High Temperature Solution Growth Research Articles

Growth, Spectroscopic Characterization and Continuous-Wave Laser Operation of Er,Yb:GdMgB5O10Crystal

A transparent Er3+,Yb3+:GdMgB5O10 single crystal with dimensions up to 24 × 15 × 12 mm was grown successfully by the high-temperature solution growth on dipped seeds technique from K2Mo3O10-based solvent. The grown crystal was characterized using PXRD, DSC and ATR techniques. Differential scanning calorimetry measurements and SEM analysis of the heat-treated solids revealed Er,Yb:GdMgB5O10 to be an incongruent melting compound with an onset point of 1087 °C. The absorption edge of the Er,Yb:GMBO sample is located in the region of 245 nm, which approximates a value of 4.8 eV. Absorption and emission spectra, and luminescence kinetics, were studied. The energy transfer efficiency from ytterbium to erbium ions was determined. The laser operation in continuous-wave mode was realized and output characteristics were measured. The maximal output power of 0.15 W with a slope efficiency of 11% was obtained at 1568 nm.

Novel application of high temperature solution growth method in simultaneously preparing SiC/Ti3SiC2/TiC using photovoltaic Si waste and Ti-bearing blast furnace slag

Photovoltaic silicon wastes (PVSWs) and Ti-bearing blast furnace slag (TBBFS) are typical new energy solid waste and traditional industrial solid waste respectively. The collaborative treatment of PVSW and TBBFS can realize the utilization of Si and Ti resources, as well as safeguard the ecosystems. Herein, an effective approach was proposed to prepare SiC, Ti3SiC2, and TiC using these two wastes as raw materials based on the innovative application of High Temperature Solution Growth Method (HTSGM). A Ti–Si alloy, which is rich in TiSi2 phase (stable) with a low melting point is synthesized from TBBFS through silicothermal reduction at a low operating temperature of HTSGM. Subsequently, the directional solidification process effectively optimized the segregation and carbon solubility of Ti–Si alloy, leading to the formation of TiC, Ti3SiC2, and SiC. The effect of directional solidification rate and the electromagnetic field is analyzed on in situ carburizing behavior and segregation of Ti–Si alloy, as well as controlled precipitation interval of the three carbides. Through the microcrystalline materialization treatment strategy of the associated waste slag, the entire process is devoid of solid waste or other pollution, achieving high-value and complete utilization of the two solid wastes. This work provides an innovative process for the green, clean, efficient, and high-quality collaborative treatment of PVSW and TBBFS.

Single Crystal Growth and X-ray Diffraction Characterization of a Quasi-Spin Chain Compound, Li2CuO2

We report the growth of single crystals and X-ray diffraction characterization of the quasi-one-dimensional spin chain compound, Li2CuO2. The single crystals were grown using the high-temperature solution growth technique. The resulting blade-shaped crystals exhibit a shiny black color, with dimensions reaching several millimeters along the crystallographic b-axis. The as-grown crystals were characterized using powder X-ray diffraction and Laue back reflection. The I-centered orthorhombic, Immm, structure was confirmed. Crystal structure parameters were determined to be a = 3.6744 Å, b = 2.8600 Å, and c = 9.4257 Å from Rietveld analysis. Our work helps to remove obstacles to the synthesis and study of a model cuprate system, Li2CuO2, facilitating the use of experimental probes that require sizable crystals.

Synthesis, crystal structure and luminescent properties of a quinary borate-phosphate compound CsNa2Dy2(BO3)(PO4)2

Abstract Borate-phosphates exhibit a wide range of compositional and structural diversity, making them ideal hosts for luminescent materials. In this work, a new borate-phosphate compound CsNa2Dy2(BO3)(PO4)2 has been prepared under high temperature solution growth method. It crystallizes in an orthorhombic space group Cmcm with the following lattice parameters determined by single-crystal X-ray diffraction: a = 6.9709(5), b = 14.9699(11), c = 10.6480(8) Å, z = 4. Its structure contains isolated BO3 planar triangles and PO4 tetrahedra, which are interconnected by Cs+, Na+ and Dy3+ ions. Solid solutions of CsNa2Y2(1−x)Dy2x (BO3)(PO4)2 (x = 0 − 0.08) are prepared and exhibit a yellow emissive luminescence by near-UV excitation due to the 4F9/2 → 6H(13/2, 15/2) transitions of Dy3+. The optimized concentration of Dy3+ is x = 0.01, and if over this critical value, the luminescent intensity will decrease due to concentration quenching. The Commission International de L’Eclairage (CIE) coordinates for CsNa2Y1.98Dy0.02(BO3)(PO4)2 are (x = 0.377, y = 0.404), corresponding to yellow color. The prepared phosphor may serve as a yellow phosphor for NUV-excited LEDs.

