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α-4CaO·5B 2 O 3 ·7H 2 O (sheet-like structure) and three polymorphs of β-4CaO·5B 2 O 3 ·7H 2 O (flower-like, succulent plant-like and book-like structure) were prepared by hydrothermal method, and characterized by XRD, FTIR, TG-DTA-DTG, SEM. The activation energies (Ea) of the two-step thermal dehydration of 4CaO·5B 2 O 3 ·7H 2 O with different morphologies and phases were calculated by Kissinger-Akahira-Sunoes (KAS) method. The most probable mechanism function of the two-step dehydration reaction was determined by Coats-Redfern (CR) method, and the average pre-exponential factor (A) of the two-step thermal dehydration of the sample was calculated. The results showed that the thermal dehydration of 4CaO·5B 2 O 3 ·7H 2 O was divided into two steps. The activation energy of thermal dehydration reaction was affected by the phase, morphology and particle size. The activation energies of the two-step thermal dehydration of β-4CaO·5B 2 O 3 ·7H 2 O(flower-like, succulent plant-like and book-like structure) all decrease in turn, which is consistent with the change trend of particle size. The average pre-exponential factor of the first-step thermal dehydration of all samples is smaller than that of the second-step thermal dehydration. The mechanism functions of the first-step and second-step thermal dehydration stages are Jander equation [1-(1-α)1/3]2 and Z-L-T equation [(1-α)−1/3-1]2, respectively, which belong to three-dimensional diffusion. The three-dimensional diffusion process of the two-step thermal dehydration was analyzed and explained. [Display omitted] • α-4CaO·5B 2 O 3 ·7H 2 O and three polymorphs of β-4CaO·5B 2 O 3 ·7H 2 O were prepared by hydrothermal method. • The activation energy of thermal dehydration reaction is affected by the phase, morphology and particle size. • The activation energy of β-4CaO·5B 2 O 3 ·7H 2 O two-step thermal dehydration varies with its orphology. • The mechanism functions of the first-step and second-step thermal dehydration stage were proposed. • The three-dimensional diffusion process of the two-step thermal dehydration is analyzed and explained. [ABSTRACT FROM AUTHOR]

Sheet-like and rod-like nano Ca 5 (PO 4) 3 (OH):0.05 Eu3+, xLi+(x = 0.01−0.07) phosphors were prepared by hydrothermal method. The structure, morphology and luminescent properties of samples were characterized by XRD, EDS, SEM, TEM and PL. The effects of morphology and Li+ doping on the luminescent properties of Ca 5 (PO 4) 3 (OH):Eu3+ were studied. The results show that Li+ doping has little effect on the luminescent peak position and CIE color coordinate of sample, but it affects the crystallinity of sample and effectively improves its luminescence intensity. It was found that the luminescent properties of the samples were greatly affected by their morphology. The optimum Li+ doping amounts of nano sheet-like and rod-like Ca 5 (PO 4) 3 (OH):0.05 Eu3+, xLi+ are 5 mol% and 3 mol% respectively. The luminescent intensity of the sheet-like sample was stronger than that of the rod-like sample. The luminescent lifetimes of nano rod-like sample is longer than that of the nano sheet-like sample. [ABSTRACT FROM AUTHOR]

Polycrystalline 4ZnO·B 2 O 3 ·H 2 O with flower-like, spherical-like and sheet-like morphologies have been synthesized and characterized by XRD, TG–DSC, SEM and TEM. The molar enthalpies of solution of 4ZnO·B 2 O 3 ·H 2 O with different morphologies in 1 mol L−1 HCl(aq) were measured. With the incorporation of the previously determined enthalpy of solution of H 3 BO 3 in 1 mol L−1 HCl(aq), the enthalpy of solution of ZnO in (HCl + H 3 BO 3)(aq) and the standard molar enthalpies of formation of ZnO(s), H 3 BO 3 (s) and H 2 O(l), the standard molar enthalpies of formation of 4ZnO·B 2 O 3 ·H 2 O with flower-like, spherical-like, and sheet-like morphologies were calculated to be -(3033.91 ± 2.03), -(3030.91 ± 2.03) and -(3025.94 ± 2.04) kJ·mol−1, respectively. [Display omitted] • The standard molar enthalpies of formation of 4ZnO·B 2 O 3 ·H 2 O with three different morphologies were measured. • The enthalpies of solution of 4ZnO·B 2 O 3 ·H 2 O with three different morphologies were determined by microcalorimeter. • The standard molar enthalpies of formation of 4ZnO·B 2 O 3 ·H 2 O with different morphologies are different. [ABSTRACT FROM AUTHOR]