Top Seeded Solution Growth Technique Research Articles

Growth, crystal structure and IR luminescence of KSrY1-xErx(BO3)2.

A series of novel KSrY1-xErx(BO3)2 (x = 0-1) phosphors that emit near-infrared radiation was synthesized using solid-state methods. Pure Y and Er crystals were grown using a KF flux via the top-seeded solution growth technique. In situ high-temperature single crystal X-ray diffraction, Raman spectroscopy and DFT calculations were used for characterization. Within the series, a polymorphic phase transition from space group P21/m to R3m was discovered between 550 and 600°C. The concentration dependence of the luminescence intensity was measured for the samples. A strong emission of Er3+ electron transition 4I13/2 → 4I15/2 was detected within the 1529-1549 nm range, with the maximum observed for the KSrY0.4Er0.6(BO3)2 composition.

High Quality and Large Size Yttrium Iron Garnet Crystal Grown by Top Seeded Solution Growth Technique

High Quality and Large Size Yttrium Iron Garnet Crystal Grown by Top Seeded Solution Growth Technique

Crystal growth, characterization, and phase transition of PbCuTe2O6

Single crystals of the three-dimensional frustrated magnet and spin liquid candidate compound PbCuTe$_2$O$_6$ were grown using both the Travelling Solvent Floating Zone (TSFZ) and the Top-Seeded Solution Growth (TSSG) techniques. The growth conditions were optimized by investigating the thermal properties. The quality of the crystals was checked by polarized optical microscopy, X-ray Laue and X-ray powder diffraction, and compared to the polycrystalline samples. Excellent quality crystals were obtained by the TSSG method. Magnetic measurements of these crystals revealed a small anisotropy for different crystallographic directions in comparison with the previously reported data. The heat capacity of both single crystal and powder samples reveal a transition anomaly around 1 K. Curiously the position and magnitude of the transition are strongly dependent on the crystallite size and it is almost entirely absent for the smallest crystallites. A structural transition is suggested which accompanies the reported ferroelectric transition, and a scenario whereby it becomes energetically unfavourable in small crystallites is proposed.

Crystal growth and properties characterization of Nd3+:Na5Lu(MoO4)4 for continuous multi-wavelength NIR laser emission

The Nd3+:Na5Lu(MoO4)4 crystal was grown in a 4Na2O–5MoO3 flux through the top-seeded solution growth technique, and achieved a continuous multi-wavelength NIR laser emission in the Nd3+:Na5Lu(MoO4)4 crystal for the first time.

Growth and spectroscopic studies of Nd3+-doped BaBi2(MoO4)4 crystal

Nd3+:BaBi2(MoO4)4 crystals have been grown using the top-seeded solution growth technique for the first time, to the best of our knowledge. The light absorption and luminescent properties of Nd3+:BaBi2(MoO4)4 have been investigated. The intensity parameters were evaluated using the Judd–Ofelt theory as Ω2 = 9.278·10−20 cm2, Ω4 = 5.663·10−20 cm2, Ω6 = 3.913·10−20 cm2. The absorption cross section at 805 nm is 5.3·10−20 cm2 with a FWHM of 5 nm. The emission cross section at 1061 nm is 8.76·10−20 cm2 and luminescence lifetime is 130 μs for 2.42 at. % of Nd3+ concentration. It has been shown that Nd3+:BaBi2(MoO4)4 crystal has a low fluorescence quenching effect and is potentially a promising solid-state laser medium for diode-laser pumping.

Phase Transitions and Local Polarity above TC in a PbZr0.87Ti0.13O3 Single Crystal

Solid solutions of PbZr1−xTixO3 (PZT) are one of the most widely used piezoelectric materials with perovskite structure. Despite the decades of research, the phase diagram of PZT reported in 1971 has not been resolved yet. Recently, it turned out that single crystals of good quality of these solid solutions can be grown. By means of top-seeded solution growth (TSSG) technique, we succeeded to grow a single PbZr0.87Ti0.13O3 crystal. Hence, a partial verification of the diagram could be performed through investigations of the optical, dielectric, pyroelectric and elastic properties of this crystal, in a wide temperature range. The obtained results confirmed that the PbZr0.87Ti0.13O3 crystal undergoes a sequence of phase transitions, such as those observed in ceramics of similar chemical composition. However, additional anomalies of investigated physical properties were observed and discussed. Moreover, the influence of electric field on optical properties has been investigated for the first time and has proven the existence of local polar character of the phase above TC in a limited temperature range.

Shedding Light on the Intrinsic Characteristics of 3D Distorted Fluorite-Type Zirconium Tellurite Single Crystals.

