Crystal growth and luminescent properties of Pr-doped K(Y,Lu)3F10 single crystal for scintillator application

Pr1%:K(Y_1−xLu_x)₃F₁₀ (x=0, 0.2, 0.4) single crystals were grown by the μ-PD method. All the grown crystals were greenish and perfectly transparent without any inclusions or cracks. Radioluminescence spectra and decay kinetics of the Pr1%:K(Y,Lu)₃F₁₀ crystals were measured. Emission from the Pr³⁺ 5d–4f transition, peaking around 260 nm and of the decay time of around 22 ns were observed. The 5d–4f emission intensities of the Pr1%:K(Y,Lu)₃F₁₀ crystals were higher than that of the standard BGO scintillator.     

Growth and optical properties of self-frequency-doubling laser crystal Yb:LuAl3(BO3)4

Single crystal of Yb:LuAl₃(BO₃)₄(Yb:LuAB) was grown by the flux method for the first time. The cell parameters of the grown crystal were estimated by X-ray diffraction analysis. The result indicates the symmetry of trigonal space group R32, with lattice parameters a=b=9.26372 Å, c=7.21405 Å, V=536.14 Å³, and Z=4. The absorption and emission spectra of Yb:LuAB crystal at room temperature has also been studied. The fluorescence lifetime for Yb:LuAB crystal is about 1.48 ms. The heat capacity was measured from 25 to 500 °C. Its second harmonic generation efficiency in LuAl₃(BO₃)₄ crystal is 3–4 times that of KDP crystal. These results show that Yb:LuAB crystal would be a potential self-frequency-doubling laser crystal.     

Crystal growth and spectroscopic properties of Yb:CaYAlO4 single crystal

A Yb³⁺-doped CaYAlO₄ laser crystal has been grown by the Czochralski technique. The segregation coefficient was measured by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The cell parameters were analyzed with X-ray diffraction experiments. Color defects in Yb:CaYAlO₄ have been evidenced to be similar to those in undoped CaYAlO₄. The polarized absorption spectra and the fluorescence spectrum of the Yb:CaYAlO₄ crystal were measured at room temperature. The fluorescence decay time of the Yb³⁺ ion was investigated. The results show that Yb:CaYAlO₄ has potential as a laser gain medium for an ultrashort laser system.     

Growth and spectral properties of Nd-doped Sr3Y(BO3)3 crystal

A new crystal of Nd³⁺:Sr₃Y(BO₃)₃ with dimension up to 25×35 mm² was grown by Czochralski method. Absorption and emission spectra of Nd³⁺: Sr₃Y(BO₃)₃ were investigated . The absorption band at 807 nm has a FWHM of 18 nm. The absorption and emission cross sections are 2.17×10⁻²⁰ cm² at 807 nm and 1.88×10⁻¹⁹ cm² at 1060 nm, respectively. The luminescence lifetime τ_f is 73 μs at room temperature     

The growth and spectroscopic characteristics of Ca3Y2(BO3)4:Er laser crystal

The Ca₃Y₂(BO₃)₄:Er³⁺ crystal with a size up to 20 mm×30 mm was grown by the Czochralski method. The absorption spectrum was measured and its absorption peaks were assigned to the corresponding transitions between the Er³⁺ energy levels. A broad emission spectrum from 1429.4 to 1662.8 nm was exhibited from 530 nm wavelength pumping. This crystal is promising as a tunable infrared laser crystal.     

Thermal and laser properties of Yb:YAl3(BO3)4 crystal

Large optical-quality Yb:YAl₃(BO₃)₄(Yb:YAB) crystals have been grown by the flux method. The thermal properties of Yb:YAB crystal were measured for the first time. The thermal properties of Yb:YAB crystal with different Yb³⁺ ion concentrations are also reported. The results show that the ytterbium concentration influences the properties of Yb:YAB crystal. The specific heat decreases with the increase of Yb³⁺ ion concentrations in the experiment range. Apparently, the thermal expansion coefficient increases along the c-direction with the increase of Yb³⁺ ion concentrations, while it changes slightly along the a-direction. The output laser in 1120–1140 nm ranges has been demonstrated pumped by InGaAs laser. The slope efficiency is 3.8%. The self-frequency-doubling output power of 1 mW is achieved.     

