Gao Shiyang

FT-IR spectroscopy of supersaturated aqueous solutions of magnesium borate.

FT-IR spectra of supersaturated aqueous solution of magnesium borate, its acidized solutions with azeotropic hydrochloric acid, and its diluted solutions with water have been recorded. The FT-IR spectra of borate in solution are obtained by difference, subtracting the FT-IR spectrum of water from that of the magnesium borate supersaturated aqueous solution. All of the results showed that various polyborate anions in the supersaturated aqueous solutions exist. The bands of symmetric pulse vibration of the corresponding polyborate anions were indicated and some assignments were tentatively given.

Thermodynamic parameters of the interaction of CsCl with monosaccharide (d-glucose, d-galactose, d-xylose, and d-arabinose) in water at

Abstract A non-liquid-junction electrochemical cell composed of a potassium ion selective electrode(K-ISE) against a chloride ion selective electrode (Cl-ISE) as a reference electrode was employed to study the thermodynamic parameters of weak interactions between aqueous cesium chloride and the monosaccharides ( d -glucose, d -galactose, d -xylose, and d -arabinose) at T=298.15 K . Activity coefficients for this system obtained from electromotive force measurements indicate that they have a close relationship with the stereostructure of the saccharide. The Gibbs free energy pair interaction parameters and salting constants were also evaluated; these can characterize the interaction between the saccharides and CsCl in water. The results were interpreted on the basis of a model of structural and electrostatic interaction and the hydration effect of the hydroxyl ion of these saccharides.

Thermochemistry of ulexite

Abstract The enthalpy of solution of ulexite NaCa[B 5 O 6 (OH) 6 ]·5H 2 O in ≈1 mol dm −3 aqueous hydrochloric acid has been measured. From this result and the enthalpies of solution of H 3 BO 3 in HCl(aq), of CaO in aqueous (hydrochloric acid + boric acid), and of NaCl in aqueous (hydrochloric acid + boric acid + calcium oxide), the standard molar enthalpy of formation of ulexite of −6762.24 ± 4.22 kJ mol −1 has been obtained. The standard molar entropy of formation of ulexite was calculated from the thermodynamic relation with the standard molar Gibbs free energy of formation of ulexite computed from its solubility in water.

Crystal structure and characterization of Rb2Ca[B4O5(OH)4]2·8H2O

Abstract Dirubidium calcium tetraborate octahydrate, Rb 2 Ca[B 4 O 5 (OH) 4 ] 2 ·8H 2 O, was prepared by reaction of Rb-borate aqueous solution with CaCl 2 and its structure has been determined by single-crystal X-ray diffraction data. It crystallizes in the orthorhombic system, space group P 2 1 2 1 2 1 with unit cell parameters, a=11.536(2) A , b=12.639(2) A , c=16.690(4) A ; Z =4, V=2433.5(8) A 3 . The structure contains alternate layers of [B 4 O 5 (OH) 4 ] 2− polyanions separated by water molecules and Rb, Ca cations. The isolated [B 4 O 5 (OH) 4 ] 2− is constructed from two BO 3 (OH) tetrahedron groups and two BO 2 (OH) triangular groups joined at common oxygen atoms. The two BO 3 (OH) tetrahedron groups are further linked by means of an oxygen bridge across the ring. The Ca 2+ ion displays seven coordination, while the two non-equivalent Rb + ions display nine and seven coordination, respectively. Infrared and Raman (4000–400 cm −1 ) spectra of Rb 2 Ca[B 4 O 5 (OH) 4 ] 2 ·8H 2 O were recorded at room temperature and analyzed. Fundamental vibrational modes were identified and band assignments were made. The dehydration of this hydrated mixed borate occurs in one step and leads to an amorphous phase which undergoes a crystallization.

Crystal structure and thermal behavior of Rb2Co[B6O7(OH)6]2·4H2O

Abstract A crystal of the complex borate Rb 2 Co[B 6 O 7 (OH) 6 ] 2 ·4H 2 O was synthesized in the molar ratio Rb 2 O/CoCl 2 /B 2 O 3 =4:1:9, and its structure was determined by single-crystal X-ray diffraction. It belongs to the P 1 triclinic space group, with the following unit cell parameters: a =7.549(1) A, b =7.872(1) A, c =10.980(2) A, α =107.87(1)°, β =94.83(1)°, γ =90.27(1)°, Z =2, V =618.45(19) A 3 . The crystal structure was solved from 2162 independent reflections until R =0.0127. The crystal structure of Rb 2 Co[B 6 O 7 (OH) 6 ] 2 ·4H 2 O consists of [B 6 O 7 (OH) 6 ] 2− polyborate anions, Co–O octahedra and Rb–O polyhedra. The isolated [B 6 O 7 (OH) 6 ] 2− polyborate anions are separated by free water molecules and Rb and Co cations. Dehydration of this hydrated mixed borate occurs in two steps and leads to an amorphous phase which undergoes crystallization.

FT-IR and Raman spectroscopic study of hydrated rubidium (cesium) borates and alkali double borates

FT-IR and Raman spectra of five hydrated alkali borates and five hydrated alkali double borates have been recorded at room temperature in the range 400 to 4000 cm−1, and analyzed. Fundamental vibrational modes have been identified and assignments tentatively made in comparison with the work of Janda and Heller, and Li Jun.

Thermal decomposition of K2O.CaO.4B2O3.12H2O

Abstract Thermal decomposition of K 2 O·CaO·4B 2 O 3 ·12H 2 O has been investigated by isothermal, non-isothermal methods. X-ray and FT-IR spectra determined the isothermal dehydrated products. The results showed that it is a multi-stage course. Structure and thermal decomposition mechanism of K 2 O·CaO·4B 2 O 3 ·12H 2 O were discussed.