2.8. Low Field Nuclear Magnetic Resonance (LF-NMR)

A certain length of extruded LSGS was weighed and placed in a NMR tube. A low-field nuclear magnetic resonance (VTMR20-010V-1, Suzhou Newmai Analytical Instrument Co., Ltd., Suzhou, China) was used to measure moisture migration and distribution in the samples [25]. During the experiment, the transverse relaxation time (T₂) of the sample was measured by CPMG pulse sequence. The test parameters of CPMG sequence were set as follows: 90° pulse time (P1) was 7 μs; 180° pulse time (P2) was 14 μs; number of echoes (NECH) was 18,000; echo time was 0.8 ms; accumulation times were conducted 8 times; sampling point (TD) was 59,992; spectral width (SW) was 200 kHz; and sampling repetition time (TW) was 3000 ms. The instrument software was used to invert the obtained data and the T₂₁, T₂₂, and T₂₃ parameters were fitted. Three replications were made.