Thermochemical property of a microporous material for mixed metal borate of Li2Sr4B12O23

A pure mixed alkali–alkaline earth metal borate of Li₂Sr₄B₁₂O₂₃ with microporous structure has been synthesized by high-temperature solid state reaction, and characterized by XRD, FT-IR, TG techniques, and chemical analysis. The molar enthalpies of solution of Li₂Sr₄B₁₂O₂₃ in 1 mol L^?1 HCl(aq), and of SrCl₂·H₂O(s) in [1 mol L^?1 HCl + H₃BO₃ + LiCl·H₂O](aq) have been determined by microcalorimeter at 298.15 K, respectively. From these data and with the incorporation of the previously determined enthalpies of solution of H₃BO₃(s) in 1 mol L^?1 HCl(aq), and of LiCl·H₂O(s) in [1 mol L^?1HCl + H₃BO₃](aq), together with the use of the standard molar enthalpies of formation for SrCl₂·6H₂O(s), LiCl·H₂O(s), H₃BO₃(s), HCl(aq), and H₂O(l), the standard molar enthalpy of formation of ?(11,534.0 ± 10.0) kJ mol^?1 for Li₂Sr₄B₁₂O₂₃ was obtained on the basis of the appropriate thermochemical cycle.     

Synthesis,Structural Characterization and Properties of Two Strontium Borates Constructed from Oxo Boron Clusters

Two strontium borates Sr₂[B₆O₉(OH)₄] (1) and Sr₂B₅O₉(OH)·H₂O (2), with acentric structures have been synthesized under hydro/solvothermal conditions. Compound 1 is reported for the first time in the strontium borates system, and it crystallizes in the monoclinic space group P2₁ with unit cell parameters a = 6.8445(5) Å, b = 8.7033(6) Å, c = 8.4632(6) Å, β = 100.581(6)°, V = 495.58(6) ų and Z = 2. Its structure consists of unusual borate layers of 3, 11-membered rings, which are interconnected via Sr–O ionic bonds and hydrogen bonds to generate a 3D supramolecular network. Compound 2 is a known strontium borate, crystallizing in the monoclinic space group C ₂ with a = 10.161 (13) Å, b = 7.965(4) Å, c = 6.393(11) Å, β = 128.0(2)°, V = 407.7(14) ų and Z = 2. Second-harmonic generation measurements on the powder samples reveal that 1 and 2 exhibits good SHG efficiency about 1.5 and 2 times that of KDP (KH₂PO₄) powder respectively.     

SrB5O7F3 Functionalized with [B5O9F3]6− Chromophores: Accelerating the Rational Design of Deep‐Ultraviolet Nonlinear Optical Materials

Fluorooxoborates, benefiting from the large optical band gap, high anisotropy, and ever‐greater possibility to form non‐centrosymmetric structures activated by the large polarization of [BO_xF_4?x]^(x+1)? building blocks, have been considered as the new fertile fields for searching the ultraviolet (UV) and deep‐UV nonlinear optical (NLO) materials. Herein, we report the first asymmetric alkaline‐earth metal fluorooxoborate SrB₅O₇F₃, which is rationally designed by taking the classic Sr₂Be₂B₂O₇ (SBBO) as a maternal structure. Its [B₅O₉F₃]^6? fundamental building block with near‐planar configuration composed by two edge‐sharing [B₃O₆F₂]^5? rings in SrB₅O₇F₃ has not been reported in any other borates. Solid state ¹⁹F and ¹¹B magic‐angle spinning NMR spectroscopy verifies the presence of covalent B?F bonds in SrB₅O₇F₃. Property characterizations reveal that SrB₅O₇F₃ possesses the optical properties required for deep‐UV NLO applications, which make SrB₅O₇F₃ a promising crystal that could produce deep‐UV coherent light by the direct SHG process.     

