Observations of the Ferroelastic Domain Structure of MP5O14 (M: La–Tb) by means of Scanning Tunneling Microscope, Electron Spin Resonance and X-Ray Diffraction

The ferroelasticity of rare earth pentaphosphate, MP5O14 (M: La-Tb) belonging to the species mmmF2/m is studied by scanning tunneling microscope (STM), electron spin resonance (ESR) and X-ray diffraction. The temperature dependence (from room temperature to 180°C) of ferroelastic domain structure and monoclinic β angle of EuP5O14 was obtained by STM and X-ray diffraction (ω scan technique). The spin Hamiltonian parameters of LaP5O14:Cr3+ at 150°C in the para phase obtained from the ESR spectra are g x = g y = g z =1.97, D = 0.45 cm-1 and E = 0.05 cm-1. The principal axes of one of the Cr3+ paramagnetic centers are given by the Eulerian angles φ=15°, θ=90° and ψ= 0°.