Two potential self-activated orthoborates Cd4NdO(BO3)3 and Ca3Nd3(BO3)5: growth, crystal structures and optical properties

Abstract

Two neodymium orthoborate crystals of Cd₄NdO(BO₃)₃ and Ca₃Nd₃(BO₃)₅ were successfully grown using the flux method. Single crystal X-ray diffraction exhibits that Cd₄NdO(BO₃)₃ crystallizes in the monoclinic space group of Cm with unit cell parameters a = 8.0536(14) Å, b = 15.872(2) Å, c = 3.5364(6) Å, β = 100.268(7)° and Ca₃Nd₃(BO₃)₅ has a hexagonal space group of P6₃mc with cell parameters a = 10.4864(2) Å, c = 6.2665(1) Å. Both compounds have high Nd³⁺ concentration with 4.5 × 10²¹ ions per cm³ in Cd₄NdO(BO₃)₃ and 1.0 × 10²² ions per cm³ in Ca₃Nd₃(BO₃)₅, respectively. The absorption and emission spectra as well as decay curves for the ⁴F_3/2 to ⁴I_11/2 transition of Nd³⁺ ions in the two compounds were measured at room temperature. The spectra indicate that both two crystals are potential materials as self-activated microchip laser media due to high Nd³⁺ contents.