A bulk beta-BaB2O4 crystal was grown from a novel BaB2O4-NaBaBO3-BaMoO4 ternary solvent system with an optimal solvent composition using top-seeded solution growth (TSSG) and its optical properties were compared to those of a reference crystal grown from the conventional binary BaB2O4-NaBaBO3 system. The linear absorption spectrum was measured for both polarizations over an exceptionally broad range from ultraviolet (UV) to terahertz (THz) range (0.2-1500 mu m), revealing high transparency and low absorption coefficients, indicative of excellent material uniformity and purity. Nonlinear optical (NLO) performance was evaluated via secondharmonic generation (SHG) at 266 nm, showing comparable efficiency to the reference sample. These results demonstrate that the ternary system enables scalable crystal growth with preserved high optical quality, making it a promising candidate for industrial production of nonlinear optical elements.

Triple system BaB2O4–NaBaBO3–BaMoO4 is studied to optimize the growth of barium metaborate crystals (β-BaB2O4) - promising materials for nonlinear optics in visible and ultraviolet ranges. Main attention is paid to the phase equilibria and characteristics of crystallization in this system. It is shown that the addition of barium molybdate decreases the solution-melt viscosity, increasing the crystal yield and quality. The key parameters and β-BaB2O4 primary crystallization regions are determined by solid-phase synthesis, differential scanning calorimetry, and powder X-ray diffraction techniques. Experiments are performed on growing spontaneous β-BBO crystals. The results obtained demonstrate the promising application of compositions of this system as solvents for β-BBO crystal growth.

В настоящей работе была исследована тройная система BaB2O4-NaBaBO3-BaMoO4 для оптимизации процесса выращивания кристаллов метабората бария (β-BaB2O4), которые являются перспективными материалами для нелинейной оптики в видимом и ультрафиолетовом диапазонах. Основное внимание уделено изучению фазовых равновесий и характеристик кристаллизации в этой системе. Показано, что добавление молибдата бария снижает вязкость раствора-расплава, увеличивая выход и качество кристаллов. Методами твердофазного синтеза, дифференциальной сканирующей калориметрии (ДСК) и рентгенофазового анализа (РФА) определены ключевые параметры, и области первичной кристаллизации β-BaB2O4. Проведены эксперименты по выращиванию спонтанных кристаллов β-BBO. Полученные результаты демонстрируют перспективность использования составов данной системы в качестве растворителей для роста кристаллов β-BBO.

The present study concerns the Li2O-B2O3-MoO3-LiF system. LiB3O5 and Li3B7O12 crystals were obtained spontaneous crystallisation and TSSG. The addition of LiF to the molybdate flux represents a promising avenue for the growth of lithium borate crystals.

Solid solutions based on (Eu,Gd)Sc3(BO3)4 , Gd)Sc 3 (BO 3 ) 4 (C2/c) and Gd 0.25 Sc 0.75 BO 3 (R R 3) in the EuSc3(BO3)4-GdSc3(BO3)4 3 (BO 3 ) 4-GdSc 3 (BO 3 ) 4 system were studied. Synthesis at 1250 degrees C provides wide homogeneity regions which are stable at room temperature. Melt-solution crystallization of both compounds from LiBO2-LiF 2-LiF flux was shown. All the obtained samples have luminescence characteristic of Eu3+ 3+ with a largest peak at 615 nm corresponding to the 5 D 0 -> 7 F 2 transition. In this series the luminescence intensity monotonically increases with an increase of Eu content. The largest quantum yield of luminescence (53 %) in the EuSc3(BO3)4-GdSc3(BO3)4 3 (BO 3 ) 4-GdSc 3 (BO 3 ) 4 system is demonstrated by EuSc3(BO3)4 3 (BO 3 ) 4 sample.

