BO3 Triangles Research Articles

Novel Sr3Bi2(BO3)4:Eu3+ red phosphor: Synthesis, crystal structure, luminescent and thermal properties

Novel compound, Sr3Bi2(BO3)4, and Sr3Bi2(BO3)4:Eu3+ series were firstly synthesized by crystallization from a melt. The crystal structures of Sr3Bi2(BO3)4 and Sr3Bi1.66Eu0.34(BO3)4 borates were refined from single crystal X-ray diffraction data to R1 = 0.051 and 0.067, respectively. Sr3Bi2(BO3)4 borate crystallizes in the orthorhombic space group Pnma, a = 7.5107 (5), b = 16.2737 (11), c = 8.8163 (5) Å, V = 1077.59 (12) Å3, Z = 4. These compounds are isotypical to those of A3REE2(BO3)4 family, A = Ca, Sr, Ba. Crystal structure consists of isolated BO3 triangles and three independent M1O8, M2O8 and M3O8 polyhedra, which are connected by corners and edges forming the framework. The distribution of Sr and Bi atoms is partially disordered over M1-M3 positions. Thermal transformations of Sr3Bi2(BO3)4:Eu3+ series were studied by DSC and TG, powder HTXRD, thermal expansion of Sr3Bi2(BO3)4 borate was investigated by powder HTXRD. The emission spectra of Sr3Bi2(BO3)4:Eu3+ show characteristic lines attributed to the intra-configurational 4f-4f transitions in Eu3+ ions. Sr3(Bi0.85Eu0.15)2(BO3)4:Eu3+ demonstrates the strongest luminescent intensity among studied in this work borates. It can be concluded that Sr3Bi2(BO3)4:Eu3+ is a promising red phosphor.

Novel borate CsZn2B3O7 single crystal with large efficient second harmonic generation in deep-ultraviolet spectral range

The linear and nonlinear optical susceptibility dispersion of CsZn2B3O7 single crystal are comprehensively investigated for a bulk structure in form of single crystal taking into account the influence of the packing structural units. The calculation highlights that the BO3 structural units packing is the main source for the large birefringence in CsZn2B3O7 due to high anisotropic electron distribution, and, hence, it affects the macroscopic second harmonic generation (SHG) coefficients. The large SHG is due to hyperpolarizablity formed by ZnO4 tetrahedra and co-parallel BO3 triangle groups. The absorption edge of CsZn2B3O7 occurs at λ = 218 nm and the optical band gap is estimated to be 5.68 eV that is in good agreement with the experimental data (5.69 eV). Therefore, CsZn2B3O7 is expected to produce a coherent radiation in deep-ultraviolet (DUV) region with SHG of about 1.5 × KDP (1.5 × 0.39 p.m./V = 0.585 p.m./V) that agrees with the measurements. This work is aimed at the report of reliable SHG value and the details of the NLO tensor for bulk CsZn2B3O7 single crystal.

Borates—Crystal Structures of Prospective Nonlinear Optical Materials: High Anisotropy of the Thermal Expansion Caused by Anharmonic Atomic Vibrations

In the present study the thermal structure evolution is reviewed for known nonlinear optical borates such as β-BaB2O4, LiB3O5, CsLiB6O10, Li2B4O7, K2Al2B2O7, and α-BiB3O6, based on single-crystal and powder X-ray diffraction data collected over wide temperature ranges. Temperature-dependent measurements of further borates are presented for the first time: α-BaB2O4 (295–673 K), β-BaB2O4 (98–693 K), LiB3O5 (98–650 K) and K2Al2B2O7 (98–348 K). In addition to the established criteria for nonlinear optical (NLO) properties of crystals, here the role of the anisotropy and anharmonicity of the thermal vibrations of atoms is analysed as well as changes in their coordination spheres and the anisotropy of the thermal expansion of the crystal structure. Non-centrosymmetric borates, especially those that have NLO properties, often show distinct anisotropies for each cation in comparison to centrosymmetric borates. All considered NLO borates contain BO3 triangles, which are the principal cause of the strong anisotropy of the thermal expansion.