Transition-metal tellurites have motivated growing research interest in both fundamental and applied chemistry, and the corresponding single crystals could serve as rich and fascinating platforms to regulate, explore, and elucidate the intrinsic characteristics of different structures from 0D to 3D architectures. In this context, a zirconium tellurite (namely, ZrTe3O8) single crystal featuring a 3D distorted fluorite-type structure with a size of 35 × 32 × 21 mm3 was successfully harvested by the top-seeded solution growth (TSSG) technique. The X-ray diffraction rocking curve reflects that the crystallinity of the as-grown ZrTe3O8 crystal is quite perfect with a small full-width at half-maximum (fwhm) value (∼39 arcsec). The temperature dependence of the thermophysical properties of the ZrTe3O8 single crystal has been systematically analyzed. The ZrTe3O8 single crystal exhibits a wide transparency window, as the UV and IR absorption cutoff edges are respectively 278 and 7788 nm. The refractive indices over the region from the visible to the near-IR have been determined and manifested relatively large values of 2.0889-2.0370 over a wavelength range of 632.8-1553 nm. Furthermore, the fundamental physical characteristics of the ZrTe3O8 single crystal associated with its distinctive 3D framework structure have been evaluated with density functional theory (DFT) calculations.

Research on the properties and LD-pumped CW laser emission at 2.7 µm in Er3+:KLu(WO4)2 and Er3+/Pr3+:KLu(WO4)2 crystals

Two laser crystals of Er3+:KLu(WO4)2 and Er3+/Pr3+:KLu(WO4)2 were successfully grown using the top-seeded solution growth technique with K2W2O7 as flux. Segregation coefficients of Er3+ ions in Er3+:KLu(WO4)2 and Er3+/Pr3+:KLu(WO4)2 crystals were 0.664 and 0.9, respectively. The density of the Pr3+ ions in the Er3+/Pr3+:KLu(WO4)2 crystal was 1.19 × 1019 cm−3, and the segregation coefficient was 0.18. The absorption and fluorescence spectra of the two crystals with Y-oriented polarization (parallel to the b axis) light were recorded. Judd–Ofelt (J–O) theory was adapted to analyze the main parameters and they were crucial for evaluating the potential of laser crystals with output wavelength of 2.7 µm. Results showed that the Er3+/Pr3+:KLu(WO4)2 crystal had good J–O intensity parameter Ωt (t = 2, 4, 6) and relatively large emission cross section at 2.7 µm. The lifetimes of the 4I11/2 state in the Er3+:KLu(WO4)2 and Er3+/Pr3+:KLu(WO4)2 crystals were fitted to be 87.13 ms and 79.36 ms, respectively. The lifetime of 4I13/2 state decreased sharply from 5.59 s in Er3+:KLu(WO4)2 to 53.19 ms with co-doping of Er3+ ions and Pr3+ ions. Laser oscillation was accomplished at 2.7 µm wavelength using a b-cut Er3+/Pr3+:KLu(WO4)2 crystal sample with size of 4 × 4 × 10 mm3. Finally, a continuous-wave (CW) laser was realized with the highest slope of 15.94%. The center wavelength of the laser output was 2740 nm, and its FWHM was approximately 1.8 nm. Therefore, the Er3+/Pr3+:KLu(WO4)2 crystal has remarkable potential for generating 2.7 µm lasers.

Development of Solvent Inclusion Free 4H-SiC Off-Axis Wafer Grown by the Top-Seeded Solution Growth Technique

This study reports our newly developed technology for SiC solution growth. In particular, we succeed in completely suppressing solvent inclusions, which have been a serious technological problem peculiar to the solution growth method. Then, we fabricate two-inch-diameter 4° off-axis SiC wafers without solvent inclusions. Moreover, we performed their crystal defects evaluation. It was found that our wafers were low resistance n-type 4H-SiC and contain almost no basal plane dislocation. As a result, the superior quality of our solution-grown crystal was confirmed.

Top-seeded solution growth and morphology change of RbTiOPO4:Ta single crystal

The RbTiOPO4:Ta single crystal with dimensions of 4 mm × 31 mm × 18 mm was successfully grown by Top Seeded Solution Growth Technique. It is concluded that the doping Ta element can strongly influence the growth and morphology of the RbTiOPO4 crystal. The evident morphology change of RbTiOPO4:Ta crystal with respect to RbTiOPO4 crystal has been observed and the (1 0 0) crystal face was more developed than any other crystal faces. The possible reasons of the morphology change were analyzed through experimental and theoretical methods. Several methods were tried to increase crystallographic a direction dimension of RbTiOPO4:Ta crystals. Finally, the RbTiOPO4:Ta single crystal with crystallographic a direction dimension up to 6 mm was obtained by using thicker seed crystal. This way makes it possible to get isometric RbTiOPO4:Ta crystals, which is beneficial for nonlinear optical applications due to larger area in x-y plane.