在空气下制备掺二价稀土的硼酸盐及二价稀土离子(RE2+=Sm,Eu,Tm,Yb)的光谱特征

本文讨论了Sm²⁺、Eu²⁺、Tm²⁺、Yb²⁺等二价稀土离子的光谱特征,特别是在一些含四面体硼酸根的硼酸盐如SrB₄O₇、SrB₆O₁₀和BaB₈O₁₃中它们的光谱性质。当以三价稀土离子取代化合物中的二价碱土离子时,利用不等价取代而产生的缺陷所带的电荷,可在高温的空气下使上述的稀土离子还     

Synthesis,characterization, and thermochemical property of a novel mixed alkali metal borate: NaCs[B10O14(OH)4]

A novel mixed alkali metal hydrated borate NaCs[B₁₀O₁₄(OH)₄] was synthesized under hydrothermal conditions. Its structure was determined by single-crystal X-ray diffraction and further characterized by FT-IR spectroscopy, TG-DTA, powder X-ray diffraction, and chemical analysis. NaCs[B₁₀O₁₄(OH)₄] crystallizes in monoclinic space group P2/c with a = 7.6588(3) Å, b = 9.0074(3) Å, c = 11.8708(6) Å, and β = 115.682(3)°. The crystal structure of NaCs[B₁₀O₁₄(OH)₄] consists of Na–O, Cs–O polyhedral, and [B₁₀O₁₄(OH)₄]^2? polyborate anions. [B₁₀O₁₄(OH)₄]^2? units are connected together through common oxygen atoms forming a 1D helical chain-like structure, which are further connected by O–H···O hydrogen bonds forming a 3D supramolecular structure. Through a designed thermochemical cycle, the standard molar enthalpy of formation of this borate was determined to be ?7888.6 ± 8.1 kJ mol^?1 by using a heat conduction microcalorimeter.     

High‐Pressure Synthesis of Cd(NH3)2[B3O5(NH3)]2: Pioneering the Way to the Substance Class of Ammine Borates

To date, the access to the substance class of borates containing nitrogen, for example, nitridoborates, oxonitridoborates, or amine borates, was an extreme effort owing to the difficult starting materials and reaction conditions. Although a number of compounds containing boron and nitrogen are known, no adduct of ammonia to an inorganic borate has been observed so far. A new synthetic approach starting from the simple educts CdO, B₂O₃, and aqueous ammonia under conditions of 4.7 GPa and 800 °C led to the synthesis of Cd(NH₃)₂[B₃O₅(NH₃)]₂ as the first ammine borate. We thoroughly characterized this compound on the basis of low‐temperature single‐crystal and powder X‐ray diffraction data, IR and Raman spectroscopy, and by quantum theoretical calculations. This contribution shows that the adduct of NH₃ to the BO₃ group of a complex B–O network can be stabilized, opening up a fundamentally new synthetic route to nitrogen‐containing borates.     

Vibrational spectra and factor group analysis of rare-earth chromium borates,RCr3(BO3)4, with R = La–Ho

Anhydrous orthoborates RM₃(BO₃)₄, where R = Y, La–Lu, M = Al, Ga, Cr, Fe, with huntite structure type are considered as multifunctional laser materials. The crystal structure of these borates is either rhombohedral with space group R32 (D₃⁷) (Z = 3) or monoclinic with space group C2/c (C_2h⁶) (Z = 4) depending on the growth conditions. Both modifications have very close polytypic structures, and it is difficult to identify them by powder diffraction data. In this context, double borates of rare-earth cations and Cr³⁺ have been grown from high-temperature solutions and are characterized by Raman and infrared spectroscopy in a crystalline state in combination with factor group analysis of vibrational modes. The assignment for the stretching and bending vibrations of BO₃³⁻ groups and external modes has been made. Some external modes have been identified by study of mass effect (Al–Cr, La–Ho). Comparison of the Raman spectra of these borates shows redistribution of band intensities of two spectral modifications, related to different symmetry groups. As predicted by factor group analysis, the number of IR-active vibrational modes of stretching and bending vibrations of BO₃³⁻ units significantly increases in infrared spectra of monoclinic borates in comparison with rhombohedral ones. The dependence of the realized borate space group on the crystal growth conditions and the sort of rare-earth atom was revealed. Both GdCr₃(BO₃)₄ and EuCr₃(BO₃)₄ borates crystallize in space group R32 irrespective of growth conditions. The borates with the large rare-earth elements La–Nd always form the monoclinic structures, irrespective of crystallization temperature. The borates SmCr₃(BO₃)₄, TbCr₃(BO₃)₄ and DyCr₃(BO₃)₄ have been obtained in two modifications in dependence of crystalline borate substance/solvent ratio and related temperature of crystallization.     