Studies on Raman Spectra of Cu2+ Ion Doped B2O3-K2O-ZnO-BaO Glasses

Glasses with compositions 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO were prepared using melt quenching technique. The effect of BaO content in present glass system doped with copper ion in place of ZnO has been studied with respect to structural properties. Raman spectroscopy is an experimental technique appropriate for providing information about  the structure, local arrangement of the atoms in the present glasses. The Raman spectra of glasses were recorded at room temperature in the range 200-1800 cm-1 using a He-Ne excitation source having wavelength 632.81 nm. The Raman peaks appeared around 760 cm-1 assigned symmetric breathing vibrations of six-membered ring with both BO3 triangle and BO4 tetrahedral. The intensity of these peaks is slightly varied with the addition of BaO content while the broadness is found to be larger at 30 mol% of BaO than 30 mol% ZnO. This indicates that certain BO4 units could be preferentially converted while those in ring groups could be stabilized. Raman studies it is concluded that present glasses are composed of [BO4] and [BO3] units in metaborate, orthoborate, diborate groups.

Crystal structure of a new polar borate Na2Ce2[BO2(OH)][BO3]2 · H2O with isolated boron triangles

Crystals of a new polar borate Na2Ce2[BO2(OH)][BO3]2 · H2O were prepared by hydrothermal synthesis. The crystals are orthorhombic, a = 7.2295(7) A, b = 11.2523(8) A, c = 5.1285(6) A, Z = 2, sp. gr. C2mm (Amm2), R = 0.0253. The formula of the compound was derived from the structure determination. The Ce and Na atoms are coordinated by nine and six O atoms, respectively. The Ce position is split, and a small amount of Ce is incorporated into the Na1 site with the isomorphous substitution for Na. The anionic moieties exist as isolated BO3 and BO2(OH) triangles. The planes of the BO2(OH) triangles with mm2 symmetry are parallel to the ab plane. The planes of the BO3 triangles with m symmetry are perpendicular to the ab plane and are rotated in a diagonal way. The splitting of the Ce positions and the polar arrangement of the BO2(OH) triangles, water molecules, and Na atoms are observed along the polar a axis. The new structure is most similar to the new borate NaCa4[BO3]3 (sp. gr. Ama2), in which triangles of one type are arranged in a polar fashion along the c axis. Weak nonlinear-optical properties of both polar borates are attributed to the quenching of the second-harmonic generation due to the mutually opposite orientation of two-thirds of B triangles in the unit cell.

Synthesis and characterization of a new borate Ba6Al4B14O33 with building blocks of AlO4, Al4O14, BO3, B6O14, and B6O13

A new barium aluminoborate, Ba6Al4B14O33, has been synthesized by the high-temperature solution reaction at 700°C. The single-crystal XRD analysis showed that it crystallizes in a new structure type with space group P1¯, a=7.0070(14)Å, b=13.880(3)Å, c =14.702(3)Å, α=86.48(3)°, β=88.99(3)°, γ=83.46(3)°, V=1417.8(5)Å3, and Z=2. The fundamental building blocks in this structure are AlO4 tetrahedra, BO3 triangles, [Al4O14]16− groups composed of two AlO4 tetrahedra and two AlO5 trigonal bipyramids, [B6O14]10− groups formed by one BO3 triangle bonded to one [B5O12]9− double ring, and [B6O13]8− groups consisting of one BO3 triangle linked to one [B5O11]7− double ring. They are held together via common O atoms to form a 3D network, with intersecting open channels accommodating Ba2+ cations. The existence of both BO3 and BO4 groups is confirmed by FT-IR spectrum and an optical band gap of 3.44eV is obtained from UV–VIS diffuse reflectance spectrum. Solid-state fluorescence spectrum has also been studied exhibiting the maximum emission peak at around 527nm. Band structure calculations by the density functional theory method indicate that it is a direct band-gap insulator.

