New improvements of CrO2-related magnetic recording materials

The increase in the magnetocrystalline anisotropy of chromium dioxide by substitution of Cr (IV) with Rh (IV) or Ir (IV) has led the authors to study the Cr
1-x
Rh
x
O
2
and Cr
1-x
Ir
x
O
2
solid solutions. The use of H
3
BO
3
as buffer agent or iron oxalate in the crystal growth process reduces the particle size and greatly improves the coercive field of Cr
1-x
Ir
x
O
2
even at low Ir concentrations (
x \simeq 5.10^{-4}
).