Growth and spectroscopic properties of Er single doped and Er–Yb co-doped YAl3(BO3)4 crystals

Er³⁺-doped and Er³⁺–Yb³⁺ co-doped yttrium aluminum borate (YAB) single crystals have been grown by the top-seeded solution growth method using a new flux system, namely NaF–MoO₃–B₂O₃. The Er³⁺ concentrations were 1.3 mol% for both single doped and co-doped crystals and the Yb³⁺ concentration in the Er³⁺–Yb³⁺ co-doped crystal was 20.0 mol% in the raw materials. The distribution coefficients of Er³⁺ single doped and Er³⁺–Yb³⁺ co-doped crystals were measured. The polarized absorption and fluorescence spectra of Er³⁺–Yb³⁺ co-doped crystal were recorded and compared with those of Er³⁺ single doped crystal. The results demonstrate that Er³⁺–Yb³⁺ co-doped YAB crystal is a potential candidate for 1.55 μm laser materials.     

Edge-defined film-fed growth of Yb:YVO4 single crystal plates

The applicability of the edge-defined film-fed growth (EFG) technique for Yb_xY_(1−x)VO₄ (x=0.05, 0.1 and 1) was approved by successful growth of crystals up to 80 mm in length as the thin plates. Low-angle grain boundaries and the crystal coloration as main defects were found. Optimal seed orientation was suggested on the strength of vanadate crystal plate morphology. Optical properties, chemical composition and the crystalline quality were investigated.     

Growth and shape control of orthorhombic Fe5(PO4)4(OH)3·2H2O single crystalline dendrites

Orthorhombic Fe₅(PO₄)₄(OH)₃·2H₂O single crystalline dendritic nanostructures have been synthesized by a facile and reproducible hydrothermal method without the aid of any surfactants. The influences of synthetic parameters, such as reaction time, temperature, the amount of H₂O₂ solution, pH values, and types of iron precursors, on the crystal structures and morphologies of the resulting products have been investigated. The formation process of Fe₅(PO₄)₄(OH)₃·2H₂O dendritic nanostructures is time dependent: amorphous FePO₄·nH₂O nanoparticles are formed firstly, and then Fe₅(PO₄)₄(OH)₃·2H₂O dendrites are assembled via a crystallization-orientation attachment process, accompanying a color change from yellow to green. The shapes and sizes of Fe₅(PO₄)₄(OH)₃·2H₂O products can be controlled by adjusting the amount of H₂O₂ solution, pH values, and types of iron precursors in the reaction system.     

Nd:YVO4 crystal growth by Czochralski technique with a submerged plate

This paper is to investigate the growth of Nd:YVO₄ (yttrium vanadate) crystal by the modified Czochralski technique with a submerged plate. Numerical studies are performed to examine melt convection and heat transfer during Nd:YVO₄ growth. The attention is paid to study the effects of initial elevation of the submerged plate, crystal diameter, and melt level on melt inclusions. It is found that the increase in crystal rotation rate and crystal diameter, and the decrease in melt level will increase the axial temperature gradient at the edge and in the center of the crystal, and change the interface shape from convex to flat. The experiments are also carried out to confirm the feasibility of the proposed new technique for controlling melt inclusions in Nd:YVO₄ crystal growth.     

Sn3O4 single crystal nanobelts grown by carbothermal reduction process

This article reports on the growth of single crystal Sn₃O₄ nanobelts and SnO by a carbothermal reduction process in two different regions of a furnace tube. Even though intermediate tin oxide compounds (Sn₃O₄) have been observed experimentally, the study of structures based on them is a challenging task. Characterization data allowed us to propose that Sn₃O₄ nanobelts grew by vapor–solid mechanism while SnO grew by self-catalyst vapor–liquid–solid mechanism. Electrical measurements of a single Sn₃O₄ nanobelt were performed at different temperatures, revealing undoped semiconductor characteristics.     