Synthesis, crystal structure and optical properties of a new nocentrosymmetric borate: Ba7(BO3)3F5

Introduction of the F− anion in the BaO-B2O3 system generates a new noncentrosymmetric (NCS) materials, Ba7(BO3)3F5, with BO3 triangles and the UV cutoff wavelength below 190nm. Ba7(BO3)3F5 crystallizes in the NCS hexagonal space group P63mc with unit-cell parameters a=11.1562(15)Å, c=7.2415(14)Å, Z=2, V=780.5(2) Å3. The calculated band structures and the density of states of Ba7(BO3)3F5 suggest that its direct gap is 4.349eV. It produces SHG intensity about 1/3 times as large as that of KH2PO4 (KDP) and is phase matchable.

Al5BO9: A Wide Band Gap, Damage‐Tolerant, and Thermal Insulating Lightweight Material for High‐Temperature Applications

The electronic structure, chemical bonding, mechanical, and thermal properties of a B‐containing mullite Al5BO9 were investigated using a combination of first‐principles calculations, Debye model, Clack model, and Slack's equation. The results show that Al5BO9 has a wide band gap of 6.4 eV. The bonding in BO3 triangle and AlO4 tetrahedron is covalent‐ionic, whereas that in AlO6 octahedra and AlO5 bipyramids is ionic‐covalent. The maximum (245 GPa) and minimum Young's modulus (161 GPa) are along [100] and [010] direction, respectively. Based on the low shear modulus (78 GPa) and low Pugh's ratio (G/B = 0.497), Al5BO9 is predicted as a damage‐tolerant ceramic. The most likely slip systems are [010](100) and [100](010). The high Debye temperature (956 K) indicates good high‐temperature stability. The minimum thermal conductivity is estimated to be 1.59 W·(m·K)−1, and the thermal conductivity decreases with temperature as 2071.9/T.

Formation of Mixed Bond‐Angle Linkages in Zinc Boromolybdate Glasses

The short and medium range structure of glassy MoO3–ZnO–B2O3 has been studied by neutron diffraction and reverse Monte Carlo simulation. The partial atomic pair correlation functions and coordination numbers are presented that are not yet reported for this system. We have established that the first neighbor distances do not depend on concentration within limit of error, the actual values are rB‐O = 1.38 Å, rMo‐O = 1.72 Å, and rZn‐O = 1.97 Å. It is found that ZnO takes part in the glassy structure as network former, as ZnO4 tetrahedral are linked both to MoO4 and to BO3 and BO4 groups. It is revealed that BO4/BO3 increases with increasing B2O3 content. We have found that only small amount of boroxol ring is present, BO3 and BO4 groups are organized into superstructure units, and a small part is in isolated BO3 triangles. The BO3 and BO4 units are linked to MoO4 or ZnO4 forming mixed [4]Mo‐O‐[3]B, [4]Mo‐O‐[4]B, [4]Mo‐O‐[4]Zn, [3]B‐O‐[4]Zn, [4]B‐O‐[4]Zn bond linkages.

Structure, Raman and infrared spectroscopic properties of new nonlinear optical material Na3VO2B6O11

In this paper we report on the structure of Na3VO2B6O11 (NVBO) single crystals which were investigated by XRD, polarized Raman spectra in the range from 10 to 1600 cm−1 and infrared spectrum (IR) in the range from 100 to 1600 cm−1. Factor group analysis has been used to study the full vibrational representation of the crystal. More than 120 phonon modes have been obtained, which are related to BO and VO vibration in the trigonal planar BO3 triangle groups and tetrahedral BO4/VO4 groups. The high frequency bands located at 1300–1415 cm−1 are assigned to stretching modes of the trigonal planar BO3 groups. Moreover, intense Raman modes located at 631 cm−1 is related to BO3 bending vibration as well. The weak band at 1158 cm−1 (A1 mode) and strong band at 431 cm−1 (A1 mode) are attributed to asymmetric stretching and bending vibration mode of tetrahedral BO4 groups respectively. The vibrational band at 765–738 cm−1 in the Raman spectra of NVBO crystal maybe related to the breathing vibration of the boroxol ring consisting of two BO4 tetrahedra. In addition, we assigned the intense band 900 (A1 mode) and 831 cm−1 (B2 mode) are relative to the v1 symmetric stretching vibration of VO4 tetrahedra. And the middle intense band at 382 (A1 mode) and 385 (A2 mode) are due to OVO vibration in VO4 tetrahedra.