TbAl3(BO3)4 should not be considered as a strictly stoichiometric compound. A variety of Tb1+xAl3-x(BO3)4 (x = -0.1-0.15) single phase compositions with the R32 space group were synthesized in the TbBO3-(Al2O3B2O3) system. The K2Mo3O10-B2O3-Al2O3 flux was used to grow Tb1+xAl3-x(BO3)4 (x = 0.06 and 0.09) crystals. The orthoborates have typical luminescence in the green range which correlated with the 5D3 -> 7F6 electron transition of Tb3+. However, deviating from stoichiometry can result in halving the quantum efficiency of luminescence. The SHG efficiency from 1064 nm radiation for Tb1+xAl3-x(BO3)4 crystals (x = 0.06 and 0.09) was found to be 1.82 and 1.53 times higher than that of KDP, respectively.

We present study on optical properties of $\boldsymbol{\beta}$-BBO crystals grown from three distinct melt solutions: initial NaBaBO 3 , $\mathrm{NaBaBO}_{3}-\mathrm{V}_{2} \mathrm{O}_{5}$, and $\mathrm{BaMoO}_{4}-\mathrm{BaF}_{2}$. Polarized VIS and FTIR spectra as well as with Raman scattering spectra were used. The mean absorption coefficient for e-waves within the $1.5-2.0 \mu \mathrm{m}$ range measured $0.015,0.03$, and $0.008 \mathrm{~cm}^{-1}$ for initial, vanadium, and molybdenum based grown crystals.

This article focuses on the top-seeded solution growth (TSSG) of single crystals of the low-temperature non-centrosymmetric modification of barium borate, β-BaB2O4 (β-BBO), using a mixed solvent comprising NaBaBO3 and V2O5. We examine the linear absorption properties across a wide spectral range and nonlinear second harmonic generation (SHG) from 532 nm to 266 nm in β-BBO samples under Nd:YAG laser radiation pumping. The mean linear absorption for ordinary waves in vanadium-based crystals at wavelengths from 300 to 600 nm is found to be an order of magnitude higher than that in standard samples, measuring 0.0059 and 0.0007 cm-1, respectively. However, crystals grown from the proposed vanadium-based solution still exhibit similar SHG efficiency to standard samples. Deviations from the quadratic dependence are observed at pump power densities exceeding 20 MW/cm2, possibly attributed to temperature effects resulting from insufficient temperature stabilization.

Phase equilibria in the BaB 2 O 4 –BaMoO 4 –BaF 2 system are studied by the modified visual polythermal analysis, solid phase synthesis, differential scanning calorimetry, powder XRD, and chemical analysis. The liquidus of the system consists of the primary crystallization regions of BaB 2 O 4 , BaMoO 4 , and BaF 2 separated by co-crystallization curves. A series of experiments on the growth of spontaneous α-BaB 2 O 4 , β-BaB 2 O 4 , BaMoO 4 , BaF 2 crystals on a platinum loop and bulky BBO crystals are conducted.

Методами модифицированного визуально-политермического анализа (ВПА), твердофазного синтеза, дифференциальной сканирующей калориметрии (ДСК), рентгенофазового анализа (РФА) и химического анализа изучены фазовые равновесия в системе BaB2O4 - BaMoO4 - BaF2. Ликвидус системы состоит из полей первичной кристаллизации трех соединений: BaB2O4, BaMoO4 и BaF2, разделенных кривыми совместной кристаллизации. Проведена серия экспериментов по выращиванию спонтанных кристаллов α-BaB2O4, β-BaB2O4, BaMoO4 и BaF2 на платиновый стержень с петлей и объемных кристаллов BBO.

A new SmSc(BO3)2 compound was discovered from the study of SmBO3–ScBO3 phase diagram.

A new lithium barium scandium borate (Li3Ba4Sc3B8O22) was obtained by solid-state synthesis and grown by spontaneous crystallization. Single-crystal X-ray diffraction analysis showed that it crystallizes in the centrosymmetric space group P-1 with the cell dimensions a = 5.2230(4) angstrom, b = 8.5609(6) angstrom, c = 11.4157(8) angstrom, alpha = 73.3750(6)degrees, beta = 78.5020(6)degrees, gamma = 87.0520(6)degrees, and V = 479.28(6) angstrom(3) and a structure that consists of two layers formed by single [BO3] and double [B2O5] triangles, [ScO6] octahedra, [BaO9] polyhedra, and disordered [LiO4] tetrahedra or squares. The diffuse optical reflection spectrum indicates that Li3Ba4Sc3B8O22 is transparent in the range of 250-800 nm. Furthermore, an effective green emission centred at 545 nm was observed for the as-prepared Tb3+-doped Li3Ba4Sc3B8O22, making this borate compound a promising host material for engineering light-emitting phosphors.