Combined DTA and XRD Study of Sintering Steps Towards YAl3(BO3)4

Sintering processes in the Y₂O₃–Al₂O₃–B₂ O₃ system and its subsystems (Y₂O₃–B₂O₃ and Al₂ O₃–B₂O₃) have been investigated by using combined DTA and XRD measurements to get a better understanding of solid state chemical changes resulting in the formation of yttrium aluminum borate (YAl₃(BO₃)₄, YAB) phase and to study the possible role and contribution of various simple borates formed also in the former processes. Two new exothermic heat effects of YBO₃ formation have been detected by DTA in the Y₂O₃–B₂O₃ system between 720 and 980°C. In the Al₂O₃–B₂O₃ system a new experimental XRD profile of Al₄B₂O₉ was observed. Formation of these borates seems to promote the nucleation of double borate YAB below 1000°C. Conversion of Al₄B₂O₉ to Al₁₈B₄ O₃₃ was observed after a long term (10 h) sintering at 1050°C. Similarly, an increased formation of YAB has been observed as a product of the sintering reaction between YBO₃ and Al₁₈B₄O₃₃ at 1150°C. The two latter single borates are found to be identical with the high temperature decomposition products of YAB. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solvothermal Syntheses and Crystal Structures of Two Novel Borates: [(CH3)3NH][B5O6(OH)4] and Na2[H2TMED][B7O9(OH)5]2

Two novel borates [(CH₃)₃NH][B₅O₆(OH)₄] (I) and Na₂[H₂TMED][B₇O₉(OH)₅]₂ (II) have been synthesized under solvothermal conditions, and characterized by elemental analyses, FT-IR spectroscopy, and single crystal X-ray diffraction. Crystal data for I: monoclinic, P2₁/c, a = 9.3693(11) Å, b = 14.0375(17) Å, c = 10.0495(9) Å, β = 91.815(9)°, Z = 4. Crystal data for II: monoclinic, P2₁/c, a = 11.6329(2) Å, b = 11.9246(3) Å, c = 10.2528(2) Å, β = 100.178(2)°, Z = 4. Their crystal structures both have 3D supramolecular framework with large channels constructed by O–H···O hydrogen-bonding among the polyanions of [B₅O₆(OH)₄]^? or [B₇O₉(OH)₅]^2? clusters. The templating organic amines cations in I and II are both located in the channels of 3D supramolecular frameworks, respectively, and interact with the polyborate frameworks both electrostatically and via hydrogen bonds of N–H···O. Na₂[H₂TMED][B₇O₉(OH)₅]₂ is the first example of heptaborate co-templated by alkali metal and organic base, which is also rare in borates. The photoluminescence property of the synthetic sample of Na₂[H₂TMED][B₇O₉(OH)₅]₂ in the solid state at room temperature was also investigated by fluorescence spectrophotometer.     

UPON SOME INORGANIC HETEROCYCLES IN THALLIUM (I) BORATES AND GERMANATES

Abstract

The structural study of some hydrated thallium (I) borates shows the existence of macroionic chains which can be considered as condensed heterocycles. In Tl [B₃O₄(OH)₂] 0.5H₂O, the unit is the well known B₃O₃ ring; it is formed by two BO₃ triangles (Δ) and one BO₄ tetrahedron (T); these units are linked to form an infinite chain; its shorthand notation is 3:∞¹ (2Δ + T). The structure of Tl₄ [B₇O₁₀(OH)₃ · OBO(OH)] H₂O contains a unit constituted by three B₃O₃ rings linked together by boron atoms; each ring is formed by two BO₄ tetrahedra and one BO₃ triangle; the corresponding fully hydrated polyanion is [B₇O₉(OH)₇]^4-. The chain is made up of units linked by BO₂(OH) triangles; the shorthand notation of this borate is: 7:∞¹ [(3Δ + 4T) + Δ].