Growth and characterization of novel piezo-/ferroelectric single crystals from the PSN-BS-PT ternary system

Bismuth-based single crystals with the nominal composition of 0.1Pb(Sc1/2Nb1/2)O3-0.315BiScO3-0.585PbTiO3 (0.1PSN-0.315BS-0.585PT) ternary complex perovskite system were successfully grown using a high-temperature solution growth (HTSG) method. A mixture of PbO and Bi2O3 in a molar ratio of 73:27 was used as flux, and the flux to charge ratio was optimized to be 70:30 (wt%). The grown crystals, with dimensions up to 3 mm, exhibit a pseudo-cubic morphology. The XRD patterns of the ground powder and naturally formed pseudo-cubic facets confirm that the grown single crystals crystallize in the perovskite structure with the rhombohedral symmetry as the major phase, and the naturally grown pseudo-cubic facets are parallel to {100}C. The domain structures in the (001)-oriented single crystals examined by polarized light microscopy (PLM) and optical crystallography reveal the coexistence of rhombohedral and monoclinic phases in majority, with the presence of a minor tetragonal phase likely grown at the late stage of the growth, demonstrating the morphotropic phase boundary (MPB) characteristics for the grown crystals. Upon heating, phase transition from the major rhombohedral and monoclinic to the cubic phase take place at TC = 370 °C. The ferroelectric properties are displayed by polarization-electric field (P-E) hysteresis loops with a remanent polarization of 17 µC/cm2 and a high coercive field of 68 kV/cm. The piezoelectric coefficient (d33) is found to be 478 pC/N. The high Curie temperature and decent piezo- and ferroelectric performance of the PSN-BS-PT crystals make this ternary complex perovskite system a promising candidate for potential applications in high-temperature and high-power electromechanical transduction.

Growth of large-sized relaxor ferroelectric PZN-PT single crystals by modified flux growth method

A novel bottom-cooling high-temperature solution growth technique is developed for growing large-sized relaxor ferroelectric 0.91Pb(Zn1/3Nb2/3O3)-0.09PbTiO3 (PZN-PT) single crystals. During the growth, an inverse temperature gradient is maintained in the crucible base by flowing air at a controlled rate. This method restricts the number of spontaneously nucleated crystals at crucible bottom, reduces loss of volatile PbO component and favours the growth of large-sized PZN-PT single crystals. Large-sized PZN-PT single crystals of dimensions ∼ 22 × 20 × 14 mm3 are reproducibly grown by the proposed method. The electrical characteristics of the PZN-PT wafers oriented along the 〈100〉, 〈010〉 and 〈001〉 directions are investigated. PZN-PT wafers oriented along the 〈001〉 direction exhibited superior piezoelectric coefficient (d33) of ∼ 2221 pm/V. The homogeneity of the physical parameters is analysed by preparing 10 elements with dimensions of ∼ 5 × 2.5 × 2.5 mm3 which were cut from single wafer oriented along the 〈001〉 direction. The ferro-, piezo- and dielectric characteristics of these wafers were found to be highly uniform with small standard deviation. The observation of d33 value with less than 2 % deviation from mean value confirms the growth of highly quality PZN-PT single crystals.

Structure, Optical Properties and Physicochemical Features of LiNbO3:Mg,B Crystals Grown in a Single Technological Cycle: An Optical Material for Converting Laser Radiation.

Two series of LiNbO3:Mg:B crystals have been grown and studied. Two doping methods-have been used. The crystals-have been co-doped with Mg and a non-metallic dopant, B. The physicochemical features of the growth-have been considered for LiNbO3:Mg:B crystals obtained from a boron-doped melt. The charge-has been prepared using different technologies: homogeneous (HG) and solid-phase (SP) doping. The same two methods have been used to grow single-doped LiNbO3:Mg crystals. A control near-stoichiometric (NSLN) crystal-has been grown via the HTTSSG (high-temperature top-seeded solution growth) method from a congruent melt (Li/Nb ≈ 0.946) with 5.5 wt% K2O. The characteristics of the LiNbO3:Mg:B crystals-have been compared with those of the LiNbO3:Mg and NSLN crystals. Physicochemical and structural reasons have been established for the differences in the distribution coefficients of magnesium (KD) during the growth of the HG- and SP-doped LiNbO3:B:Mg and LiNbO3:Mg crystals. The optical characteristics of the LiNbO3:B:Mg crystals-have been studied via optical spectroscopy, laser conoscopy and photoinduced light scattering (PILS). The influence of boron on the microstructure, compositional and optical uniformities and optical damage resistance of the LiNbO3:Mg:B crystals-has been estimated. Optimal technological approaches to growing optically uniform LiNbO3:B:Mg crystals have been determined. LiNbO3:Mg:B crystals have been shown to have a significant advantage over the commercially used LiNbO3:Mg crystals since large LiNbO3:Mg:B crystals can be grown without stripes. Such stripes usually appear perpendicular to the growth axis. In addition, the photorefractive effect is suppressed in LiNbO3:Mg:B crystals at lower magnesium concentrations ([Mg] ≈ 2.5 mol%) than in LiNbO3:Mg ([Mg] ≈ 5.5 mol%).