Crystal growth and optical characterization of terbium and niobium doped BTO single crystals

In this study, single crystals of Bi12TiO20 doped with niobium and terbium were grown by Top Seeded Solution Growth technique (TSSG). Samples with good optical quality were obtained and were investigated concerning optical absorption, optical activity, electro-optic effect, and photoconductivity. It was verified that doping with terbium and niobium changes the defects structure characteristic of sillenites, affecting in different ways the optical behavior of crystals.

High-Frequency Ultrasonic Imaging with Lead-free (Na,K)(Nb,Ta)O3 Single Crystal.

Lead-free (Na,K)(Nb,Ta)O3 (KNNT) piezoelectric single crystal has been successfully grown using the top-seeded solution growth technique. The electromechanical coupling factors are very high ( k33 = 0.827, kt = 0.646), and the dielectric loss tangent is as low as 0.004. Acoustic impedance was calculated to be 26.5 MRayl. From the single crystal, a single element transducer was fabricated. The transducer achieved a 57.6% -6 dB bandwidth and 32.3 µm axial resolution at the center frequency of 45.4 MHz, which can identify the cornea of porcine eyeball with high resolution. Comparison between KNNT single crystal and lead-based single crystal was discussed. The results suggest that this single crystal transducer is an excellent candidate to replace lead-containing transducer for high-frequency ultrasonic imaging applications.

Growth of High Quality Al-Doped CsLiB6O10 Crystals Using Cs2O-Li2O-MoO3 Fluxes

High quality and large size Al-doped CsLiB6O10 (CLBO) single crystals have been successfully grown by top-seeded solution growth (TSSG) technique using Cs2O–Li2O–MoO3 fluxes. The advantages of this newly developed flux system were investigated by viscosity measurements and growth experiments. Al-doped CLBO presents a very high transmittance in the visible region and the weak absorption values at 1064 nm along a and c axes are only 140 and 50 ppm/cm, respectively. The measured LIDT of Al-doped CLBO at λ = 1064 nm and τ = 5.0 ns is 5.10 GW/cm2. Moreover, Al-doped CLBO exhibits an apparent enhancement of the hygroscopic nature in contrast with the undoped crystal as determined by the humidity experiments. Finally, a high fourth harmonic generation (FHG) conversion efficiency of 63% utilizing Al-doped CLBO has been achieved by a picosecond mode-locked Nd:YAG laser, the results also reveal that Al doping has no obvious impact on the FHG conversion efficiency.

Numerical simulation and growth of Li2Zn2(MoO4)3 single crystals by the top seeded solution growth technique

Li2O – ZnO – MoO3 pseudo ternary system was used for the growth of Li2Zn2(MoO4)3 crystals by the top seeded solution growth technique in which MoO3 was used as a solvent. Properties of the melts (density, viscosity) have been experimentally measured at different temperatures and compositions of Li2O – ZnO – MoO3 pseudo ternary system. Heat mass transfer in the crystal growth setup was numerically simulated. Using the simulation results a real growth setup was made, Li2Zn2(MoO4)3 crystals were grown and their properties were studied.

Ferroelectric and antiferromagnetic properties of a ternary multiferroic BiFeO3-Pb(Fe1/2Nb1/2)O3-PbTiO3 single crystal

A multiferroic crystal of 0.25BiFeO3-0.59Pb(Fe1/2Nb1/2)O3-0.16PbTiO3 with dimension of 7×7×5mm3 was firstly grown by a top-seeded solution growth (TSSG) technique. The structure, dielectric, ferroelectirc and magnetic properties of the grown crystal were characterized. The crystal shows a pure tetragonal perovskite structure with space group of P4mm (99). The Curie temperature TC is close to 417K with a low dielectric constant at room temperature (ɛRT~422 at 1000Hz). The hysteresis loop shows that the remanent polarization Pr and the coercive field EC in [001]-oriented crystal are 26.3μC/cm2 and 8.6kV/cm, respectively. The piezoelectric coefficient d33 reaches 345pC/N in [001]-oriented sample, much higher than the other BiFeO3-based crystals. The magnetic hysteretic loops at 2K and temperature dependence of magnetization show the crystal material is weak antiferromagnetic with Neel Temperature TN~125K.

