1：Experimental Design and Method Selection:

The study used pulsed electron spin resonance (ESR) at X-band frequency (9.7 GHz) to measure T1 and T2 of SiV0 centers in diamond samples. The Orbach process model was employed to explain the temperature and orientation dependence of spin relaxation.

2：7 GHz) to measure T1 and T2 of SiV0 centers in diamond samples. The Orbach process model was employed to explain the temperature and orientation dependence of spin relaxation. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Two high-purity {110} diamonds were used: D1 (doped with boron and silicon during growth, annealed, with SiV0 concentration of 4 × 10^16 cm^-3) and D2 (doped with boron and implanted with silicon, with SiV0 concentration of 5.1 × 10^15 cm^-3). Data were collected from ESR spectra and time-resolved measurements.

3：1 × 10^15 cm^-3). Data were collected from ESR spectra and time-resolved measurements. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment includes a Bruker Elexsys 580 system with a 1.4-T electromagnet, dielectric resonator (Bruker MD5), vector microwave source (Agilent E8267D), cryostat (Oxford CF935), laser (532 nm), amplifiers, switches, and digitizing boards. Materials include diamond samples with specific dopants and isotopes.

4：4-T electromagnet, dielectric resonator (Bruker MD5), vector microwave source (Agilent E8267D), cryostat (Oxford CF935), laser (532 nm), amplifiers, switches, and digitizing boards. Materials include diamond samples with specific dopants and isotopes. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: T1 was measured using a three-pulse inversion recovery sequence, and T2 was measured using a two-pulse Hahn echo sequence with optical spin polarization. The magnetic field orientation was varied, and temperature was controlled from 5 K to higher temperatures.

5：Data Analysis Methods:

Data were fitted using Arrhenius plots and rate equations for the Orbach process. Numerical simulations were performed for dipolar interactions and spin relaxation models.