The elastic constantsC₁₁,C₁₂ andC₄₄ of sodium chlorate single crystal have been evaluated using 10 MHz ultrasonic pulse echo superposition technique. The values areC₁₁=4.90,C₁₂=1.39,C₄₄=1.17 (× 10¹⁰N/m²) at 298 K and 6.15, 2.16, 1.32 (×10¹⁰N/m²) at 77 K. The data agree well with the values measured earlier up to 223 K. Brief mention is also made of the low temperature bonding problems in these soft crystals.

The elastic constantsC₁₁,C₁₂ andC₄₄ of sodium bromate single crystals have been evaluated using 10 MHz ultrasonic pulse echo superposition technique. The values areC₁₁=5.57₈,C₁₂=1.07₅,C₄₄=1.51₀ (×10¹⁰ N/m²) at 290 K and 6.35, 1.98 and 1.65 (×10¹⁰ N/m²) at 77 K. The present room temperature values agree closely with the recent values of Gluyaset al. but the other earlier measurements show some scatter. A comparison between the elastic constants of sodium bromate and sodium chlorate is also made.