Structure (neutron) of potassium iodate at 100 and 10 K

KIO3, Msub(r)=214.001, P1, Z=4, neutron powder diffraction (Rietveld method), lambda=1.9090(1) A, F(000)=320, Dsub(m)(300 K)=3.89 g cm-3; at T=100 K: a=7.6982(4), b=7.6597(2), c=7.6912(5) A, α=108.999(5), β=109.745(2), γ=109.085(5)0, V=351.60(2) A3, Dsub(chi)=4.04 g cm-3, Rsub(I)=8.12% for 799 integrated Bragg intensities; at T=10 K: a=7.6818(5), b=7.6504(3), c=7.6896(5) A, α=109.062(5), β=109.786(2), γ=109.012(5)0, V=350.22(3) A3, Dsub(chi)=4.06 g cm-3, Rsub(I)=7.95% for 786 integrated Bragg intensities. The previously reported phase transitions to phase IV (below 263 K) and phase V (below 83 K) are found not to involve significant atomic-scale change to the room-temperature phase III triclinic structure. The observed marked variations in the ferroelectric behaviour that prompted the transitions proposal are considered to originate from domain- or twin-scale changes within the sample. (orig./BUD)