Structural, magnetic and magnetostrictive properties of Tb0.2Pr0.8(Fe0.4−xCo0.6+x)1.93 (0 ⩽ x ⩽ 0.2) alloys have been investigated by means of x-ray diffraction, ac initial susceptibility, a superconducting quantum interference device magnetometer and a standard strain gauge technique. A single (Tb, Pr)(Fe, Co)2 Laves phase with a cubic MgCu2-type structure is formed when 0.05 ⩽ x ⩽ 0.2. Increasing the Co content in the Tb0.2Pr0.8(Fe0.4−xCo0.6+x)1.93 alloys reduces the magnetocrystalline anisotropy constant K1 and improves the magnetostrictive properties at relatively low magnetic fields at room temperature. The Tb0.2Pr0.8(Fe0.35Co0.65)1.93 alloy with a single Laves phase has a spontaneous magnetostriction λ111 as high as 1900 ppm, a large magnetostriction λa (= λ∥ − λ⊥) at a relatively low magnetic field and a large λa/K1, and may make it a promising magnetostrictive material.

Nd2Fe14B/Nd-O thin films with high-energy product (BH)max = 33.9 MGOe are fabricated by a one-step sputtering process, i.e. dc magnetron sputtering on a Si substrate heated at 600–650 °C, without a post-deposition annealing process. The highly anisotropic Nd-Fe-B/Nd-O thin film with high-energy product is realized immediately after the deposition, owing to the anisotropic growth of both the Nd-O and the Nd2Fe14B phases. The coexistence of the nanoscale Nd2Fe14B and Nd-oxide phases in the thin films is confirmed by means of x-ray diffraction, high-resolution transmission electron microscopy (HRTEM) and energy-filtered transmission electron microscopy. The boundaries between the buffer layer and the Nd-Fe-B layers and the different phases are investigated by HRTEM.