Exploring the Colour of 3d Transition‐Metal Ions in Trigonal Bipy­ramidal Coordination: Identification of Purple‐Blue (CoO₅) and Beige‐Red (NiO₅) Chromophores in LiMgBO₃Host

Abstract

Abstract:In an attempt to develop new coloured inorganic oxides, we have investigated the substitution of 3d transitionmetal ions in LiMgBO 3 host [where Mg II has a trigonal bipyramidal (TBP) oxygen coordination]. We find that singlephase materials are formed for LiMg 1-x Co II x BO 3 (0 < x ≤ 1.0),

Exploring the Corundum Structure as a Host for Colored Compounds – Synthesis, Structures, and Optical Studies of (MM′)3TeO6 (M = Mg, Mn, Co, Ni, Zn; M′ = Mg, Mn, Co, Ni, Cu)

“…Of the many studies, the observations of the blue color in Mn 3+ ‐substituted YInO 3 and Co 2+ ‐substituted ZnMoO 4 as well as the different colors in copper‐substituted apatites and transition‐metal‐substituted MgTi 2 O 5 have shown much promise. Recently, we explored the distorted coordination geometries of transition elements in different hosts, which resulted in uniquely colored compounds . Continuing our efforts in this direction, we have now investigated the corundum‐related structure of the general formula (MM′) 3 TeO 6 (M = Mg, Mn, Co, Ni, Zn; M′ = Mg, Mn, Co, Ni, Cu).…”

Color Tuning in Garnet Oxides: The Role of Tetrahedral Coordination Geometry for 3 d Metal Ions and Ligand–Metal Charge Transfer (Band‐Gap Manipulation)

“…In the recent past, we explored distorted coordination geometries of the transition elements in many hosts and produced uniquelyc olored solids. [9][10][11] Many minerals have been known to form with bright colors, [1] and this is due to doping of transition elements of varying concentrations.O ft he many minerals, Garnet is important, forms in ac ubic symmetry (space group: Ia3 d), and has the general formula [A 3 ][B 2 ][C 3 ]O 12 ,i nw hich the A, B, andC cations are 8-(dodecahedron), 6-(octahedron), and 4-(tetrahedron) coordinate, respectively.W ell-known garnets include Y 3 Al 5 O 12 (YAG), Y 3 In 5 O 12 (YIG), and Y 3 Ga 5 O 12 (YGG), and they have been investigated as laser hosts over the years. [12] The coordination variability of the cations in the garnets tructure has been gainfully exploited by producing many interesting compounds.…”

“…There has also been interest to study the distorted geometries of transition elements, as they produce optical transitions that are different from those of the regular coordination geometries. In the recent past, we explored distorted coordination geometries of the transition elements in many hosts and produced uniquely colored solids …”

Developing Intense Blue and Magenta Colors in α‐LiZnBO3: The Role of 3d‐Metal Substitution and Coordination

“…[2,3] We recently reported the substitution of Co II andN i II ions into trigonal bipyramidal (TBP) Mg II sites of LiMgBO 3 ,w hich resulted in purple-blue and beige-red colors in the host. [10] The zinc analogueo fLiMgBO 3 is also well documented and has two polymorphicp hases:1 ) a-LiZnBO 3 (high-temperature phase), which is stabilized at approximately 810 8Ca nd has as tructure composed of ZnO 4 tetrahedra, LiO 5 TBPs, and BO 3 triangles [11] and 2) b-LiZnBO 3 (low-temperature phase), which is prepared by ah ydrothermalm ethoda nd has as tructure composed of LiO 5 and ZnO 5 TBPs and BO 3 triangles, similar to LiMgBO 3 . [12] Havinga lready investigated LiMgBO 3 ,w hich is iso-structural with b-LiZnBO 3 ,w en ow examine a-LiZnBO 3 (space group C2/c; a = 8.746, b = 5.091, c = 6.129 ; b = 118.758)a s ap ossible host in which the LiO 5 TBPs and ZnO 4 tetrahedra are distorted( Figure 1a nd Ta ble 1).…”