Citation: Zhang, Wenyao; Jin, Wenqi; Cheng, Meng; Zhang, Ruonan; Yang, Zhihua; Pan, Shilie (2021). From centrosymmetric to noncentrosymmetric: effect of the cation on the crystal structures and birefringence values of (NH4)n-2AE(PO2F2)n (AE = Mg, Sr and Ba; n = 2, 3 and 4).. Dalton transactions (Cambridge, England : 2003), 50, pp. 10206-10213.