A correlation between the structural and magnetic phase transitions for the mixed systems: KMn1-xNixF3 and KMn1-xCoxF3 I. Structural phenomena

X-ray diffraction measurements of the lattice parameters as a function of temperature are reported for the mixed compounds KMn_1-xNi_xF₃ and KMn_1-xCo_xF₃ where x 0.10. From the splitting of the cubic 400 Bragg reflections the transition temperatures of the structural phase transitions were determined. In the KMn_0.99Co_0.01F₃ and KMn_0.97Ni_0.03F₃ crystals three structural phase transitions were established. It was concluded that higher admixture quantities lead to a change in phase transition character which appeared to be smeared over a temperature range.