Designer's Guide Results
The following is a list of materials, selected and ranked per your specification.

MaterialVolume Resistivity
Alumina 94%> 1014 ohm-cm
Alumina 99.5%> 1014 ohm-cm
Alumina 99.9%> 1014 ohm-cm
Boron Nitride> 1014 ohm-cm
Macor> 1014 ohm-cm
Sapphire> 1014 ohm-cm
Sialon> 1014 ohm-cm
Zirconia-PSZ> 1014 ohm-cm
Zerodur2 x 1013 ohm-cm
Silicon Nitride> 1013 ohm-cm
Zirconia Toughened Alumina (ZTA)> 1013 ohm-cm
Zirconia-TZP> 1013 ohm-cm
Reference Materials
Diamondn/a
Stainless Steeln/a
Tool Steeln/a

All properties values are at room temperature unless otherwise noted. Engineering data are representative, and are not intended as absolute nor warrantable. Data shown is blended from multiple sources and therefore illustrates the marketplace. The relative rankings are approximate and are based on representative values if the particular material has a range of values for a given property.

Wikipedia Definition(s) :  Volume Resistivity;

Check Different Properties

Please Note:  This Designers guide is compiled of materials currently machined by Insaco and a few others included for reference.