Realization of high performance PZN-PT single crystal based piezoelectric flexural mode hydrophone for underwater sensor applications

In this article, attempts are made to grow large size PZN-PT single crystals using high temperature solution growth method by implementing novel bottom cooling technique. The grown crystals are oriented and poled along 〈001〉 direction and obtained larger piezoelectric strain coefficient (d33 > 2000 pm V−1) suitable for development of underwater acoustic sensor requirements. Flexural mode hydrophone is realized using the oriented PZN-PT single crystal discs. Finite element modeling is employed to examine the design of the flexural mode hydrophone and an equivalent circuit model is also applied to study its acoustic characteristic at two extreme boundary conditions like simply supported and clamped edge condition. The underwater acoustic response of the PZN-PT single crystal based flexural mode hydrophone is evaluated over the frequency range (100 Hz to 12 kHz) and its responses are compared with the FEM and equivalent circuit model results. The predicted results from FEM and equivalent circuit model are found to be in good agreement with the experimental results. The receiving sensitivity of the PZN-PT single crystal-based hydrophone is 12 dB higher than the PZT 5A based hydrophone in the frequency range of 2 kHz to 6 kHz. The fabricated PZN-PT single crystal-based hydrophone offers better performance than the conventional piezo ceramic based flexural hydrophone.

Superconductivity and magnetic and transport properties of single-crystalline CaK(Fe1−xCrx)4As4

Members of the CaK(Fe$_{1-x}$Cr$_{x}$)$_{4}$As$_{4}$ series have been synthesized by high-temperature solution growth in single crystalline form and characterized by X-ray diffraction, elemental analysis, magnetic and transport measurements. The effects of Cr substitution on the superconducting and magnetic ground states of CaKFe$_4$As$_4$ ($T_c$ = 35 K) have been studied. These measurements show that the superconducting transition temperature decreases monotonically and is finally suppressed below 1.8 K as $x$ is increased from 0 to 0.038. The magnetic transition temperature increases in a roughly linear manner as Cr substitution increases. A temperature-composition (\textit{T}-\textit{x}) phase diagram is constructed, revealing a half-dome of superconductivity with the magnetic transition temperature, $T^*$, appearing near 22~K for $x$ $\sim$ 0.017 and rising slowly up to 60~K for $x$ $\sim$ 0.077. The $T$-$x$ phase diagrams for CaK(Fe$_{1-x}$$T$$_{x}$)$_4$As$_4$ for $T$ = Cr and Mn are essentially the same despite the nominally different band filling; this is in marked contrast to $T$ = Co and Ni series for which the $T$-$x$ diagrams scale by a factor of two, consistent with the different changes in band filling Co and Ni would produce when replacing Fe. Superconductivity of CaK(Fe$_{1-x}$Cr$_{x}$)$_{4}$As$_{4}$ is also studied as a function of magnetic field. A clear change in $H^\prime_{c2}$($T$)/$T_c$, where $H^\prime_{c2}$($T$) is d$H_{c2}$($T$)/d$T$, at $x$ $\sim$ 0.012 is observed and probably is related to change of the Fermi surface due to magnetic order. Coherence length and the London penetration depths are also calculated based on $H_{c1}$ and $H_{c2}$ data. Coherence lengths as the function of $x$ also shows changes near $x$ = 0.012, again consistent with Fermi surfaces changes associated with the magnetic ordering seen for higher $x$-values.

