The Sign of the Trigonal Field Splitting of B-Site Ions in Spinel

Electron spin resonance experiments were performed at 9.5 to 9.7 and 23.08 Gc/sec and the spin Hamiltonian parameters were determined: ${}_{\mathrm{g\parallel }}{\text{=1.985±0.001,\hspace{0.17em}}}_{\mathrm{g\perp }}\text{=1.983±0.003}$ , and 2D=+1.83±0.004 cm⁻¹ (+55 Gc/sec). The g values and absolute value of 2D are in close agreement with those obtained earlier. The present value of 2D was obtained from the M = ½ to $\frac{3}{2}$ transition and the sign determined by the relative intensity change with temperature of the M = ½ to $\frac{3}{2}$ and M = −$\frac{3}{2}$ to −½ transitions (high magnetic field quantum numbers used). The positive sign obtained directly in this work contradicts the previous indirect determination which yielded a negative sign.