Chromium and vanadium impurities in natural green euclase and their relation to the color

The giant magnetic anisotropy energy of Fe+ ions in SrCl2

“…2 This value is much higher than ZFS parameter values, |D|, measured for usual Kramers ions in inorganic insulators involving simple anions like F À , Cl À or O 2À . In these cases, |D| is typically found to be in the range 0.01-1 cm À1 for common impurities 4,5,12 like Fe 3+ , Cr 3+ or Mn 2+ . Understanding the origin of large ZFS is the key to designing better materials in these fields.…”

“…15 This idea is consistent with the experimental g > = 2.60 and g J = 2.02 values measured 13 for SrCl 2 : Fe + , which exhibit a much higher anisotropy than that encountered for the 3d 3 Cr 3+ impurity in oxides where |g > À g J | usually lies between 0.003 and 0.01. 4,12 Moreover, the fact that the EPR signal in SrCl 2 : Fe + is not reduced when approaching 4.2 K 14 suggests that D should be positive. Another interesting aspect of large MAEs in off-center impurity sites is that these materials display a magnetoelectric effect similar to that of multiferroic systems 16 since the direction of distortion and the magnetic easy-axis associated with it can be changed by applying electric fields.…”

“…Let us now focus on the microscopic origin of the giant D value calculated for SrCl 2 : Fe + which is at least 50 times larger than the largest values measured for Fe 3+ , Cr 3+ or Mn 2+ in inorganic insulating materials. 4,5,12 The ZFS parameter, D, of ions with S 4 1/2 originates from the combined action of both spin-orbit coupling and axial distortion. Due to the spin-orbit coupling, the ground state with S = 3/2 can be mixed with excited states with the same spin but also with states of the d 7 manifold with S = 1/2.…”

Mn3+ and the pink color of gem-quality euclase from northeast Brazil

“…DOI: https://doi.org/10.2138/am-2021-7838. http://www.minsocam.org/ Cr 3+ (Krambrock et al, 2008). Fe-substitution in the Al-site is at the origin of a Fe 2+ -Fe 3+…”

Combustion Synthesis of Some Cr3+-Activated Aluminate Phosphors

“…Several investigations have been devoted to study of this emission. Apart from a better knowledge of gemstones like ruby (Al 2 O 3 :Cr 3+ ) [1], emerald (Be 3 Si 6 Al 2 O 18 :Cr 3+ ) [2], alexandrite (BeAl 2 O 4 :Cr 3+ ) [3], and ruby spinel (MgAl 2 O 4 :Cr 3+ ) [4], as well as other minerals containing Cr 3+ [5][6][7][8], such investigations have given rise to the development of devices like lasers and high-pressure manometers [9]. The first solid-state laser was realized in ruby [10] while Cr 3+ -doped chrysoberyl (Be 2 AlO 4 ) known as alexandrite is also widely used tunable solid-state laser [11].…”