Figure 2
Plot of the a parameter against x for a range of Mg–Al (circles) and Mg–Ga (triangles) layered double hydroxides (LDH) reported in the literature; the data for the Mg–Al LDH involve a variety of interlayer anions (i.e. OH−, CO32−, NO3−, Cl−) and are from: Mg–Al: Bellotto et al., 1996 ; Bîrjega et al., 2005 ; Brindley & Kikkawa, 1979 ; Budhysutanto et al., 2011 ; Gastuche et al., 1967 ; Han et al., 1998 ; Jinesh et al., 2010 ; Kaneyoshi & Jones, 1999 ; Kukkadapu et al., 1997 ; Mascolo & Marino, 1980 ; Miyata, 1980 ; Pausch et al., 1986 ; Rao et al., 1998 ; Sato et al., 1988 ; Shen et al., 1994 ; Valente et al., 2011 ; Xu & Zeng, 2001 ; Yun & Pinnavaia, 1995 ; Mg–Ga: Bellotto et al., 1996 ; López-Salinas et al., 1997 . The full lines are the result of the linear regression analyses of both sets of data and the filled diamond represents the β polymorph of magnesium hydroxide (i.e. brucite). The dashed lines represent the values of a calculated from theory [using equation (15) in Richardson, 2013b ]. The open diamond can be taken to represent a theoretical α form of magnesium hydroxide (Richardson, 2013b ). The bold numbers correspond to the ordered distributions of M3+ ions in the octahedral layer that are illustrated in Fig. 1 ; the three compositions that are labelled `x' are explained in the text. |