Syntheses and characterization of two alkaline and transition metal orthoborates, LiMBO3 (M = Zn, Cd)

Two alkaline and transition metal orthoborates, LiMBO3 (M = Zn, Cd), have been synthesized and their crystal structures determined by single-crystal XRD methods with the following crystal data: LiZnBO3, P1¯(No.2), a = 5.0559 (15) Å, b = 6.097 (2) Å, c = 8.0359 (18) Å, α = 75.75 (2)°, β = 89.86 (2)°, γ = 89.79 (3) °, Z = 4; LiCdBO3, P21/c (No.14), a = 10.4159 (14) Å, b = 9.005 (2) Å, c = 10.756 (2) Å, β = 92.521 (13)°, Z = 16. The crystal structure of LiZnBO3 is composed of edge-sharing ZnO5 trigonal bipyramids which are bound together via ZnO4 tetrahedra and BO3 planar triangles to form a polyanionic framework. LiCdBO3 also features a 3D framework, but constructed by edge-sharing CdO5 trigonal bipyramids and BO3 triangles. Both structures afford open channels that are occupied by Li+ cations. IR spectra further confirm that these two compounds contain the planar triangular BO3 groups. UV–VIS diffuse reflectance spectra show band gaps of about 3.10 and 4.28 eV and solid-state fluorescence spectra demonstrate emission bands at around 542 and 412 nm for LiZnBO3 and LiCdBO3, respectively. Band structure calculations by the density functional theory method indicate that both compounds are direct band-gap insulators.

Polarized Raman spectra of LiBaB9O15 single crystal

We use polarized Raman spectroscopy to obtain the room temperature phonon modes of LiBaB9O15 single crystal, that crystallizes in a trigonal structure belonging to the space group R3¯c(D3d6) with two molecules per primitive cell (ZB=2). The structure of the LiBaB9O15 crystal consists of a three-dimensional borate framework, formed by two BO3 triangles and one BO4 tetrahedra. Since BO3 and BO4 units share the oxygen atoms, we can not obtain a correlation scheme where their internal modes are distributed in terms of the irreducible representations of the D3d factor group. The only modes that can unambiguously be assigned are the ν3(BO4) with A1g symmetry at 983cm−1 and the ν1(BO3) with Eg symmetry at 932cm−1. We observed 7A1g+6Eg out of 11A1g+25Eg vibrations predicted by the Group Theory.

Effect of alkali metal ions (Li+, Na+ and K+) on the luminescence properties of CaMgB2O5: Sm3+ nanophosphor

A series of CaMgB2O5 phosphors co-doped with Sm3+ and alkali metal ions (Li+, Na+ and K+) were prepared by combustion method. The crystal structure of the phosphors was investigated by using X-ray diffraction (XRD) after annealing the phosphor at 900 °C. The crystal structure belongs to the monoclinic phase of CaMgB2O5with space group P21/b. FTIR spectra shows the absorption bands for various structural units of borate mainly BO3 triangles and lattice vibrations of Ca–O and Mg–O. The luminescence and spectral properties were studied by photoluminescence (PL) and diffuse reflectance (DR) spectroscopy. The result shows that under 400 nm excitation, the phosphor shows characteristic emission of Sm3+ ion with the main orange–red peak at 600 nm. The optimum dopant concentration of Sm3+ ion was 1.5 mol% and the main mechanism for concentration quenching was dipole–dipole (d–d) interaction determined by using Dexter’s theory. As a charge compensator, alkali metal ions (Li+, Na+ and K+) were incorporated into the host lattice of CaMgB2O5: Sm3+ phosphors, which enhanced the PL intensities. The calculated CIE coordinates (0.59, 0.41) under 400 nm excitation were found to be in the orange–red region of the spectrum.

