattering spectra. The results of the surface analysis indicated that some groups in the main chain and branch chain of the polyimide molecules are oriented parallel to the polyimide surface after rubbing.

Effect of salt types on salt precipitation and water transport in saline sandy soil

AbstractSalt precipitation on the surface of porous media significantly affects water transport processes. Most studies on salt precipitation mainly focused on single salts, but in nature, salt precipitation usually occurs as mixtures. Consequently, information on the crystallization of salt mixtures and its effect on water transport remains scarce. This study investigated the precipitation of mixtures (the mass ratios of NaCl:Na2SO4 were 3:7, 5:5, and 7:3, respectively) of NaCl (typical efflorescence) and Na2SO4 (typical subflorescence) in the initially saturated sandy soil columns and its effect on evaporation and compared it with the cases of the two salts individually. The results showed that salt mixtures exhibited a mixed pattern of crystals including both efflorescence and subflorescence, and the efflorescence showed granular aggregation, unlike the mono‐salts. The crystallization coverage of the salt mixtures was smaller than that of NaCl mono‐salt; high (7:3) and low (5:5 and 3:7) proportions of NaCl led to larger and smaller crystallization coverage than that of Na2SO4 mono‐salt, respectively. While the salt mixtures had less crystallization coverage than the mono‐salts, they showed lower evaporation because the salt mixtures formed a denser crystallization structure of efflorescence‐subflorescence‐soil layer, this crystallization structure exhibited greater inhibition of water vapour diffusion, thus reducing evaporation. In addition, the crystallization of the salt mixtures with higher NaCl proportion afforded greater resistance of evaporation. The mixed crystallization pattern formed by the salt mixtures significantly enhances the crystallization resistance to evaporation.

Experimental demonstration on 400 nm-scale bandwidth optical parametric chirped-pulse amplification based on mixed cascaded crystals.

We present an optical parametric chirped-pulse amplification (OPCPA) based on mixed cascaded crystals, taking advantage of the unique parametric phase-matching of lithium triborate (LiB3O5, LBO) and yttrium calcium oxyborate ((YCa4O(BO3)3, YCOB) crystals. The OPCPA properties of LBO at 880 nm and YCOB at 750 nm are studied respectively. After amplification by two LBO and two YCOB crystals, a total signal gain of 108 and spectral bandwidth close to 400 nm is obtained. After accurate dispersion compensation with a grating-pair compressor and chirped mirror compensator, a pulse duration of 9.4 fs is obtained by a SHG-frequency-resolved optical grating (FROG). This approach will be of great significance in high energy amplifier for high peak power few-cycle laser sources.

Q-switched laser operation of mixed vanadate crystal Nd:LuYLaVO4

The laser properties of Nd:LuYLaVO4 mixed crystal have been investigated in this study. To the best of our knowledge, the operations of passively and actively Q-switched lasers are realized by employing the Nd:LuYLaVO4 crystal as the gain medium, for the first time. In the passively Q-switched laser experiment, a pulse duration of 1.53 ns and a single pulse energy of 12.37 μJ are obtained, and the counterparts of the actively Q-switched laser experiment are 24.80 ns and 85 μJ, respectively. The results indicate the great potentials of Nd:LuYLaVO4 mixed crystals in pulsed laser applications.

Efficient energy transfer between Er and Dy achieved in perfluoride glass ceramics by tailoring crystallization characteristics

Perfluoride glass ceramics (FGCs) with SrF2/CaF2 mixed crystals were prepared using a concurrent rapid-quenching-crystallization process. The FGCs contained dense, homogeneous, round crystals of sizes less than 1 μm with high transmittance (exceeding 80 % at 3–8 μm) and low phonon energy (508 cm−1). The fluorescence properties of the FGCs doped with Er and Dy were investigated. The energy transfer efficiency between Er and Dy reached 93.81 % and 98.13 %, corresponding to Er: 4I11/2 to Dy: 6H5/2 and Er: 4I13/2 to Dy: 6H11/2, respectively. This enhancement is attributed to the enrichment of rare-earth ions in the crystals induced by phase-separation and low phonon energy of the host material, FGC. Moreover, the average lifetime of Er: 4I11/2 in FGC reached 10.13 ms, which is the highest reported value for glass ceramics to our knowledge. This study enriches the research theory of FGC and provides guidance for expanding the properties of materials for mid-infrared photonics.

Low Thermal Conductivity and High Thermoelectric Performance of Nb-Doped Quarternary Mixed Crystal Nb0.05W0.95-xMox(Se1-xSx)2.

