Multilevel Tunnelling Systems and Fractal Clustering in the Low-Temperature Mixed Alkali-Silicate Glasses

Table 2

Extracted parameters for fits to the heat capacity data for SiO₂ and (SiO₂)_1−𝑥(K₂O)_𝑥 glasses, with 𝐷_min = 0.87 K and 𝑉₀ = −0.42 K as fixed.

Glass type	𝑥	𝐵ph×10^8	𝐵2LS×10^8	𝐵ATS×10^8	𝑥𝑗
	mol	Jm^−3 K^−4	Jm^−3 K^−2	Jm^−3 K^−4	ppm
SiO2	0	245.55	70.65	—	—
K-Si	0.05	260.92	155.23	22.77	29.86
K-Si	0.08	266.36	196.11	36.44	18.15
K-Si	0.10	269.46	221.62	45.55	10.54
K-Si	0.20	281.42	337.19	91.11	3.00