The structure of Tl₈Ge₅O₁₄ is composed of isolated Ge₅O₁₄ units; they are formed by a crown of four GeO₄ tetrahedra linked by shared oxygens; two other oxygens of two of these GeO₄ tetrahedra belong also to a fifth GeO₄ tetrahedron which is located at the center of the crown.     

RbMT3(BO3)2O3 (M=Ba,Sr; T=Al,Ga): New Double-Layered Oxyborates Constructed from [BO3] Triangles and [TO4] Tetrahedra

Four new alumino-/galloborates RbMT₃(BO₃)₂O₃ (M=Ba, Sr; T=Al, Ga) have been synthesized for the first time by using a high-temperature solution method. All the title compounds have Sr₂Be₂B₂O₇-like structures, in which the [BO₃] triangles and [TO₄] tetrahedra form the final double-layered configurations with the M- and Rb-site atoms located between and in the double layer, respectively. The structure evolution from Sr₂Be₂B₂O₇ to RbMT₃(BO₃)₂O₃ series is discussed. The broader energy bandgaps in Al-based borates when compared with Ga-based ones can be entirely attributed to the location of Al/Ga s orbitals near the Fermi surface. Both experimental and computational approaches were used to study their structure-property relationships.     

Synthesis of glass ceramics containing finely dispersed particles of aluminum-doped M-type strontium hexaferrite

Glasses with nominal compositions SrFe₁₀Al₂O₁₉+4(SrB₂O₄+Sr₂B₂O₅) (1) and SrFe₉Al₃O₁₉+4(SrB₂O₄+Sr₂B₂O₅) (2) were prepared by rapid quenching of melts. Thermal treatment of glass samples at 600–900 °C resulted in crystallization of the magnetic phase SrFe_12−x Al_xO₁₉ (x = 1.1±0.1) and strontium borates. Platelet hexaferrite particles with average sizes from (250×60) nm² to (450×140) nm² were prepared. The coercive force of glass ceramics is 580 and 475 kA m⁻¹ for glasses 1 and 2, respectively. The coercive force of 580 kA m⁻¹ is the highest known value compared to hexaferrite particles prepared earlier by glass crystallization.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 74–77, January, 2005.     

Synthesis and thermochemistry of SrB2O4·4H2O and SrB2O4

Two pure strontium borates SrB₂O₄·4H₂O and SrB₂O₄ have been synthesized and characterized by means of chemical analysis and XRD, FT-IR, DTA-TG techniques. The molar enthalpies of solution of SrB₂O₄·4H₂O and SrB₂O₄ in 1 mol dm⁻³ HCl(aq) were measured to be −(9.92 ± 0.20) kJ mol⁻¹ and −(81.27 ± 0.30) kJ mol⁻¹, respectively. The molar enthalpy of solution of Sr(OH)₂·8H₂O in (HCl + H₃BO₃)(aq) were determined to be −(51.69 ± 0.15) kJ mol⁻¹. With the use of the enthalpy of solution of H₃BO₃ in 1 mol dm⁻³ HCl(aq), and the standard molar enthalpies of formation for Sr(OH)₂·8H₂O(s), H₃BO₃(s), and H₂O(l), the standard molar enthalpies of formation of −(3253.1 ± 1.7) kJ mol⁻¹ for SrB₂O₄·4H₂O, and of −(2038.4 ± 1.7) kJ mol⁻¹ for SrB₂O₄ were obtained.     

