ABSTRACTIV-VI semiconductor Pb1−xsSnxsSe1−ysTeys quaternary alloys were grown on (111) BaF2 by liquid phase epitaxy (LPE). X-ray diffraction analysis shows that liquid (Pb1−x1Snx1)0.99(Se1−y1Tey1)0.01 solutions produce alloys lattice-matched with the substrate wheny1 = 60%, 58%, and 57%, and x1 = 20%, 40%, and 60%, respectively. These data suggest that the chemical potential of tellurium in the Pb1−xsSnxsSe1−ysTeys solid solution decreases as tin and tellurium concentrations increase. It is argued that this reduction is due to decreasing strain energy driven segregation of tellurium from the solid to the liquid as the tin concentration increases.