Transition-metal dichalcogenide WSe2 has attracted increasing interest due to its large thermopower (S), low-cost, and environment-friendly constituents. However, its thermoelectric figure of merit, ZT, of WSe2 is limited due to its large lattice thermal conductivity (κL) and low electrical conductivity. In view of WSe2 and MoS2 having the same crystal structure, here we designed and prepared Nb-doped quarternary mixed crystal (MC) Nb0.05W0.95-xMox(Se1-xSx)2 (0 ≤ x ≤ 0.095). The results indicate that the κL of the MC can reach as low as 0.12 W m K-1 at 850 K, being 93% smaller than that of WSe2. Our analysis reveals that its low κL originates chiefly from intense scattering of both high-frequency phonons from point defects (mainly alloying elements) and mid/low-frequency phonons from MoS2 inclusions residual within MC. In addition, the alloying of WSe2 with MoS2 causes a 5-fold increase in cation vacancies (VW‴'), leading to a large increase in hole concentration and electrical conductivity, which gives rise to a ∼7.5 times increase in power factor (reaching 4.2 μ W cm-1 K-2 at 850 K). As a result, a record high ZTmax = 0.63 is achieved at 850 K for the MC sample with x = 0.076, which is 20 times larger than that of WSe2, demonstrating that MC Nb0.05W0.95-xMox(Se1-xSx)2 is a promising thermoelectric material.

Optical Absorption Properties in Pentacene/Tetracene Solid Solutions.

Modifying the optical and electronic properties of crystalline organic thin films is of great interest for improving the performance of modern organic semiconductor devices. Therein, the statistical mixing of molecules to form a solid solution provides an opportunity to fine-tune optical and electronic properties. Unfortunately, the diversity of intermolecular interactions renders mixed organic crystals highly complex, and a holistic picture is still lacking. Here, we report a study of the optical absorption properties in solid solutions of pentacene and tetracene, two prototypical organic semiconductors. In the mixtures, the optical properties can be continuously modified by statistical mixing at the molecular level. Comparison with time-dependent density functional theory calculations on occupationally disordered clusters unravels the electronic origin of the low energy optical transitions. The disorder partially relaxes the selection rules, leading to additional optical transitions that manifest as optical broadening. Furthermore, the contribution of diabatic charge-transfer states is modified in the mixtures, reducing the observed splitting in the 0-0 vibronic transition. Additional comparisons with other blended systems generalize our results and indicate that changes in the polarizability of the molecular environment in organic thin-film blends induce shifts in the absorption spectrum.

General stability analysis of the steady states in the continuous mixed-suspension crystallizer

We report new mathematical tools to analyze the continuous mixed suspension crystallizer, which is widely used across industries, as it enables the manufacture of crystalline materials under well-controlled conditions. In particular, we develop a general framework to assess the stability of its steady states based on the birth rate ν, which denotes how many secondary nuclei a crystal forms throughout its lifetime in the crystallizer. A stable steady state is defined as follows: (i) ν(css)=1, the birth rate at the steady state concentration must equal one. (ii) dν/dc>0, the derivative of the birth rate must be positive. (iii) c0>css, the steady state must maintain a positive suspension density. These conditions enable the steady state analysis under general conditions, i.e., for arbitrary rate expressions of crystal growth and secondary nucleation, for size-dependent crystal growth and withdrawal, and for growth rate dispersion.The application of this theory to compounds with multiple solid forms, i.e., polymorphic and chiral compounds, is of particular interest. The analysis of the polymorphic steady states agrees with and generalizes the existing approaches. Concerning chiral compounds, enantiopure steady states are found to be unstable with respect to the racemic steady state, hence explaining the experimental challenges in the enantiopure crystallization of chiral compounds.

Growth, characterization, and efficient laser operation of Czochralski- and micro-pulling-down-grown Yb3+:YScO3 mixed sesquioxides

We report on the growth, spectroscopy and laser operation of Yb3+-doped mixed sesquioxide crystals. Various Yb3+-doped crystals with compositions close to (Y0.5Sc0.5)2O3 have been successfully grown by the Czochralski method and by the micro-pulling down (µ-PD) method. Our spectroscopic investigations reveal broadened stimulated emission and absorption cross-section spectra originating from the structural disorder of the mixed crystals. We find the peak wavelengths to shift by ∼1.6 nm between Y:Sc-ratios of 54:46 and 46:54 and confirm a linear relation of the peak position with the lattice constant of the host composition. In the laser experiments, we obtain highly efficient continuous-wave laser operation under pumping with an optically-pumped semiconductor laser (OPSL) at ∼975 nm, reaching slope efficiencies of up to 89% at optical-to-optical efficiencies exceeding 80% at laser wavelengths between 1037 nm and 1086 nm.

Innovative photovoltaic approach: Cd1-xBexTe mixed semiconductor crystals for novel dye-sensitized solar cells

This paper deals with the synthesis and properties of new ternary mixed Cd1-xBexTe (cadmium beryllium telluride) crystal-based electrodes for photovoltaic cells which is a modified version of dye- sensitized solar cells. We determined the thermal stability and photovoltaic performance of the obtained devices. Cd1-xBexTe crystals are grown using the Bridgman technique at high temperatures and pressure for different compositions. Using the modified doctor blade method, we fabricated dye-sensitized solar cells (DSSC) using Cd1-xBexTe-based film as working electrodes. The mixed crystals with the highest beryllium content (10 %) and the lowest (1 %) are used. At the same time, the counter electrode and polymer electrolytes are common. Comparative studies with standard DSSC are also undertaken to compare the stability and charge mechanism. As prepared, DSSC using ternary Cd1-xBexTe showed efficiency as high as 3.11 % at 1 sun condition. The life span measurement indicated promising results, and DSSC is stable up to 720 h with a reasonable decrease in fill factor from 84 to 55.