Bulk crystal growth of congruent MgO-doped LiNbO3 crystal with stoichiometric structure and its second-harmonic-generation properties

A new LiNbO₃ bulk crystal has been grown by doping with MgO (cs-MgO:LN; Li₂O:Nb₂O₅:MgO=45.30:50.00:4.70, (Li_0.906Mg_0.047V^Li_0.047)NbO₃), which successfully has the congruent point coinciding with the stoichiometric point. Its second-harmonic-generation (SHG) properties were evaluated. It was found that cs-MgO:LN has a much more homogeneous composition leading to uniform in-plane distribution of the non-critical phase-matching wavelength than the conventional LiNbO₃ crystals such as congruent LiNbO₃ (c-LN), stoichiometric LiNbO₃ (s-LN), and MgO-doped congruent LiNbO₃ (5MgO:LN). This homogeneity arose from the observation that none of the solute components including ionic species were segregated at the interface during growth. The SHG conversion efficiency of cs-MgO:LN is comparable to those of s-LN and 5MgO:LN.     

Environmental SEM investigation on surface defects in 0.92Pb(Zn1/3Nb2/3)O3–0.08PbTiO3 single crystal

In this paper, the technique of environmental scanning electron microscopy (ESEM) has been employed to investigate the surface defects of the (1 1 1) appearing face in 0.92Pb(Zn_1/3Nb_2/3)O₃–0.08PbTiO₃ (PZN–8%PT) crystals. From the ESEM images, we succeeded in observing and studying the growth hillocks and etch pits, low-angle grain boundaries, and sub-grain boundaries in (1 1 1) face, which were related to the generation of dislocation and stacking faults, respectively. On the other hand, an image of a unique multi-layer lamellar structure and fine step structure obtained in the (1 1 1) face reveals that the dominant fast growth mechanism of PZN–8%PT crystal grown by the flux method is a sub-step mechanism, unlike the screw dislocation growth mechanism.     

Flux growth of PbMg1/3Ta2/3O3 single crystals

Single crystals of PbMg_1/3Ta_2/3O₃ (PMT) were grown by the flux method. The PbO–Pb₃O₄–B₂O₃ system was used as a solvent. Transparent and light yellow PMT single crystals of rectangular shape and dimensions up to 10×6×4 mm³ were obtained. For the applied growth conditions only, the crystals of the perovskite structure were grown. X-ray diffraction tests showed that at room temperature PMT exhibits cubic symmetry with lattice parameter a=4.042(1) Å. Dielectric studies pointed to relaxor properties of PMT. The characteristic broad and frequency-dependent maximum of dielectric permittivity was observed at 179.7 K (1 kHz).     

Flux growth and characterizations of NdPO4 single crystals

Neodymium phosphate single crystals, NdPO₄, have been grown by a flux growth method using Li₂CO₃-2MoO₃ as a flux. The as-grown crystals were characterized by X-ray powder diffraction(XRPD), differential thermal analysis (DTA) and thermogravimetric analysis (TG) techniques. The results show that the as-grown crystals were well crystallized. The crystal was stable over the temperature range from 26 to 1200 °C in N₂. The specific heat of NdPO₄ crystal at room temperature was 0.41 J/g °C. The absorption and the fluorescence spectra of NdPO₄ crystal were also measured at room temperature.     

Growth and property of Zn-doped near-stoichiometric LiTaO3 crystal

Near-stoichiometric LiTaO₃ (SLT) and Zn-doped near-stoichiometric LiTaO₃ (Zn:SLT) crystals with 10–15 mm in diameter and 10 mm in length were grown by using TSSG technique with K₂O as the flux. The effect of adding amount of K₂O was discussed in the growing process. The crystals were characterized by inductively coupled plasma-optical emission (ICP-OES), X-ray diffraction (XRD) and differential thermal analysis (DTA). The lattice constants of Zn:SLT were smaller than those of SLT and Curie temperature was higher than that of SLT. It was found that Zn doping is an efficient way to improve the optical damage resistance ability of SLT crystal. Compared with SLT crystal, Zn:SLT exhibited a much higher optical damage threshold, more than 500 MW/cm², which was attributed to Zn self-compensated effect that formed the charge compensated complexes, (Zn_Ta)³⁻–3(Zn_Li)⁺ in SLT crystal.     