Single Crystal Growth of Synthetic Sulfide- and Phosphide-Based Minerals for Physical Measurements

In this work, we review recent advances in the use of high-temperature solution growth that allow for the growth of single crystalline samples of synthetic minerals. We outline how low-melting binary or ternary solutions are attractive solvents for solution growth and provide examples of the growth of bismuthinite (Bi2S3), galena (PbS) and parkerite (Ni3Bi2S2). We then focus on the Rh-S, Pd-S and Ni-P phase spaces to discuss how the low-melting regions near transition metal-main group eutectic compositions make excellent solvents for crystal growth of several binary and ternary minerals containing both high melting and volatile elements as well as for the discovery of new materials. We end by discussing the growth of synthetic canfieldite (Ag8SnS6) and argyrodite (Ag8GeS6) from Ag2S–Sn-S-based solutions.

Single crystal synthesis and magnetic properties of a Shastry-Sutherland lattice compound BaNd2ZnS5

Single crystals of a Shastry-Sutherland magnetic semiconductor, BaNd2ZnS5, were synthesized through a high-temperature solution growth technique. Physical properties were characterized by powder and single crystal x-ray diffraction, temperature- and field-dependent magnetization, and temperature-dependent specific heat measurements. BaNd2ZnS5 orders antiferromagnetically at 2.9 K, with magnetic moments primarily aligned within the ab-plane. Magnetic isothermal measurements show metamagnetic transitions at ~ 15 kOe for the [110] direction and ~ 21 kOe for the [100] direction. Estimated magnetic entropy suggests a double ground state for each Nd ion.

High-temperature solution growth of large size chalcogenide FeTxSe (T: Fe, Co) superconducting single crystals

We report the growth of high quality Fe excess and Co doped, Fe T x Se single crystals in nominal ratio via slow cooling method of high temperature solution growth technique and, their structural and physical properties through the X-ray diffraction, Raman spectroscopy, magnetic and transports measurements. Selective area electron diffraction (SAED) patterns and X-ray diffraction of cleavage piece confirm the growth of single crystals in ( h0l ) orientations. Observations of phonon vibration modes (A 1g and B 1g ) in Raman spectroscopy measurements mark the qualitative analysis of these single crystals. Low temperature magnetic and electrical transport studies manifest the superconducting nature of both single crystals.

Growth and Spectroscopy of Yb:YMgB5O10 Crystal

A transparent Yb:YMgB5O10 single crystal with dimensions up to 25 × 23 × 25 mm and weight 10.337 g was grown using a high-temperature solution growth on dipped seeds technique with a K2Mo3O10 solvent. The Yb3+ concentration was calculated to be 4.7 at.% (NYb = 3.71 × 1020 atoms/cm3) with a distribution coefficient Kd of 0.59. The grown crystal was characterized by means of PXRD, TGA-DSC and ATR-FTIR techniques. The spectroscopic characteristics of the Yb:YMgB5O10 crystal were demonstrated. Absorption cross-section spectra were produced. The luminescence spectra of the Yb:YMgB5O10 crystal were measured in the spectral range of 950–1100 nm. The luminescence kinetics of the 2F5/2 energy level were investigated and the lifetime was determined.

Synthesis and Physical Properties of NbMnP Single Crystals

Single crystalline NbMnP was grown by the high-temperature solution growth technique and characterized by room temperature X-ray diffraction, temperature- and field-dependent magnetization, temperature-dependent resistivity, and heat capacity measurements. NbMnP is isostructural to TiNiSi with the space group of Pnma. Physical characterizations suggest that NbMnP is metallic and goes through an anti-ferromagnet transition at around 230 K with a weak magnetic anisotropy. A small ferromagnetic component is found to be perpendicular to [010].

Crystal growth, layered structure and luminescence properties of K2Eu(PO4)(WO4).

K2Eu(PO4)(WO4) has been prepared via the high-temperature solution growth (HTSG) method using K2WO4–KPO3 molten salts as a self-flux and characterized by single-crystal X-ray diffraction analysis, IR and luminescence spectroscopy. The structure of this new compound features a 2D framework containing [EuPO6]4− layers, which are composed of zigzag chains of [EuO8]n interlinked by slightly distorted PO4 tetrahedra. Isolated WO4 tetrahedra are attached above and below these layers, leaving space for the K+ counter-cations. The photoluminescence (PL) characteristics (spectra, line intensity distribution and decay kinetics) confirm structural data concerning one distinct position for europium ions. The luminescence color coordinates suggest K2Eu(PO4)(WO4) as an efficient red phosphor for lighting applications.

