Search

In this work, the high-temperature crystallographic evolution of crystalline phases in a complex lithium disilicate glass was investigated using synchrotron X-ray powder diffraction. The lattice parameters and unit cell volume of Li2SiO3 (LS), Li2Si2O5 (LS2), Li3PO4 (LP), and ZrO2 as a function of temperature were determined upon heating. It is found that the lattice parameter c of LS2 shows a "V"-shaped trend during heating. The crystallographic evolution of the LS2 phase has a close correlation with the LS phase, indicating the mutual interaction between LS and LS2 phases along the c axis during the nucleation/crystallization process. The phase evolution processes were different upon heating and cooling, and the unit cell volume of both LS and LP phases demonstrated different change rates. In this glass system, no LS2 was detected during cooling and the main phases formed during cooling process were LP, LS, β-cristobalite, and β-quartz. Interestingly, there were two forms of β-quartz with slightly different lattice constants, and the silica phases showed a near-zero expansion behavior. The crystallographic evolution mechanism is discussed. [ABSTRACT FROM AUTHOR]

A series of new titanium(IV) complexes with symmetric or asymmetric cis-9,10-dihydrophenanthrenediamide ligands, cis-9,10-PhenH2(NR)2Ti(OiPr)2 [PhenH2 = 9,10-dihydrophenanthrene, R = 2,6-iPr2C6H3 (2a), 2,6-Et2C6H3 (2b), 2,6-Me2C6H3 (2c)], cis-9,10-PhenH2(NR1)(NR2)Ti(OiPr)2 [R1 = 2,6-iPr2C6H3, R2 = 2,6-Et2C6H3 (2d); R1 = 2,6-iPr2C6H3, R2 = 2,6-Me2C6H3 (2e)], and [cis-9,10-PhenH2(NR1)2][o-C6H4(CH-NR2)]TiOiPr [R1 = 2,6-iPr2C6H3, R2 = 2,6-Et2C6H3 (3a); R1 = 2,6-iPr2C6H3, 2,6-Me2C6H3 (3b)], have been synthesized from the reactions of TiCl2(OiPr)2 with o-C6H4(CH-NR)Li [R = 2,6-iPr2C6H3, 2,6-Et2C6H3, 2,6-Me2C6H3]. The symmetric complexes 2a—2c were obtained from the reactions of TiCl2(OiPr)2 with 2 equiv of the corresponding o-C6H4(CH-NR)Li followed by intramolecular C—C bond-forming reductive elimination and oxidative coupling processes, while the asymmetric complexes 2d—2e were formed from the reaction of TiCl2(OiPr)2 with two different types of o-C6H4(CH-NR)Li sequentially. The complexes 3a and 3b were also isolated from the reactions for complexes 2d and 2e. All complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structures of 2a, 2b, 2e, and 3a were determined by X-ray crystallography. [ABSTRACT FROM AUTHOR]