X-ray powder analysis of solid solution of NaH₂PO₄ and KH₂PO₄ with H₃BO₃ was carried out. Both the systems were observed to be tetragonal. The crystallographic data are reported.

A new optical interferometric technique to measure the electrostrictive coefficients of XH₂PO₄/H₃BO₃ binaries (where X=Na, K and NH₄) is reported. This direct method is found to be advantageous in measuring the positive as well as the negative sign of the electrostrictive coefficients. Design of the apparatus and its merits are discussed. In XH₂PO₄/H₃BO₃ binaries the addition of boric acid is found to decrease the value of binary electrostriction coefficient in comparison to their pure samples.

Thermomechanical properties like thermal expansion (α_c) and electrostriction along with ΔH and transition temperature are reported for the KNO₂-H₃BO₃ binary phase. The transition is classified as second order phase transition. Some of these properties were compared with those of its pure compound. On the basis of thermodynamic properties it is predicted that binary phase is more stable rather than its pure phase.

Linear thermal expansion coefficient, dielectric data and transition temperature of KH₂PO₄-H₃BO₃ binary are reported. The transition temperature obtained from differential scanning calorimetry (DSC) is in concurrence with the dielectric and thermal expansion data. Further, this transition is classified as first order. Thermal expansion coefficients and enthalpy values of the binary are reported and compared with the data of pure KH₂PO₄.