Zwei Fluoridborate des Gadoliniums: Gd2F3[BO3] und Gd3F3[BO3]2

Two Fluoride Borates of Gadolinium: Gd₂F₃[BO₃] and Gd₃F₃[BO₃]₂ By flux‐supported solid‐state reaction of Gd₂O₃ and GdF₃ with B₂O₃ (flux: CsCl, molar ratio: 1 : 1 : 1 : 6, sealed tantalum capsule, 700 °C, 7 d) the new gadolinium fluoride borate Gd₂F₃[BO₃] (monoclinic, P2₁/c; a = 1637.2(1), b = 624.78(4), c = 838.04(6) pm, β = 93.341(8)°; V_m = 64.418(6) cm³/mol, Z = 8) was obtained as colourless, prismatic, face‐rich single crystals. The four crystallographically different Gd³⁺ cations (CN = 9) are all capped square‐antiprismatically surrounded by fluoride and oxide anions, in which the latter represent always components of isolated trigonal planar [BO₃]^3— anions. The six crystallographically independent F^— anions all reside in more or less planar coordination of three Gd³⁺ cations. Thus the constitution of Gd₂F₃[BO₃] can be described as a sequence of alternating layers each of the composition Gd[BO₃] and GdF₃ parallel (100), respectively. The crystal structures of Gd₂F₃[BO₃] and the shortly published Gd₃F₃[BO₃]₂ (monoclinic, C2/c; a = 1253.4(1), b = 623.7(1), c = 836.0(1) pm, β = 97.404(6)°; V_m = 97.571(9) cm³/mol, Z = 4) are compared with each other. Due to the structural analogies between these two gadolinium fluoride borates, a disorder model of the boron atoms frequently found for Gd₂F₃[BO₃] is able to be transferred to Gd₃F₃[BO₃]₂ as well.     

The new pentaborate Na3SrB5O10

Sodium strontium pentaborate, Na₃SrB₅O₁₀, maintains the same, previously unobserved, structure type at 200, 250 and 293 K. The fundamental building units are anionic [B₅O₁₀]⁵⁻ groups distorted from mm2 point symmetry. The Sr atoms are eightfold coordinated by O atoms, forming trigonal dodecahedra. The Na atoms appear in three crystallographically different environments. The present single‐crystal results correct a previous report in which a monoclinic cell was deduced for this compound on the basis of powder diffraction data. The structure of the title compound is discussed in the crystalochemical context of other borates with the same formula type. Although the unit cell of the present compound is similar to that determined in a previous study of the analogous Ca‐containing compound, this study demonstrates that the structures of the two are different. These novel alkali–alkaline earth borates are considered as potential host materials for optical applications (fluorescence materials or phosphors).     

Transesterification of glyceryl tributyrate with methanol using strontium borate as the solid base catalyst

Four kinds of strontium borates were prepared and characterized by XRD, SEM, EDS, TG-DTA and Hammett titration method, and their catalytic activities were examined in the transesterification of glyceryl tributyrate with methanol for the first time. The separate effects of the molar ratio of methanol to oil, the reaction time, and reusability were investigated. In addition, the catalytic activities of Sr(OH)₂ and SrCO₃ were also examined for the comparison. The results showed that the basicity and catalytic activity of these catalysts were decreased as the following order: Sr(OH)₂ > SrB₂O₄·4H₂O > SrB₆O₁₀·5H₂O > SrB₂O₄ > SrB₆O₁₀ > SrCO₃, and the reusability decreases as the following order: anhydrous strontium borates (SrB₂O₄, SrB₆O₁₀) > hydrated strontium borates (SrB₂O₄·4H₂O, SrB₆O₁₀·5H₂O) > Sr(OH)₂. The results indicate that the SrB₂O₄·4H₂O with regular morphology, which was obtained at low temperature by a simple preparation method, might be as one kind of good potential alkaline earth salts catalyst for transesterification. Moreover, the possible reaction mechanism is proposed and analyzed.     

Oxonium Ions Substituting Cesium Ions in the Structure of the New High‐Pressure Borate HP‐Cs1−x(H3O)xB3O5 (x=0.5–0.7)