Flux Growth and Properties of Volatile Bromine-Containing UV Nonlinear Optical Crystal K3B6O10Br

A UV Nonlinear optical (NLO) crystal is one of the key devices in all-solid-state laser technology, and borate halides show outstanding potential due to their abundant structural diversity and short UV cut-off edges. In this article, the sizable UV NLO crystal of K3B6O10Br (KBOB) has been grown with lead-containing and lead-free fluxes systems using the high-temperature top-seeded solution growth (TSSG) method. Energy Dispersive X-ray Spectroscopy (EDS) and transmittance spectra illustrate the influence of Pb2+ ions on the transmittance properties and laser-induced damage threshold (LDT). The thermal property, namely, thermal expansion, thermal conductivity, and thermal diffusivity curves, were characterized. Moreover, a small variation of thermal refractive indexes was analyzed to illustrate the advantage of KBOB in the application for temperature-fluctuated specific regions.

Transitions intensities and cross-sections of Tb3+ ions in YAl3(BO3)4 crystal

A Tb3+:YAB crystal was grown using a high-temperature solution growth on dipped seeds technique. Polarized ground state absorption and fluorescence spectra from the 5D4 level, as well as a fluorescence decay curves of 5D4 and 5D3 levels, were recorded at room temperature. Radiative properties such as emission probabilities, branching ratios, and radiative lifetime were investigated within the theory of 4f-4f transition intensity in the case of the intermediate configuration interaction.

Synthesis, crystal structure and luminescence properties of a new samarium borate phosphate, CsNa2Sm2(BO3)(PO4)2.

A new caesium sodium samarium borate phosphate, CsNa2Sm2(BO3)(PO4)2, has been obtained successfully by the high-temperature solution growth (HTSG) method and single-crystal X-ray diffraction analysis reveals that it crystallizes in the orthorhombic space group Cmcm. The structure contains BO3, PO4, NaO7 and SmO7 polyhedra which are interconnected via corner- or edge-sharing O atoms to form a three-dimensional [Na2Sm2(BO3)(PO4)2]∞ network. This network delimits large cavities where large Cs+ cations reside to form the total structure. Under 402 nm light excitation, CsNa2Sm2(BO3)(PO4)2 exhibits three emission bands due to the 4f→4f transitions of Sm3+. Furthermore, we introduced Gd3+ into Sm3+ sites to optimize the Sm3+ concentration and improve the luminescence intensity. The optimal concentration is Gd/Sm = 98/2. The luminescent lifetime of a series of CsNa2Gd2(1-x)Sm2x(BO3)(PO4)2 phosphors shows a gradual degradation of lifetime from 2.196 to 0.872 ms for x = 0.01-0.10. The Commission Internationale de l'Eclairage (CIE) 1931 calculation reveals that CsNa2Gd1.96Sm0.04(BO3)(PO4)2 can emit orange light under 402 nm excitation.

Anisotropic magnetic properties of trigonal ErAl2Ge2 single crystal

We report the anisotropic magnetic properties of the ternary compound ErAl2Ge2. Single crystals of this compound were grown by high temperature solution growth technique,using Al:Ge eutectic composition as flux. From the powder x-ray diffraction we confirmed that ErAl2Ge2 crystallizes in the trigonal CaAl2Si2-type crystal structure. The anisotropic magnetic properties of a single crystal were investigated by measuring the magnetic susceptibility, magnetization, heat capacity and electrical resistivity. A bulk antiferromagnetic ordering occurs around 4 K as inferred from the magnetic susceptibility and the heat capacity. The susceptibility is larger along the ab-plane and flattens out below the magnetic transition temperature () and the magnetization in the ordered state increases more rapidly along the ab-plane than along the c-axis suggesting that the moments are inclined more towards the ab-plane. The magnetic susceptibility, magnetization and the 4f -derived part of the heat capacity in the paramagnetic regime analysed based on the point charge model of the crystalline electric field (CEF) indicate a relatively low CEF energy level splitting.

Growth and Characterization of RMgB5O10 (R = Y, La, Gd) Crystals

We have studied and optimized conditions for spontaneous flux growth of RMgB5O10 (R = Y, La, Gd) crystals and assessed the feasibility of seeded growth of such crystals. Using high-temperature solution growth with K2Mo3O10 as a solvent, we have prepared optical-quality (Er,Yb):YMgB5O10 single crystals and measured their thermal conductivity and optical characteristics to assess their potential for use in diode-pumped lasers operating in the spectral range 1.5–1.6 μm. Absorption cross section spectra of an (Er,Yb):YMgB5O10 single crystal have been measured in the spectral ranges 800–1100 and 1400–1650 nm. The results demonstrate that (Er,Yb):YMgB5O10 single crystals are similar in characteristics to (Er,Yb):YAl3(BO3)4, promising for use in advanced near-IR laser systems, and are capable of replacing RAl3(BO3)4 materials in such devices because they are simpler to grow.