Dielectric and piezoelectric properties of lead-free (K0.44Na0.46)NbO3-0.5%MnO2 single crystals grown by the TSSG method

Lead-free (K0.44Na0.46)NbO3-0.5%MnO2 (KNN-0.5%MnO2) single crystals with dimensions of Ф30×10mm were successfully grown by a top seeded solution growth technique (TSSG). The X-ray diffraction pattern has shown that the as-grown crystals have an orthorhombic perovskite structure. The orthorhombic-tetragonal (TO-T) and tetragonal-cubic phase transition temperature (the Curie temperature TC) of the single crystal were found at 184°C and 412°C, respectively. The KNN-0.5%MnO2 single crystals exhibited high piezoelectric constants d33 and dielectric permittivity εr, being 261pC/N and 275. Well saturated P-E hysteresis loop with remnant polarization Pr=22.06µC/cm2 and coercive field Ec=17.93kV/cm was obtained at a maximum electric field of 3kV/mm. A high strain (0.24%) and electromechanical coupling coefficient Kt (65.9%) were obtained along the (001) orientation. These excellent results indicated that the KNN-0.5%MnO2 single crystals could be used as high quality lead-free material.

Assessment of the spectroscopic properties and laser performance of a prominent Nd3+:NaLu(MoO4)2 laser crystal

A prominent laser crystal Nd3+:NaLu(MoO4)2 with dimension of 25 × 20 × 8 mm3 was successfully grown from a flux of Na2Mo2O7 by the mean of top-seeded solution growth technique. The crystal phase was confirmed by the XRD powder diffraction. The results of the DSC measurements indicate that the melting point of this crystal is 1060 ± 5 °C and that the crystal will decompose into the compounds of Na2MoO4 and Lu2(MoO4)3 when the temperature is above its melting point. The hardness of the crystal is about 440 VDH. The crystal has broad absorption and emission cross-sections. The largest absorption cross-sections are 11.48 × 10−20 cm2 and 4.05 × 10−20 cm2 at about 817 nm for the π- and σ-polarizations with the full width at half-maximum (FWHM) of 10 nm and 16 nm, respectively. The emission cross-sections reach to 12.31 × 10−20 cm2 at 1064 nm for the π-polarization and 6.22 × 10−20 cm2 at 1069 nm for the σ-polarization. The lifetime is estimated to be 127.6 μs. The laser experiment has also been performed and the highest slope efficiency is about 30.6%. All the results demonstrate that Nd3+:NaLu(MoO4)2 crystal may be a potential laser gain medium for the diode laser pumping.

On the dispersion of dielectric properties of BaTiO3 single crystals grown by a top-seeded solution growth technique

ABSTRACTThe present paper is devoted to the investigations of the dispersion of dielectric properties of BaTiO3 single crystal measured at 10−3÷2·107 Hz and 20÷150°C. It is shown that in this frequency range dielectric response consists of two independent components which are the lattice response and the intrinsic conduction. The splitting of the response into components was made and presented in 3D plots. The effect of spontaneous change of the dielectric dispersion and the reduction of the characteristic frequency by three orders of magnitude was detected. This phenomenon is related to the Barkhausen effect and to the changes in screening conditions because of transformations of the domain structure.

Growth and properties of (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 (x=0.07–0.11) ferroelectric single crystals by a top-seeded solution growth method

The relaxor-based single crystals of complex perovskite solid solutions, Pb(Mg1/3Nb2/3)O3–PbTiO3 [PMN–PT] and Pb(Zn1/3Nb2/3)O3–PbTiO3 [PZN–PT], exhibit extraordinary piezoelectric performance: displaying extremely high piezoelectric coefficients, very large electromechanical coupling factors, and exceptionally high strain. These materials outperform the currently used Pb(Zr1−xTix)O3 [PZT] ceramics, making them the materials of choice for the next generation of electromechanical transducers for a broad range of advanced applications. In this article, the PZN–xPT (x=0.07–0.11) single crystals near the morphotropic phase boundary were prepared using the top-seeded solution growth technique. Ferro-/dielectric and piezoelectric properties, crystal chemistry, domain structure, and electromechanical coupling properties were systematically characterized. It is showed that the top-seeded solution growth method is an effective alternative technique for preparing the high quality PZN–xPT ferroelectric crystals, which is effective in controlling nucleation/growth of the PZN–xPT single crystals and suppressing the undesired Pb deficient pyrochlore phase by providing a Pb rich environment.

The crystal structure and luminescence quenching of poly- and single-crystalline KYW2O8:Tb3+

Terbium-substituted KYW2O8 single crystals of high optical quality were grown by the top seeded solution growth technique. The degree of yttrium–terbium mixed occupancy was determined for two samples through structure refinements on the basis of single crystal X-ray diffractometer data. Temperature dependent magnetic susceptibility data underline the paramagnetic nature of terbium doped crystals. No magnetic ordering is evident down to 2K. Luminescence measurements yield the typical excitation and emission spectra as expected for Tb3+ activated materials. The decay time of Tb3+ decreases linearly with the Tb3+ concentration, while the excess of thermal quenching does not change significantly. At about 405K the decay time is reduced by roughly 50% relative to the low-temperature value, both for the powders as for the single crystals.