| 1. |
- Lv, Zhong-Peng, et al.
(författare)
-
Cation field-strength effects on ion irradiation-induced mechanical property changes of borosilicate glass structures
- 2023
-
Ingår i: Journal of The American Ceramic Society. - 0002-7820 .- 1551-2916. ; 106:10, s. 5766-5780
-
Tidskriftsartikel (refereegranskat)abstract
- We examine the impact of the glass network-modifier cation field strength (CFS) on ion irradiation-induced mechanical property changes in borosilicate (BS) glasses for the ternary M2O-B2O3-SiO2 systems with M = {Na, K, Rb} and the quaternary [0.5M((2))O-0.5Na(2)O]-B2O3-SiO2 systems with M = {Li, Na, K, Rb Mg, Ca, Sr, Ba}. B-11 nuclear magnetic resonance (NMR) experiments on the as-prepared BS glasses yielded the fractional population of four-coordinated B species (B-[4]) out of all {B-[3], B-[4]} groups in the glass network, along with the fraction of B-[4]-O-Si linkages out of all B-[4]-O-Si/B bonds. Both parameters correlated linearly with the (average) CFS of the M+ and/or {M(2)+, Na+} cations. Both the nanoindentation-derived hardness and Young's modulus values of the glasses reduced upon their irradiation by Si2+ ions, with the property deterioration decreasing linearly with increasing Mz+ CFS, that is, for higher Mz+center dot center dot center dot O interaction strength. The irradiation damage of the glass network also increased linearly with the fraction of B-[4]-O-Si linkages, which are the second weakest in the structure after the Mz+center dot center dot center dot O bonds. Our results underscore the advantages of employing BS glasses with high-CFS cations for enhancing the radiation resistance for nuclear waste storage.
|
|
| 2. |
- Lv, Zhong-Peng, et al.
(författare)
-
Impact of the cation field strength on physical properties and structures of alkali and alkaline-earth borosilicate glasses
- 2022
-
Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 48:13, s. 18094-18107
-
Tidskriftsartikel (refereegranskat)abstract
- The impact of the cation field strength (CFS) of the glass network-modifier cations on the structure and properties of borosilicate glasses (BS) were examined for a large ensemble of mixed-cation (R/2)M(2)O–(R/2)Na2O–B2O3–KSiO2 glasses with M+ ={Li+, Na+, K+, Rb+} and M2+ ={Mg2+, Ca2+, Sr2+, Ba2+} from four series of {K, R} combinations of K = n(SiO2)/n(B2O3) = {2.0, 4.0} and R =[n(M(2)O) + n(Na2O)]/n(B2O3) = {0.75, 2.1}. Combined with results from La3+ bearing glasses enabled the probing of physical-property variations across a wide CFS range, encompassing the glass transition temperature (Tg), density, molar volume and compactness, as well as the hardness (H) and Young's modulus (E). We discuss the inferred composition–structure/CFS–property relationships. Each of Tg, H, and E revealed a non-linear dependence against the CFS and a strong Tg/H correlation, where each property is maximized for the largest alkaline-earth metal cations, i.e., Sr2+ and Ba2+, along with the high-CFS La3+ species. The 11B MAS NMR-derived fractional BO4 populations decreased linearly with the average Mz+/Na+ CFS within both K–0.75 glass branches, whereas the NBO-rich K–2.1 glasses manifested more complex trends. Comparisons with results from RM2O–B2O3–KSiO2 glasses suggested no significant “mixed alkali effect”.
|
|
| 3. |
- Lv, Peng, et al.
(författare)
-
BO3/BO4 Intermixing in Borosilicate Glass Networks Probed by Double-Quantum 11B NMR : What Factors Govern BO4-BO4 Formation?
- 2023
-
Ingår i: The Journal of Physical Chemistry C. - 1932-7447 .- 1932-7455. ; 127:40, s. 20026-20040
-
Tidskriftsartikel (refereegranskat)abstract
- We examine the borate group intermixing in a series of 25 borosilicate (BS) glasses from the [0.5M(2)O–0.5Na2O]–B2O3–SiO2 systems with M = {Li, K, Rb, Mg, Ca} along with ternary K2O–B2O3–SiO2 and Na2O–B2O3–SiO2 glasses by double-quantum–single-quantum (2Q–1Q) 11B correlation nuclear magnetic resonance (NMR) experiments. The alterations of the fractional populations of B[3]–O–B[3], B[3]–O–B[4], and B[4]–O–B[4] linkages in the glass networks were monitored for variable nSi/nB molar ratios, nonbridging O contents of the glass, and the (average) cation field strength (CFS) of the Mz+/Na+ network modifiers. A significant B[4]–O–B[4] bonding is observed in all glasses, thereby conclusively demonstrating that the normally assumed “BO4–BO4 avoidance” is far from strict in BS glasses, regardless of the Mz+ field strength. We show that the degree of B[4]–O–B[4] bonding depends foremost on its underlying BO4 population and to a lesser degree on the NBO content of the glass; we also provide a straightforward prediction of the B[4]–O–B[4] population in an arbitrary BS glass from parameters readily obtained by routine 11B NMR. The propensity for forming B[4]–O–B[4] linkages increases concurrently with either the CFS or the amount of glass network modifiers, roughly scaling as the square root of the “effective CFS” that encompasses both parameters. Although BO3–BO3 and BO3–BO4 pairs remain favored throughout all examined BS glass networks, the borate group intermixing randomizes significantly for increasing effective CFS, out of which the amount and charge of the glass-network modifier cations dominate over their size. Our results are discussed in relation to the two prevailing but formally mutually exclusive “random network” and “superstructural unit” models of borate and BS glasses.
|
|
