Thermochemical property of a microporous material for mixed metal borate of Li 2 Sr 4 B 12 O 23

A pure mixed alkali–alkaline earth metal borate of Li 2 Sr 4 B 12 O 23 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 Li 2 Sr 4 B 12 O 23 in 1 mol L −1 HCl(aq), and of SrCl 2 ·H 2 O(s) in [1 mol L −1 HCl + H 3 BO 3 + LiCl·H 2 O](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 H 3 BO 3 (s) in 1 mol L −1 HCl(aq), and of LiCl·H 2 O(s) in [1 mol L −1 HCl + H 3 BO 3 ](aq), together with the use of the standard molar enthalpies of formation for SrCl 2 ·6H 2 O(s), LiCl·H 2 O(s), H 3 BO 3 (s), HCl(aq), and H 2 O(l), the standard molar enthalpy of formation of −(11,534.0 ± 10.0) kJ mol −1 for Li 2 Sr 4 B 12 O 23 was obtained on the basis of the appropriate thermochemical cycle.