Growth and scintillation properties of the Na2W2O7 crystal

The growth and scintillation properties of the Na₂W₂O₇ crystal are reported. The solid reaction between Na₂CO₃ and WO₃ is used to synthesise the Na₂W₂O₇ material. The Na₂W₂O₇ single crystal has been grown by the Bridgman method. And the Na₂W₂O₇ single crystal with sizes 14×7×6 mm³ has been achieved. The transmission spectra, the Ultraviolet fluorescence spectra and the X-ray excited luminescence spectra of the Na₂W₂O₇ crystal are measured. The measurement results show that the Na₂W₂O₇ crystal is a promising intrinsic scintillator.     

Growth and properties of Nd:Lu3Ga5O12 laser crystal by floating-zone method

Neodymium (Nd) doped lutetium gallium garnet (Nd:Lu₃Ga₅O₁₂, Nd:LuGG) single crystal was successfully grown by the optical floating-zone method for the first time to our knowledge. Its absorption and luminescence spectra at room temperature were measured. By using the J–O theory, the spectral parameters of Nd:LuGG were calculated, which indicated that Nd:LuGG should possess comparable and even better laser properties than Nd:YAG. The maximum output power of 855 mW at 1062 nm was achieved with slope efficiency of 23.4% under a pump power of 5.2 W, and optical conversion efficiency of 16.4%. All the results show that Nd:LuGG is a potential laser material.     

Growth and properties of Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 single crystals directly from melt

Pb[(Zn_1/3Nb_2/3)_0.91Ti_0.09]O₃ (PZNT91/9) single crystals were grown by a modified Bridgman method directly from melt using an allomeric Pb[(Mg_1/3Nb_2/3)_0.69Ti_0.31]O₃ (PMNT69/31) single crystal as a seed. X-ray diffraction (XRD) measurement confirmed that the as-grown PZNT91/9 single crystals are of pure perovskite structure. Electrical properties and thermal stabilization of PZNT91/9 crystals grown directly from melt exhibit different characters from those of PZNT91/9 crystals grown from flux, although segregation and the variation of chemical composition are not seriously confirmed by X-ray fluorescence analysis (XPS). The [0 0 1]-oriented PZNT91/9 crystals cut from the middle part of the as-grown crystal boules exhibit broad dielectric-response peaks at around 105 °C, accompanied by apparent frequency dispersion. The values of piezoelectric constant d₃₃, remnant polarization P_r, and induced strain are about 1800–2200 pC/N, 38.8 μC/cm², and 0.3%, respectively, indicating that the quality of PZNT crystals grown directly from melt can be comparable to those of PZNT91/9 single crystals grown from flux. However, further work deserves attention to improve the dielectric properties of PZNT crystals grown directly from melt. Such unusual characterizations of dielectric properties of PZNT crystals grown directly from melt are considered as correlating with defects, microinhomogeneities, and polar regions.     

Epitaxial growth of the CoFe2O4 film on SrTiO3 and its characterization

Cobalt ferrite (CoFe₂O₄) thin film is epitaxially grown on (0 0 1) SrTiO₃ (STO) by laser molecular beam epitaxy (LMBE). The growth modes of CoFe₂O₄ (CFO) film are found to be sensitive to laser repetition, the transitions from layer-by-layer mode to Stranski–Krastanov (SK) mode and then to island mode occur at the laser repetition of 3 and 5 Hz at 700 °C, respectively. The X-ray diffraction (XRD) results show that the CFO film on (0 0 1) SrTiO₃ is compressively strained by the underlying substrate and exhibits high crystallinity with a full-width at half-maximum of 0.86°. Microstructural studies indicate that the as-deposited CFO film is c-oriented island structure with rough surface morphology and the magnetic measurements reveal that the compressive strained CoFe₂O₄ film exhibits an enhanced out-of-plane magnetization (190 emu/cm³) with a large coercivity (3.8 kOe).