1：Experimental Design and Method Selection:

Single crystals of tetramethylammonium cadmium chloride were grown by slow evaporation technique at room temperature.

2：Sample Selection and Data Sources:

High purity tetramethylammonium chloride and cadmium chloride in the ratio of 2:1 were used. Deionized water was used as a solvent.

3：List of Experimental Equipment and Materials:

Bruker AXS KAPPA APEX-2 diffractometer, Bruker AXS D8 Advance, PerkinElmer spectrum, Bruker RF S27, Varian Cary 5 UV–Vis–NIR spectrometer, SDT Q600 thermal analyzer, Leitz Wetzlar Vicker’s microhardness tester, HIOKI 3532 LCR HITESTER, JOBIN YVON FLUROLOG-3-11 spectro?uorometer, Lakeshore 7404 series.

4：Experimental Procedures and Operational Workflow:

The parent solution was stirred by a magnetic stirrer for 4 h and then ?ltered to obtain a homogeneous solution. The ?ltered solution was kept at room temperature for crystal growth.

5：Data Analysis Methods:

The presence of functional groups was determined by FTIR and FT Raman studies. The optical absorption studies were conducted using UV–Vis–NIR spectrometer. The thermal analysis was performed using TG/DTA. The mechanical measurements were taken using Vicker’s microhardness tester. The dielectric property was studied using LCR HITESTER. The magnetic property was studied using VSM.