The LiBa12(BO3)(7)F-4 crystals doped Nd3+ and Pr3+ were grown from high-temperature solution melts, using the TSSG method. All the samples have the wide absorption band in the visible range of 350-650 nm related to the dichroism, which is typical for other colored "antizeolites". Strong radiation bands are associated with well known electronic transitions of Pr3+ (P-3(0) -> H-3(6) at 630 nm, P-3(0) -> F-2(2) at 670 nm) and Nd3+ (F-4(3/2) -> I-4(9/2) at 875 nm, F-4(3/2) -> I-4(11/2) at 1054 nm). In addition crystals of Nd-doped barium fluoride borate solid solutions NdxBa12(BO3)(8-x)F-6x were grown from high temperature solution. Using X-ray single-crystal diffraction, the structure was solved and refined in I4/mcm space group that are similar to other colored "antizeolites" built with the positively charged framework of [Ba-12(BO3)(6)](6+) cation pattern which contains channels built of alternating barium cubes and anticubes. According to the structure refinement of NdxBa12(BO3)(8-x)F-6x, cube channel segments are populated mainly by [F-4](4-) and [NdF4](-) clusters, whereas anticube ones - by (BO3)(3-) anions.

The authors employ methods of spontaneous crystallization on a platinum loop, modified visual polythermal analysis (VPA), solid phase synthesis, differential thermal analysis (DTA), X-ray powder diffraction (XRD) analysis and chemical analyses, in order to study chemical processes and phase formation in the BaB2O4-LiF-Li2O system. In this system the fields of primary crystallization of beta-BaB2O4 are determined. The primary crystallization field of the low-temperature barium borate phase for the BaB2O4-LiF-Li2O system is proved to lie in the range 72-60 mol% BaB2O4. A series of experiments have been carried out on the growth of bulk barium borate crystals in this system.

Phase equilibria in the BaB2O4-LiF-NaF section of the quaternary reciprocal system Li, Na, Ba // BO2, F are studied by the solid-phase synthesis, differential thermal analysis, and visual polythermal analysis techniques. It is shown that this system can be used for the growth of bulk -BaB2O4 crystals.

Non-centrosymmetric borates K7CaR2(B5O10)3 have been synthesized by solid state reaction and successfully grown by the top seeded solution growth method using K2O-B2O3-CaF2 flux. IR, Raman, absorption spectra as well as data on melting temperature for the crystals were obtained. Optical properties like UV absorption edge and SHG intensity were compared with KH2PO4 (KDP) and K7CaY2(B5O10)3.

In order to find the optimum solvent for the growth of nonlinear optical β-BaB 2 O 4 crystals, the phase relationships in the ternary reciprocal system Li, Ba // BO 2 , F have been studied using solid state synthesis, differential thermal analysis and X-ray powder diffraction. Isothermal and polythermal sections of the system Li, Ba // BO 2 , F are reported. In the studied system, the following compounds are formed: LiBa 2 B 5 O 10 (melts by peritectic reaction at 930°C, i.e. 1203 K) and LiBaF 3 (melts incongruently at 850°C, i.e. 1123 K). Visual polythermal analysis of seeding and growth of β-BaB 2 O 4 crystals in this system was carried out. The primary crystallization field of β-BaB 2 O 4 was defined. Using the top-seeded pulling technique, a β-BaB 2 O 4 crystal of 93 mm in diameter, 34 mm in height and 520 g in weight has been grown.

The bulk crystals of LiBa12(BO3)7F4 were obtained from two flux compositions by the top seeded solution growth method. Crystals grown from BaCO3:BaF2:H3BO3:Li2CO3 = 3:3:3:1 charge were found to have a distinct linear dichroism effect at 0.35–0.65 and around 0.73 μm. This suggests application of the material in the production of polarizing filters and attenuators for visible range lasers.