Fontarnauite, (Na,K)2(Sr,Ca)(SO4)[B5O8(OH)](H2O)2, A New Sulfate-Borate Mineral From Doğanlar (Emet), Kütahya Province, Western Anatolia, Turkey

Fontarnauite was discovered in cores recovered from the Kutahya-Emet 2 and 188 (named here as Doganlar) boreholes drilled in the Emet borate basin near the village of Doganlar, Kutahya Province, Western Anatolia, Turkey. The Emet (or Emet- Hisarcik) basin is one of the Neogene basins in western Turkey bearing a borate-rich unit intercalated with Miocene sediments. Fontarnauite is most commonly associated with probertite, glauberite, and celestine and occurs as isolated colorless to light-brown prismatic crystals or as clusters of crystals less than 5 mm long. Fontarnauite is brittle, with a Mohs hardness of 2½–3, and perfect {010} cleavage. D calc = 2.533 g/cm3. The new mineral is optically biaxial (−), α 1.517(2), β 1.539(2), γ 1.543(2) (590 nm); 2 V meas = 46(1)o; 2 V calc = 46o; X ^ a 95.0° (β obtuse); Y // b , Z ^ c 81.9° (β acute). Dispersion is r > v , medium to weak. The chemical composition (electron microprobe; B and H from the crystal-structure refinement) is as follows: SO3 17.75, B2O3 38.66, CaO 2.26, SrO 18.98, Na2O 12.65, K2O 1.70, H2O 10.01, total 102.01 wt.%. The empirical formula (based on 15 O atoms per formula unit) is (Na1.84K0.16)Σ2.00(Sr0.82Ca0.18)Σ1.00S1.00B5H5O15; the endmember formula is Na2Sr(SO4)[B5O8(OH)](H2O)2 based on the crystal-structure refinement. Single-crystal X-ray studies gave the space group P 21/c, a 6.458(2), b 22.299(7), c 8.571(2) A, β 103.047(13)o, V 1202.5(1.0) A3, Z = 4. Structure refinement ( R 1 = 2.9%) revealed that two BO4 tetrahedra and three BO3 triangles share vertices to form B5O10(OH) units that link to other B5O10(OH) units along [100] and [001] to give a [B5O8(OH)] sheet parallel to (010). Within the central cavities of opposing sheets are the H2O groups, SO4 tetrahedra, and Na (1) sites; the Sr and Na (2) sites occupy the interstices of a given sheet. The region of the structure where opposing cusps of neighboring sheets approach each other is dominated by weaker H-bonding associated with the OH and H2O groups, in accord with the observed perfect {010} cleavage. The strongest lines in the powder X-ray diffraction pattern, obtained after profile fitting using the Le Bail method, are as follows [ d in A ( I ) ( hkl )]: 11.1498 (100)(020), 3.3948 (8)(061), 3.3389 (20)(042), 3.1993, 3.1990 (10)(160, ![Formula][1] 42), 3.0458(10)(052), 3.0250(7)(220), 2.7500 (10)(![Formula][2] 22,142), 2.3999 (8)(260), 2.2300, 2.2284(7)(0 10 0, 222), 1.9241, 1.9237(7)(311,![Formula][3] 24). The holotype is deposited in the mineralogy collection of the Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada, accession number [M56745][4]. [1]: /embed/mml-math-1.gif [2]: /embed/mml-math-2.gif [3]: /embed/mml-math-3.gif [4]: /lookup/external-ref?link_type=GEN&access_num=M56745&atom=%2Fcanmin%2Fearly%2F2016%2F02%2F23%2Fcanmin.1400088.atom

Linear and nonlinear optical properties of aluminum borate crystal Al5BO9: Experiment and calculation

Abstract

Pb7O(OH)3(CO3)3(BO3): first mixed borate and carbonate nonlinear optical material exhibiting large second-harmonic generation response.

