The solubility properties of the Zn(NO~3)~2-His/Met/Phe-H~2O systems at 25℃ in the whole concentration ranges have been investigated by semimicro phase equilibrium method. The corresponding equilibrium diagrams and refractive index diagrams were constructed. The congruently soluble compounds of Zn(His)(NO~3)~2.(1/2)H~2O and Zn(Met) (NO~3)~2.(1/2)H~2O and incogruently soluble compounds of Zn(Met)~3 (NO~3)~2.H~2O, Zn(Phe)(NO~3)~2.H~2O and Zn(Phe)~3(NO~3)~2.H~2O, which have not been reported in the literature are discovered and synthesized. These compounds are charactered by IR spectroscopy, X- ray diffraction, TG-DTG, as well as chemical and elemental analyses.

Key words: ZINC NITRATE, AMINO ACID, ZINC COMPLEX, PHASE EQUILIBRIUM, THERMAL STABILITY, TERNARY SYSTEM, STRUCTURE CHARACTERISTICS, ELEMENTAL ANALYSIS, INFRARED SPECTROPHOTOMETRY, X-RAY DIFFRACTION ANALYSIS