Thermochemical properties of two mixed alkali-alkaline earth metal borates with NLO properties for NaCaBO3 and Li4CaB2O6

Two alkali-alkaline earth metal borates with NLO properties for NaCaBO 3 and Li 4 CaB 2 O 6 have been synthesized and characterized by XRD, FT-IR, and chemical analysis. The molar enthalpies of solution of NaCaBO 3 (s) and Li 4 CaB 2 O 6 (s) in 2.00 cm 3 of 1 mol·dm −3 HCl (aq) were measured by microcalorimeter at T  = 298.15 K, respectively. The molar enthalpies of solution of CaCl 2 ·2H 2 O(s) in the mixture solvent of 2.00 cm 3 of (1 mol·dm −3 HCl + H 3 BO 3  + NaCl) (aq), and {2.00 cm 3 of 1 mol·dm −3 HCl + H 3 BO 3  + LiCl·H 2 O} (aq) were also measured, respectively. With the incorporation of the previously determined enthalpies of solution of H 3 BO 3 (s) in 2.00 cm 3 of 1 mol·dm −3 HCl (aq), NaCl (s) in the mixture solvent of (2.00 cm 3 of 1 mol·dm −3 HCl + H 3 BO 3 ) (aq) and LiCl·H 2 O(s) in the mixture solvent of {2.00 cm 3 of 1 mol·dm −3 HCl + H 3 BO 3 } (aq), together with the standard molar enthalpies of formation for CaCl 2 ·2H 2 O (s), NaCl(s)/LiCl·H 2 O (s), H 3 BO 3 (s), HCl (aq) and H 2 O (l), the standard molar enthalpies of formation of – (1664.5 ± 0.9) kJ·mol −1 for NaCaBO 3 (s) and – (3391.7 ± 1.9) kJ·mol −1 for Li 4 CaB 2 O 6 (s) at T  = 298.15 K were obtained on the basis of the appropriate thermochemical cycles .