The first borate carbonate UV nonlinear optical material Pb7O(OH)3(CO3)3(BO3) was hydrothermally synthesized, which features a (3,9)-connected IrSi3-like structure constructed by Pb7O(OH)3(BO3) units and carbonates. This compound exhibits a large second-harmonic generation (SHG) response about 4.5 times that of KH2PO4 (KDP), attributed to synergistic interactions between the stereoeffect of the Pb(II) cations and coparallel BO3 and CO3 triangles groups.

Effect of Fe on the structure of potassium borosilicate glasses

The behavior of Fe in the structure of Fe-containing potassium borosilicate glasses with different relationships between network-forming and modifier cations has been studied by Mossbauer and vibrational spectroscopies. The results demonstrate that the Fe-free and Fe-containing potassium borosilicate glasses differ in the distribution of the modifier cations over their structural units. The presence of Fe in the composition of potassium borosilicate glasses is shown to reduce the coordination of the boron, which shows up as a decrease in the percentage of BO4 tetrahedra and an increase in that of BO3 triangles. This is accompanied by an increase in the percentage of Q3 silicon-oxygen structural units containing nonbridging oxygens, the breaking of mixed silicon borate rings, and the formation of Si-O-Fe3+ bridge bonds and Si-O− nonbridging bonds coordinated by K+ ions.

Ionothermal synthesis of tetranuclear borate clusters containing f- and p-block metals.

The reactions of simple oxides or halides of trivalent lanthanides and actinides or bismuth with boric acid in the ionic liquid 1-butyl-3-methylimidazolium chloride at 150 °C result in the formation and crystallization of a series of isomorphous tetranuclear borate clusters with the general formula M4B22O36(OH)6(H2O)13 (M = La, Ce, Pr, Nd, Sm, Eu, Gd, Pu, and Bi). These clusters do not assemble with trivalent cations smaller than Gd(3+), suggesting that the formation of the clusters is dictated by the size of the metal ion. The cations are found in cavities along the periphery of a cage assembled from the corner- and edge-sharing interactions of BO3 triangles and BO4 tetrahedra, yielding a complex chiral cluster. Both enantiomers cocrystallize. The metal ions are nonacoordinate, and their geometries are best described as distorted tridiminished icosahedra. This coordination environment is new for both Pu(3+) and Bi(3+). In addition to detailed structural information, UV/vis-NIR absorption and photoluminescence spectra are also provided.

Temperature-dependent Raman spectroscopic study of bismuth borate Bi2ZnOB2O6**Project supported by the National Natural Science Foundation of China (Grant Nos. 50932005 and 51102239).

A temperature-dependent Raman spectroscopic study on Bi2ZnOB2O6 crystal was carried out to investigate the structure change of the crystal with the increase of temperature. Raman spectra of crystal Bi2ZnOB2O6 were recorded in the spectral range 10–1600 cm−1 at room temperature first. Compared with the vibrational spectra of the referred compounds, satisfactory assignment of most of the high-energy modes to vibrations of Bi–O, B–O, and Zn–O bonds was achieved. In particular, the Raman high-frequency peak located at 1344 cm–1 was attributed to the B–O vibration in the BO3 triangle. This temperature-dependent Raman spectroscopic study was carried out up to 600 °C. It was found that all the Raman lines exhibit decreases in frequency and the widths of the Raman peaks increase with increasing temperature. No phase transition was observed under 600 °C.

Synthesis and optical properties of the first lead borate bromide with isolated BO3 groups: Pb2Ba3(BO3)3Br.

Single crystals of a new compound Pb2Ba3(BO3)3Br have been grown by a spontaneous crystallization method. They crystallize in the noncentrosymmetric orthorhombic space group C2221 with isolated BO3 triangles and distorted PbO polyhedra. UV-Vis-NIR diffused reflectance spectroscopy measurements indicate that the absorption edge is at 326 nm. Second-harmonic generation (SHG) measurements using 1064 nm radiation show that Pb2Ba3(BO3)3Br exhibits relative large NLO response about 3.1× that of KH2PO4 (KDP) and is type I phase-matchable. First-principles electronic structure calculations show that the isolated BO3 groups and PbO4 polyhedra play an important role in the total SHG response.