The new high‐pressure borate HP‐Cs_1?x(H₃O)_xB₃O₅ (x=0.5–0.7) was synthesized under high‐pressure/high‐temperature conditions of 6 GPa/900 °C in a Walker‐type multianvil apparatus. The compound crystallizes in the monoclinic space group C2/c (Z=8) with the parameters a=1000.6(2), b=887.8(2), c=926.3(2) pm, β=103.1(1)°, V=0.8016(3) nm³, R1=0.0452, and wR2=0.0721 (all data). The boron–oxygen network is analogous to those of the compounds HP‐MB₃O₅, (M=K, Rb) and exhibits all three structural motifs of borates—BO₃ groups, corner‐sharing BO₄ tetrahedra, and edge‐sharing BO₄ tetrahedra—at the same time. Channels inside the boron–oxygen framework contain the cesium and oxonium ions, which are disordered on a specific site. Estimating the amount of hydrogen by solid‐state NMR spectroscopy and X‐ray diffraction led to the composition HP‐Cs_1?x(H₃O)_xB₃O₅ (x=0.5–0.7), which implies a nonzero phase width.     

Synthesis, Characterization and Thermochemistry of 2MgO：B2O3：1.5H2O

Introduction　　 2MgO·B2 O3(Mg2 B2 O5)and 2MgO·B2 O3·H2 Omightbepreparedaswhiskermaterials .12MgO·B2 O3·H2 OnamedszaibelyiteisamagnesiumboratemineralwithastructuralformulaofMg2 [B2 O4 (OH) 2 ].2 Itisdifficulttosynthesizethiscompoundinthelaboratory .Recently ,weobtainedasimilarcompound 2MgO·B2 O3·1 5H2 Owhenwetriedtopreparewhiskerof 2MgO·B2 O3·H2 Obythephasetransformationof 2MgO·2B2 O3·MgCl2 ·14H2 OinH3BO3solutionunderhydrothermalcondition .Itishope fultopreparewh…     

白硼钙石的合成新方法及其热化学研究(英)

0IntroductionTherearemanykindsofhydratedcalciumbo-rates,bothnaturalandsynthetic.Someofthemarematerialsusedinglass,potteryandporcelainenamelindustry,especiallyinunalkaliglassindustry.4CaO·5B2O3·7H2O,calledpriceite,isacalciumboratemin-eral,notfoundinCaO-B…     

Pr(BO2)3 und PrCl(BO2)2: Zwei meta‐Borate des Praseodyms im Vergleich

Pr(BO₂)₃ and PrCl(BO₂)₂: Two Praseodymium meta‐Borates in Comparison Single‐crystalline PrCl(BO₂)₂ can be obtained by the reaction of praseodymium, Pr₆O₁₁ and PrCl₃ with a small excess of B₂O₃ in evacuated silica tubes after seven days at 850 °C. If NaCl is additionally used as flux, single crystals of Pr(BO₂)₃ dominate the main product. Both praseodymium(III) meta‐borates are air and water stable. The crystals of PrCl(BO₂)₂ emerge as long, thin, pale green needles which tend to severe twinning due to their fibrous habit. The crystal structure (triclinic, P1¯; a = 420.56(4), b = 655.42(7), c = 808.34(8) pm, α = 82.361(8), β = 89.173(9), γ = 71.980(7)°, Z = 2) exhibits zigzag chains {[(B1)o^t_1/1O^e_2/2(B2)O^t_1/1O^e_2/2]²⁻} (≡ {[BO₂]⁻}) of corner‐linked [BO₃]³⁻ triangles with syndiotactic orientation of the terminal oxygen atoms which are running parallel to the [100] direction. The Pr³⁺ cations are surrounded by three Cl⁻ and seven O²⁻ anions with the shape of a tetracapped trigonal prism. The green, transparent crystals of Pr(BO₂)₃ (monoclinic, C2/c; a= 984.98(9), b = 809.57(8), c = 641.02(6) pm, β = 126.783(9)°, Z = 4) appear either lath‐shaped or rather spherical. In the crystal structure the B³⁺ cations reside both in trigonal planar as well as in tetrahedral coordination of oxygen atoms. Both types of borate polyhedra ([BO₃]³⁻ and [BO₄]⁵⁻) are linked via corners to form chains of the composition {[(B2)‐O^t_1/1O^e_2/2(B1)O^e_4/2(B2)O^t_1/1O^e_2/2]³⁻} (≡ {[BO₂]⁻}) which run parallel [101]. The coordination sphere of the Pr³⁺ cations consists of ten oxide anions which build up a bicapped square antiprism.